WASHINGTON — Could something about teaching — perhaps the years of contact with kids and their germs — increase the risk of serious immune system diseases such as multiple sclerosis and lupus?
A new study suggests it might, backing the theory that if someone is genetically susceptible to a certain disease, environment could trigger the onset.
University of Connecticut researchers who examined 11 years of death certificates found that deaths from some autoimmune diseases among K-12 teachers were more than twice as high as those of people in other professions.
Autoimmune diseases such as multiple sclerosis, lupus and rheumatoid arthritis are caused when the body's immune system goes awry and attacks its own tissue.
The diseases are rare, and even the higher death rates among teachers are relatively low, considering other causes of death.
"We didn't publish the study to scare people," said researcher Stephen J. Walsh, a co-author.
Still, finding occupations that seem to have a higher risk may help scientists pin down just what environmental triggers play a role in these little-understood diseases.
Dr. Joel Rose, director of the Autoimmune Disease Research Center at Johns Hopkins University, said more research is required on the link, but called Walsh's study "extremely important work."
"The article sort of implies that infection may be the important component, and it's certainly not an unreasonable suggestion," he said.
The study, published this summer in The Journal of Rheumatology, supports the theory that infections may act as triggers for people genetically susceptible to autoimmune diseases by revving up an immune system reaction. Rheumatic fever, for instance, is associated with a streptococcus infection. The causes of most autoimmune diseases aren't known.
The study examined death certificates that listed the deceased's occupation. Walsh found 2.3 percent of schoolteacher's death certificates listed one of 13 autoimmune diseases as a cause of death, compared with only 1.7 percent of death certificates for other professions.
The increased risk was statistically significant for four diseases: multiple sclerosis, rheumatoid arthritis, systemic lupus and Sjogren's syndrome, which inhibits the body's ability to produce moisture.
Teachers who died between the ages of 35 and 44 were twice as likely to die of complications from autoimmune diseases. Among high school teachers of that age, the rate was even higher. Walsh hypothesized that might be related to the Epstein-Barr virus, which is more common among high school students than those in elementary school.
The longer teachers lived, the less likely autoimmune disease was related to their death.
Autoimmune diseases often are chronic, not fatal. But they can weaken the body's ability to fight off infections. They also lead to other problems, such as kidney failure, pneumonia and heart disease.
The worst cases take 10 to 15 years to run their course, Walsh said, speculating that susceptible teachers could be infected by viral or bacterial triggers in their 20s, early in their careers.
Autoimmune diseases strike women more often than men. But Walsh said the fact that more women are teachers didn't skew the data — both male and female teachers had a higher autoimmune death rate than people in other professions.
"No matter how we look at the teachers, no matter what gender or what racial group, for most of the age groups we see this pattern," Walsh said.
He also found a higher risk for some conditions among certain other professions, including hairdressers, nurses' aides, health technicians, social workers and elevator operators.
The possible teacher connection first surfaced in 1997, when a government study of four years' worth of death certificates suggested a link. Hunting firmer evidence, Walsh culled the same federal database, examining 860,648 death certificates from 1985-1995.
He hopes the study encourages other researchers to study public school teachers. They're good test subjects, he said, since they generally stay in one place throughout their careers and can be easily tracked.
Teachers' union representatives welcomed the findings, saying members have known for years that their school environments were affecting their health.
"My first three years of teaching, I was sick, literally, half the time," said Jerald Newberry of the National Education Association's Health Information Network. "Then I was never sick again."
Darryl Alexander of the American Federation of Teachers said the union would push for more research into the connection between teacher illness and what she called the poor environmental conditions and air quality in many schools.
"We've been worried about communicable disease exposure for a long, long time," she said.
On the Net:
Abstract of article: www.jrheum.com/abstracts/abstracts01/1537.html