Helminth infection does not reduce risk for chronic inflammatory disease in a population-based cohort study.

BACKGROUND & AIMS: Parasitic helminth infections can suppress symptoms of allergy, type 1 diabetes, arthritis, and inflammatory bowel disease in animal models. We analyzed data from a large, population-based cohort study to determine whether common childhood enterobiasis protects against these diseases.

METHODS: We collected information on individual prescriptions filled for the drug mebendazole against Enterobius vermicularis for all children born in Denmark 1995-2008 from the National Register of Medicinal Product Statistics (n = 924,749; age 0-14 years); 132,383 of these children (14%) filled a prescription for mebendazole, 102,482 of the children (11%) had a household peer who was registered with a filled mebendazole prescription, and the remaining 689,884 children (75%) comprised the reference group. Children diagnosed with asthma, type 1 diabetes, juvenile arthritis, ulcerative colitis, or Crohn's disease were identified from the National Patient Registry. We used Poisson regression to estimate confounder-adjusted incidence rate ratios for first in- or outpatient hospital diagnosis of chronic inflammatory disease according to history of mebendazole treatment prescribed to children in the study.

RESULTS: Chronic inflammatory disease was diagnosed in 10,352 children during 6.4 million person-years of follow-up. The incidence rate ratios was 1.07 for asthma (95% confidence interval [CI]: 1.00-1.13), 1.05 for type 1 diabetes (95% CI: 0.79-1.12), 1.13 for juvenile arthritis (95% CI: 0.94-1.37), 0.77 for ulcerative colitis (95% CI: 0.41-1.46), and 1.44 for Crohn's disease (95% CI: 0.82-2.53). Results were not modified by number of treatments or age at treatment.

CONCLUSIONS: Based on a population-based analysis, enterobiasis does not reduce risk for asthma, type 1 diabetes, arthritis, or inflammatory bowel disease.