Community-wide infection with soil-transmitted helminths in the delta region of Myanmar after long-term mass drug administration

Abstract

Soil-transmitted helminths (STH) infect more than 1.4 billion people. Myanmar, a country in Southeast Asia, has had an STH mass drug administration (MDA) programme since 2003 and has achieved over 75% coverage in school-aged children (SAC) and preschool-aged children since 2006. The aim of this thesis was to assess the impact of expanding MDA to community-wide treatment over the course of one year and examining the impact of MDA on prevalence and intensity of STH. The study was conducted in two villages in the delta region of Myanmar. Three surveys were completed from August 2015 to June 2016, collecting stool samples from 808 participants followed by treatment with albendazole. Stool samples were examined for STH infection by the Kato-Katz (KK) technique. Samples from the third survey were tested by quantitative PCR (qPCR) for STH infection. At the first survey, prevalence of infection with any STH was 27.81%, peaking at 36.08% in SAC. Trichuris trichiura was the most prevalent STH at 18.12%. There was also a large burden of infection with hookworm and T. trichiura in the adult populations. Examining stool samples from participants who had a KK result and stored stool for qPCR, prevalence of any STH, by KK, had decreased to 20.64%. However, prevalence at the third survey by qPCR was 45.06%, indicating that KK has lower sensitivity for STH infection than qPCR. There was evidence for individual predisposition of infection between study rounds. This study highlights the need for expanded monitoring and evaluation activities for STH in all areas that are considering a change in MDA policy, particularly in areas that may be shifting their goals from control to interruption of transmission. Infection in adults needs to be considered as well as the possible underestimation of prevalence by using solely the KK method.