Environmental and Occupational DisordersReduced risk of atopy among school-age children infected with geohelminth parasites in a rural area of the tropics☆,☆☆
Section snippets
Study population
The study area covered schools (for children aged 5-19 years) in the Districts of Pedro Vicente Maldonado, Puerto Quito, and Los Bancos in Pichincha Province. The area is a subtropical-tropical rain forest at altitudes of 200 to 1100 meters above sea level. All 55 schools included in the study served rural communities that ranged in size from approximately 100 to 3000 individuals. All children attending the schools were eligible to participate. Informed verbal consent was obtained from the
Results
Stool and skin test examinations were performed on samples from 2865 (88.2%) subjects of a total eligible school population of 3249 attending 55 schools. The main reason for nonparticipation was failure to provide a stool sample (366 [95.3%] of 384 nonparticipants). There were only slight differences in the mean age (10.3 vs 10.6 years), sex distribution (boys 46.9% vs girls 52.5%), prevalence of recent anthelmintic treatment (63.4% vs 63.6%), and prevalence of atopy (21.9% vs 22.4%) between
Discussion
The results of our cross-sectional study indicate that current infections with geohelminths are protective against allergen skin test reactivity. To our knowledge, this is the first large study to show a protective effect among school-age children living in an endemic rural area. A strong protective effect was observed for the presence of any of the 3 locally endemic geohelminth parasites (A lumbricoides , T trichiura , and A duodenale ) after controlling for the effects of age, sex, recent
Acknowledgements
We thank David Gaus, Carlos Burneo, and Carlos Sandoval for help in choosing the field site and setting up a field laboratory, for facilitating approval of the study through local Ministry of Health offices, and for their long-term collaborative support through the foundation Salud y Desarollo Andino (SALUDESA). We also thank Martin Chapman for his helpful advice and assistance at the start of the study and Ms Brenda Rae Marshall for help in preparing this manuscript.
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Cited by (0)
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Supported in part by the Wellcome Trust.
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Reprint requests: Thomas B. Nutman, MD, LPD, NIAID, 4 Center Drive, Room 4/126, NIH, Bethesda, MD 20892.