King County, WA, residents are being warned not to consume raw or undercooked shellfish after more than twice the usual number have been sickened this summer by Vibrio parahaemolyticus infection. There were 14 confirmed or probable cases of Vibrio infection, known as Vibrosis, reported in July, compared to the average of four for that month in previous years. Another eight cases have been confirmed so far in August. County health officials estimate there are 142 unreported cases for each one reported. Symptoms of Vibrosis can include moderate to severe diarrhea, abdominal cramps, nausea, vomiting, fever, chills and headache. The bacteria can also cause a skin infection when open wounds are exposed to warm sea water. People with preexisting medical conditions or who regularly take antacids are at higher risk for illness from Vibrio infection. Cooking shellfish just until the shells open is not sufficient to kill the bacteria. Shellfish should be cooked to an internal temperature of 145 degrees F for at least 15 seconds. The Vibrio bacteria naturally occur in sea water but grow more rapidly during summer months. Health officials said the bacteria decline when temperatures start cooling in October. The King County Health Department has posted a special Website with more information about Vibrio parahaemolyticus and Vibrosis.