Cost of interventions to control schistosomiasis: A systematic review of the literature

Background: Schistosomiasis, a disease caused by blood flukes of the genus Schistosoma, belongs to the neglected tropical diseases. Left untreated, schistosomiasis can lead to severe health problems and even death. An estimated 800 million people are at risk of schistosomiasis and 250 million people are infected. The global strategy to control and eliminate schistosomiasis emphasizes large-scale preventive chemotherapy with praziquantel targeting school-age children. Other tools are available, such as information, education, and communication (IEC), improved access to water, sanitation, and hygiene (WASH), and snail control. Despite available evidence of the effectiveness of these control measures, analyses estimating the most cost-effective control or elimination strategies are scarce, inaccurate, and lack standardization. We systematically reviewed the literature on costs related to public health interventions against schistosomiasis to strengthen the current evidence-base. Methodology: In adherence to the PRISMA guidelines, we systematically searched three readily available electronic databases (i.e., PubMed, WHOLIS, and ISI Web of Science) from inception to April 2019 with no language restrictions. Relevant documents were screened, duplicates eliminated, specific rules on studies to consider were defined, and the eligible studies fully reviewed. Costs of schistosomiasis interventions were classified in three groups: (i) preventive chemotherapy; (ii) preventive chemotherapy plus an individual diagnostic test to identify at-risk population; and (iii) test-and-treat interventions. Principal findings: Fifteen articles met our inclusion criteria. In general, it was hard to compare the reported costs from the different studies due to different approaches used to estimate and classify the costs of the intervention assessed. Costs varied considerably from one study to another, ranging from US$ 0.06 to US$ 4.46 per person treated. The difference between financial and opportunity costs only played a minimal role in the explanation of the costs’ variation, even if delivery costs were two times higher in the analyses including economic costs. Most of the studies identified in our systematic review focused on sub-Saharan African countries. Conclusions/Significance: The degree of transparency of most of the costing studies of schistosomiasis interventions found in the current review was limited. Hence, there is a pressing need for strategies to improve the quality of cost analyses, and higher reporting standards and transparency that should be fostered by peer-review journal policies. Cost information on these interventions is crucial to inform resource allocation decisions and those regarding the affordability of scaling-up interventions. Author summary: Schistosomiasis is one of about 20 neglected tropical diseases. It affects millions of people mainly in poor settings in African countries. The global strategy to control and eliminate schistosomiasis emphasizes large-scale preventive chemotherapy with praziquantel targeting school-age children. Evidence of the effectiveness of these control measures is largely available, while less is known about the costs of their implementation. We systematically reviewed the literature and analyzed studies that estimated costs of schistosomiasis interventions. We summarized the available evidence in three intervention groups: (i) preventive chemotherapy; (ii) preventive chemotherapy plus an individual diagnostic test to identify at-risk population; and (iii) test-and-treat interventions. Costs were overall hard to compare and varied considerably from one study to another. There is a need for higher reporting standards and transparency that should be fostered by peer-review journal policies. Cost information on these interventions is crucial to inform resource allocation decisions and those regarding the affordability of scaling-up interventions.