Restrictions Urged on Sale of Oysters

Analyzing a series of illnesses and deaths in Los Angeles linked to contaminated oysters, researchers put some of the blame on restaurants and seafood markets that failed to warn customers about the dangers of eating raw shellfish from the Gulf of Mexico.

Moreover, the tragedies may have been prevented if there were tougher state regulations on the sale of raw oysters from the gulf--the most common source of the tainted bivalves--concluded the study, published today in the Journal of the American Medical Assn.

It suggested that the raw gulf oysters, which are available year-round in California, be sold only during colder months from November to April, when they are less likely to be contaminated by the potentially deadly bacteria Vibrio vulnificus, which cannot be detected by sight, smell or taste. Thorough cooking destroys the bacteria.

The study was conducted by researchers from the Los Angeles County Department of Health Services and the federal Centers for Disease Control and Prevention. They examined the 11 cases of Vibrio poisoning--including seven deaths--that were reported to county health authorities between 1993 and 1995.

Before eating the oysters, all the victims had documented liver disease or were at risk of liver damage from excessive alcohol consumption. People with liver disease, diabetes, or weakened immune systems are especially susceptible to Vibrio infection, which can lead to deadly blood poisoning within days. Ten of the victims were primarily Spanish-speaking, raising the issue of whether public health messages were adequately reaching Latinos.

Since 1991, California has required that restaurants and markets selling raw gulf oysters post health warnings in English and Spanish. But when the researchers checked some of the establishments where the victims bought the shellfish, they found that only one of four markets and three of six restaurants displayed a warning.

The researchers say that the state should consider requiring that health warnings appear directly on restaurant menus.

There were five documented Vibrio poisonings last year, with four deaths. No poisoning cases have been reported so far this year.