Up to 23.5 million Americans suffer from autoimmune disease (AD), one of the leading causes of death for women under age 65. In developed countries around the world, 5 to 7 percent of the population is affected—and rates are soaring, an expert panel reported at the “Global State of Autoimmunity” briefing for international health ministers hosted by the United Nations’ NGO Health Committee and the American Autoimmune Related Disease Association (AAARD) on September 25th of this year.
There are more than 100 autoimmune diseases, in which the body attacks its own organs or tissue. Genes play a key role, reported panelist Yehuda Shoenfeld, MD, incumbent chair for research of autoimmune diseases at Tel-Aviv University. “Among identical twins, if one has an autoimmune disease, there’s a 30 percent chance the other twin will also develop one, though not always the same disease.”
While genes may load the gun, by making some people more susceptible to AD, environment appears to pull the trigger, explaining 70 percent of risk. One study found that lupus is four times more likely to strike people of African descent who live in London than those who live in sub-Saharan Africa. In India, where AD is rare among the poor, rates are now rising among the middle class. Globally, a similar trend applies, since autoimmune disease remains uncommon in developing countries, while increasing in developed nations.
Although the cause of autoimmune disease isn’t yet known, such findings have inspired the “hygiene hypothesis,” the theory that in the modern world, we may be too clean for our own good, explains Joel Weinstock, MD, director of the division of gastroenterology/hepatology at Tufts Medical Center in Boston. “Throughout human history, humans lived in crowded conditions with poor sanitation, in close proximity to animals.”
As a result, infectious diseases and intestinal parasites were common in the past, adds Dr. Weinstock, a panelist at the conference. “Lack of these exposures during childhood may be turning off regulatory circuits in the immune system,” making it more likely to overreact to harmless substances, sparking allergies and autoimmune disease. “As we get rid of worms all over the world, the incidence of inflammatory bowel disease (IBD) has gone from 1 in 10,000 people to one in 200.”
Dr. Weinstock is conducting clinical trials of an unusual “medication” for Crohn’s disease (a type of IBD): treatment with live whipworms, an intestinal parasite. “The study found that 50 percent of patients had a major improvement, compared to 15 percent of those in the control group.” Mike, 31, of Bronx, New York says that after 15 years of suffering from debilitating Crohn’s disease that didn’t respond to drugs or three surgeries, he tried the experimental worm therapy and went into remission.
Other speakers at the conference also discussed a striking global pattern: The further someone lives from the Equator, the higher their risk for some types of AD, including type 1 diabetes and multiple sclerosis. This suggests that vitamin D deficiency, which is most common in northern countries that get less sunlight in winter, could be another trigger. And since autoimmune disease disproportionately strikes women, estrogen may also play a role.
Some outbreaks of AD have been linked to exposure to toxic chemicals. “Behavior also influences risk,” adds Betty Diamond, MD, center director, department of autoimmune diseases at Feinstein Institute for Medical Research in Manhasset, New York. “People with certain genes are at five times higher risk for rheumatoid arthritis, but you have the genes and also smoke, the risk of getting it is 20 times higher,” yet another compelling reason for tobacco users to kick the habit.
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