Illnesses Caused by Tainted Oysters Lead to Warning

A spate of illnesses linked to contaminated oysters prompted state health officials to urge Californians to cook the shellfish before eating it.

About 70 people in Western states, including 24 in California, have become ill after eating oysters from Washington state over the last couple of weeks. Health officials issued recalls on oysters harvested since July 13.

Oysters are “filter feeders” that pump water through their bodies, sometimes concentrating contaminants in their tissue. The illnesses are caused by a naturally occurring bacterium, vibrio parahaemolyticus, a pathogen found in low levels in the ocean except during summer months, when it flourishes as water warms.

Sometimes poor refrigeration during transport and storage of the shellfish allows the bacteria to multiply to unhealthful levels. Jordan Traverso of the California Restaurant Assn. said food-handlers are trained in the proper care and handling of shellfish.

The bacterium causes infections with symptoms such as diarrhea, abdominal cramps, headache, fever and chills. Severe cases may require medical treatment, but infections are rarely fatal.

The California Department of Health Services recommends oysters be cooked to 145 degrees to destroy bacteria. Some steamed oysters, oysters Rockefeller or marinated oysters in ceviche also pose risks.

“It’s best to thoroughly cook raw oysters no matter where they are from or the time of year they are harvested,” said Dr. Mark Horton, a state public health officer. “The potential for developing a food-borne illness is always high when handling or eating raw shellfish.”