SEATTLE, May 17 (UPI) -- Oyster consumers should be cautious about a potential build-up of bacteria in the shellfish, Washington state health officials say.

The State Department of Health says increasing temperatures of water sources in the area can precipitate increased growth of a strain of bacteria called Vibrio parahaemolyticus, which can cause sickness in humans, The Seattle Times said Saturday.

The medical condition from eating infected oysters, Vibriosis, can be life-threatening in those with chronic liver disease or weakened immune systems.

Symptoms such as diarrhea, stomach cramps, nausea and fever can last between two to seven days and can range from mild to moderate levels.

The Times said oyster eaters should immediately refrigerate fresh oysters and thoroughly cook the mollusks until they reach a temperature of 145 degrees.

State health officials are attempting to prevent bacterial spread by instituting a new set of stringent oyster harvesting guidelines starting Monday, the newspaper said.