Childhood infections may mitigate serious illness

Did you know that many childhood illnesses we are trying to prevent through vaccination actually have valuable health benefits? The following articles and studies explain that individuals who have had these illnesses are less likely to develop ovarian cancer, heart disease, and allergies, and may experience tumor regression.

Mumps infection may protect women against ovarian cancer.

The study Mumps and ovarian cancer: modern interpretation of an historic association shows that women who had symptomatic mumps were less likely to have ovarian cancer.  This 2010 paper pooled eight earlier studies and found a 19 percent lower risk. This means that if 1 in 91 women in the general population is diagnosed with ovarian cancer, among women who had a symptomatic case, it would be closer to 1 in 112. Researchers have found that when the salivary glands are injured or inflamed during mumps, it alters the MUC1 protein, which is also present on ovarian cancer cells. After having made antibodies against this protein during mumps, the body may now recognize it on nascent cancer cells and wipe them out. The researchers point out that the mumps vaccine only produces antibodies against the virus, not against MUC1, because those require an actual case of mumps.

Measles and mumps infections in childhood might protect against heart attacks and strokes during adulthood.

This 2015 Japanese study, Association of measles and mumps with cardiovascular disease: The Japan Collaborative Cohort (JACC), found that middle-aged men and women who had been infected with measles and/or mumps died from heart attacks and strokes at lower rates than those who hadn’t had either illness. It followed about 104,000 people for twenty years, starting in 1988. None of them had been vaccinated against either disease; they were all too old to have gotten the shots.

Men who had reported having both illnesses had 20 percent fewer cardiovascular deaths, 29 percent fewer deaths from heart attack, and 17 percent fewer from stroke. Women who had reported both had 17 percent fewer cardiovascular deaths. The more infections a person had, the lower the risk went. The association was strongest among men. In women, measles alone showed no benefit; only those who had had both showed benefit.

In absolute terms, among the men in this study who had neither illness, about 106 out of every 1,000 died of cardiovascular disease over the twenty years. Among those who had both measles and mumps, it was about 86. That is roughly 20 fewer deaths per 1,000 men. For heart attack specifically, about 18 per 1,000 became about 13, and for stroke, about 45 per 1,000 became about 37. Among the women who had neither illness, about 77 out of every 1,000 died of cardiovascular disease. Among those who had both, about 64, or roughly 13 fewer deaths per 1,000 women. For stroke, about 32 per 1,000 became about 27, or roughly 5 fewer deaths per thousand.

The researchers believe this happens because the infection prompts the body to produce regulatory T cells, which keep inflammation in check, and that inflammation in the artery walls hardens the arteries. Animal studies show a measles virus protein doing exactly this. The researchers come at this from the hygiene hypothesis, the idea that the immune system needs to be challenged early to develop properly.

Having had more childhood illnesses was associated with a lower risk of coronary heart disease.

A study of Swedish individuals, Dual role of infections as risk factors for coronary heart disease, shows that the more childhood illnesses one had, the lower the risk of a heart attack and unstable angina. This 2007 study showed that each additional illness lowered the risk by about 11 percent (14 percent when adjusting only for age and sex, and 11 percent once the chronic infection antibody levels were also accounted for). The study also found the opposite for chronic infections. Individuals with high antibody levels to enterovirus, herpes simplex virus, or the bacterium Chlamydia pneumoniae were more likely to have had a coronary event, and the more of them, the greater the risk.

The illnesses children pass through and recover from appear to train the immune system, while infections that persist in the body damage the arteries. The researchers also hypothesized that the more sanitary a child’s background, the less the immune system is trained and the more susceptible they are to heart disease as an adult.

While the authors present this as a dual role of infection, it appears that they are really talking about two different phenomena. An illness a child gets over leaves behind a better-trained immune system. An infection that never clears keeps the body inflamed for years, and it is that ongoing inflammation that damages arteries.

Kids who get the chickenpox infection are less likely to develop asthma and eczema than vaccinated children.

The study, Chickenpox in childhood is associated with decreased atopic disorders, IgE, allergic sensitization, and leukocyte subsets, published in 2011, was conducted in Brooklyn, NY, pediatric practices. The researchers compared 100 children who caught chickenpox before age 8 with 323 children who got the varicella vaccine instead. All of them came from the same pediatric practices in Brooklyn, and their chickenpox was diagnosed by a doctor at the time, making the diagnosis more reliable than data based on memory. The study found that the children who had chickenpox were less likely to develop asthma, allergic rhinoconjunctivitis [hay fever], or eczema. Food allergies showed no difference.

They also examined their bloodwork. Children who had had chickenpox carried lower IgE, the antibody that drives allergic reactions, and the difference was still there more than ten years later. They were also far less likely to test positive on specific allergy tests. The researchers noted that the wild virus carries features that the weakened vaccine strain doesn’t, and the illness itself, with its fever and its rash, may be part of what changes how the immune system develops.

While most of the chickenpox cases were born before 1998, most of the vaccinated children were born after, so the two groups grew up in different years, at a period when allergy diagnoses were rising. Though the researchers accounted for birth year, the groups aren’t a perfect match. And in the practices they studied, there was no third group, no children who had neither the illness nor the shot, so they could not measure what the vaccine does on its own.

Note: Asthma and eczema rates have been increasing, and for concerned parents, this is one of the few studies that puts children who had the illness next to children who got the shot and measures the difference in a lab rather than on a questionnaire. It doesn’t settle the question, and the researchers say so. They also say what would settle it. Their own suggestion for a better study: “A possible alternative design might be to conduct a prospective study by following children whose parent(s) have already refused vaccination, and future studies may employ this approach.”

A number of instances of tumor regression with measles have been reported.

In a 2018 review of clinical trials, Clinical Trials with Oncolytic Measles Virus: Current Status and Future Prospects, Mayo Clinic researchers trace the field back to the first case report, published in Cuba in 1949, of Hodgkin’s lymphoma regressing after a wild measles infection.

In their July 1971 letter, Regression of Burkitt’s lymphoma in association with measles infection, researchers described the case of an eight-year-old Ugandan boy who was admitted to Mulago Hospital in Kampala in December 1970 with a confirmed case of Burkitt’s lymphoma. On December 13, before any treatment was started, he broke out with a measles rash, and the tumor immediately began shrinking. Within two weeks, both the tumor and the rash were gone. Four months later, he was still in complete remission, having received no cancer treatment at all.

In March 1971, Zenona Zygiert also described cases of confirmed Hodgkin’s disease remission. In a letter published in The Lancet, Hodgkin’s disease: remissions after measles, she related the cases of three children in Warsaw who, out of 98 with confirmed Hodgkin’s, caught measles while under observation. All three improved: nodes shrank, fever fell, blood measures normalized. None had been treated with radiation, chemotherapy, or steroids for at least three weeks before. Two had slight relapses, one at 19 months and one at 26 months, were treated, and were in good health in the fourth and sixth years after diagnosis. The third remained in remission six years later.

In a May 1981 letter published in the Lancet, Regression of Hodgkin’s disease after measles, researchers described the case of a seven-year-old Nigerian girl whose neck masses shrank over a week after she caught measles, before her biopsy result came back.

Measles is known to suppress cell-mediated immunity; according to researchers Avrum Bluming and John Ziegler, measles should have made the Ugandan boy worse. They say the regression was “unexpected” and spend much of their letter working through explanations and rejecting them: spontaneous regression, direct destruction of tumor cells by the virus, steroid hormones released by the illness, interferon. None fit.

Researchers, building on these cases of natural tumor regression, are working to engineer a measles virus designed to have the same effect on tumor cells without anyone having to contract measles. In January 2010, the paper Enhanced Antitumor Effects of an Engineered Measles Virus Edmonston Strain Expressing the Wild-type N, P, L Genes on Human Renal Cell Carcinoma sheds light on why the vaccine strain alone is a weaker cancer killer than wild measles. Researchers found that adding specific wild-type measles genes back into the vaccine strain, genes that let the virus resist interferon, killed cancer cells more effectively.

What they are building is nothing like catching measles. It is now in clinical trials, injected directly into the tumor, at doses vastly larger than the amount of virus in a vaccine, and so far the usual result in patients has been that the cancer stops growing rather than goes away.

In conclusion:

These studies show an inverse relationship between childhood illnesses and later cancers and chronic diseases. We have to consider that there may be other cancers and conditions mitigated by childhood illnesses without us ever knowing they occurred. The immune system is very complex, and suppressing parts of it may have greater ramifications than we know.

For a detailed look at measles specifically, including clinical picture, risk data, and treatment, see: Measles: What It Is, What It Does, and How to Manage It

Featured image by Polesie Toys.URL