Salmonella: CDC investigating outbreak linked to unknown food source

The U.S. Centers for Disease Control and Prevention warned of a "fast-growing" salmonella outbreak in at least 29 states linked to an unknown food source.

The agency shared a notice on Sept. 23 identifying 279 people infected with the strain of Salmonella Oranienburg, up from just 20 reported infections on Sept. 2. No deaths have been reported but 26 people have been hospitalized.

The first illness was reported on Aug. 3, the CDC said — noting that the investigation has not yet identified a specific food linked to the outbreak.

State and local officials have collected food items from some of the restaurants where sick people ate, saying the strain of Salmonella Oranienburg was found in a sample taken from a takeout condiment cup containing cilantro and lime.

"The sick person reported that the condiment container also contained onions, but none were left in the cup when it was tested," the CDC said. "Because multiple food items were present in the container and in the sample that was tested, it is not possible to know which food item was contaminated."

"We are using this information in conjunction with other available information to help narrow the list of possible foods linked to illness," the agency added.

Salmonella bacteria

FILE - Salmonella bacteria, a common cause of foodborne disease, are pictured invading an immune cell. (Photo by: IMAGE POINT FR/NIH/NIAID/BSIP/Universal Images Group via Getty Images)

RELATED: Hostess recalls hotdog, hamburger buns over listeria and salmonella concerns

Current CDC data suggests the most number of illnesses have been reported in Texas, Oklahoma, Virginia, Illinois, Minnesota and Massachusetts, though the outbreak has been reported in a range of states.

But the agency said the figures are likely an undercount because many recover without treatment and are not tested for Salmonella infection. Also, recent illnesses may not have been reported yet as it usually takes three to four weeks to determine if a sick person is part of an outbreak, according to the CDC.

Most people infected with Salmonella report experiencing diarrhea, fever and stomach cramps. Symptoms usually begin six hours to six days after swallowing the bacteria, officials say. Most recover without treatment after four to seven days.

Some people, particularly children younger than 5, adults 65 and older, and people with weakened immune systems, may experience more severe illnesses that require medical treatment or hospitalization.

There are other current Salmonella outbreaks that the CDC is following, including one linked to Italian-style deli meats. This outbreak has been reported across 17 states and was linked to Fratelli Beretta brand prepackaged Uncured Antipasto trays with "best by" dates on or before February 11, 2022, the agency said.

RELATED: Dog food recalled over salmonella, listeria concerns

This story was reported from Cincinnati.