Schistosoma mansoni-specific immune responses and allergy in Uganda.

Low allergy-related disease (ARD) prevalence in low-income countries may be partly attributed to helminth infections. In the Schistosoma mansoni (Sm)-endemic Lake Victoria islands (Uganda), we recently observed positive helminth-allergy associations, despite low ARD prevalence. To understand how Sm-induced cytokine and antibody profiles might influence allergic response profiles in this population, we assessed Schistosoma worm (SWA)- and egg antigen (SEA)-specific Th1 (IFN-γ), Th2 (IL-5, IL-13) and regulatory (IL-10) cytokine profiles (n = 407), and total (n = 471), SWA-, SEA- and allergen (house dust mite [HDM] and cockroach)-specific (as)IgE and IgG4 profiles (n = 2117) by ELISA. Wheeze was inversely associated with SWA-specific IFN-γ (P < .001) and IL-10 (P = .058), and SEA-specific IL-5 (P = .004). Conversely, having a detectable asIgE response was positively associated with SWA-specific IL-5 (P = .006) and IL-10 (P < .001). Total, SWA-, SEA- and allergen-specific IgE and IgG4 responses were higher among Sm Kato-Katz positive (SmKK+) and skin prick test (SPT)+ individuals compared to SmKK- and SPT- individuals. However, total and asIgG4/IgE ratios were lower among SPT+ and wheezing individuals. We conclude that, in this population, helminth-induced antibody and cytokine responses may underlie individual positive helminth-atopy associations, while the overall IgG4-IgE balance may contribute to the low overall prevalence of clinical allergies in such settings.

Helminths are positively associated with atopy and wheeze in Ugandan fishing communities: results from a cross-sectional survey.

BACKGROUND: Parasitic helminths are potent immunomodulators and chronic infections may protect against allergy-related disease and atopy. We conducted a cross-sectional survey to test the hypothesis that in heavily helminth-exposed fishing villages on Lake Victoria, Uganda, helminth infections would be inversely associated with allergy-related conditions. METHODS: A household survey was conducted as baseline to an anthelminthic intervention trial. Outcomes were reported wheeze in last year, atopy assessed both by skin prick test (SPT) and by the measurement of allergen-specific IgE to dust mites and cockroach in plasma. Helminth infections were ascertained by stool, urine and haemoparasitology. Associations were examined using multivariable regression. RESULTS: Two thousand three hundred and sixteen individuals were surveyed. Prevalence of reported wheeze was 2% in under-fives and 5% in participants ≥5 years; 19% had a positive SPT; median Dermatophagoides-specific IgE and cockroach-specific IgE were 1440 and 220 ng/ml, respectively. S. mansoni, N. americanus, S. stercoralis, T. trichiura, M. perstans and A. lumbricoides prevalence was estimated as 51%, 22%, 12%, 10%, 2% and 1%, respectively. S. mansoni was positively associated with Dermatophagoides-specific IgE [adjusted geometric mean ratio (aGMR) (95% confidence interval) 1.64 (1.23, 2.18)]; T. trichiura with SPT [adjusted odds ratio (aOR) 2.08 (1.38, 3.15)]; M. perstans with cockroach-specific IgE [aGMR 2.37 (1.39, 4.06)], A. lumbricoides with wheeze in participants ≥5 years [aOR 6.36 (1.10, 36.63)] and with Dermatophagoides-specific IgE [aGMR 2.34 (1.11, 4.95)]. No inverse associations were observed. CONCLUSIONS: Contrary to our hypothesis, we found little evidence of an inverse relationship between helminths and allergy-related outcomes, but strong evidence that individuals with certain helminths were more prone to atopy in this setting.