Abstract
BackgroundMass drug administration (MDA) for lymphatic filariasis (LF) programs has delivered more than 2 billion treatments of albendazole, in combination with either ivermectin or diethylcarbamazine, to communities co-endemic for soil-transmitted helminthiasis (STH), reducing the prevalence of both diseases. A transmission assessment survey (TAS) is recommended to determine if MDA for LF can be stopped within an evaluation unit (EU) after at least five rounds of annual treatment. The TAS also provides an opportunity to simultaneously assess the impact of these MDAs on STH and to determine the frequency of school-based MDA for STH after community-wide MDA is no longer needed for LF.Methodology/Principal FindingsPilot studies conducted in Benin and Tonga assessed the feasibility of a coordinated approach. Of the schools (clusters) selected for a TAS in each EU, a subset of 5 schools per STH ecological zone was randomly selected, according to World Health Organization (WHO) guidelines, for the coordinated survey. In Benin, 519 children were sampled in 5 schools and 22 (4.2%) had STH infection (A. lumbricoides, T. trichiura, or hookworm) detected using the Kato-Katz method. All infections were classified as light intensity under WHO criteria. In Tonga, 10 schools were chosen for the coordinated TAS and STH survey covering two ecological zones; 32 of 232 (13.8%) children were infected in Tongatapu and 82 of 320 (25.6%) in Vava'u and Ha'apai. All infections were light-intensity with the exception of one with moderate-intensity T. trichiura.ConclusionsSynchronous assessment of STH with TAS is feasible and provides a well-timed evaluation of infection prevalence to guide ongoing treatment decisions at a time when MDA for LF may be stopped. The coordinated field experiences in both countries also suggest potential time and cost savings. Refinement of a coordinated TAS and STH sampling methodology should be pursued, along with further validation of alternative quantitative diagnostic tests for STH that can be used with preserved stool specimens.
Highlights
Soil-transmitted helminthiasis (STH) is a neglected tropical disease (NTD) that characteristically affects the poorest individuals in developing nations
Refinement of a coordinated transmission assessment survey (TAS) and soil-transmitted helminthiasis (STH) sampling methodology should be pursued, along with further validation of alternative quantitative diagnostic tests for STH that can be used with preserved stool specimens
The TAS provides an opportune platform to simultaneously conduct STH assessments and make informed programmatic decisions about STH control. Through piloting this coordinated TAS and STH survey approach in Benin and Tonga, we found that after 5–6 rounds of annual mass drug administration (MDA), STH prevalence was 4.2% in Benin and 13.8–25.6% in Tonga
Summary
Soil-transmitted helminthiasis (STH) is a neglected tropical disease (NTD) that characteristically affects the poorest individuals in developing nations. 890 million children worldwide reside in STH-endemic areas and are at risk of STHrelated anemia, malnutrition, and impaired physical and cognitive development [1]. To reduce this morbidity, the World Health Organization (WHO) recommends preventive chemotherapy (PC), mass drug administration (MDA) of anthelminthic drugs to school-aged children and other at-risk individuals. Program to Eliminate Lymphatic Filariasis (GPELF) has delivered some 2 billion treatments of PC that includes albendazole donated by GlaxoSmithKline [2]. Mass drug administration (MDA) for lymphatic filariasis (LF) programs has delivered more than 2 billion treatments of albendazole, in combination with either ivermectin or diethylcarbamazine, to communities co-endemic for soil-transmitted helminthiasis (STH), reducing the prevalence of both diseases.
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