Cost-effectiveness of mass drug administration with ivermectin against strongyloidiasis: a modelling study

Background Strongyloidiasis, caused by the parasitic intestinal worm Strongyloides stercoralis , infects hundreds of millions of people globally. Current school-based preventive chemotherapy (PC) programs that use benzimidazole derivatives (e.g., albendazole) against soil-transmitted helminths do not effectively treat strongyloidiasis, which requires treatment with ivermectin. We estimate the cost-effectiveness of mass drug administration with ivermectin for the control of strongyloidiasis. Methods We developed a mathematical model to simulate the population dynamics of S. stercoralis and the impact of school-based and community-wide PC across a range of epidemiological settings. We simulated 10-year PC programs with varying treatment coverages. We estimated a primary outcome of disability-adjusted life years (DALYs) averted by each PC strategy and calculate the programmatic cost (US$) of each strategy. We estimated cost-effectiveness by comparing strategies by their incremental cost-effectiveness ratios (US$/averted DALY) and expected loss curves. Findings The model found community-based PC was the most cost-effective strategy (≤600 US$ / DALY averted), despite costing approximately 5 times as much as school-based PC. Community-based PC targeted at ages 5 and above reduced infection levels close to 0% within 5 to 6 years. School-based PC was predicted to have very little impact. These results were robust across a range of epidemiologic settings above a measured prevalence of 2-5% in school age children. Interpretation Annual community-based PC is the most cost-effective public health strategy to control strongyloidiasis, being superior to school-based PC due to most of the infections and mortality occurring in adults. A baseline prevalence of 2% of infection in school age children, as measured by Baermann or stool culture, is a suitable minimum threshold for cost-effective implementation of community-based PC. Funding World Health Organization. ### Competing Interest Statement NCL reports consulting fees from the World Health Organization related to guidelines on strongyloidiasis. ### Funding Statement The research described here was performed as part of an Agreement for Performance of Work between Erasmus MC, University Medical Center Rotterdam, The Netherlands and the World Health Organization, Geneva, Switzerland under WHO Registration 2023/1339288-1 and WHO Purchase Order 203102918-1 (awarded to LEC). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data used in this study originate from the public domain (i.e., estimates from published literature) or are available as open-source software. The output data from the simulation model and the code that generated it are available on request and will be made readily and publicly available for the peer-reviewed version of the paper.