As of February 2, 2022, the multistate outbreak of Salmonella Oranienburg infections linked to onions is over.
CDC, FDA, and public health and regulatory officials in several US states collected different types of data to investigate the outbreak.
Epidemiologic and traceback data showed that this outbreak of Salmonella Oranienburg infections was linked to whole, fresh onions imported from the State of Chihuahua, Mexico.
Epidemiologic Data
As of January 20, 2022, a total of 1,040 people infected with the outbreak strain of Salmonella Oranienburg were reported from 39 states, the District of Columbia, and Puerto Rico. Illnesses started on dates ranging from May 31, 2021, to January 1, 2022.
Sick people ranged in age from less than 1 year to 101 years, with a median age of 38, and 58% were female. Of 778 people with information available, 260 (33%) were hospitalized. No deaths were reported.
The true number of sick people in an outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because many people recover without medical care and are not tested for Salmonella. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.
State and local public health officials interviewed people about the foods they ate in the week before they got sick. Of 407 people with information, 294 (72%) reported eating or maybe eating raw onions or dishes likely containing raw onion before they became sick.
Laboratory Data
Public health investigators used the PulseNet system to identify illnesses that were part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).
Whole genome sequencing of bacteria from 1,012 people’s samples did not predict any antibiotic resistance. Nine people’s samples were predicted to be resistant to one or more of the following antibiotics: amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftriaxone, ciprofloxacin, gentamicin, streptomycin, sulfamethoxazole, and tetracycline.
Standard antibiotic susceptibility testing of five people’s samples by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory found no resistance. Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, this resistance is unlikely to affect the choice of antibiotic used to treat most people because it is rare.
Public Health Actions
On October 20, 2021, ProSource Produce LLC issued a recall. On October 22, 2021, Keeler Family Farms also issued a recall. Recalls were also issued by multiple companies that used the onions as ingredients in new products or repackaged them.
For more information:
CDC
Tel: +1 800-232-4636
https://wwwn.cdc.gov/dcs/contactus/form