Food-safety investigators still can’t pinpoint the source of drug-resistant Salmonella found in raw turkey meat as the nationwide outbreak expands just before the largest turkey consumption day of the year.

The Centers for Disease Control last week offered its first update since July on the chronic outbreak that began last November. It said the number of reported illnesses has nearly doubled to 164, including 17 in Minnesota — the most of any U.S. state. There’s been one reported death in California as a result of handling or consuming tainted turkey.

Still, the CDC and the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) aren’t telling consumers to stop eating turkey, instead authorities are reminding the public on the importance of proper handling and cooking techniques.

Consumers should always wash their hands and all surface areas where the meat has been prepared, but never wash the meat itself as that increases the risk of contaminating other areas of the kitchen. Always thaw the turkey on a separate plate in the refrigerator, in cold water that is changed every 30 minutes or in the microwave. Never leave meat to thaw on the counter. Use a meat thermometer to cook and reheat the meat to an internal temperatures of 165 degrees Fahrenheit. The CDC also discourages consumers from feeding their pets a raw-food diet.

The cases have been surfacing at a steady rate and over a wide area. Illnesses have been linked to a variety of turkey brands, companies, processing facilities and retailers in 35 states.

It has been traced to raw turkey pet food, a discovery made by the Minnesota Health Department, and a variety of raw turkey products. Some turkey plant workers have even become ill through contact with live birds.

The CDC and FSIS knows of at least 22 slaughter facilities and seven processing plants where tainted product passed, but the agencies have not released specific details. FSIS did not say why it wasn’t releasing that information other than the investigation is ongoing and the original source not yet known.

Minnesota is the nation’s top turkey producing state, raising around 45 million birds every year. Two of the nation’s three largest turkey-producing companies, Hormel’s Jennie-O Turkey Store and Cargill, are based in Minnesota. Both companies decline to comment, referring all media questions to the National Turkey Federation, which is representing the entire industry on this outbreak.

“For consumers, the bottom line is that all turkey is safe when properly cooked and handled, and that turkey producers and processors are continually working to make them even safer,” the federation said in a statement. “The turkey industry remains committed to reducing Salmonella and continuing to explore scientific and technological innovations that would help control naturally occurring pathogens in food products.”

Ryan Osterholm, a Minneapolis attorney who is representing a five-year-old Minnesota girl and several other people who have been severely sickened by the outbreak, said this is among the worst strains of salmonella he’s seen. It’s resistant to multiple antibiotics used to treat infections in humans and it doesn’t have a single source, making it a systemic problem, possibly originating in a large-scale hatchery that sells baby birds to growers and operators.

“There’s a lot more that we don’t know than we know right now,” Osterholm said. “I try not to be alarmist … but, in my opinion, this is a major public health risk not being fully addressed by industry or the USDA.”

The child he is representing developed osteomyelitis, a serious and painful bone infection. She and at least one other sickened Minnesota child live in homes that fed their dogs raw pet food containing ground turkey, according to the Minnesota Department of Health.

“(My clients) were doing exactly what everyone else does with their turkey. They weren’t doing anything crazy,” Osterholm said. “But when it is this virulent, just a little can get you sick, even under the very best of preparation methods.”

Consumer Reports and The Center for Science in the Public Interest, a Washington, D.C.-based watchdog and consumer advocacy group, are urging the USDA to release the names of the suppliers it has identified as being associated with food tainted in the outbreak.

“When an outbreak is widespread and slow burning, and the agency still hasn’t figured out the source, they are in a difficult position because they don’t have that very specific advice to give consumers in terms of issuing a recall,” said Laura MacCleery, CSPI’s policy director. “But when you are coming up on a major holiday where you know consumers are likely to consume the food in question, we think the agency has an obligation to give consumers whatever information it does have.”