Contrary to a widely held theory, measles does not protect individuals from atopic allergic diseases such as rhinitis and asthma, new research conducted in Finland indicates (JAMA 2000;283:343-6). "The most important finding to come out of this study is that measles and atopy go hand-in-hand and not vice versa, as has been suggested," says Dr. Mikko Paunio, lead investigator and a senior medical officer with the Ministry of Social Affairs and Health in Finland. "I think the only explanation must be genes. They must determine to a large extent the natural history and sequelae of measles infection."
The Finnish researchers examined data on nearly 550 000 children and teenagers, ranging in age from 14 months to 19 years, to understand the association between measles and eczema, rhinitis and asthma. After adjusting for age, the lifetime prevalence of these 3 diseases was found to be 32% to 67% higher among those who had had measles than among those who had never had the disease.
Specifically, the population-based, cross-sectional study found that the prevalence ratio of atopic symptoms among those who had had measles compared with those who had not was 1.32 for eczema, 1.41 for rhinitis, and 1.67 for asthma. This positive association between measles and atopy was found at all ages, in both urban and rural residents, and among those with both many and few contacts at home or in day care.
"The most important lesson learned from our study is that prevention of infectious diseases is still the number one target in disease prevention," says Paunio. "We should not allow premature or unproven ideas to affect key policies and health targets, however attractive they may be at first glance."
In an editorial that appears in the same issue as the European study, Dr. James Gern from the University of Wisconsin Medical School and Dr. Scott Weiss from Harvard University caution that "it should not be assumed that all infectious diseases have the same effects on the risk for allergies and asthma." They recommend that prospective studies be conducted to evaluate the effect of childhood infections on the development of the immune system.