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PLoS Negl Trop Dis. 2016 Jul 21;10(7):e0004794. doi: 10.1371/journal.pntd.0004794. eCollection 2016 Jul.

Global Assessment of Schistosomiasis Control Over the Past Century Shows Targeting the Snail Intermediate Host Works Best.

Author information

1
Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America.
2
Marine Science Institute, and Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, United States of America.
3
Michigan Society of Fellows, University of Michigan, Ann Arbor, Michigan, United States of America.
4
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America.
5
Children's National Health System, Washington, D.C., United States of America.
6
The George Washington University, Washington, D.C., United States of America.
7
Biomedical Research Institute, Rockville, Maryland, United States of America.
8
Western Ecological Research Center, U.S. Geological Survey, Santa Barbara, California, United States of America.
9
Department of Bioengineering, Stanford University, Stanford, California, United States of America.

Abstract

BACKGROUND:

Despite control efforts, human schistosomiasis remains prevalent throughout Africa, Asia, and South America. The global schistosomiasis burden has changed little since the new anthelmintic drug, praziquantel, promised widespread control.

METHODOLOGY:

We evaluated large-scale schistosomiasis control attempts over the past century and across the globe by identifying factors that predict control program success: snail control (e.g., molluscicides or biological control), mass drug administrations (MDA) with praziquantel, or a combined strategy using both. For data, we compiled historical information on control tactics and their quantitative outcomes for all 83 countries and territories in which: (i) schistosomiasis was allegedly endemic during the 20th century, and (ii) schistosomiasis remains endemic, or (iii) schistosomiasis has been "eliminated," or is "no longer endemic," or transmission has been interrupted.

PRINCIPAL FINDINGS:

Widespread snail control reduced prevalence by 92 ± 5% (N = 19) vs. 37 ± 7% (N = 29) for programs using little or no snail control. In addition, ecological, economic, and political factors contributed to schistosomiasis elimination. For instance, snail control was most common and widespread in wealthier countries and when control began earlier in the 20th century.

CONCLUSIONS/SIGNIFICANCE:

Snail control has been the most effective way to reduce schistosomiasis prevalence. Despite evidence that snail control leads to long-term disease reduction and elimination, most current schistosomiasis control efforts emphasize MDA using praziquantel over snail control. Combining drug-based control programs with affordable snail control seems the best strategy for eliminating schistosomiasis.

PMID:
27441556
PMCID:
PMC4956325
DOI:
10.1371/journal.pntd.0004794
[Indexed for MEDLINE]
Free PMC Article

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