Impact of community-based integrated mass drug administration on schistosomiasis and soil-transmitted helminth prevalence in Togo

Abstract

Background

Togo has conducted annual, integrated, community-based mass drug administration (MDA) for soil-transmitted helminths (STH) and schistosomiasis since 2010. Treatment frequency and target populations are determined by disease prevalence, as measured by baseline surveys in 2007 and 2009, and WHO guidelines. Reported programmatic treatment coverage has averaged over 94%. Togo conducted a cross-sectional survey in 2015 to assess the impact of four to five years of MDA on these diseases.

Methodology/Principal findings

In every sub-district in the country outside the capital, the same schools were visited as at baseline and a sample of fifteen children age 6 to 9 years old was drawn. Each child submitted urine and a stool sample. Urine samples were tested by dipstick for the presence of blood as a proxy measure of Schistosoma haematobium infection. Stool samples were analyzed by the Kato-Katz method for STH and Schistosoma mansoni. At baseline, 17,100 children were enrolled at 1,129 schools in 562 sub-districts; in 2015, 16,890 children were enrolled at the same schools. The overall prevalence of both STH and schistosomiasis declined significantly, from 31.5% to 11.6% for STH and from 23.5% to 5.0% for schistosomiasis (p<0.001 in both instances). Egg counts from both years were available only for hookworm and S. mansoni; intensity of infection decreased significantly for both infections from 2009 to 2015 (p<0.001 for both infections). In areas with high baseline prevalence, rebound of hookworm infection was noted in children who had not received albendazole in the past 6 months.

Conclusions/Significance

After four to five years of MDA in Togo, the prevalence and intensity of STH and schistosomiasis infection were significantly reduced compared to baseline. Data on STH indicate that stopping MDA in areas with high baseline prevalence may result in significant rebound of infection. Togo’s findings may help refine treatment recommendations for these diseases.

Author summary

Mass drug administration (MDA) is a key component of programs aimed at controlling soil-transmitted helminths (STH) and schistosomiasis, diseases that disproportionately impact individuals in developing countries and adversely affect physical and cognitive development. The World Health Organization recommends evaluating the impact of mass drug administration on the prevalence of these infections after five years of MDA. We present here a study of the impact of four to five years of MDA on the prevalence and intensity of STH and schistosomiasis infections in school children in Togo. The prevalence and intensity of these infections in 2015 were significantly reduced compared to a baseline survey conducted in 2009. Local baseline prevalence in 2009 was the strongest predictor of infection in 2015. These infections are more prevalent in boys than in girls, and in older versus younger children. We found that in areas with high baseline prevalence of hookworm the risk of rebound of infection is high among children who do not receive bi-annual treatment. This information is important for programs weighing the decision to stop MDA in areas where prevalence has been reduced through treatment. This and other findings from this study may help refine treatment recommendations for these diseases.