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The emergence of West Nile virus in the United States renewed vigilance for mosquito-borne diseases and rejuvenated mosquito surveillance activities in Washington State. As part of these activities, the Zoonotic Disease Program, Washington Department of Health, and the United States Army Center for Health Promotion and Preventive Medicine-West collaborated to produce this revision of the distribution of mosquitoes in Washington State. Data from these organizations, the US Air Force, and county surveillance records, as well as published literature and mosquito collections, were used to develop this statewide mosquito distribution checklist.

A high incidence (71.5%) of Vibrio parahaemolyticus was found in samples of water, oysters, and sediment from a Washington State estuary which produces a significant amount of commercial product. Strains of V. parahaemolyticus capable of hydrolyzing urea comprised 58.4% of all V. parahaemolyticus isolates tested. Values for fecal coliforms were within certification criteria for commercial harvest and were not correlated with levels of V. parahaemolyticus.

During a 3-month period in the late summer and fall of 1981, six cases of gastroenteritis and one wound infection due to Vibrio parahaemolyticus were reported to public health agencies in Washington and Oregon. An investigation revealed that all of the gastroenteric illnesses were associated with eating raw oysters; that oysters eaten by five of the six patients were harvested at four divergent sites at Willapa Bay, Washington, a large commercial growing area; and that the V. parahaemolyticus isolates from those five patients were all Kanagawa positive, belonged to serotype 04:K12, and exhibited an atypical biochemical reaction, urea hydrolysis. No further cases linked to Willapa Bay oysters have been reported, and the infecting strain could not be found in sediment samples from the bay in February 1982. Thus, even though the origin of this self-limiting outbreak is obscure, the investigation demonstrated that the geographic distribution of V. parahaemolyticus infection in the United States includes the Pacific seacoast . Furthermore, oysters must be considered, along with crabs, shrimp, and lobster, as a vehicle of transmission of this infection in the United States.