Federal officials as well as officials in Oregon and Washington are investigating Salmonella illnesses linked to Papa Murphy’s raw cookie dough products.

“cookie Dough has been an ongoing Salmonella risk to consumers,” said William Marler, food safety attorney and publisher of Food Safety News. “However, in recent years the suspected contaminated ingredient has turned from eggs to flour, which to most consumers is both unsettling and unusual.”

Washington officials were first to report the outbreak with the Oregon officials soon joining the investigation because of cases in their state. The U.S. Centers for Disease Control and Prevention are assisting with the investigation.

The CDC is reporting that there are 18 patients across six states. Specific information has been released by Oregon and Washington.

Two patients have been hospitalized, but the CDC has not reported their states of residence. “The true number of sick people is likely higher than the number reported, and the outbreaks may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Salmonella,” according to the CDC.

Eating raw chocolate chip cookie or S’mores Bar dough sold by Papa Murphy’s restaurants was significantly associated with contracting this strain of Salmonella. Papa Murphy’s, headquartered in Vancouver, WA., sells uncooked or “take-and-bake” pizzas and cookie dough across the country that are intended to be baked at home, according to the Oregon Health Authority.

Efforts to trace the specific source of the Salmonella are ongoing. Health officials did not report whether the implicated cookie dough is made in-house or purchased from a third party.

“Those who have eaten the raw cookie dough products and feel ill should consult their health care provider immediately,” Washington health officials said.

Epidemiologists from the Oregon Health Authority are investigating the cluster of illnesses, which all are infected with an identical strain of Salmonella. The patients on Oregon range in from 20 to 57 years old.

In Washington, there are six confirmed patients ranging in age from 15 to 54 years old. They live in six counties: Clark (1), King (1), Lincoln (1), Pierce (1), Spokane (1) and Whatcom (1). One person has been hospitalized. The investigation is ongoing, however, four of six people so far report eating raw take-and-bake cookie dough products from Papa Murphy’s. This raw cookie dough is meant to be cooked before eating. It is not known at this time if other flavors of dough are implicated.

The strain of Salmonella that is infecting patients in Washington is the same as that that has infected patients in Oregon. It is not yet known if people in other states are sick or if Papa Murphy’s locations in other states may have any of the implicated dough.

Washington health department officials are working with local and federal public health partners to investigate the Salmonella outbreak likely linked to Papa Murphy’s Take ‘N’ Bake Pizza from multiple locations in Washington state. The company has discontinued selling the raw cookie dough products at this time.

In Oregon, the patients’ onset of symptoms was between April 1 and April 21. None of the patients were hospitalized, and there have been no deaths.

“To date, it is unknown yet which ingredient within the cookie dough is the source of the contamination,” according to Washington public health officials.

Raw cookie dough generally has raw eggs and raw flour as ingredients, both of which are known to be often contaminated with Salmonella and other foodborne pathogens.

Health officials recommend anyone who has any of the potentially contaminated cookie or S’mores Bar dough to discard it and wash their hands immediately afterward. Also, any containers, utensils or surfaces that have come into contact with the cookie dough should be thoroughly washed and dried with paper towels.