RT Journal Article SR Electronic T1 Environmental cholera (Vibrio cholerae) dynamics in an estuarine system in southern coastal Ecuador JF bioRxiv FD Cold Spring Harbor Laboratory SP 110189 DO 10.1101/110189 A1 Sadie J. Ryan A1 Anna M. Stewart Ibarra A1 Eunice Ordóñez A1 Winnie Chu A1 Julia L. Finkelstein A1 Christine A. King A1 Luis E. Escobar A1 Christina Lupone A1 Froilan Heras A1 Erica Tauzer A1 Egan Waggoner A1 Tyler G. James A1 Washington B. Cárdenas A1 Mark Polhemus YR 2017 UL http://biorxiv.org/content/early/2017/02/27/110189.abstract AB Cholera emergence is strongly linked to local environmental and ecological context. The 1991- 2004 pandemic emerged in Perú and spread north into Ecuador’s El Oro province, making this a key site for potential re-emergence. Machala, El Oro, is a port city of 250,000, near the Peruvian border. Many livelihoods depend on the estuarine system, from fishing for subsistence and trade, to domestic water use. In 2014, we conducted biweekly sampling for 10 months in five estuarine locations, across a gradient of human use, and ranging from inland to ocean. We measured water-specific environmental variables implicated in cholera growth and persistence: pH, temperature, salinity, and algal concentration, and evaluated samples in 5 months for pathogenic and non-pathogenic Vibrio cholerae, by polymerase chain reaction (PCR). We found environmental persistence of pandemic strains O1 and O139, but no evidence for toxigenic strains. Cholera presence was coupled to algal and salinity concentration, and sites exhibited considerable seasonal and spatial heterogeneity. This study indicates that environmental conditions in Machala are optimal for cholera re-emergence, with risk peaking during September, and higher risk near urban periphery low-income communities. This highlights a need for surveillance of this coupled cholera– estuarine system to anticipate potential future cholera outbreaks.