Material and Method: The study was undertaken as part of the Prospective Cohort Study of Thai Children (PCTC) that followed all births in the year 2001 from rural districts in Thailand. The family histories of allergic diseases were validated by the physicians’ diagnoses and medical record reviews. Fresh stool examinations were carried out at 18 to 36 months of age.

Results: Of 1,076 live births in the cohort, 659 children had complete information. A family history of allergy presented in 5.4% of the children. The prevalence of any helminthic infection, Ascaris lumbricoides, Trichuris trichiura, and hookworm were 25.0%, 18.2%, 9.2%, and 5.3%, respectively. The adjusted odds ratio of a family history of allergy for helminthic infection was 0.28 (95% CI, 0.08-0.95).

Conclusion: A family history of allergic diseases independently increases resistance to helminthic infection.

Keywords: Helminth infections, Allergic family history, Protective effect