Foster Farms’ raw chicken products have been linked to a Salmonella outbreak that sickened nearly 300 people in 18 states, according to the U.S. Dept. of Agriculture (USDA).

"The outbreak is continuing," USDA's Food Safety and Inspection Service said in a statement.

The contaminated products are believed to have been produced at three Foster Farms sites in California. Most of the cases of illness are concentrated in California, Oregon, and Washington. According to the Associated Press, the outbreak began in March and the illnesses were brought to the USDA’s attention in July. Patients were reportedly sickened by Salmonella Heidelberg.

Salmonella infections are caused by eating raw or uncooked meat, eggs, or poultry products. Symptoms include nausea, vomiting, abdominal pain, and diarrhea. According to Mayo Clinic, although most symptoms of Salmonella infection subside after about five days, it could take several months for one’s bowels to return to normal.

Foster Farms said that it is making every effort to ensure that all of its products are properly handled to avoid another incident like this one.

"In addition to collaborating with FSIS and CDC, the [Foster Farms[ has retained national experts in epidemiology and food safety technology to assess current practices and identify opportunities for further improvement," Foster Farms President, Ron Foster, said in a statement. “We are committed to ensuring the safety of our products, and our family-owned company has maintained an excellent food safety record during its near 80-year history."

No recall for the raw chicken is in effect because the infections are caused by undercooking or improperly handling the chicken. Officials believe that if cooked correctly, the affected chicken will be safe for consumption. The California Dept. of Public Health stressed the importance of cooking meat thoroughly to avoid illness.

"This is the important public health issue," said Anita Gore, spokeswoman for the California Dept. of Public Health. "Chicken can carry bacteria, and chicken needs to be fully cooked."