Effect of helminthic infections together with mite allergen exposure on the risk of wheeze in preschool children.

Although some studies have indicated that helminthic infections and house dust mite exposure may have an alleviating effect on wheeze, an interaction effect of both risk factors has not been examined in Thailand. The objective of this study was to investigate whether exposure to helminthic infections together with house dust mite allergen was associated with wheeze in children aged 18-36 months, living in an area of southem Thailand where helminthic infections are endemic. This study was undertaken as a part of The Prospective Cohort Study of Thai Children which recruited 1,076 children born between December 2000 and November 2001. A home dust sample was collected once when the infants were 12-18 months old to measure house dust mite allergen (Der p1). Questionnaire data on wheeze and a stool specimen for soil-transmitted helminth analysis were collected at age 18-36 months. Prevalence of exposure to house dust mite allergen (Der p1) > 10 microg/g dust was 31.8%. Soil-transmitted helminths were present in 25.0%, predominately Ascaris lumbricoides. Hookworm infection was associated with a physician's diagnosis of wheeze (OR 4.20, 95% CI 1.45-12.10) and hospitalized wheeze (OR 5.40, 95% Cl 1.26-23.01). Hospitalized wheeze was significantly higher in subjects exposed to Der p1 2-10 microg/g dust. Helminthic infections were not associated with a significant interaction effect with mite allergen against a risk of wheeze. Our survey confirms that hookworm infection and mite allergen exposure are independent risk factors for childhood wheeze and there is no evidence of important interaction between the two.