Predictability of Vibrio cholerae in Chesapeake Bay
Valerie R. Louis, Estelle Russek-Cohen, Nipa Choopun, Irma N. G. Rivera, Brian Gangle,
Sunny C. Jiang, Andrea Rubin, Jonathan A. Patz, Anwar Huq, and Rita R. Colwell
Appl. Environ. Microbiol. 2003. 69(5): 2273-2285 - highlighted in ASM News (Jun. 2004)
Vibrio cholerae is autochthonous to natural waters and can pose a health risk when it is consumed via
untreated water or contaminated shellfish. The correlation between the occurrence of V. cholerae in Chesapeake
Bay and environmental factors was investigated over a 3-year period. Water and plankton samples were
collected monthly from five shore sampling sites in northern Chesapeake Bay (January 1998 to February 2000)
and from research cruise stations on a north-south transect (summers of 1999 and 2000). Enrichment was used
to detect culturable V. cholerae, and 21.1% (n=427) of the samples were positive. As determined by serology
tests, the isolates, did not belong to serogroup O1 or O139 associated with cholera epidemics. A direct
fluorescent-antibody assay was used to detect V. cholerae O1, and 23.8% (n= 412) of the samples were positive.
V. cholerae was more frequently detected during the warmer months and in northern Chesapeake Bay, where
the salinity is lower. Statistical models successfully predicted the presence of V. cholerae as a function of water temperature and salinity. Temperatures above 19°C and salinities between 2 and 14 ppt yielded at least a
fourfold increase in the number of detectable V. cholerae. The results suggest that salinity variation in
Chesapeake Bay or other parameters associated with Susquehanna River inflow contribute to the variability
in the occurrence of V. cholerae and that salinity is a useful indicator. Under scenarios of global climate change,
increased climate variability, accompanied by higher stream flow rates and warmer temperatures, could favor
conditions that increase the occurrence of V. cholerae in Chesapeake Bay.
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