Epidemiology of soil-transmitted helminths following sustained implementation of routine preventive chemotherapy: Demographics and baseline results of a cluster randomised trial in southern Malawi

Malawi has successfully leveraged multiple delivery platforms to scale-up and sustain the implementation of preventive chemotherapy (PCT) for the control of morbidity caused by soil-transmitted helminths (STH). Sentinel monitoring demonstrates this strategy has been successful in reducing STH infection in school-age children, although our understanding of the contemporary epidemiological profile of STH across the broader community remains limited. As part of a multi-site trial evaluating the feasibility of interrupting STH transmission across three countries, this study aimed to describe the baseline demographics and the prevalence, intensity and associated risk factors of STH infection in Mangochi district, southern Malawi. Between October-December 2017, a community census was conducted across the catchment area of seven primary healthcare facilities, enumerating 131,074 individuals across 124 villages. A cross-sectional parasitological survey was then conducted between March-May 2018 in the censused area as a baseline for a cluster randomised trial. An age-stratified random sample of 6,102 individuals were assessed for helminthiasis by Kato-Katz and completed a detailed risk-factor questionnaire. The age-cluster weighted prevalence of any STH infection was 7.8% (95% C.I. 7.0%-8.6%) comprised predominantly of hookworm species and of entirely low-intensity infections. The presence and intensity of infection was significantly higher in men and in adults. Infection was negatively associated with risk factors that included increasing levels of relative household wealth, higher education levels of any adult household member, current school attendance, or recent deworming. In this setting of relatively high coverage of sanitation facilities, there was no association between hookworm and reported access to sanitation, handwashing facilities, or water facilities. These results describe a setting that has reduced the prevalence of STH to a very low level, and confirms many previously recognised risk-factors for infection. Expanding the delivery of anthelmintics to groups where STH infection persist could enable Malawi to move past the objective of elimination of morbidity, and towards the elimination of STH. Trial registration: NCT03014167.

Completion of Baseline Trachoma Mapping in Malawi: Results of Eight Population-Based Prevalence Surveys Conducted with the Global Trachoma Mapping Project

Purpose: Following a first phase of trachoma mapping in Malawi with the Global Trachoma Mapping Project, we identified and mapped trachoma districts previously suspected to be non-endemic, although adjacent to districts with estimated trachoma prevalences indicating a public health problem.

Methods: We conducted population-based surveys in eight evaluation units (EUs) comprising eight districts in Malawi (total population 3,230,272). A 2-stage cluster random sampling design allowed us to select 30 households from each of 30 clusters per EU; all residents aged 1 year and older in selected households were examined for evidence of trachomatous inflammation–follicular (TF) and trachomatous trichiasis (TT).

Results: None of the eight EUs had a TF prevalence in 1–9-year-olds ≥10%, one district (Dedza) had a TF prevalence between 5.0% and 9.9%, and only one district (Karonga) had a trichiasis prevalence in adults ≥0.2%.

Conclusion: The prevalence of TF and TT in six of eight EUs surveyed was consistent with an original categorization of trachoma being unlikely to be a public health problem. In the absence of formal surveys, health management information system data and other locally available information about trachoma is likely to be useful in predicting areas where public health interventions against trachoma are required.