부산대학교 도서관

Mass drug administration (MDA), targeted at school-aged children (SAC) is recommended by the World Health Organization for the control of morbidity induced by soil-transmitted helminth (STH) infection in endemic countries. However, MDA does not prevent reinfection between treatment rounds, and research suggests that only treating SAC will not be sufficient to interrupt transmission of STH. In countries with endemic infection, such as Ethiopia, the coverage, community-groups targeted, and rates of reinfection will determine how effective MDA is in suppressing transmission in the long-term. In this paper, individually-linked longitudinal data from three epidemiological STH surveys conducted between November 2018 and November 2020 in the Wolaita region of Ethiopia are analysed to determine how STH prevalence and intensity changes according to individual level treatment data collected over two rounds of MDA. This study demonstrates that while community-wide MDA successfully reduces overall infection intensity across the villages treated, the observed levels of non-compliance to treatment by individuals acts to maintain levels of parasite abundance whereby transmission interruption is not possible at to, despite reasonable levels of MDA coverage in the communities studied (ranging from 65% to 84% of the village populations). This quantifies with substantial data the often-postulated difference between coverage (accepting treatment) and compliance (swallowing of treatment), the latter impacting the former to a previously unquantified level. The paper highlights the need to focus treatment to partially treated, or never treated groups of individuals within existing community wide MDA control activities to interrupt the transmission of STH, and to reduce the basic reproductive number, R0, of the parasites to less than unity in value. Author summary: Soil-transmitted helminths (STH) are a group of parasites that remain a public health challenge across developing countries. The high number of global infections is ongoing despite significant financial investment in reducing the disease burden in endemic countries. In recent years WHO recommendations have shifted morbidity reduction to the possibility of transmission elimination through MDA and WaSH measures. One concern with attempting this route towards transmission interruption remains the impact that compliance and coverage has on effectiveness of community-wide treatment. The problem of STH reinfection means that a sustainable break in transmission remains difficult to achieve across an entire community. Despite repeated rounds of treatment, non-compliant individuals can shed infective eggs into the environment, essentially exposing treated individuals to become re-infected. This study highlights this problem, despite the overall effectiveness in reducing infection intensity across communities in the study area, prevalence remains at levels that would not indicate transmission interruption. This in part is due to the non-compliant individuals remaining viable reservoirs for infection that will lead to reinfection of that community before repeated round of MDA. This study indicates the importance of understanding treatment compliance and tools to combat the problem in settings where transmission interruption is being sought. [ABSTRACT FROM AUTHOR]