Oyster-associated hepatitis: lessons from the Louisiana experience.

An outbreak of oyster-associated hepatitis occurring in Louisiana during the months of October and November 1973 has been shown to be related directly to two similar outbreaks occurring at the same time in Houston, Texas and Calhoun, Georgia. Oysters incriminated in all three outbreaks were traced to approved oyster growing areas along the east Louisiana coast. Although no entirely satisfactory explanation could be found for the mode of contamination of these oysters, the epidemiologic and enviornmental data are most consistent with the conclusion that Mississippi River flooding provided the necessary source of fecal pollution into the oyster growing areas. These data also support recent experimental evidence indicating the under natural conditions shellfish eliminate bacteria and viruses differently and may retain certain enteroviruses for as long as two months after these organisms have disappeared from surrounding waters.