Oyster-associated hepatitis. Failure of shellfish certification programs to prevent outbreaks.

During October and November 1973, outbreaks of hepatitis A associated with consumption of raw oysters occurred in Houston and in Calhoun, Ga. The oysters implicated in both outbreaks had been harvested in two Louisiana bays. Although the bays had been contaminated with polluted Mississippi River water two months before the oysters were harvested, at the time of harvesting the bays met national sanitation standards for shellfish growing and were certified for oyster fishing. These epidemics raise serious questions about the adequacy of shellfish sanitation monitoring systems currently in use.