According to the San Francisco Chronicle, the U.S. Department of Agriculture’s Food and Safety Inspection Service is investigating 40 illnesses in nine states – including five people in the California counties of Orange and Tulare – who have been sickened. At least four people have been hospitalized.

The state public health department released a list of affected retailers, mostly Safeway stores in Northern California and Vons stores in Southern California. The meat was produced June 5-23 and would have been sold sometime last month. A Safeway spokeswoman said Thursday that ground beef purchased from June 6 to July 14 should be discarded or returned to the store for a refund. List of California stores impacted:

The strain of bacteria associated with the outbreak is Salmonella Newport, which is resistant to many drugs typically used to treat infections, according to the Food and Safety Inspection Service. Salmonella can be life-threatening, especially in people with weak immune systems such as babies, the elderly and people with HIV infection or undergoing chemotherapy.