Anti-<b><i>Ascaris</i></b> IgE as a Risk Factor for Asthma Symptoms among 5-Year-Old Children in Rural Bangladesh with Even Decreased <b><i>Ascaris</i></b> Infection Prevalence

Abstract

<b><i>Background:</i></b> Epidemiological studies have indicated that anti-<i>Ascaris</i> IgE enhances asthma and allergies under specific conditions although the association between them is still controversial. The association of anti-<i>Ascaris</i> IgE with increased asthma symptoms among children from a general population with a mild to moderate <i>Ascaris</i> infection prevalence was investigated. <b><i>Methods:</i></b> A total of 126 children aged 5 years with wheezing during the previous year and 110 children who did not have wheezing were selected randomly from the rural service area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Serum levels of total, anti-<i>Ascaris</i>, anti-<i>Dermatophagoides pteronyssinus</i>, and anti-cockroach IgEs were tested, and their risks for wheezing were analyzed. The wheezing children were then classified by hierarchical cluster analysis to investigate the contribution of anti-<i>Ascaris</i> IgE to wheezing. <b><i>Results:</i></b> The anti-<i>Ascaris</i> IgE levels in wheezing and never-wheezing children were 1.07 and 0.65 U_A/mL, and it contributed to 11% of wheezing in children. Anti-<i>Ascaris</i> IgE was significantly associated with wheezing (odds ratio [OR] per log_e increment: 1.37 [95% CI: 1.01–1.87], <i>p</i> = 0.046). The ORs, which were adjusted for sex, parental asthma, pneumonia history, helminth infections, <i>Haemophilus influenzae</i> type B combination vaccination, antibiotic use during infancy, and total and specific IgE levels, increased even when only children with more specific symptoms of asthma were included in the analysis. Namely, the ORs for wheezing with sleep disturbance, four or more attacks, and wheezing with speech difficulties during the previous 1 year were OR = 1.44/log_e increment [95% CI: 1.01–2.07], OR = 1.90/log_e increment [95% CI: 1.11–3.25], and OR = 1.78/log_e increment [95% CI: 1.01–3.14], respectively. <b><i>Conclusions:</i></b> The anti-<i>Ascaris</i> IgE levels in wheezing and never-wheezing children in the current study significantly decreased concurrently with <i>Ascaris</i> infection prevalence compared with their corresponding values in 2001. The contribution of anti-<i>Ascaris</i> IgE to wheezing also dropped from 26% in 2001 to 11% in the current study. Despite significant decreases in the levels and the seroprevalence and its contribution to wheezing, anti-<i>Ascaris</i> IgE remained significantly associated with increased risk of wheezing. Anti-<i>Ascaris</i> IgE significantly increased the risk of wheezing in a general population with a mild to moderate <i>Ascaris</i> infection prevalence, suggesting robustness as a risk factor and a possible dose-response relationship.