02835nas a2200457   4500000000100000008004100001653001400042653005300056653001800109653002000127653003100147100001200178700001400190700001300204700001800217700001600235700001300251700001300264700001400277700001200291700001200303700001200315700002300327700001500350700001200365700001200377700001400389700001300403700001400416700001500430700001300445700001400458700001400472700001500486700001300501700001300514245010800527856007500635520165300710022001402363       2019                            d10aBilharzia10aEcological levers for infectious disease control10asnail control10aspatial ecology10aUrogenital schistosomiasis1 aWood CL1 aSokolow S1 aJones IJ1 aChamberlin AJ1 aLafferty KD1 aKuris AM1 aJocque M1 aHopkins S1 aAdams G1 aBuck JC1 aLund AJ1 aGarcia-Vedrenne AE1 aFiorenza E1 aRohr JR1 aAllan F1 aWebster B1 aRabone M1 aWebster J1 aBandagny L1 aNdione R1 aSenghor S1 aSchacht A1 aJouanard N1 aRiveau G1 aDe Leo G00aPrecision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission.  uhttps://www.pnas.org/content/pnas/early/2019/10/22/1903698116.full.pdf3 a<p>Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world's largest recorded schistosomiasis epidemic-the Lower Senegal River Basin in Senegal-intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we identified several environmental proxies that were more effective than snail variables for predicting human infection: the area covered by suitable snail habitat (i.e., floating, nonemergent vegetation), the percent cover by suitable snail habitat, and size of the water contact area. Unlike snail surveys, which require hundreds of person-hours per site to conduct, habitat coverage and site area can be quickly estimated with drone or satellite imagery. This, in turn, makes possible large-scale, high-resolution estimation of human urogenital schistosomiasis risk to support targeting of both mass drug administration and snail control efforts.</p>
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