School-based preventive chemotherapy program for schistosomiasis and soil-transmitted helminth control in Angola: 6-year impact assessment

BackgroundA school preventive chemotherapy (PC) program for soil-transmitted helminths (STHs) and schistosomiasis has operated in Huambo, Uige and Zaire provinces, Angola, since 2013 and 2014, respectively; complemented by a school water, sanitation and hygiene (WASH) program in a subset of schools from 2016. Conducted in 2021, this is the first impact assessment of the school program for the control of schistosomiasis and STHs. Methodology/Principal findingsA two-stage cluster design was used to select schools and schoolchildren for parasitological and WASH surveys. The rapid diagnostic tests (RDTs), point of care circulating cathodic antigen (POC-CCA) and Hemastix, were used to estimate Schistosoma mansoni and Schistosoma haematobium prevalence, respectively. Kato Katz was used to detect STHs, and quantify STH and S. mansoni infections. Urine filtration was used to quantify S. haematobium infections. Prevalence, infection intensity, relative prevalence reduction and egg reduction rates were calculated for schistosomiasis and STHs. Cohen's Kappa co-efficient was used to assess agreement between RDTs and microscopy. Chi-square or Fisher's exact test was used to compare WASH indicators in WASH-supported and WASH-unsupported schools.Overall, 17,880 schoolchildren (599 schools) and 6,461 schoolchildren (214 schools) participated in the schistosomiasis and STH surveys, respectively. Prevalence of any schistosomiasis in Huambo was 29.6%, Uige 35.4%, and Zaire 28.2%. Relative reduction in schistosomiasis prevalence from 2014 for Huambo was 18.8% (95% confidence interval (CI) 8.6, 29.0), Uige -92.3% (95%CI -162.2, -58.3), and Zaire -14.0% (95%CI -48.6, 20.6). Prevalence of any STH in Huambo was 16.3%, Uige 65.1%, and Zaire 28.2%. Relative reduction in STH prevalence for Huambo was -28.4% (95%CI -92.1, 35.2), Uige -10.7% (95%CI -30.2, 8.8), and Zaire -20.9% (95%CI -79.5, 37.8). A higher proportion of WASH-supported schools had improved water sources, and toilet and handwashing facilities compared to WASH-unsupported schools. Conclusions/SignificanceThe limited impact this school program has had in controlling schistosomiasis and STHs identifies the need for a comprehensive understanding of individual, community, and environmental factors associated with transmission, and consideration for a community-wide control program. Author summarySchistosomiasis and soil-transmitted helminths (STHs) have long been recognized as public health problems in Angola, including Huambo, Uige and Zaire provinces. To address these neglected tropical diseases, the Angolan Ministry of Health, in conjunction with the MENTOR Initiative and END Fund have been implementing school preventive chemotherapy (PC) from 2013 for STHs and 2014 for schistosomiasis. Additionally, the school PC program has been complemented by a school WASH program in a subset of schools from 2016. To assess the impact of the school program on the prevalence and burden of schistosomiasis and STHs, parasitological surveys were conducted in 2021 that included 17,880 schoolchildren from 599 schools in the schistosomiasis survey and 6,461 schoolchildren from 214 schools in the STH survey. Access and use of WASH interventions was also assessed via questionnaires for each school participating in the parasitological surveys, and compared between WASH supported and unsupported schools. When compared to the results of the 2014 survey there has been limited reduction in the prevalence of schistosomiasis and STHs across the three provinces. A higher proportion of schools that received WASH support provided schoolchildren with better WASH conditions.

Automated summary

A school PC program for STHs and schistosomiasis has been implemented in Huambo, Uige, and Zaire provinces, Angola since 2013 and 2014. The first impact assessment conducted in 2021 showed limited reduction in the prevalence of schistosomiasis and STHs across the three provinces.