Control programs for strongyloidiasis in areas of high endemicity: an economic analysis of different approaches

Abstract

Background Implementation of control programmes for Strongyloides stercoralis infection is among the targets of the World Health Organization Roadmap to 2030. Aim of this work was to evaluate the possible impact in terms of economic resources and health status of two different strategies of preventive chemotherapy (PC) compared to the current situation (strategy A, no PC): administration of ivermectin to school-age children (SAC) and adults (strategy B) versus ivermectin to SAC only (strategy C). Methods The study was conducted at the IRCCS Sacro Cuore Don Calabria hospital, Negrar di Valpolicella, Verona, Italy, at the University of Florence, Italy, and at the WHO, Geneva, Switzerland, from May 2020 to April 2021. Data for the model were extracted from literature. A mathematical model was developed in Microsoft Excel to assess the impact of strategies B and C in a standard population of 1 million subjects living in a strongyloidiasis endemic area. In a case base scenario, 15% prevalence of strongyloidiasis was considered; the 3 strategies were then evaluated at different thresholds of prevalence, ranging from 5 to 20%. The results were reported as number of infected subjects, deaths, costs, and Incremental-Effectiveness Ratio (ICER). A 1-year and a 10-year horizons were considered. Results In the case base scenario, cases of infections would reduce dramatically in the first year of implementation of PC with both strategy B and C: from 172 500 cases to 77 040 following strategy B and 146 700 following strategy C. The additional cost per recovered person was United States Dollar (USD) 2.83 and USD 1.13 in strategy B and C, respectively, compared to no treatment in the first year. For both strategies, there was a downtrend in costs per recovered person with increasing prevalence. The number of adverted deaths was larger for strategy B than C, but cost to advert one death was lower for strategy C than B. Conclusions This analysis permits to estimate the impact of two PC strategies for the control of strongyloidiasis in terms of costs and adverted infections/deaths. This could represent a basis on which each endemic country can evaluate which strategy can be implemented, based on available funds and national health priorities.

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

“…Our findings contrast those found in a recent cost-effectiveness study which suggested that school-based PC was more cost-effective against strongyloidiasis than community-based PC. 32 The authors performed a Markov-model-like analysis and estimated that the cost per recovered (i.e., infection-free) person was US$1.97 for school-based PC and US$3.43 for community-based PC, and that the cost per averted death for a 10-year time horizon was US$288 (school-based PC) or US$969 for (community-based PC). The key differences in this study that explain the difference in findings include their assumptions that the risk of hyperinfection and death was the same for all ages, whereas this is probably low in children and higher in the elderly.…”

“…These values were based on the expected cost of generic ivermectin prequalified by WHO, as also recently used in a recent cost-effectiveness analysis by Buonfrate et al . 32 In a sensitivity analysis, we also considered the option that drugs would be donated to control programs free of charge.…”

Progress towards the implementation of control programmes for strongyloidiasis in endemic areas: estimation of number of adults in need of ivermectin for strongyloidiasis

“…Furthermore, it should be considered that all infected people are at risk of disseminated strongyloidiasis, in case of immunosuppressant conditions/treatments [21]. Moreover, a population-based approach is expected to achieve a more rapid and deep decrease of the prevalence of infection in the general population than a school-based PC approach [12] (though there is no direct evidence for this).…”

“…MDA at community level, as implemented for example for the control of filarial infections [2,10,11], would have higher costs, because of the need to establish a distribution infrastructure (that in the case of children and STH is already present, actualized in the school-based distribution strategy), but would presumably impact the outcome of the intervention, with a sharper decrease of the prevalence of S. stercoralis infection in the target community [12].…”

Soil-Transmitted Helminths and Anaemia: A Neglected Association Outside the Tropics

“…Due to the chronic nature and life-long persistence in the host of strongyloidiasis, its burden persists several decades after a person has left a disease-endemic area. No public health strategies for controlling the disease are currently active at a global level [ 6 ], but the WHO now recommends a control program for strongyloidiasis; controlling this disease is one of the targets of the WHO Roadmap to 2030 [ 14 ].…”