Oyster Testing Program Widened : Safety: Discovery of cholera in Gulf oyster triggers government concerns and more problems for the industry.

The recent discovery of cholera in Gulf of Mexico oysters has forced federal and state officials to launch an intensified testing program in the region to monitor for the spread of the infectious bacterium.

The finding is a public relations nightmare for the Gulf seafood industry, already hurt by fears that the area’s mollusks host another potentially harmful and related bacterium: Vibrio vulnificus.

Cholera, a debilitating diarrheal disease that has reached epidemic proportions in South America and Africa, was found in an oyster collected off Cedar Point, Ala., a commercial fishing area. (A fin fish from the same area also hosted cholera. But the fish, a sheepshead, is less of a concern because virtually all such species are cooked before eating--cooking destroys the organism. Furthermore, sheepshead is not a major commercial variety.)

“We did identify a toxin-producing strain of cholera in an oyster and a fin fish sample,” said Chris Lecos, an FDA spokesman in Washington. “The FDA and the state of Alabama are still doing sampling, but all the subsequent tests are coming up negative.”

There have been no reported cases of cholera in Alabama since the discovery.

Federal officials have yet to determine if the Gulf bacterium is the exact strain-- Vibrio cholera 01--that is causing the illness and deaths elsewhere in the world. Federal officials claim that even if the Alabama and South America bacteria are identical, it is unlikely that any such infected Gulf oysters reached consumer channels. This particular oyster bed, located in Mobile Bay, has been closed to fishing since May, while the contaminated oyster was collected in July. Yet, such assurances are far from guaranteed: Federal officials have long acknowledged the existence of illegal harvesting from closed waters along the entire Gulf coast, which runs from Texas to Florida.

FDA’s intensified monitoring efforts include laboratory testing of raw Gulf crab, shrimp, crawfish, oysters and fin fish. Processed and cooked products including crab, shrimp and crawfish are also being analyzed. Water samples from the region are being tested for cholera as well.

Traditionally, oyster harvesting in the Gulf is restricted in the summer months because of the increased likelihood of contaminants plaguing the mollusks in the hot weather. Elevated temperatures provide the perfect environment for the growth of bacteria. The Gulf closures, such as those in Alabama, also provide the species a respite from fishing during a period when it is spawning.

The cholera bacterium can be destroyed by thorough cooking. However, a good portion of the oysters sold in this country are consumed raw or undercooked and can be a vehicle for cholera transmission if infected mollusks are eaten without reaching an internal temperature of 170 degrees.

An Alabama state representative said that the oyster bed that produced the cholera strain is considered a “major oyster harvesting area” when seasonal fishing is permitted.

“We are still looking at how this happened. It is a mystery especially from that particular area because there is no source point (sewage) pollution,” said Bill Knight, with the state’s department of Public Health in Montgomery, Ala.

There has not been a reported case of cholera in Alabama in more than 25 years, Knight said. He estimates that the state’s crab and oyster industries generate about $25 million annually.

Earlier this year, the FDA, in conjunction with the Centers for Disease Control, estimated that one out of every 1,000 servings of raw or undercooked molluskan shellfish--oysters, clams or mussels--causes food poisoning. Health officials believe the popular practice of eating raw shellfish poses the highest risk of food-borne illness, with an estimated 51,000 cases a year. Some of these illnesses result in fatalities, particularly to high-risk individuals such as the elderly, pregnant women, alcoholic cirrhosis patients and those with compromised immune systems.

In March, the California Department of Health Services, under emergency authorization, required that all retail outlets selling Gulf oysters post warning signs alerting high-risk groups to the potential danger of eating the product raw, or partially cooked, because of the potential presence of V. vulnificus. Since California required the warning, sales of Gulf oysters have dropped between 40% and 60%, according to various estimates.

A representative of the Louisiana Seafood Promotion and Marketing Board said his state has not been directly affected by the cholera discovery in neighboring Alabama.

“We have not had this (bacteria) turn up in Louisiana, and the problem is isolated in a small portion of the Gulf. It is not widespread at all,” said Karl Turner, executive director of the marketing board in New Orleans. “What this (discovery) does show is that health authorities are evaluating and monitoring the (oyster) growing waters. The public can feel safe that the area is being monitored. And when the (conditions) are not safe then they are closed down.”

A Louisiana health official said that the state normally has one or more cholera cases each year but there have not been any such illnesses this year.

Louise McFarland Ph.D., state epidemiologist with the Louisiana Department of Health and Hospitals, said that her agency will meet this week to decide whether to expand cholera testing of the state’s seafood, the largest such industry in the Gulf.

The National Fisheries Institute, an Arlington, Va.-based seafood trade group, has said that eating raw oysters is safe if several precautions are taken. The institute recently stated: “Commercially available oysters, clams and mussels harvested from approved, certified waters, packed under sanitary conditions and kept properly refrigerated are considered safe for raw, lightly cooked or marinated consumption by healthy individuals.”