Patterns of Schistosoma haematobium infection, impact of praziquantel treatment and re-infection after treatment in a cohort of schoolchildren from rural KwaZulu-Natal/South Africa.

Elmar Saathoff,Chris C Appleton,Wilhelm Becker,Jane D Kvalsvig,Annette Olsen,Pascal Magnussen

doi:10.1186/1471-2334-4-40

Abstract

BackgroundSchistosomiasis is one of the major health problems in tropical and sub-tropical countries, with school age children usually being the most affected group. In 1998 the Department of Health of the province of KwaZulu-Natal established a pilot programme for helminth control that aimed at regularly treating primary school children for schistosome and intestinal helminth infections. This article describes the baseline situation and the impact of treatment on S. haematobium infection in a cohort of schoolchildren attending grade 3 in a rural part of the province.MethodsPrimary schoolchildren from Maputaland in northern KwaZulu-Natal were examined for Schistosoma haematobium infection, treated with praziquantel and re-examined four times over one year after treatment in order to assess the impact of treatment and patterns of infection and re-infection.ResultsPraziquantel treatment was highly efficacious at three weeks after treatment when judged by egg reduction rate (95.3%) and cure rate of heavy infections (94.1%). The apparent overall cure rate three weeks after treatment (57.9%) was much lower but improved to 80.7% at 41 weeks after treatment. Re-infection with S. haematobium was low and appeared to be limited to the hot and rainy summer. Analysis of only one urine specimen per child considerably underestimated prevalence when compared to the analysis of two specimens, but both approaches provided similar estimates of the proportion of heavy infections and of average infection intensity in the population.ConclusionAccording to WHO guidelines the high prevalence and intensity of S. haematobium infection necessitate regular treatment of schoolchildren in the area. The seasonal transmission pattern together with the slow pace of re-infection suggest that one treatment per year, applied after the end of summer, is sufficient to keep S. haematobium infection in the area at low levels.

Highlights

Schistosomiasis is one of the major health problems in tropical and sub-tropical countries, with school age children usually being the most affected group
The schistosomiasis endemic area in South Africa is situated in the northeast and covers roughly one quarter of the country, with Schistosoma haematobium being the most common species [2]
School age children usually present with the highest prevalence and intensity of S. haematobium infection [8]

Summary

Introduction

Schistosomiasis is one of the major health problems in tropical and sub-tropical countries, with school age children usually being the most affected group. In 1998 the Department of Health of the province of KwaZulu-Natal established a pilot programme for helminth control that aimed at regularly treating primary school children for schistosome and intestinal helminth infections. Schistosomiasis is one of the major health problems in tropical and sub-tropical countries [1]. The schistosomiasis endemic area in South Africa is situated in the northeast and covers roughly one quarter of the country, with Schistosoma haematobium being the most common species [2]. School age children usually present with the highest prevalence and intensity of S. haematobium infection [8]. Negative health consequences are not limited to this group since high intensity infections can cause serious chronic disease long after initial infection [9]. Some studies suggest that schistosomiasis may play a role as a risk factor for HIV infection and that helminth infections in general negatively affect the immune system of HIV infected persons [10,11]

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