High titre of anti-Ascaris immunoglobulin E associated with bronchial asthma symptoms in 5-year-old rural Bangladeshi children

Background: Increasing interest has arisen whether helminthic infections protect against asthma and allergy. The prevalence of wheezing among Bangladeshi children is higher in rural areas where helminthic infectious burden is greater, which is contrary to the general assumption. Objective: We therefore examined the association between Ascaris infection, serum level of anti-Ascaris IgE, which should be investigated differently from the infection, and wheezing in 5-year-old children from rural Bangladesh. Methods: A total of 219 children who reported wheezing during the previous 12 months and 122 randomly selected age-matched individuals who had never experienced wheezing were tested for serum levels of total and specific Ascaris, Dermatophagoides pteronyssinus, alternaria and cockroach IgEs, and for intestinal helminth infection as well. Results: Anti-Ascaris IgE levels were significantly and independently associated with current wheezing during the previous 12 months [odds ratio (OR) per log_e increment is 1.31 (95% confidence interval (CI) 1.08-1.60), P=0.007], a history of at least four episodes of wheezing [OR per log _e increment is 1.52 (95% CI 1.18-1.96), P=0.001], wheezing with sleep disturbances [OR per log_e increment is 1.35 (95% CI 1.10-1.64), P=0.011] and wheezing with speech disturbances [OR per log_e increment is 1.57 (95% CI 1.19-2.08), P=0.001]. These were adjusted for gender, pneumonia history, parental asthma, Trichuris infection, use of dry leaves as fuel and other specific IgE levels. The prevalence of Ascaris infection by the presence of wheezing was not significantly different (76% vs. 72%, respectively). Conclusion: We conclude that a high titre of anti-Ascaris IgE is associated with an increased risk of asthma symptoms among 5-year-old rural Bangladeshi children with a high helminthic infectious load.