The Centers for Disease Control and Prevention was unable to find a source for the recent outbreak of Salmonella infantis in chicken, and the agency said it was ending its investigation.
But the CDC noted that it's likely more illnesses will be announced "because this particular strain appears to be widespread in the chicken industry," said Colin Basler, D.V.M., M.P.H., a veterinary epidemiologist who is part of the CDC team looking into the outbreak.
The first illness was reported in January 2018 and the outbreak has sickened 129 across 32 states. One death, which was reported in New York City, was connected to the outbreak.
The strain was identified in samples taken from raw chicken products, including raw chicken in pet food, and in live chickens, but the CDC was unable to determine a single common supplier, brand, or point of purchase. In interviews, ill people reported eating different types and brands of chicken products purchased from many locations.
"Because of the number of unknowns remaining in this salmonella outbreak, and how dangerous this salmonella strain appears to be, it's particularly important to follow safe handling procedures with raw chicken right now," said James E. Rogers, Ph.D., director of food safety research and testing at Consumer Reports. "This means carefully washing your hands and preparation surfaces, and always cooking chicken to 165° F.”
Basler at the CDC said the decision to end the investigation was prompted by a decrease in the number of new cases being reported.
"That said, if we saw a spike in new cases, we would certainly reopen the investigation," he said.
The CDC and the USDA's Food Safety and Inspection Service (FSIS) are still talking with members of the poultry industry and state health officials in order to figure out why this outbreak has been so widespread.
"Unfortunately we have no concrete leads at this time," he said.
Because this strain of salmonella is resistant to a number of different antibiotics, the CDC has issued special instructions to healthcare providers regarding how to test potential victims and which antibiotics may be most effective in treating them.
At least 2 million Americans contract an antibiotic-resistant infection every year, and 23,000 die, according to the CDC. CR’s calculations show that about 20 percent of these infections are linked to food.
Most cases of salmonella infection last 4 to 7 days and do not require treatment. But if a case is serious enough, antibiotics may be called for.
"The information the CDC released today is extremely concerning," said Jean Halloran, director of food policy initiatives at Consumer Reports. "The CDC is closing the investigation, and says only that it and the USDA are talking to the industry about the problem. Talk is not enough."
Halloran said that the USDA should conduct broad testing of growing and slaughtering facilities to identify those harboring this dangerous pathogen. Those facilities should be shut down and decontaminated, and the FSIS should immediately disclose to the public the facilities identified as containing this strain of salmonella.