Occurrence of Vibrio parahaemolyticus and Related Hemolytic Vibrios in Marine Environments of Washington State 1

Abstract

Samples of sediment, water, and fauna were tested for the presence of Vibrio parahaemolyticus and the related biotype V. alginolyticus. Altogether, 379 samples were analyzed quantitatively by using a starch-agar medium. Invertebrate and sediment samples were invariably positive for V. parahaemolyticus, whereas water samples were quite variable. Samples of the Pacific oyster (Crassostrea gigas), obtained on a regular basis for 26 months from a single environment, showed a close correlation between total numbers of mesophilic vibrios and the overlying water temperature; the seasonal counts of oysters ranged from less than 10 to greater than 100,000 per g. Ecological implications and possible pathogenicity of these vibrios are discussed.