The federal Centers for Disease Control and Prevention in Atlanta on Friday added 39 people to its list of those apparently sickened by salmonella-tainted Foster Farms chicken.
The new count stood at 317 people sick in 20 states, including 232 in California. But CDC spokeswoman Barbara Reynolds said the cases may not be new ones. Of those sickened as of Thursday, 42 percent were hospitalized, the CDC said.
"We are getting a better characterization of it as health care providers have been told to look for it," Reynolds said.
An increase in reported cases does not mean new cases were found, but may be from earlier this week that are now linked to the outbreak, Reynolds said.
"Through DNA fingerprinting you are trying to develop information that the person did have exposure to the product," she said. "It takes a little bit of disease detective work."
She said the salmonella outbreak is a "serious threat."
"We are seeing antibiotic resistant strains and so many different strains," Reynolds said, adding that the high volume of people hospitalized is also a cause for concern.
The outbreak is one of 30 clusters of food-borne illnesses the CDC is investigating with 9,000 of 13,000 employees on furlough because of the federal government shutdown.
"We have world-renowned scientists who can't sign on to a computer," Reynolds said.
– Marc Benjamin