Soil-transmitted Helminthiases Re-infection Rates in a Thai Village with 100% Latrine

Abstract

Abstract

Five hundred and eighty individuals in a village of houses having 100% latrine in Nakhon Si Thammarat Province were examined for soil-transmitted helminth infections by Katz’s modified thick smear method. It was found that 74.0% (429/580) were infected: 57.9% with hookworm, 62.9% with Trichuris trichiura and 10.2% with Ascaris lumbricoides. The infected cases were treated with 100 mg mebendazole twice daily for 3 consecutive days. Twenty-one days after administration, their stools were re-collected and examined. Uncured cases were treated again. Re-infection rates were assessed at 3, 6, 9 and 12 months after they had been cured by each treatment interval. The percent infection rates of hookworm, T. trichiura and A. lumbricoides were 21.2, 15.6 and 3.0 after 3 months; 10.9, 12.0 and 4.5 after 6 months; 6.0, 11.5 and 2.1 after 9 months; 9.3, 12.9 and 1.5 after 12 months. The cumulative re-infection rates of hookworm, T. trichiura and A. lumbricoides were 47.4, 52.0 and 11.1, respectively. The prevalence of hookworm infection was highest between October and December (rainy season) and lowest between April and June (Summer). The prevalences for T. trichiura and A. lumbricoides infections were similar in each 3-monthly period of the study.

Keywords : soil-transmitted helminth, re-infection rate, prevalence, intensity, latrine, mebendazole