Factors associated with the performance and cost-effectiveness of using lymphatic filariasis transmission assessment surveys for monitoring soil-transmitted helminths: a case study in Kenya.

Jennifer L Smith,Jimmy Kihara,Hugh J W Sturrock,Sammy M Njenga,Birgit Nikolay,Charles S Mwandawiro,Simon J Brooker,Liya Assefa

doi:10.4269/ajtmh.14-0435

Jennifer L Smith, Jimmy Kihara + Show 6 more

Open Access

https://doi.org/10.4269/ajtmh.14-0435

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Abstract

Transmission assessment surveys (TAS) for lymphatic filariasis have been proposed as a platform to assess the impact of mass drug administration (MDA) on soil-transmitted helminths (STHs). This study used computer simulation and field data from pre- and post-MDA settings across Kenya to evaluate the performance and cost-effectiveness of the TAS design for STH assessment compared with alternative survey designs. Variations in the TAS design and different sample sizes and diagnostic methods were also evaluated. The district-level TAS design correctly classified more districts compared with standard STH designs in pre-MDA settings. Aggregating districts into larger evaluation units in a TAS design decreased performance, whereas age group sampled and sample size had minimal impact. The low diagnostic sensitivity of Kato-Katz and mini-FLOTAC methods was found to increase misclassification. We recommend using a district-level TAS among children 8–10 years of age to assess STH but suggest that key consideration is given to evaluation unit size.

Highlights

The three main species of soil-transmitted helminths (STHs), Ascaris lumbricoides, Trichuris trichiura, and hookworm, are responsible for an estimated loss of 5.18 million disability-adjusted life years.[1]
We investigate the impact of varying design parameters, including the age range of sampled children and size of the evaluation unit, on performance and compare the results to standard survey designs recommended by the World Health Organization (WHO)
This study has provided the first assessment of the impact of these operational choices on performance using computerized simulations, providing the means to compare a full range of designs in a realistic epidemiological context

Summary

Introduction

The three main species of soil-transmitted helminths (STHs), Ascaris lumbricoides, Trichuris trichiura, and hookworm, are responsible for an estimated loss of 5.18 million disability-adjusted life years.[1]. Current guidelines for lymphatic filariasis (LF) elimination programs recommend that transmission assessment surveys (TAS) are conducted in areas, which have achieved five rounds of community-based deworming with albendazole exceeding 65% coverage.[5] These surveys seek to 1) initially determine whether transmission has been reduced to a level so that deworming activities through communities or schools can be discontinued, and 3 years after cessation of community-based deworming to 2) evaluate potential re-emergence of transmission.[5] As albendazole is effective against both LF and STH it has recently been proposed to integrate STH surveillance into the TAS to evaluate the impact of LF programs on STH, and guide the transition from community-based deworming for LF control to school-based

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