Supplemental Information associated with the manuscript: A Century of Schistosomiasis Control: An Empirical Evaluation

Despite decades of control effort, human schistosomiasis remains prevalent in many areas of Africa, Asia, and South America. The overall global burden of schistosomiasis has changed little since discovery of the drug of choice, praziquantel, promised widespread control.

We tested the value of large-scale schistosomiasis control attempts over the past century and across the globe, and analyzed factors that predict control program success. To enable an empirical evaluation, we compiled detailed historical information on control tactics and their quantitative outcomes for countries or territories in which: (1) schistosomiasis has been deemed "eliminated," "eradicated," or "no longer endemic," or transmission has been interrupted, or (2) schistosomiasis remains endemic to varying degrees.

Among three main control strategies evaluated: snail control (e.g., molluscicides or biological control), mass drug administrations (MDA) with praziquantel, or a combined strategy using both, control programs using snail control extensively were significantly associated with the greatest success, especially in wealthier countries and when control began earlier in the 20th century.

Our data support the hypothesis that intensive snail control has been the most effective way to reduce schistosomiasis prevalence. Despite the historical success of snail control for long-term disease reduction and elimination, most current schistosomiasis control efforts focus on immediate human health outcomes and mass drug administration of a cheap and effective drug, praziquantel. These results suggest that by complementing contemporary drug-based control programs with affordable snail control, global elimination of schistosomiasis might come within reach.