Age- and Risk-Targeted Control of Schistosomiasis–Associated Morbidity Among Children and Adult Age Groups

For helminth parasites, selection of optimal chemotherapy-based control of infection-related morbidity can take cues from several perspectives. One can focus on limiting intensity of infection or its spread within the community at any given time, and ask for efficient interventions to reduce either type of infectious burden. Alternatively, one can look at the long-term effects of infection and ask for control strategies aimed only at preventing long-term morbidity through structured treatments that vary by age. The latter approach is currently favored for schistosomiasis, where acute infection per se is believed to be less detrimental to health than the cumulative damage caused by long-term heavy infection. Here, we extend earlier approaches to modeling control of late-onset morbidity using age-stratified interventions, and then additionally consider population heterogeneity in terms of subgroups at high and low risk for development of chronic disease. We study the long-term effect age-structured mass therapy applied to the whole population vs. varying coverage for different population age strata. Given different subgroup risks for chronic disease, we also examine the possible utility of pretreatment risk screening towards optimal allocation of treatment resources.