According to the Washington State Department of Health, Vibrio in shellfish have caused 30 confirmed illnesses in Washington this summer. The presence of the bacteria has closed three commercial growing areas, including Totten Inlet near Olympic, North Bay, and Dabob Bay in north Hood Canal for the rest of the summer.
Vibriosis, the illness caused by the bacteria Vibrio parahaemolyticus, is caused by eating raw or undercooked oysters. Despite the typical recommendation of cooking shellfish until they open, that is not enough to destroy Vibrio. To be safe, shellfish should be cooked to an internal temperature of 145 degrees F for 15 seconds. In addition, rinsing cooked oysters in seawater can re-contaminate them. And, some pathogens can’t be “cooked out” of shellfish. Some biotoxins can be impervious to heat and make you ill or kill you if consumed.
Vibrio bacteria multiply in warm temperatures and at low tides. The symptoms of vibriosis include diarrhea, stomach cramps, nausea, vomiting, fever, headache, and chills. The illness can be life-threatening for people who have compromised immune systems or chronic liver disease, in addition to people who take antacids, heart or diabetes medication, and anyone who is undergoing cancer treatments or is being treated with antibiotics.
Before you harvest clams, oysters, and other shellfish, check for public health warnings about beach closures and bacterial outbreaks. When you buy or harvest shellfish, put it on ice immediately. And be sure that you are purchasing shellfish from reputable sources that handle the food correctly. The state of Washington has put together a Recreational Shellfish Harvesting fact sheet to help.