Epidemiology of helminth infections: implications for parasite control programmes, a South African perspective

Objectives., To determine the epidemiology of helminthic infections and the efficacy of parasite treatment among rural South African primary school children in the province of KwaZulu-Natal. To assess the South African government's parasite control policy. Methods: The study recruited 268 school children, aged 8 to 10, and randomly allocated them into treatment and placebo groups (treatment consisted of a single dose of albendazole (400 mg) and praziquantel (40 mg/kg)). Anthropometric measurements and the prevalence and intensity of helminth infections were taken at baseline (prior to treatment) and 16 weeks post treatment. Two weeks after treatment prevalence and intensity were again measured for an approximate 50% sub-sample of the children to investigate efficacy of treatment. An analysis of the South African government's policies concerning parasite control is assessed in the light of these epidemiological findings. Results: Low levels of both stunting and wasting were observed throughout the study (approximately 10% and 1%, respectively), but did not vary significantly across either treatment group or time period (P > 0.50). At baseline the observed prevalences for the three main helminths found in this study among the treated children were Ascaris lumbricoides 29.5%, Trichuris trichiura 51.9% and Schistosoma haematobium 22.3%. These prevalences declined significantly to 4.7% (P < 0.0005), 38.0% (P < 0.03) and 3.3% (P < 0.0002), respectively, 16 weeks post treatment. The majority of infections observed at baseline were of light intensity, namely A. lumbricoides (50%), T. trichiura (80%) and S. haematobium (100%), and following treatment these levels were reduced significantly (P < 0.0001, P < 0.05 and P < 0.005, respectively). The levels of both prevalence and intensity in the untreated group remained constant. The cure rates over the first two weeks of the study were found to be 94.4% for A. lumbricoides, 40% for T. trichiura and 72.2% for S. haematobium. Conclusion: The benefits of targeted, school-based treatment in reducing the prevalence and intensity of infection supports the South African government's focus of using school-based interventions as part of an integrated parasite control programme. These strategies and programmes are consistent with recommendations of the World Health Organization (WHO) and The United Nations Children's Fund (UNICEF).