Epidemiology

Autism: Is There Really An Epidemic?

Robert F. Kennedy Jr has reported that there is an epidemic of autism. It is clear that autism is being diagnosed more frequently in the last 10 years, but does that represent an increase in the incidence of autism or better diagnosis? In this post I will review the literature about autism in order to give an evidence-based answer to that question.

Diagnostic Criteria Changes Over Time

There is an excellent paper describing how the criteria for diagnosing autism has changed over time: Update on diagnostic classification in autism. The following information is taken from that paper.

The diagnosis of autism was first described in 1943 by Kanner. Prior to that children with severe autism symptoms were diagnosed as “schizophrenia of childhood.” In 1944 Ausberger reported on a group of children who had similar symptoms to the children Kanner described, but they had no intellectual deficits.

It was not until 1980 that the diagnostic criteria for autistic disorder were included in the Diagnostic and Statistical Manual (DSM)-III). Core features were onset prior to 30 months of age, pervasive lack of responsiveness to others, gross deficiencies in language development, peculiar speech patterns, and bizarre responses to the environment, including resistance to change and fascination with objects. This led to a marked increase in the diagnosis of more severe autism. In 1987, DSM-III-R expanded the menu of symptoms supporting the diagnosis of autism, and formally separated core features into three domains of impairment in social interaction, communication, and restricted or repetitive behaviors.

The next significant change occurred in the DSM -IV in 1994 with the introduction of the diagnosis of Asperger’s disorder. Aspergers’s disorder included what used to be called high functioning autism (autism without intellectual disability). The addition of diagnostic criteria for less severe forms of autism led to another increase in the diagnosis of autism.

In the years since the introduction of the DSM-IV criteria, advances in genetics found that all of the autism disorders had a strong genetic component and that the different forms of autism-like illnesses probably were manifestations of the same condition. In 2013 in DSM V, all of the the autism like illnesses including Asperger’s syndrome were combined into something called autism spectrum disorder.

Subsequent research showed that autism could be diagnosed as early as 18 months of age. This led to the recommendation by the American Academy of Pediatrics that all children should be screened for autism at 18 and 24 months of age. This universal screening has resulted in finding many more cases of autism at an early age that would have been missed previously, or the diagnosis delayed.

Causes of Autism

Genetics is a causal factor in 60%-90% of Autism. Autism is also is associated with prematurity, older parents, low birth weight, air pollution, and perhaps other environmental factors. Autism is not associated with any vaccines or with thimersol. Multiple large well designed studies have found no association between any vaccine, multiple vaccines, and thimersol with autism.

Neurodiversity

An alternate way to view the autism spectrum is not as a disorder, but as an example of neurodiversity. In the neurodiversity perspective, there is natural variation in human brains and minds and there is no single “normal” way to think, learn or behave. Neurodiversity encompasses the wide range of neurological differences, including those often associated with conditions like autism, ADHD, and dyslexia. The neurodiversity paradigm views these differences as strengths and not deficits, promoting acceptance and inclusion of all individuals. Organizations of persons with autism like the Autism Self-Advocacy network promote autism as neurodiversity rather than the medical model of a disorder.

Bottom Line

It is clear that the increased sensitivity to diagnosing autism as well as the universal screening of children at 18 and 24 months has led to the increase in the diagnosis of autism from one in 150 in 2000 to one in 36 in 2020. There is no evidence that there is an epidemic of autism, but rather that diagnosis has improved tremendously. Children on the autism spectrum, even the ones with the severe form of the condition do much better when diagnosed early. There is no cure for autism (and the autism advocacy movement would say that no cure is needed), but the earlier it is diagnosed and interventions begun, the better the long term outcomes.

Inflammation: Pathway to Chronic Diseases

Inflammation is activation of the immune system in response to threat or injury to the body. Acute inflammation mobilizes the immune system to repair an injury or fight an infection. Once healing takes place the immune system goes back to baseline. Chronic inflammation, however, involves long term activation of the immune system caused by some ongoing stress to the body. More and more, researchers are beginning to show that chronic inflammation is the common pathway to many diseases. There are multiple causes of chronic inflammation. In this post I will write about the causes of chronic inflammation. I will also do a series of posts about the many diseases that chronic inflammation causes. These posts will be based on the structure of an excellent book: Inflamed – Deep Medicine and the Anatomy of Injustice. It is not easy to read because it is disturbing but I highly recommend it. I will also write about a test to measure chronic inflammation. I will write about things you can do to decrease chronic inflammation if you have it and how to prevent it if you don’t. There are many causes of chronic inflammation that have to do with the structure of our society. These are things an individual cannot control. These societal causes will take ongoing efforts by all of us to change some of the toxic structures of society.

The Process of Inflammation

The inflammatory process starts with damage or threat of damage to the body. That can be an infection, a wound, or perceived threat of such. The immune system mobilizes white blood cells called macrophages to the injured area or site of infection. The cells of the immune system also release a cascade of messenger molecules called cytokines that amplify inflammation. These include interleukin 1ß, interleukin- 6 and tumor necrosis factor -α. The liver also releases a protein called c-reactive protein. When the threat is neutralized the immune system helps the body start to heal by releasing anti-inflammatory cytokines including interleukin (IL)-1 receptor antagonist, IL-4, IL-10, IL-11, and IL-13.

In chronic inflammation the pro-inflammatory cytokines continue to predominate and the c-reactive protein continues to be elevated.

Causes of Chronic Inflammation

Causes an individual can do something about

  • Low levels of physical activity.
  • Having a BMI at or above 30 , especially when excess weight is deep within your belly (visceral fat). The best way to measure belly fat is to use a tape measure to measure your waist at the widest point. Increased belly fat is greater than 35 inches for women or greater than 40 inches for men
  • An imbalance of healthy and unhealthy bacteria in your intestine (dysbiosis). Dysbiosis can be caused by antibiotics and by eating foods low in soluble fiber.
  • Regularly eating foods that cause inflammation, especially highly processed foods, or foods high in sugar or salt
  • Inadequate sleep
  • Using tobacco products.
  • Regularly drinking too much alcohol
  • Periodontal disease (gum infection) and tooth decay
  • Perceived stress

Societal Causes

  • Experience of racism (structural or personal)
  • Poverty
  • Homelessness
  • Worry about debt
  • Work stress
  • Exposure to air pollution
  • Exposure to chemicals (pesticides and herbicides for farm workers, glyphosphate (RoundUp) for everyone, microplastics in our bloodstreams for everyone. Every day, we are surrounded by thousands of synthetic chemicals. They are in our food, clothes, tools, furniture, toys, cosmetics and medicines. We know the health effects of only a few of these).

Diseases caused by chronic inflammation

  • Cardiovascular Disease (coronary artery disease, heart attacks, congestive heart failure)
  • Strokes
  • Type 2 diabetes
  • Cancer (multiple types)
  • Inflammatory bowel disease (crohns disease, ulcerative colitis)
  • Rheumatoid Arthritis
  • Lupus and similar autoimmune diseases
  • Asthma
  • COPD
  • Pulmonary fibrosis
  • Depression

Tests to measure chronic inflammation

All of the inflammatory cytokines can be measured but those are expensive tests. A simple inexpensive test that measures inflammation, both acute and chronic is high sensitivity CRP. It will also be high with an acute infection or injury, but will return to normal after the infection or injury have resolved. If it remains elevated when you are not sick or injured it is a sign of chronic inflammation. It may be worth asking your doctor to order this test if you have any of the individual or societal risk factors for chronic inflammation. A normal hs-CRP is less than 0.55 mg/dl in men and less than 1.0 mg/dl in women. If your hs-CRP is high in the absence of acute infection or injury, that can serve as motivation to make lifestyle changes to decrease your chronic inflammation and put you in a population that has less risk of developing any of the diseases associated with chronic inflammation.

Anti-inflammatory lifestyle

  • Exercise regularly. The CDC recommends 30 minutes of moderate exercise (walking briskly) for 30 minutes at least 5 days a week.
  • Eat mostly unprocessed or minimally processed foods and avoid sugary drinks or foods with added sugar or high fructose corn syrup. Also include foods with high soluble fiber such as beans, carrots, sweet potatoes, nuts, berries and most fruits (not fruit juice). Organic foods, while more expensive, have no residual pesticides or herbicides. If you eat meat buy grass fed beef, and pasture raised chicken and pork. Eat more plant-based foods than meat.
  • Avoid taking antibiotics as much as possible
  • Sleep. Average at least 8 hours a night
  • Floss your teeth daily, brush twice a day and see your dentist every 6 months
  • If you don’t smoke, don’t start and if you do smoke quit.
  • It is better not to drink alcohol at all, but if you do limit it to 1 drink a day or less.
  • Learn meditation or self hypnosis to manage stress. There are good books and videos, but an in person course is best if it is available.
  • Drink only filtered water and not bottled water in plastic bottles
  • Gas stoves cause significant indoor air pollution. If possible switch to an electric stove. Induction type burners actually heat more quickly than gas. If you have to use a gas stove, be sure to turn the ventilator fan on and open a window if possible.

Bottom Line

Chronic inflammation is the common pathway for many chronic diseases. There are many individual strategies that reduce or prevent chronic inflammation. Many of these strategies are not possible for people with socioeconomic problems. The stress black people experience from structural and individual racism, homelessness or inadequate housing, anxiety over debt, exposure to environmental synthetic chemicals, and exposure to air pollution are societal problems that we all have a responsibility to address.

My next post will deal with chronic inflammation and cardiovascular disease.

Antivaxxers – What Motivates Them?

The scientific evidence is clear that vaccines, starting with the smallpox vaccine developed by Edward Jenner in 1796 have saved millions of lives. Mild adverse reactions such as fever, sore arm and fatigue are relatively common. Serious adverse reaction to any and all vaccines in use today are extremely rare, on the order of one in a million. These serious reactions are almost always severe allergic reactions that occur immediately and can be treated successfully.

Despite the overwhelming evidence of the safety and efficacy of vaccines, there have always been people who were opposed to vaccines starting with the smallpox vaccine in the 1790’s. Recently, perhaps due to the influence of social media, there are an increasing number of people who think that vaccines are harmful and refuse them for themselves and their children. These beliefs tend to be strongly held and not very amenable to change even when they are presented with the scientific evidence.

In this post I’m going to write about the reasons antivaxxers give for refusing vaccines and explore some possible reasons that it is so hard to change these erroneous beliefs.

Concerns about Safety of Vaccines

Autism

In 1998 Andrew Wakefield and twelve other authors authored a paper that was published in the New England Journal of Medicine suggesting that the MMR vaccine was associated with autism. The paper was eventually found to be based on fraudulent data and it was retracted. In the aftermath of the Wakefield article several large well designed studies showed no evidence of a connection between MMR or any other vaccine with autism. Nonetheless many people opposed to vaccines continue to site the discredited Wakefield paper.

Pertussis Vaccine

In the 1950’s there were some reports of children developing seizures after pertussis immunizations. An extensive review of these cases found no evidence that pertussis vaccine was the cause of the seizures. Because of public concern, the pertussis vaccine was reformulated so that it did not contain dead pertussis bacteria. This is now called acellular pertussis vaccine so that the combined diphtheria tetanus and acellular pertussis vaccine is abbreviated DTaP.

Thimerosal

In the 1960’s some people became concerned that some of the components of vaccines were toxic. The biggest concern was about a preservative called thimerosal, which contained a small amount of mercury. The vast majority of studies showed no evidence of any association between thimerosal exposure in vaccines and any adverse neurologic outcomes, but a few studies showed a slight association. Since 2001, no vaccines contain thimerosal.

Aluminum

Many vaccines contain a small amount of aluminum which serves to as an adjuvant, which means it increases the effectiveness of the vaccine. In large doses aluminum can cause neurological problems and autoimmune diseases. Some people have been concerned about the safety of aluminum in vaccines. Some people think Aluminum in vaccines causes autism. Aluminum is present in food and water in much higher doses than that present in vaccines. It is poorly absorbed and what is absorbed is quickly excreted in the urine.  An FDA analysis shows that the body burden of aluminum following injections of aluminum-containing vaccines never exceeds safe US regulatory thresholds based on orally ingested aluminum even for low birth-weight infants. As noted previously a possible link to autism has been disproved by several large well designed studies.

Formaldehyde

Some people have expressed concern that formaldehyde in vaccines is toxic for children. Formaldehyde has a long history of safe use in the manufacture of certain viral and bacterial vaccines. It is used to inactivate viruses so they don’t cause disease and to detoxify bacterial toxins, such as the toxin used to make diphtheria vaccine. Almost all the formaldehyde is removed in the manufacturing process, but tiny amounts can remain. The body actually makes more formaldehyde which it uses in DNA synthesis than the tiny amount that remains in vaccines.

Lack of Trust

Although all of these concerns about toxins in vaccines have been addressed or disproved, there are still some people who lack trust in the vaccine manufacturers, the medical system and the CDC whose Advisory Committee on Immunization Practices (ACIP) makes recommendations for vaccine administration. Because of this mistrust, no amount of evidence from these groups will convince these people that vaccines are safe.

Religious Objections to vaccines

Although no major religions are opposed to vaccines, certain religious groups refuse vaccination. One common religious objection is that certain vaccines are manufactured by growing virus in fetal fibroblast cells from an aborted fetus. These cells were originally obtained from two aborted fetuses in the 1960’s. The cells have been cultured since then, so it is not necessary to obtain any more cells from fetuses. The viruses are separated from the cells, so that vaccines contain no fetal tissue. The vaccines that are grown in fetal fibroblast cells are the live virus vaccines including measles, mumps, rubella, chicken pox, the Imovax vaccine for rabies and the Janssen vaccine for COVID-19.

Opposition to Mandates

Americans are overwhelmingly supportive of all vaccination mandates with support ranging from a high 90 percent of respondents for DTaP, polio, chickenpox, and MMR to a low of 68 percent for COVID-19. Support of the HPV vaccine is somewhat lower, but still more than 50%. A smaller number of people feel that they should not be forced to vaccinate themselves or their children through state mandates. Some of this group may be willing to receive vaccinations if they feel they have a choice.

Philosophical Objections

There is a group of people who see some benefit in having their children contract certain preventable diseases. Some parents believe that natural immunity is better for their children than is immunity acquired through vaccinations. Others express the belief that if their child contracts a preventable disease, it will be beneficial for the child in the long term, as it will help make the child’s immune system stronger as he grows into adulthood. Some parents believe that the diseases for which we vaccinate are not very prevalent so their children are at minimal risk of contracting these diseases. For this reason, they also believe that the possible negative side effects of vaccine administration outweigh the benefits of the vaccines. Many parents do not see the preventable diseases as serious or life-threatening and would prefer to not put extra chemicals into their children’s bodies. Other parents think if their children have healthy diets and lifestyles they are at a decreased risk of contracting preventable childhood diseases. They also are under the assumption that if they were to contract one of the diseases that it would be easily treatable. Although all of this sounds reasonable on the surface it is absolutely wrong. See the good reasons to administer vaccinations in one of the sections below.

Conspiracy Theorists

Some people have a worldview that it’s commonplace for groups of elites to conduct elaborate and sinister hoaxes on the public, and to do so in near-perfect secrecy. They think this is just how the world works, and to believe anything else is naïve. There is a very strong correlation’s between conspiracy thinking and vaccine resistance.

Beliefs about conspiracies are very difficult to change. Evidence presented against the conspiracy by health care professionals are seen as part of the conspiracy. Conspiracy beliefs about vaccines can include believing the pharmaceutical companies or the CDC are covering up adverse effects of vaccines including that they cause autism.

Desire for Additional Information

Some parents are concerned about what they have seen on social media about vaccines and just want more information from health professionals about the safety and reasons for vaccines. This type of vaccine hesitancy is the most amenable for change by providing honest and clear information about the safety of vaccines.

The Good Reasons to Give Recommended Vaccines

It is true that many (but not all) of the diseases preventable by vaccines were relatively mild in most children. Prior to vaccines, however, 30 per cent of children died before the age of 5 from infectious diseases that are treatable or preventable today. Parents today have never seen a child with diphtheria, whooping cough, or tetanus. These were diseases that killed children prior to the vaccines and they could recur if enough people refuse vaccines.

Polio

The polio virus attacks the nervous system in children. It was a feared disease in the late 19th and early 20th century. In an outbreak in the early 1950’s. Over 2000 people died and many children had permanent paralysis. Paralysis of the respiratory system led to many children being placed in external respirators called iron lungs. Epidemics tended to occur in the summer. Parents kept children away from public gatherings like swimming pools and movie theaters. On April 12, 1955 the Salk vaccine was introduced and mass immunizations began, often in schools. Cases dropped dramatically. Several years later the Sabin oral polio vaccine was introduced. It was so effective that polio was completely eradicated in the United States. Polio vaccine is therefore no longer recommended for children in the US. Pockets of polio virus infection remain in other parts of the world. The most recent cases were in Gaza during the Israeli invasion of Gaza. Emergency vaccination of children in Gaza were carried out and the disease was brought under control.

Measles

Although measles is a relatively mild disease for most children it can be very severe and cause death for some. Before the introduction of measles vaccine in 1963 and widespread vaccination, major epidemics occurred approximately every two to three years and caused an estimated 2.6 million deaths each year.

Mumps

Mumps prior to the mumps vaccine was very common and mild in most children. Complications of mumps include inflammation of the testes, ovaries and pancreas, hearing loss, meningitis, and encephalitis. These are more common in adults than in children. Mumps was one of the most common causes of aseptic meningitis and hearing loss in children in the United States prior to the introduction of the vaccine.

Rubella

Rubella (German measles) is a mild disease but if contracted by a pregnant mother can result in severe fetal deformities and sometimes still birth. The rubella vaccine prevents rubella infection.

Influenza

Influenza occurs in epidemics. One strain in 1918 caused a pandemic with millions of deaths. There are always deaths from influenza in unvaccinated people every year. Influenza vaccine is effective in preventing or reducing the severity of illness. The influenza virus develops new mutations easily, so the vaccine has to be changed every year. The flu season in the southern hemisphere occurs during our summer, so flu vaccines for the northern hemisphere are developed based on the strains found to be circulating in the southern hemisphere flu season. This process can cause some variation in the effectiveness of the flu vaccine from year to year, but it always offers some protection and reduces the severity of illness from influenza virus.

Haemophilus Influenza

Before the Haemophilus influenza vaccine, this bacteria was the leading cause of bacterial meningitis, joint infection and ear infection in children. This vaccine was introduced after I was already in practice. I treated one case of bacterial meningitis in a child and several joint infections caused by H-flu. After widespread vaccination, I never saw another case.

Varicella (Chicken Pox)

Varicella is a very infectious disease in childhood. There are a few people, especially young infants who have severe disease requiring hospitalization. In the 25 years before the varicella vaccine was available there were over 2000 deaths from varicella. Giving the vaccine at 12-15 months of age protects vulnerable infants, and older people with chronic disease.

Human Papilloma Virus

The human papilloma virus (HPV) , which is transmitted by sexual intercourse, causes cervical cancer in some infected women. The HPV vaccine, given to preadolescent girls and boys prevents 90 % of cervical cancer in women.

Respiratory Syncytial Virus (RSV)

Most children and adults with RSV have mild cold-like symptoms with cough. About 3 per cent of babies with RSV have severe disease and require hospitalization and sometimes have to be placed on a mechanical ventilator. Young infants are more at risk as well as older adults, especially those with chronic disease. There is a vaccine for both babies and adults that is very effective at preventing RSV.

Rotavirus

Rotavirus is a highly contagious virus that infects the lining of the intestines. Symptoms include: High fever, Severe and persistent vomiting, and Diarrhea. It can usually be treated at home, but can cause severe dehydration. Prior to the availability of the oral rotavirus vaccine rotavirus was a leading cause of severe diarrhea in infants and children. There were 70,000 hospitalizations a year for rotavirus and 20-60 deaths per year. The oral vaccine is very effective at preventing rotavirus infection.

Hepatitis b

Hepatitis b can be contacted through sexual intercourse or by contaminated needles. Unlike hepatitis C, there is no effective treatment for hepatitis b. Hepatitis b can cause cirrhosis of the liver as well as liver cancer. Initially the vaccine was given only to high risk people, but it turned out that we were really bad at identifying who was at risk. Hepatitis b vaccine is now given to all babies and it has essentially eliminated hepatitis b.

Pneumoccocus

Before the vaccine, every year pneumococcus caused about 700 cases of meningitis, 17,000 cases of bloodstream infections, 200 deaths and 5 million ear infections in children. The pneumococcus vaccine is very effective at preventing these infections.

Meningococcus

Meningococcus is a bacterium that can cause meningitis or blood stream infection (sepsis). When it occurs It can be treated with antibiotics if caught quickly enough but it progresses so rapidly that people are deathly ill by the time they make it to the doctor. There is now a vaccine to prevent meningococcus infection. It is recommended for all adolescents between ages 11 and 12.

Shingles

Shingles is a reactivation in adults of childhood infection with chicken pox. It is a painful blistering rash along the distribution of a nerve on one side of the body. It can occur on any part of the body. Some people have persistent pain long after the rash is gone. This is called post herpetic neuralgia. Two doses of the vaccine called Shingrix is 98% effective at protecting adults from developing shingles. It is recommended for all adults age 50 and over.

Bottom Line

People can be opposed to receiving vaccines for themselves or their children for many reasons. Some people who just want more information can often be convinced of the safety of vaccines and then agree to be vaccinated. Other reasons such as mistrust of medical and public health sources of information and conspiracy thinking are very resistant to change. Philosophical objections including the belief that getting childhood illnesses gives better immunity and the low risk of infection of vaccine preventable diseases obviates the need for vaccinations are also resistant to change. The diseases that current vaccines prevent, although often mild in most people all have caused hospitalizations and deaths in the period prior to vaccine availability. All current vaccines have been shown to be very safe and associated with only mild transient side effects. Serious reactions to vaccines are extremely rare (on the order of one in a million) and are almost all amenable to treatment.

Mosquito Borne Diseases: Risks, Prevention & Treatment

Diseases carried by mosquitos have been in the news recently. Dr. Fauci had West Nile virus, which is carried by mosquitos. Some parks in Massachusetts have started an evening curfew because of cases of Eastern Equine Encephalitis, another mosquito borne disease. Mosquito borne diseases are rare in the US, but worldwide, mosquitos are the deadliest animal in the world. Worldwide, mosquito borne diseases kill 2.7 million people a year, 90% of which occur in Africa. As climate change causes increased global warming we are likely to see an increase in mosquito borne diseases in the US. In this post I will catalog all the mosquito borne diseases, which species of mosquitos carry them, and what areas have the most risk. Only a few species of mosquitos transmit diseases, but that information is primarily useful for epidemiologists and public health specialists. When a mosquito bites you, you are not going to know what species it is!

West Nile Virus

West Nile Virus is the most common disease transmitted by mosquitos, primarily by mosquitos of the culex species. Mosquitos get infected from birds and birds can get infected from infected mosquitos, so the disease passes back and forth between birds and mosquitos. People who get infected with West Nile cannot transmit it back to mosquitos that bite them.

Symptoms

Most people infected with West Nile virus do not have any symptoms but about 1 in 5 people who are infected develop a fever, headache, weakness, muscle pain, or joint pain, gastrointestinal symptoms and a transient rash. The illness usually lasts a few days, but can last for weeks. About 1 out of 150 infected people develop serious illness that invades the brain and spinal cord. This is called neuroinvasive illness. Sometimes this is fatal and if a person survives it they are likely to have permanent disability.

Species of mosquitos that carry it

Culex especially culex tarsalis

Treatment

There is no treatment or vaccine, so avoiding mosquito bites is the only way to keep from getting it when it has been identified in your area. I will write about the ways to avoid mosquito bites near the end of this post.

Who is at risk?

Cases are primarily in the summer and fall. Cases of West Nile disease have been reported across the continental United States. The CDC keeps track of human cases and cases identified in dead birds. West Nile virus occurs in epidemics in some years with few cases in others. So far in 2024 in the US there have been 289 cases of people with non-neuroinvasive West Nile illness and 189 cases of the serious neuroinvasive disease. Since 80% of infected people have no symptoms, that means the number of people with non-neuroinvasive infection so far this year is likely 5 x 289 = 1445. That is still a tiny percentage of the entire US population. Here is a link to the CDC web page showing 2024 West Nile cases by state and by county: West Nile Current Year Data (20240. If you live in an area where West Nile virus has has been identified in birds or humans, then you are at some increased risk.

Eastern Equine Encephalitis

The virus is maintained in fresh water hardwood swamps by birds and a particular species of mosquito called Culiseta melanura. This mosquito almost exclusively bites birds, so is not a significant risk to humans. The problem comes when infected birds are bitten by other species of mosquitos that do bite humans. Those species can infect humans.

Symptoms

Fortunately this is a rare disease. Thirty per cent of people infected with this virus die. Those who survive often have serious neurological problems. Symptoms are  fever, headache, vomiting, diarrhea, seizures, behavioral changes, and drowsiness.

Species that transmit the disease to humans

Aedes, Coquillettidia, and Culex

Treatment

There is no vaccine or treatment for Eastern Equine Encephalitis. Avoiding mosquito bites is the only prevention. More about how to avoid mosquito bites later in this post.

Who is at risk?

Most cases are in the Eastern US. There have been only 4 cases so far this year according to the CDC data, but there was a death from a case just in the last few days in New Hampshire. The states that have recorded cases so far this year are Vermont, Massachusetts, New Jersey, Wisconsin and now New Hampshire. People who live in the northeast may need to be especially careful this year.

Cache Valley Virus

This virus is named for the Cache Valley in Utah where it was first recorded. It is very rare. Less than 10 cases have ever been reported. It has been reported in Illinois, Michigan, Missouri, New York, North Carolina, and Wisconsin. It is a severe disease.

Symptoms

Symptoms include stiff neck, confusion, loss of coordination, difficulty speaking, or seizures.

Species that transmit the disease

The virus has been found in several species (Anopheles, Culiseta, Coquillettidia). The main species that transmits the disease is not known.

Treatment

There is no vaccine or treatment. Avoiding mosquito bites is the only prevention. More about how to avoid mosquito bites later in this post.

Who is at risk?

This disease is so rare that there is no particular region of the US that is at risk. Mosquitos carrying the Cache Valley virus have been found in many additional locations in North America and in parts of Central America.

Jamestown Canyon Virus

The virus is maintained by mosquitos biting infected animals, mostly deer. Mosquitos cannot transmit disease from biting infected humans, so humans are considered a “dead end” host.

Symptoms

This is another relatively rare disease, but more frequent than Cache Valley Virus. Most infected people do not have symptoms, but a few people get severe neuroinvasive disease. The CDC counts only the severe cases, so the number of cases substantially underestimate the number of people infected. There are about 23 severe cases reported a year, mostly in the spring through fall. Symptoms include fever, fatigue and headache. Some people have respiratory symptoms such as cough, sore throat or runny nose. Symptoms of severe disease can include stiff neck, confusion, loss of coordination, difficulty speaking, or seizures. Death is rare from this disease.

Species that transmit the disease

Aedes, Culex, Coquillettidia

Treatment

There is no vaccine or treatment. Avoiding mosquito bites is the only prevention.

Who is at risk

Jamestown virus is found through most of the US, but Minnesota and Wisconsin have reported more than half of the cases. Again, there is no vaccine or treatment. Prevention is again the best option.

LaCrosse Virus

La Crosse virus circulates in the environment between tree hole breeding mosquitoes and small mammals, such as chipmunks or squirrels.

Symptoms

Most infected people do not have symptoms, but the disease can be severe especially in children under 16 years of age. Initial symptoms can include fever (usually lasting 2-3 days), headache, nausea, vomiting, fatigue , and lethargy. Symptoms of severe disease include high fever, headache, neck stiffness, stupor, disorientation, coma, seizures, muscle weakness, vision loss, numbness, and paralysis. Most patients recover but death from LaCrosse virus happens rarely.

Species that transmit the disease

 Eastern tree hole mosquito (Aedes triseriatus). The tree hole mosquito is found almost exclusively in wooded or shady areas, and usually does not fly more than 200 yards from the area where it developed.

Treatment

There is no vaccine or treatment Avoiding mosquito bites is the only prevention.

Who is at risk?

Most cases occur in the upper Midwestern, mid-Atlantic, and southeastern states. LaCrosse virus is a rare disease. So far in 2024 there have been 13 cases of LaCrosse disease reported from Tennessee, North Carolina and South Carolina.

St Louis Encephalitis

St Louis Encephalitis virus circulates in the environment between mosquitos and birds.

Symptoms

Most infected people do not have symptoms. Severe disease usually occurs in older or immunocompromised people. Symptoms are fever, headache, dizziness, nausea, and generalized weakness. People with severe disease can develop stiff neck, confusion, disorientation, dizziness, tremors, and unsteadiness. 5-20% of infected people die from this disease. The risk of dying increases with age.

Species that transmit the infection

Culex

Treatment

There is no vaccine or treatment. Avoiding mosquito bites is the only prevention.

Who is at risk

In recent years sporadic cases and outbreaks have occurred in the Southwest. This is a rare disease and there have been no cases reported in 2024. In some years there are outbreaks primarily in urban areas. Again there is no vaccine or treatment for St Louis Encephalitis.

Dengue

Unlike many of the diseases discussed previously, Dengue virus circulates between humans and mosquitos. Mosquitos who bite infected people then spread the virus by biting other people. People can get Dengue multiple times.

Symptoms

Most infected people have no symptoms but 1 in 4 have symptoms which include Fever and bone and muscle pain. The pain can be severe. Dengue is also known as “break bone fever.” About 1 in 10 people who get sick have severe Dengue. Severe Dengue can result in shock, internal bleeding, and death. People with Dengue who have any of the following symptoms should go immediately to a hospital emergency department: belly pain or tenderness; vomiting; bleeding from the nose or gums; vomiting blood or blood in the stool.

Species that transmit the infection

Aedes.aegypti and Aedes.albopictus

Treatment

There is a vaccine for Dengue but it is only recommended for children who have already had one episode of Dengue. It is not available in the US. The only treatment is hospitalization and supportive care for severe illness.

Who is at risk?

Most Dengue in the US is in travelers from endemic areas. Endemic areas include the Caribbean, Central America, South America, Southeast Asia and the Pacific Islands. Many of these are popular tourist destinations, so the biggest risk for US citizens is travel to one of these regions. There have been some local outbreaks of Dengue in the US in Florida, Hawaii, Texas, Arizona, and California.

Treatment

Once again, other than the vaccine for children who have already had Dengue, treatment is supportive hospital care for people with severe Dengue. Travelers to endemic Dengue areas should use mosquito bite preventive measures, discussed further later in this post.

Chikungunya

Chikungunya virus, like Dengue, circulates in mosquitos and humans. Mosquitos become infected by biting a person with chikungunya virus and then spread the virus by biting other humans.

Symptoms

The most common symptoms are fever and joint pain and can include headache, muscle pain, joint swelling, or rash. Most patients feel better within a week, but joint pain can be severe and disabling and might persist for months. Death from chikungunya virus is rare.

Species that transmit the disease

Aedes.Stegomyia, Aedes.aegypti and Aedes.albopictus

Treatment

There is a vaccine for chikungunya. Travelers traveling to endemic areas may want to consider vaccination. There is no specific treatment. Avoiding mosquito bites is the only prevention.

Who is at risk?

There have been no cases of chikungunya in the US and US territories since 2019. Travelers to endemic areas are at risk. Endemic areas include Africa, the Americas, Asia, Europe, and islands in the Indian and Pacific Oceans. Travelers should check with the CDC travel website to see if outbreaks are occurring at their destinations.

Zika Virus

Like Dengue and chikungunya, Zika circulates between mosquitos and humans. If a mosquito bites a person infected with Zika virus in the first week of infection, the mosquito carries Zika to the next person it bites. Zika can also be transmitted through sex and can be transmitted from a pregnant mother to her fetus. Zika can cause severe birth defects when a pregnant mother is infected.

Symptoms

Most infected people have no symptoms, and when symptoms occur they tend to be mild. They include fever, rash, headache, joint pain, conjunctivitis (red eyes) and muscle pain. Symptoms are rarely severe enough to need hospitalization. The biggest problem with Zika is the birth defects caused by infection of pregnant women.

Species that transmit the disease

Aedes. aegypti and Aedes. albopictus

Treatment

There is no vaccine or treatment for Zika virus.

Who is at risk?

There have been no local cases of Zika in the US or US territories since 2019. People most at risk are travelers to countries that have outbreaks. Outbreaks occur in Mexico and South America and in certain countries in Africa and India. Other countries including the US have the Aedes species that can transmit Zika. Travelers to these areas should check with the CDC about current Zika outbreaks.

Yellow Fever

Yellow fever virus is maintained in forests between mosquitos and monkeys. People who work in forests where monkeys live can contract the virus this way. Mosquitos biting infected people can also spread the virus when mosquitos bite other people. Epidemics in urban areas occur this way.

Symptoms

Most people infected with yellow fever virus will either have no symptoms or mild symptoms and completely recover. Symptoms can include sudden onset of fever, chills, severe headache, back pain, general body aches, nausea, vomiting, fatigue, and weakness. Most people who develop symptoms improve within one week. A few people will develop a more severe form of the disease. Severe symptoms include high fever, yellow skin or eyes (jaundice), bleeding, shock, and organ failure. Among those who develop severe disease, 30-60% die

Species that transmit the disease

Primarily Aedes Aegypti

Treatment

There is an effective vaccine for prevention of yellow fever. Travelers going to an endemic yellow fever region should receive the vaccine before they travel. There is no treatment once someone has yellow fever.

Who is at risk?

There is no local transmission of yellow fever in the US. Yellow fever in travelers only rarely occurs. Yellow fever is endemic in Africa and South America.

Malaria

Malaria is caused by a parasite that resides in the liver and then infects red blood cells. It is maintained by circulation between mosquitos and humans. Mosquitos get infected from biting humans with malaria and then can transmit the parasite by biting other humans.

Symptoms

Malaria symptoms range from very mild illness to severe disease and even death. Early symptoms can include: Fever and flu-like illness, Chills, Headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur. If not treated quickly, the infection can become severe. Severe symptoms can include kidney failure, seizures, mental confusion, coma and death.

Species that transmit the disease

Anopheles

Treatment

Malaria can be treated successfully with several different drugs depending on the type and resistance. There are drugs that travelers can take if they are traveling to an area where malaria is present that will prevent infection. The newest development is a malaria vaccine that can be given to children in endemic malaria regions.

Who is at risk?

There is virtually no local transmission of malaria in the US in modern times. In a typical year, the U.S. reports about 2,000 cases of malaria, almost all of which are in travelers who have been to an endemic region. Malaria occurs only in tropical regions and below 6,500 feet above sea level. Most cases of malaria occur in sub-Saharan Africa, but it also occurs in parts of Oceania (such as Papua New Guinea) and in parts of Central and South America and Southeast Asia. Worldwide, malaria has caused 608,000 deaths in the past year. Malaria is one of the world’s most severe public health problems, with nearly half of the world’s population at risk for infection.

How to prevent mosquito bites.

Indoors

Make sure all windows have screens and any holes in the screens are patched. Use air conditioning if you have it during the spring and summer when mosquitos are most active.

Outdoors

Mosquitos lay eggs in standing water. Remove or empty any receptacles outside that allow water to pool such as saucers under flower pots. Tightly cover any water storage containers. If you have a birdbath, use a battery or solar powered agitator. Mosquitos only lay eggs in still water.

Residential outdoor misting systems that use permethrin provide good mosquito control and are safe for humans, birds and animals. They are somewhat expensive, however.

Use an EPA-registered insect repellant with one of the following ingredients:

  • DEET (Has been shown to be non-toxic for humans and repels but does not kill insects)
  • Picaridin (known as KBR 3023 and icaridin outside the United States)
  • IR3535
  • Oil of lemon eucalyptus (OLE)—A plant-derived ingredient (must be applied more frequently than DEET)
  • Para-menthane-diol (PMD)
  • 2-undecanone—A plant-derived ingredient

Wear loose long sleeved shirts and long pants when outside when mosquitos are active

Treat items such as boots, pants, socks, and tents with permethrin or buy permethrin-treated clothing and gear.

Bottom Line

Mosquitos transmit many diseases, but all of these are quite rare in the US. Global warming may well increase mosquito transmitted diseases in the US in the future. The vast majority of mosquito bites in the US are just a nuisance and do not transmit disease. In other parts of the world mosquito disease transmission is a major public health problem. Travelers to areas where mosquito borne diseases are prevalent should use mosquito bite prevention strategies, especially EPA-approved insect repellents. Travelers to areas endemic for yellow fever should be vaccinated prior to travel. Travelers to malaria prevalent regions should start preventive medicine 1 week before and continue 1 week after travel.

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Diet and Heart Disease – Not as Simple as We Thought

We have all been told for years that the main dietary risk factor for heart disease and stroke is how much saturated fat we eat. We have also been told that eating foods high in cholesterol also increases risk of heart disease and stroke. Evidence is accumulating that consumption of saturated fat increases risk of heart disease and stroke little if at all. Since your body makes cholesterol itself, eating cholesterol rich foods has almost no effect on serum cholesterol. Other aspects of diet have a much greater effect on increasing the risk of heart disease and stroke. In this post I will summarize the evidence and spend some time discussing things we eat and drink that do substantially increase the risk of heart disease, stroke and other chronic diseases.

The Seven Country Study

The most famous study that led to the saturated fat hypothesis was carried out by Ancel Keys. The study started in 1956 and was published in 1978. He looked at the dietary patterns of 7 different countries. The countries included Finland, Greece, US, Italy, Yugoslavia, Netherlands and Japan. He found that saturated fat intake was correlated with increased risk of heart attack and stroke. The country with the lowest saturated fat intake was Crete in Italy, which also had the lowest incidence of heart disease and stroke of the 7 countries. The diet of Crete is the basis for the famous Mediterranean Diet.

Diets of free living humans are notoriously difficult to measure. Keys did his best to accurately determine diet. He had a subset of his subjects in each country weigh their food for a number of days, which is considered the gold standard for dietary studies. The problem with any population study like this is that populations in different countries differ in lots of other ways besides diet. Also diets are complex, so some other factor or factors in diet could account for the low heart disease incidence in Crete. Another problem was that diet was measured in Crete during Lent, when most people did not eat meat. All Keys could really say was that saturated fat intake was associated with heart disease, but he could not say that saturated fat caused heart disease.

People who adhered to the Mediterranean Diet did reduce their population risk of heart disease, but there is a lot more to the Mediterranean Diet than reduced saturated fats. It also includes little added sugar, lots of vegetables and fruit and mostly unprocessed foods. It is not clear that reduction in saturated fat is responsible for the health benefits of the Mediterranean Diet.

The Framingham Study

The next big population study was the Framingham Study. A large group of people in Framingham Massachusetts was followed over many years with surveys about diet, activity, smoking and laboratory measurements of total cholesterol, LDL, HDL and triglyerides among other measurements. Heart attacks, strokes, death from either of these things and death from any cause were recorded in the study group. This was the first large study that implicated cigarette smoking as a cause of cardiovascular disease and cancer. It was also found that the higher the total cholesterol and especially the higher the LDL (low density lipoprotein) the higher the risk of cardiovascular disease. It was also one of the first studies that showed that the higher the blood pressure, the greater the risk of cardiovascular disease. This was a tremendously important and well done study.

The Diet-Heart Hypothesis

The diet-heart hypothesis is that saturated fat is the main dietary cause of cardiovascular disease. It has been very influential over 60 years and is still promoted by the American Heart Association and many cardiologists. Here is the train of thought. The 7 country study implicated saturated fat as associated with cardiovascular disease. It has been found through multiple studies that saturated fat intake raises LDL (so called bad cholesterol). The Framingham study showed that increased LDL was a major risk factor for cardiovascular disease. Since saturated fat raises LDL, therefore saturated fat must cause cardiovascular disease.

That makes perfect sense, so many randomized trials were carried out to nail down the diet-heart hypothesis. Unfortunately, as is often the case with beautiful theories, further randomized trials did not consistently show the expected increase in heart disease from eating saturated fat. The other part of the hypothesis was that eating polyunsaturated fats would decrease the population risk of heart disease. That was based on the observation that consuming polyunsaturated fats decreased LDL levels. Randomized trials have generally failed to consistently show that eating polyunsaturated fats reduces the risk of cardiovascular disease.

Reduced Risk of Cardiovascular Disease in US

Heart disease was epidemic in the US, peaking in the 60’s. Since then, the incidence of heart disease in the US and most other developed countries has decreased by 60%! Scientists debate the cause for this decline. Although saturated fat consumption decreased some, Americans still eat much more saturated fat than the 5% of fat recommended by the American Heart Association. So the fact that we eat somewhat less saturated fat does not explain the remarkable decline in heart disease over the last 60 years. What else changed?

Cigarette Smoking

In the 1940’s half of all Americans said they smoked cigarettes. Smoking began to decline in the US in the 60’s and today only 11.5% of Americans smoke tobacco! This has to be a major factor in the decline of cardiovascular disease (and lung cancer).

High Blood Pressure

High blood pressure is a major risk factor for heart disease. The number of people with high blood pressure successfully controlled on medicine has more than doubled since 1960. This is clearly another major factor in the decline of cardiovascular disease

Trans Fats

The rise of trans fat consumption was an unintended consequence of the heart-diet hypothesis. Because animal fat (mostly saturated fat) was postulated to cause heart disease, the food industry started figuring out how to use vegetable oil to replace lard and butter, which were high in saturated fats. They needed something that would be solid, not liquid at room temperature. They discovered that if they partially hydrogenated vegetable oil, then it would be solid at room temperature and could substitute for lard and butter. They marketed these products as healthier because they were only partially saturated fats, not saturated fats. The medical establishment bought this story and recommended margarine as a substitute for butter and Crisco (the most successfully marketed shortening substitute) as healthier alternatives. I have been unable to find statistics on trans fat consumption in the US, but it was very large.

It turns out that consumption of trans fats markedly increased the risk of cardiovascular disease. For every 2% increase in the consumption of trans fats, heart disease increased by 23%. This is a shocking number! The consumption of trans fats certainly contributed to the epidemic of heart disease in the 50’s and 60’s. The FDA essentially banned the addition of trans fats to food in June of 1978. The elimination of trans fats is almost certainly another major factor in the decline of heart disease.

Interesterification

Since trans fats have been banned, food companies have come up with a new way to make vegetable oil solid and spreadable. It is called interesterification. It is complicated, but the simplest explanation is that it involves changing the arrangement of fatty acids on a glycerol backbone. These are fully hydrogenated fats, so are not trans fats. We know very little about how these new industrial fats affect human health, but the information we do have suggests that these new products may be just as bad for you as trans fats. You would do best to avoid them until we know more. More about how to do this later in this post.

Do we need to limit red meat consumption?

The main risk of consumption of any food is eating too much of it. It is total calorie intake that makes us fat, and being fat increases the risk of cardiovascular disease, diabetes and some cancers. Eating red meat by itself is very unlikely to increase your risk of heart disease as long as your total calorie intake is equal to the calories you burn up. So there is very little health risk to you in eating red meat, but there is a big risk to the environment. Cattle raising worldwide contributes about 16% of greenhouse gas emissions. Here is a link to a balanced discussion of greenhouse gas emissions from cattle raising: Livestock Don’t Contribute 14.5% of Global Greenhouse Gas Emissions.

The other thing to think about when consuming any meat product, including chicken is that almost all the meat you buy in the grocery store comes from giant factory farms, where animals are treated very inhumanely. That in itself is bad enough, but raising all those animals together increases risk of spreading disease to the people who eat them. Antibiotics are used in many factory farms to keep animals from getting sick. This contributes to the evolution of bacteria that are resistant to most antibiotics.

If you are not willing to give up eating meat entirely, try to find locally raised beef, pork and poultry. Farmer’s Markets are a good place to find meat from locally raised animals. It may be a little more expensive, but likely a lot safer.

What about eating fish?

If you are at high risk of cardiovascular disease or have cardiovascular disease then eating oily fish (salmon, sardines, anchovies, herring, mackerel, tuna, swordfish) twice a week reduces your risk of a heart attack by 50%. If you are at average risk, these fish don’t have unusual health benefits but if you like them, it’s fine to eat them. Because most of these fish contain some mercury they should probably be avoided by pregnant women and children. If you get canned tuna, get Pacific Island Tuna at Walmart. It is sustainably caught. Here is a link to an article from the Nature Conservancy about it: The Nature Conservancy. By the way taking fish oil is not nearly as good for you as eating fish.

Highly Processed Foods

There are convincing data that consumption of lots of highly processed foods leads to health concerns ranging from increased risk of obesity, high blood pressure, breast and colorectal cancer, to dying prematurely from all causes.These foods all also contain additives whose health effects have never been adequately tested. How do you recognize them? Just look at the label where the ingredients are listed. If there are more than two things you don’t recognize, put it back on the shelf. Here is an example of an ingredients list from a loaf of bread!

This is not bread you would want to eat! If you mostly stay out of the central aisles of the grocery store you will avoid most highly processed foods. Just be sure to look at the ingredients label before you buy anything.

It is all well and good for me to make these recommendations, but highly processed foods and factory farmed meat are cheap. People who are poor cannot afford to buy anything else. This is only one of the things that have led to the major health inequities that are present in this richest country in the world.

Foods that decrease risk of cardiovascular disease

Fiber

Increased dietary fiber has been shown to decrease risk of cardiovascular disease. This may well have to do with promoting a healthy microbiome in the intestine. Sources of fiber that promote growth of healthy gut bacteria are ones that contain inulin. The highest sources of inulin are leeks, asparagus, onions, wheat, garlic, chicory, oats, soybeans, and Jerusalem artichoke. Sourdough bread (no added sugar, honey, or high fructose corn syrup) is also a good source of fiber. Whole grains, fruits, nuts and vegetables are also good sources of fiber.

Fresh Fruits

Fresh fruits are a good source of fiber and also contain many beneficial nutrients including vitamins and antioxidants. Data from multiple studies show that eating fresh fruit daily reduces risk of cardiovascular disease.

Nuts

Eating a handful of nuts per day reduces your risk of heart disease by 20%. Peanuts are technically of legume, not a nut, but legumes reduce the risk of cardiovascular disease as well. Unsalted nuts are better for you than salted.

Whole grains

Whole grains are also a good source of fiber and other beneficial nutrients. Eating whole grains most days is associated with decreased obesity, diabetes and heart disease. Examples of whole grains are

  • Barley.
  • Bulgur, also called cracked wheat.
  • Farro.
  • Millet.
  • Quinoa.
  • Black rice.
  • Brown rice.
  • Red rice.
  • Wild rice.
  • Oatmeal.
  • Popcorn.
  • Whole-wheat flour.
  • Whole-grain breakfast cereals.
  • Whole-wheat bread, pasta or crackers.

Make sure to read the ingredients label for cereals and crackers. Don’t buy anything that has more than two ingredients you don’t recognize.

Fresh Vegetables

Fresh vegetables are also a good source of fiber. Sorry folks, but potato chips and french fries do not count as fresh vegetables! Once again eating fresh vegetables daily significantly lowers your risk of cardiovascular disease.

Bottom Line

Eating red meat and saturated fats does very little to increase your risk of heart disease, but it also does not reduce your risk. Raising livestock on factory farms causes significant harm to the environment and puts people at risk of infectious disease. Eating meat from locally raised animals is safer.

Eating high fiber foods, whole grains, nuts, fruits and vegetable does substantially reduce your risk of cardiovascular disease as well as cancer.

Eating highly processed foods, and this includes the new industrial fats made by interesterfication increases your risk of cardiovascular disease and cancer. The biggest risk of these is probably because they encourage people to eat more calories than they need and have almost certainly led to the epidemic of obesity.

The most concise recommendation for a healthy diet comes from author Michael Poulin: “Eat food (food is anything your grandmother would have recognized as food), mostly plants, not too much.”

Chronic Stress Response: It Can Make You Sick or Kill You

All mammals, including humans have an innate response to perceived threat or stress. The more common name for it is the “flight or fight” response. Our remote ancestors faced many real threats. Let’s say for example one encountered a saber tooth tiger. As soon as he (or she) saw the tiger, several things happened. Epinephrine and norepinephrine were released, speeding up the heart rate in preparation for running away. A surge of cortisol was also released, which increased glucose in the bloodstream for fuel for muscles and the brain. Cortisol also increases mental alertness. Inflammatory molecules were released to promote wound healing should that be needed.

This kind of acute stress response is a good thing. People or animals with this kind of response were more likely to survive and reproduce. Once the acute threat was over, all the hormones and neurotransmitters quickly returned to their baseline levels.

In today’s world, threats from predators are not a problem for the vast majority of people. The threats we perceive are things like poor work conditions; experiencing discrimination, hate, or abuse; poverty; homelessness; divorce or other family discord; having little control over outcomes; feeling overwhelmed.

These are all things that produce the stress response, but unlike our remote ancestors, these threats are chronic. They are either lifelong or at least last a long time. Instead of returning to normal, the stress hormones and neurotransmitters stay elevated for long periods of time. A chronic stress response is definitely not a good thing!

Allostatic Load

The medical term for the acute stress response is called allostasis. Here is the definition of allostasis from Wikipedia: “Allostasis is the efficient regulation required to prepare the body to satisfy its needs before they arise by budgeting those needed resources such as oxygen, insulin etc., as opposed to homeostasis, in which the goal is a steady state.” Allostasis is an adaptive response to acute stress. Allostatic load on the other hand is the long-term result of failed allostasis, resulting in dysregulation (abnormal function) of multiple systems including the neuroendocrine, cardiovascular, immune, and metabolic systems.

Allostatic load is measured traditionally by 10 indicators of chronic stress. Primary indicators are the hormones and neurotransmitters released by stress. Secondary outcomes are measurements of the systemic effects of the primary indicators. All of these indicators are associated with the perception of stress. Below is a table showing the 10 indicators, how they are measured, and which body systems are affected. Here is a link to the full article from which this table comes: Allostatic Load: Importance, Markers, and Score Determination in Minority and Disparity Populations

CategoryMarkerFunctional purpose
Primary mediatorsDehydroepiandrosterone sulfate (DHEA), serumSecreted by the adrenal glands. When high with stress it tends to lower cortisol and be protective in the stress response.
Cortisol, urinaryIntegrated measure of 12-hour hypothalamic–pituitary–adrenal axis activity. Secreted by the adrenal glands. Has multiple effects in stress response.
Epinephrine, urinaryIntegrated indices of 12-hour sympathetic nervous system activity. Sympathetic nervous system activation increases heart rate and blood pressure.
Norepinephrine, urinary
Secondary outcomesSystolic blood pressureIndices of cardiovascular activity and major risk factor for vascular disease
Diastolic blood pressure
Waist–hip ratioIndex of long-term levels of metabolism and adipose (fat) tissue deposition. High value means fat around internal organs which increases inflammation and increases LDL (bad cholesterol) and triglycerides.
High-density lipoprotein cholesterolIndex of atherosclerotic risk protection. Low value increases risk of heart disease.
Total cholesterolIndex of long-term atherosclerotic risk
Hemoglobin A1CIntegrated measure of high blood sugar over 2–3 months

Each indicator that is a certain distance out of the normal range counts as one point. The score can range from zero to ten. The higher the score, the greater the risk of illness or death.

Other Indicators

Although the ten indicators were the ones described in the original papers about allostatic load, other indicators have been used as well.

  • Heart rate variability is the normal beat to beat variability in the heart rate. In a healthy heart there is slight variation in the timing of one heartbeat to the next. Chronic stress reduces or even eliminates this beat to beat variation.
  • High sensitivity C-reactive protein (CRP). This is a measure of systemic inflammation that can result from chronic stress.

How is the stress reaction triggered?

The stress reaction begins in the brain. Something in the environment is perceived in a part of the front of the brain called the prefrontal cortex. This is the executive decision maker in the brain. If the prefrontal cortex perceives something in the environment as a threat, then it sends messages to the limbic system (the part of the brain that is involved with emotions). It also sends messages to centers lower in the brain, especially the hypothalamus. The hypothalamus sends messages to the adrenal glands which secrete cortisone, norepinephrine and epinephrine. The hypothalamus secretes DHEA. Messages from the hypothalamus are also sent to the white blood cells which secrete inflammatory chemicals called cytokines. All of this prepares the body to deal with the perceived threat. Different people may perceive different things as a threat. It is the reaction to perceived threats that causes allostatic load. If another person experiences the same thing in the environment as not a threat, then there is no stress reaction.

Diseases associated with high allostatic load (high chronic stress)

A high allostatic load score is not disease in itself, but if chronic stress continues then disease in the cardiac, metabolic, neuroendocrine and immune system can occur. Here is a list of diseases associated with persistent high allostatic load.

  1. Heart disease, primarily progressive blockage of the coronary arteries. This can lead to angina and/or heart attack. Congestive heart failure and arrhythmia like atrial fibrillation can also occur
  2. Peripheral arterial disease. That is blockage in arteries in the legs and sometime fingers.
  3. High blood pressure
  4. Stroke
  5. Autoimmune diseases like rheumatoid arthritis or lupus
  6. Diabetes
  7. Fibromyalgia
  8. Chronic Fatigue Syndrome
  9. Dementia or decreased cognitive function
  10. Depression
  11. PTSD
  12. Cancer, particularly breast and ovarian cancer. The increase in cancer is probably related to decreased immune system function

Allostatic Load and Mortality

Many studies have shown that people with persistently hight allostatic load have about a 25% higher premature death rate than people with low allostatic load.

Disparities in Health Outcomes

The response to chronic stress (allostatic load) may explain some of the disparities we see in health outcomes. We know, for example that Adverse Childhood Events (ACE), which include things like abandonment and abuse, increase the risk of many chronic diseases in adulthood. Studies have shown that adults with a history of ACE have high allostatic load scores.

African Americans have higher incidence of many cancers, as well as poorer outcomes from those cancers. They also have worse outcomes from heart disease, high blood pressure and diabetes. While a good portion of these poorer outcomes are related to lack of access to health care, these disparities persist to some degree even in middle class and upper middle class African Americans. Almost all African Americans have experienced or still experience racism on a chronic basis. African Americans of all social classes have higher allostatic load scores than caucasians. Chronic stress and response to it may be the common denominator for these disparities as well as for health outcome disparities in other marginalized populations.

How to reduce allostatic load

There is typically a long time between the presence of indicators of allostatic load and illness and death caused by diseases associated with these indicators. That presents an opportunity to reduce allostatic load before the chronic stress response leads to illness and death. So how do we reduce allostatic load?

Some of the things that cause allostatic load can only be reduced by societal changes. Things like poverty, structural racism and homelessness cannot be decreased by individual effort. Even these causes, though, can respond to the mind body methods discussed below. On the other hand, if you don’t have enough to eat, have no home, or have a job that gives you no control of your life, it is not likely that you will have the energy or the will, or the financial means to do many of the mind body methods discussed below. We should not be distracted from working to decrease the inequities that are responsible for societal causes of chronic stress.

Mind-Body Medicine

Remember that an external threat is first received by the peripheral nervous system and transmitted to the pre-frontal cortex. In order to reduce allostatic load we can either reduce the threat perception in the prefrontal cortex (top down) or reduce the transmission of threat in the peripheral nerves (bottom up).

Top Down Treatments

Top down treatments start with intentional activity in the prefrontal cortex. The idea is to decrease activation of the limbic system and the hypothalamus. This can be accomplished by mindfulness meditation, hypnosis (including self hypnosis), mental imagery and progressive muscle relaxation. All of these techniques when done regularly have been found to decrease allostatic load indicators and to reduce the risk of stress related illnesses.

Bottom Up Treatments

Bottom up treatments decrease the threat transmission to the prefrontal cortex. They include yoga, Tai Chi, massage and biofeedback. These treatments have also been shown to decrease allostatic load and to reduce stress related illness.

Bottom up and top down are somewhat of an oversimplification. All of these treatments have some aspects of both top down and bottom up. Yoga, for example includes aspects of meditation. The same goes for Tai Chi. Biofeedback involves some attention from the prefrontal cortex. Massage also includes progressive muscle relaxation.

Bottom Line

The body’s reaction to a perceived threat includes a complex cascade of messages from the executive center in the prefrontal cortex to multiple body systems including the nervous system, the endocrine system, the cardiovascular system and the immune system. All of these things prepare the body to deal with the threat. As long as the threat is short term the stress response is very useful to the organism.

Perception of chronic stress leads to continuous secretion of all the stress hormones and inflammatory cytokines and this leads to dysfunction of multiple body systems and eventually to illness and death.

Mind body treatments, both top down and bottom up can reduce the allostatic load (chronic stress response) and reduce the risk of stress induced illness and death.

Many causes of chronic stress have to do with the structure of our society, such as poverty, homelessness and structural racism. Individual effort is not likely to ameliorate the effect of these causes of chronic stress. All of us should be working toward societal change to reduce chronic stress response in marginalized populations.

Common Cancers: How to Decrease Your Population Risk

Although we talk about cancer as if it were one disease, it is actually many different diseases. Some are common, and some are rare. In this post I’m going to write about the five most common cancers in the United States. I will focus on incidence (how common they are in the population), risk factors for these cancers, and especially risk factors that can be reduced or eliminated. I will not talk about screening for cancer. That will be the subject for another post

Breast Cancer

Breast cancer is the most common cancer in the U.S. The incidence of breast cancer in the U.S. is 128 new cases per 100,00 women per year (men get breast cancer too, but at a much lower rate). That means that one tenth of one percent of women in the U.S get breast cancer every year. The population risk increases with age. The lifetime risk of developing breast cancer is 13 per cent, or about one in eight women. The majority of that risk is in women over the age of 65. Overall, 20% of women with breast cancer eventually die from it. That means the cure rate is 80%.

Risk Factors for Breast Cancer (from the CDC)

Things you can do to reduce your risk of getting breast cancer

  • Eat a high fiber diet with lots of vegetables and avoid lots of red meat, animal fat and processed foods. Studies have shown that this kind diet reduces the risk of getting breast cancer. Of course this kind of diet also reduces the risk of heart disease and stroke as well, as I have written about in previous posts.
  • Be physically active. Women who are not physically active have a higher risk of getting breast cancer. There are lots of ways to be physically active. Take at least one flight of stairs instead of taking the elevator. Park as far as you can from the store when you are shopping. Take some long walks in your neighborhood if that is safe where you live. If not, drive or take the bus to a nearby park to walk.
  • Maintain a healthy body weight. Older women who are overweight or have obesity have a higher risk of getting breast cancer than those at a healthy weight.
  • Don’t take hormones (if you can help it). If you do need hormones for menopausal symptoms, take estrogen only, not estrogen and progesterone and take it for less than 5 years if possible. Some forms of hormone replacement therapy (those that include both estrogen and progesterone) taken during menopause can raise risk for breast cancer when taken for more than five years. Certain oral contraceptives (birth control pills) also have been found to raise breast cancer risk.
  • Reproductive decisions. Have your first pregnancy before age 30 if possible, and breast feed for as long as is practical whatever age you have children. Having a first pregnancy after age 30, not breastfeeding, and never having a full-term pregnancy can raise breast cancer risk.
  • Don’t drink alcohol or have no more than one drink per day. Studies show that a woman’s risk for breast cancer increases with the more alcohol she drinks.
  • Don’t smoke, or quit if you do: Studies show that smoking cigarettes increases women’s risk for breast cancer

Risk Factors for Breast Cancer You Can’t Change

  • Getting older. The risk for breast cancer increases with age. Most breast cancers are diagnosed after age 50.
  • Genetic mutations. Women who have inherited changes (mutations) to certain genes, such as BRCA1 and BRCA2, are at higher risk of breast and ovarian cancer.
  • Reproductive history. Starting menstrual periods before age 12 and starting menopause after age 55 expose women to hormones longer, raising their risk of getting breast cancer.
  • Having dense breasts. Dense breasts have more connective tissue than fatty tissue, which can sometimes make it hard to see tumors on a mammogram. Women with dense breasts are more likely to get breast cancer.
  • Personal history of breast cancer or certain non-cancerous breast diseases. Women who have had breast cancer are more likely to get breast cancer a second time. Some non-cancerous breast diseases such as atypical hyperplasia or lobular carcinoma in situ are associated with a higher risk of getting breast cancer.
  • Family history of breast or ovarian cancer. A woman’s risk for breast cancer is higher if she has a mother, sister, or daughter (first-degree relative) or multiple family members on either her mother’s or father’s side of the family who have had breast or ovarian cancer. Having a first-degree male relative with breast cancer also raises a woman’s risk.
  • Previous treatment using radiation therapy. Women who had radiation therapy to the chest or breasts (for instance, treatment of Hodgkin’s lymphoma) before age 30 have a higher risk of getting breast cancer later in life.
  • Exposure to the drug diethylstilbestrol (DES). DES was given to some pregnant women in the United States between 1940 and 1971 to prevent miscarriage. Women who took DES, or whose mothers took DES while pregnant with them, have a higher risk of getting breast cancer.
  • Hormonal changes from night shift work: Some studies have shown that night shift work may increase the risk of breast cancer.

There is no point in worrying about things you can’t change, but if you are at increased risk for breast cancer from one or more of these risk factors, that might affect your decisions about whether and when to get screening mammograms. More about screening in another post.

Prostate Cancer

Prostate cancer is the second most common cancer in the U.S. It is the most common cancer in men. The incidence of prostate cancer in the U.S. is 113 per 100,00 men per year. That means, like breast cancer for women, about one tenth of one per cent of men will be diagnosed with prostate cancer every year. Like breast cancer, the population risk increases with age. The lifetime risk of developing prostate cancer for a male is 13 per cent or about 1 in 8. That is about the same lifetime risk risk for women for breast cancer. Overall 3.2% of men will eventually die from prostate cancer. That is a cure rate of 96.2%, much higher than for breast cancer. Part of the reason for the low death rate is that many prostate cancers grow so slowly that more men die with prostate cancer than from prostate cancer.

Risk Factors for Prostate Cancer

Things you can do to reduce your population risk of getting prostate cancer

  • Diet: Once again, a diet low in animal fat, high in unprocessed and high fiber foods, especially cruciferous vegetables like broccoli and cauliflower seem to be especially protective. Tomato based products, which are high in lycopene also seem to reduce population risk of prostate cancer. Soy intake as well as drinking coffee also seems to be protective.
  • Alcohol. Alcohol intake does not seem to be a a risk factor for prostate cancer. It is a risk factor for some other cancers that I will write about later.
  • Don’t smoke cigarettes (or marijuana). Smoking both cigarettes and marijuana increase the risk of prostate cancer
  • Maintain a normal body weight. Like for breast cancer, obesity increases the risk for prostate cancer.
  • Exercise. While exercise is good for you in lots of ways, it does not seem to decrease the population risk for prostate cancer.

Risk Factors for prostate cancer you can’t change

  • Age. Prostate cancer rarely occurs before the age of 40, but peaks between age 65 and 74. Autopsy studies have shown that low grade prostate cancer, never diagnosed during life, is extremely common as age increases. In men 71-80 it can be up to 73%! These low grade prostate cancers never caused any symptoms and the men in the autopsy studies died from something else.
  • Heredity. If family members have had prostate cancer, especially first degree relatives (father, grandfather) your population risk for prostate cancer is substantially increased
  • Race. Black men are more likely to get prostate cancer and also more aggressive prostate cancer.
  • Chemical exposure. Exposure to certain chemicals, especially the herbicide agent orange increase the population risk of prostate cancer.

Once again, there is no point in worrying about things you can’t change. Screening for prostate cancer is very controversial. More about that in another post.

Lung Cancer

Lung cancer is the third most common cancer in the U.S. The incidence of lung cancer is 52 per 100,000 per year, which translates to five one hundredths of 1 per cent of the U.S. population per year that will be diagnosed with lung cancer. The lifetime risk of lung cancer is about 6% of people in the U.S. Of those diagnosed with lung cancer, only 23% will live 5 years after diagnosis. That is a much lower cure rate than for breast cancer and prostate cancer.

Risk Factors for Lung Cancer (American Cancer Society)

Risk Factors you can change

  • Smoking. Smoking cigarettes or cigars or smoking a pipe are the biggest risk factor for lung cancer. People who quit smoking before age 40 have a 90% reduction in smoking related diseases including lung cancer. People who quit smoking by age 54 reduce their risk by two thirds. The risk of lung cancer is still somewhat increased for former smokers as compared to never smokers even 30 years after quitting smoking.
  • Second Hand Smoke. Breathing other smoker’s smoke also increases your risk of getting lung cancer by 20-30%.
  • Radon. Radon is the second leading cause of lung cancer after smoking.  Radon is a naturally occurring gas that forms in rocks, soil, and water. It cannot be seen, tasted, or smelled. It can accumulate in buildings, especially basements. Homes can be tested for Radon and a simple ventilation fan can decrease radon to safe levels. If your house has not been tested for Radon, it should be. You can buy Radon test kits at a hardware store or on Amazon.
  • Asbestos Exposure. People who have been exposed to asbestos have an increased risk of lung cancer. Asbestos used to be used as insulation in buildings, but has been banned for years. Asbestos is still in some homes. It is of no risk to residents of those homes as long as it is not disturbed. The risk comes when houses that contain asbestos are torn down or re-modeled.
  • Other Workplace Exposures.
    • Other carcinogens (cancer-causing agents) found in some workplaces that can increase lung cancer risk include:
    • Radioactive ores such as uranium
    • Inhaled chemicals such as arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, and chloromethyl ethers
    • Diesel exhaust

Risk Factors you cannot change

  • Previous radiation therapy to the lungs
  • People who have had radiation therapy to the chest for other cancers are at higher risk for lung cancer, particularly if they smoke. Examples include people who have been treated for Hodgkin disease or women who get chest radiation after a mastectomy for breast cancer. Women who have radiation therapy to the breast after a lumpectomy do not appear to have a higher than expected risk of lung cancer. 
  • Air pollution: in cities, air pollution (especially near heavily trafficked roads) appears to raise the risk of lung cancer slightly. This risk is far less than the risk caused by smoking, but some researchers estimate that worldwide about 5% of all deaths from lung cancer may be due to outdoor air pollution.
  • Personal or family history of lung cancer
    • If you have had lung cancer, you have a higher risk of developing another lung cancer.
    • Brothers, sisters, and children of people who have had lung cancer may have a slightly higher risk of lung cancer themselves, especially if the relative was diagnosed at a younger age. It’s not clear how much of this risk might be due to shared genes among family members and how much might be from shared household exposures (such as tobacco smoke or radon).
    • Researchers have found that genetics seems to play a role in some families with a strong history of lung cancer.

Once again, there is no point in worrying about risk factors you cannot change. There is a screening test for lung cancer for people who are current or former smokers. More about that in another post.

Colorectal Cancer

Colorectal cancer is the fourth most common cancer in the U.S. The incidence of colorectal cancer is about 38 per 100,000 people per year in the U.S. This means that 4 one hundredths of one per cent of people in the U.S. get colorectal cancer every year. The lifetime risk of getting colorectal cancer is about 4% of people in the U.S. Overall, 35% of people who have colorectal cancer eventually die from it giving an overall cure rate of 65%. The risk of death from colorectal cancer is very dependent on the stage of cancer when it is diagnosed. If colorectal cancer is diagnosed when it is localized, the cure rate is 91%. If it is diagnosed when it has already spread to other parts of the body, the cure rate is 15%.

Risk Factors for Colorectal Cancer (CDC)

Risk Factors you can change

These are exactly the same modifiable risk factors for breast cancer and prostate cancer. Improving diet, maintaining a normal weight, limiting or eliminating alcohol consumption, and not smoking or quitting smoking decreases population risk of three different cancers.

Risk Factors you cannot change

Because chance of cure of colorectal cancer is so much greater when diagnosed at an early stage, screening for colorectal cancer can make a big difference. More about this in another post.

Melanoma Skin Cancer

Melanoma of the skin is the 5th most common cancer in the U.S. It is necessary to specify melanoma of the skin, because melanoma can also occur in the retina of the eye or in any other organ that contains melanocytes (pigment cells). These non-skin melanomas are fortunately rare. The incidence of melanoma of the skin is about 23 per 100,000 people per year or 2 one hundredths of 1 per cent per year. Of those people who develop melanoma of the skin, 6.3% eventually die from it, giving a cure rate of 93.7%. The lifetime risk of getting melanoma is about 2 per cent of people in the U.S.

What do skin melanomas look like?

Warning Signs  

  • a new spot on the skin or a spot that is changing in size, shape, or color.
  • a spot that looks different from all of the other spots on your skin (known as the ugly duckling sign).
  • The ABCDE rule.
    • A is for Asymmetry: One half of a mole or birthmark does not match the other.
    • B is for Border: The edges are irregular, ragged, notched, or blurred.
    • C is for Color: The color is not the same all over and may include different shades of brown or black, or sometimes with patches of pink, red, white, or blue.
    • D is for Diameter: The spot is larger than 6 millimeters across (about ¼ inch – the size of a pencil eraser), although melanomas can sometimes be smaller than this.
    • E is for Evolving: The mole is changing in size, shape, or color.

Here are a few pictures of actual skin melanomas

Risk Factors (American Cancer Society)

Risk Factors you can do something about

Ultraviolet Light Exposure.

  • Exposure to ultraviolet (UV) rays is a major risk factor for most melanomas. Sunlight is the main source of UV rays. Tanning beds and sun lamps are also sources of UV rays.While UV rays make up only a very small portion of the sun’s rays, they are the main cause of the damaging effects of the sun on the skin. UV rays damage the DNA (genes) inside skin cells. Skin cancers can begin when this damage affects the DNA of genes that control skin cell growth.
  • The pattern and timing of the UV exposure may play a role in melanoma development. For example, melanoma on the trunk (chest and back) and legs has been linked to frequent sunburns (especially in childhood). This might also have something to do with the fact that these areas aren’t constantly exposed to UV light. Some evidence suggests that melanomas that start in these areas are different from those that start on the face, neck, and arms, where the sun exposure is more constant.

Sunscreen

High protection value sunscreens do prevent sunburn, but paradoxically, people who use high protection sunscreens have an increased risk of skin melanoma. Does that mean sunscreens cause melanoma? No, it means that people who use high protective value sunscreens and apply them frequently are more likely to purposely spend time in the sun (sun bathing). The increased ultraviolet exposure overwhelms the protective value of the sun screen. Avoiding sun bathing and using high protective sun screen when you are working outdoors, as well as wearing a hat and protective clothing is the best way to reduce your population risk of skin melanoma (as well as other types of skin cancers.

Be Vigilant

Be aware of the warning signs above. If you have a mole or a skin lesion that meets any of the warning sign criteria, it is worth a trip to the doctor to check it out.

Risk Factors you can’t do anything about

Moles

A mole (also known as a nevus) is a benign (non-cancerous) pigmented tumor. Babies are not usually born with moles; they often begin to appear in children and young adults.

Having many moles: Most moles will never cause any problems, but someone who has many moles is more likely to develop melanoma.

Atypical moles (dysplastic nevi): These moles look a little like normal moles but also have some features of melanoma. They are often larger than other moles and have an abnormal shape or color. (See Signs and Symptoms of Melanoma Skin Cancer for descriptions of how moles and melanomas look.) They can appear on skin that is exposed to the sun as well as skin that is usually covered, such as on the buttocks or scalp. Dysplastic nevi often run in families. A small percentage of dysplastic nevi may develop into melanomas. But most dysplastic nevi never become cancer, and many melanomas seem to arise without a pre-existing dysplastic nevus.

Dysplastic nevus syndrome (atypical mole syndrome): People with this inherited condition have many dysplastic nevi. If at least one close relative has had melanoma, this condition is referred to as familial atypical multiple mole and melanoma syndrome, or FAMMM. People with this condition have a very high lifetime risk of melanoma, so they need to have very thorough, regular skin exams by a dermatologist (a doctor who specializes in skin problems). Sometimes full body photos are taken to help the doctor recognize if moles are changing and growing. Many doctors recommend that these patients be taught to do monthly skin self-exams as well.

Congenital melanocytic nevi: Moles present at birth are called congenital melanocytic nevi. The lifetime risk of melanoma developing in congenital melanocytic nevi is estimated to be between 0 and 5%, depending on the size of the nevus. People with very large congenital nevi have a higher risk, while the risk is lower for those with small nevi. For example, the risk for melanoma is very low in congenital nevi smaller than the palm of the hand, while those that cover large portions of back and buttocks (“bathing trunk nevi”) have significantly higher risks

Lots of irregular or large moles. The chance of any single mole turning into cancer is very low. However, anyone with lots of irregular or large moles has an increased risk for melanoma.

Fair skin, freckling, and light hair

The risk of melanoma is much higher for whites than for African Americans. Whites with red or blond hair, blue or green eyes, or fair skin that freckles or burns easily are at increased risk.

Family history of melanoma

Your risk of melanoma is higher if one or more of your first-degree relatives (parents, brothers, sisters, or children) has had melanoma. Around 10% of all people with melanoma have a family history of the disease.

Personal history of melanoma or other skin cancers

A person who has already had melanoma has a higher risk of getting melanoma again. People who have had basal or squamous cell skin cancers are also at increased risk of getting melanoma.

Having a weakened immune system

A person’s immune system helps fight cancers of the skin and other organs. People with weakened immune systems (from certain diseases or medical treatments) are more likely to develop many types of skin cancer, including melanoma.

Being older

Melanoma is more likely to occur in older people, but it is also found in younger people. In fact, melanoma is one of the most common cancers in people younger than 30 (especially younger women). Melanoma that runs in families may occur at a younger age.

Being male

In the United States, men have a higher rate of melanoma than women, although this varies by age. Before age 50, the risk is higher for women; after age 50 the risk is higher in men.

Xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare, inherited condition that affects skin cells’ ability to repair damage to their DNA. People with XP have a high risk of developing melanoma and other skin cancers when they are young, especially on sun-exposed areas of their skin.

Bottom Line

These five cancers account for half of the cancer diagnoses made every year in the U.S. There are other less common types of cancer, only a few of which have screening tests to detect them early. I will write about some of those cancers in my coming post on screening for cancer. While everyone worries about cancer, the majority of people in the U.S. will never get cancer. The lifetime overall population risk for a U.S.male of getting any kind of cancer other than skin cancer is 40%. For women, that lifetime risk is 39%. These risks average together people at high risk and people at low risk. Your population risk could be substantially lower (or higher) than this average risk.

Omicron Variant of SARS-COV-2

I will continue the series of posts on healing relationships, but I think we have enough information about the omicron variant of SARS-COV-2 to spend some time talking about it. In this post I will discuss infectivity, vaccine resistance, and some prevalent misinformation which continues to complicate rational measures to combat the virus.

Infectivity

First a little review on epidemiology. Those of you who want a more complete review can look at my previous post Epidemiology Made Simple. The potential infectivity of any virus or bacteria is described by a number called R0. R0 is the average number of other people that one infected person infects. R0 for the original SARS-COV-2 virus detected in Wuhan, China was about 2.5. That means that on average one infected person infected between two and three other people. The delta variant of SARS-COV-2 has an R0 of about 7. That means that on average one person infected with the delta variant infects 7 other people. The delta variant is almost three times as infectious as the original virus!

So far it looks like the omicron variant has an R0 of about 10. To put that in perspective, the most infectious virus that we know of is the measles virus. It has an R0 of 13. That means the omicron variant is almost as infectious as measles. That is why it is spreading so fast. Cases in the U.K. where omicron is predominant are doubling every two to three days! That makes it almost impossible to limit the spread by contact tracing.

R0 refers only to the potential infectivity of the virus in people who have no immunity. This potential infectivity can be reduced by measures that either increase immunity (such as vaccination or previous infection) and/or that limit the spread of the virus in people such as masking, social distancing and avoiding small, poorly ventilated indoor spaces.

Effectiveness of vaccines for omicron

Effectiveness of vaccines is measured two ways. First is the effectiveness of the vaccine in prevention of infection in the first place. Second and much more important is the effectiveness of the vaccine in preventing hospitalization and death.

Omicron has more than thirty mutations in the spike protein. This means that it looks very different from the original virus isolated in Wuhan. The previous definition of fully vaccinated was two immunizations. Those people who had two vaccinations had about 70% protection from infection with the delta variant, but so far in the U.K. it looks more like 10% protection from omicron infection. Protection from being sick enough to be in the hospital, though is still very good, even without a booster. Having a booster gives about 80% protection from symptomatic infection and about 99.9% protection from hospitalization and death.

Does the omicron variant cause milder disease?

It is too early to be sure about that. Hospitalization rates for people infected with the omicron variant are lower so far, but that is in countries such as the U.K. with very high vaccination rates, or like South Africa that has high numbers of people who have had COVID previously. We don’t yet know the hospitalization rate for the unvaccinated, but hospitalizations are starting to go up in the U.K. and in much of the U.S. What we can say so far is that the omicron variant does not seem to cause more severe disease, but that is all we can say at this point. Because omicron is so contagious, we will see huge increases in case numbers and therefore hospitalizations no matter what the severity of illness omicron causes.

What about children?

There have been a number of articles in the press recently about hospitalizations going up for children with COVID. While that is true, the numbers are still tiny compared to hospitalizations for adults. Children are still at substantially lower risk of symptomatic infection even with the omicron variant. That does not mean that they don’t get infected at all, just that their infections are much more likely to have no symptoms. In a recent large antibody study in Texas (more about this later) a third of the children in the study showed evidence of previous COVID. Over half of those children had no history of any symptoms at all. That is good news for the children, but bad news for adults exposed to them. It appears that infected children without symptoms could be major spreaders of COVID.

Vaccines protect children five to twelve years old as well as they protect adults. The only serious side effect for children is mild inflammation of the heart called myocarditis. This occurs in about one in one million doses, almost never requires hospitalization and goes away by itself.

There has been a great deal of misinformation about the risk of vaccination in children. A U.S. virologist, Dr Robert Malone, has posted a video claiming that the spike protein fragments created by the vaccine are toxic and cause damage to multiple organs in children. This is utterly false. Millions of children have received the Pfizer vaccine and there is not one shred of evidence that there is any organ damage other than the mild transient myocarditis that occurs in one in a million.

Is having had and recovered from COVID as good protection as having a vaccine?

There definitely is some protection from having COVID in the past. It is not as good as protection from the vaccine though, and it tends to wane more quickly than protection from the Pfizer or Moderna vaccine. In the Texas study that I mentioned earlier, called Texas Cares, the University of Texas Health Science Center recruited over 87,000 people in Texas ages 8 to 80. I was a participant in that study. Every participant filled out a survey asking about symptoms of COVID and dates of vaccinations. Then blood was drawn at a local lab at baseline and every 3 months for two more times. The survey was repeated before each blood draw.

Two antibody tests were done on each sample. One test measured the N antibody. People who were positive for N antibody had COVID at some previous time. The other test measured antibodies to the SARS-COV-2 spike protein. The spike protein antibodies are the neutralizing antibodies that protect you from severe illness with COVID. People who had only the spike protein antibody had been vaccinated but had never had COVID. The preliminary results were recently published. What they found was that spike protein antibodies in unvaccinated people with a previous infection peak at 120 days after infection and then decrease. Unvaccinated people with a previous infection overall had lower levels of spike protein antibodies than people who were vaccinated. People who had a previous infection and were vaccinated had the highest levels of spike protein antibodies.

As an example I will use my own data from this study as well as the data from a friend who had COVID but had not been vaccinated. My initial spike protein antibody level was over 300. His was 30. Three weeks after my booster of the Pfizer vaccine I went for the second blood draw. My spike protein antibodies at that blood draw were over 2,500.

This study clearly suggests that COVID vaccines give better protection than previous COVID infection and that boosters cause a big increase in neutralizing antibody. The combination of previous COVID infection and vaccination gives the best protection of all.

Should I wear a mask even if I am vaccinated and boosted?

The omicron variant is so contagious that even vaccinated and boosted people could still get infected even though that infection is likely (but not guaranteed) to be mild. My personal feeling (and the CDC recommendation) is that everyone should continue to mask indoors in public places, like grocery stores, department stores or any other public place indoors where multiple people not known to you congregate. U.S. made N-95 masks are now readily available and provide much better protection than cloth masks.

Bottom Line

The omicron variant is extremely contagious, almost as much as measles. Vaccines, especially with a booster give 80% protection from symptomatic infection and 99% protection from hospitalization and death. Children frequently get infection without symptoms and may serve to spread infection to others. Vaccinating children five to twelve is safe and effective. Having had a COVID infection in the past gives some protection but is less than protection from vaccines. Because omicron is so contagious N-95 masks should be worn in indoor public places regardless of vaccination status.

Basic Epidemiology II: How Superspreading Events Work

In a previous post I talked about R, the reproduction number for an infectious agent such as SARS-COV2. R is the average number of other people a person with infection infects. The basic idea is that if R is less than one, the infection dies out. This works for infections like influenza which spreads pretty much evenly in susceptible populations.

There is another epidemiologic number called k, which is the dispersion factor. The math is somewhat technical, but if k is substantially less than one that means that the infection is spread primarily by a small number of superspreader events. It is estimated that k for SARS-COV2 is about 0.1

As we learn more about how this virus spreads, we have discovered that about 80% of people who are infected are unlikely to infect anyone else. The virus is spread primarily by “superspreader events” where one infected person is responsible for as many to as 50 or 100 infections. In other words, about 20% of infected people are responsible for the majority of the spread of the pandemic.

Superspreader events are relatively rare, so if we could focus on preventing the conditions that lead to super spreader events, then we could get the pandemic under much better control without having to shut down the whole economy.

There are some well known superspreader events. The Biogen leadership conference in Boston led to infection of 99 people in Massachusetts alone. A funeral in Albany Georgia led to infection of more than 100 people. Infection in a single person in a choir practice in Washington state led to 52 infected people, two of whom died. In Arkansas an infected pastor and his wife infected 30 church member at services over several days. Three of them died. An additional 26 people were infected from church members, one of whom died.

There are common factors in each of these events. They all happened in large groups of people who were close together, mostly in poorly ventilated indoor spaces. They involved people who were talking, often loudly, or singing or eating (you can’t wear a mask while you are eating or drinking). Talking or singing produces lots of particles and are likely to aerosolize (tiny droplets hanging in the air) the virus and make it much more likely to spread. It also turns out that exercising vigorously in a closed space, such as a gym also can cause superspreader events. For example fitness dance classes in South Korea with up to 22 people in a room led to 65 new cases. On the other hand, yoga classes were not associated with new cases.

So how do we prevent superspreader events? Obviously by avoiding situations where large groups are close together in enclosed spaces eating talking or singing. That means no indoor dining in most restaurants, no exercising in gyms in groups larger than 5-10 people, and no church services indoors. It also means avoiding indoor bars. Alcohol disinhibits people and makes them less careful. It means prohibiting crowds of spectators at sporting events or concerts.

Large indoor retail spaces where it is possible to keep social distancing and wear masks are unlikely sources of super spreading events. Time of contact is important too. If you are in contact with an infected person for less than 5 minutes, you are unlikely to become infected. That means passing people briefly indoors or out is unlikely to create a superspreader event.

People have also worried about using public bathrooms. Although it is true that public bathrooms are for the most part poorly ventilated enclosed spaces, no one stays there very long. Even though flushing a toilet creates a plume of particles, they don’t hang in the air very long. As far as we know, there has been no documented case of infection due to using a public bathroom.

An excellent article that goes into more detail about super spreading events and their importance can be found in an article in Scientific American. It is written in non technical language and is easy to understand. Here is a link to that article.

Bottom Line

COVID-19 infections are primarily transmitted by superspreader events. Eighty percent of infected people do not infect others. The vast majority of infections that maintain the spread of infection are produced by twenty percent of infected people. Superspreader events are associated with large groups of people in closed indoor spaces where talking, singing, eating and drinking, and vigorous exercise are occurring.