Officials say 278 people have become sick in 18 states, but most of the illnesses were reported in California.
The USDA says that strains of Salmonella Heidelberg are associated with chicken distributed to retail outlets in California, Oregon and Washington state.
A specific product sickening people has not been identified, and there is no recall, but the USDA mark on suspect packages would read: P6137, P6137A and P7632.
A Foster Farms spokesman said the infections were caused by eating undercooked or improperly handled chicken.
Health officials stressed that the public should properly handle and cook raw chicken. Cooking chicken to 165 degrees kills the Salmonella bacteria.
"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," said Foster Farms President Ron Foster in a statement. "We deeply regret any foodborne illness that may be associated with any of our products."
The Centers for Disease Control and Prevention is partnering with state health departments to monitor the outbreak while the USDA's Food Safety and Inspection Service investigates.
The Associated Press contributed to this report.
