A large study of children in Europe has demonstrated an inverse association between measles infection and development of allergies.
The prevalence of allergic disorders has increased during past decades, coinciding with reduced rates of many childhood infections and increasing use of vaccinations, Helen Rosenlund, at Karolinska Institutet in Stockholm, and co-authors note in the March issue of Pediatrics. However, studies looking for any link between allergy, measles infection, and measles vaccination have run the gamut from showing positive, inverse, and negative associations.
The Prevention of Allergy-Risk Factors for Sensitization in Children Related to Farming and Anthroposophic Lifestyle (PARSIFAL) study included 12,540 children 5 to 13 years of age. According to the investigators, "an anthroposophic lifestyle is characterized by restricted use of antibiotics, antipyretics, and vaccinations, and by high consumption of biodynamic foods."
Questionnaire responses indicated that 73% of children were vaccinated against measles, 20% had been infected with measles, and 14% had neither exposure. Eleven percent of vaccinated children also had had a bout of measles.
Rosenlund's group observed a statistically significant positive association between measles vaccination and rhinoconjunctivitis (not associated with a head cold) among those who never had measles infection.
Among the 3378 children tested for immunoglobulin E, there was a trend towards inverse associations between vaccination, infection, or both, and atopic sensitization.
To reduce bias caused by disease-related modification of exposure, the researchers excluded children with symptoms of wheezing and/or eczema during their first year of life. This analysis showed an inverse association between measles infection and allergy, whereas no association was observed for measles vaccination.
"Most studies on measles vaccination and measles infection in relation to allergic disease have not considered the time sequence of events," the researchers note. They therefore recommend that "causal associations should be further investigated in prospective cohort studies."
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