Schistosome infection is negatively associated with mite atopy, but not wheeze and asthma in Ghanaian schoolchildren

Clin Exp Allergy. 2014 Jul;44(7):965-75. doi: 10.1111/cea.12307.

Abstract

Background: Epidemiological evidence suggests that helminth infection and rural living are inversely associated with allergic disorders.

Objective: The aim of the study was to investigate the effect of helminth infections and urban versus rural residence on allergy in schoolchildren from Ghana.

Methods: In a cross-sectional study of 1385 children from urban-high socio-economic status (SES), urban-low SES and rural schools, associations between body mass index (BMI), allergen-specific IgE (sIgE), parasitic infections and allergy outcomes were analysed. Allergy outcomes were skin prick test (SPT) reactivity, reported current wheeze and asthma.

Results: Helminth infections were found predominantly among rural subjects, and the most common were hookworm (9.9%) and Schistosoma spp (9.5%). Being overweight was highest among urban-high SES (14.6%) compared to urban-low SES (5.5%) and rural children (8.6%). The prevalence of SPT reactivity to any allergen was 18.3%, and this was highest among rural children (21.4%) followed by urban-high SES (20.2%) and urban-low SES (10.5%) children. Overall, SPT reactivity to mite (12%) was most common. Wheeze and asthma were reported by 7.9% and 8.3%, respectively. In multivariate analyses, factors associated with mite SPT were BMI (aOR 2.43, 95% CI 1.28-4.60, P = 0.007), schistosome infection (aOR 0.15, 95% CI 0.05-0.41) and mite sIgE (aOR 7.40, 95% CI 5.62-9.73, P < 0.001) but not area. However, the association between mite IgE and SPT differed by area and was strongest among urban-high SES children (aOR = 15.58, 95% CI 7.05-34.43, P < 0.001). Compared to rural, urban-low SES area was negatively associated with current wheeze (aOR 0.41, 95% CI 0.20-0.83, P = 0.013). Both mite sIgE and mite SPT were significantly associated with current wheeze and asthma.

Conclusion and clinical relevance: Infection with schistosomes appeared to protect against mite SPT reactivity. This needs to be confirmed in future studies, preferably in a longitudinal design where schistosome infections are treated and allergic reactions reassessed.

Keywords: Africa; Schistosoma; allergy; asthma; atopy; body mass index; cockroach; helminth; mite; rural; urban; wheeze.

MeSH terms

  • Adolescent
  • Animals
  • Arachis / adverse effects
  • Asthma / diagnosis
  • Asthma / epidemiology
  • Asthma / etiology*
  • Child
  • Child, Preschool
  • Cockroaches / immunology
  • Female
  • Geography, Medical
  • Ghana / epidemiology
  • Humans
  • Hypersensitivity, Immediate / diagnosis
  • Hypersensitivity, Immediate / epidemiology*
  • Hypersensitivity, Immediate / etiology*
  • Immunoglobulin E / blood
  • Immunoglobulin E / immunology
  • Male
  • Mites / immunology*
  • Odds Ratio
  • Prevalence
  • Respiratory Sounds / diagnosis
  • Respiratory Sounds / etiology*
  • Risk Factors
  • Schistosoma / immunology*
  • Schistosomiasis / complications*
  • Schistosomiasis / epidemiology
  • Skin Tests
  • Surveys and Questionnaires
  • Urban Population

Substances

  • Immunoglobulin E