Raw oysters harvested from Apalachicola Bay, FL, and purchased from a retail outlet in Tallahassee, FL, were tested monthly from March 1989 through March 1990 for the presence of Vibrio species. We studied the temporal relationship between Vibrio levels found in these oysters and the incidence of raw oyster-associated Vibrio illnesses with onset dates in 1989–1990 among persons living in counties located adjacent to or near Apalachicola Bay. Five of the six Vibrio species implicated in raw oyster-associated gastroenteritis or septicemia in the study area during 1989–1990 were recovered from the retail raw oysters. With the exception of Vibrio vulnificus, which was recovered during the warmest months, recovery of other Vibrio species from oysters was distributed widely throughout the year. Thirty-seven patients in the study area with 39 Vibrio infections with onset of illness from January 1989 through December 1990 were reported to the Florida Department of Health and Rehabilitative Services. Thirty-three (89%) of these patients reported eating raw oysters during the week before onset of illness and experienced gastroenteritis (32 patients) or septicemia (1 patient).
+Present address: Epidemiology Branch (HFS-728), Food and Drug Administration, Washington, DC 20204.