Investigation Details

Posted April 1, 2021

April 1, 2021

CDC and public health officials in several states are collecting different types of data to investigate a multistate outbreak of Salmonella Typhimurium infections in people.

Epidemiologic and laboratory data show that contact with wild songbirds and bird feeders is likely making people sick in this outbreak.

Epidemiologic Data

As of March 30, 2021, a total of 19 people infected with the outbreak strain of Salmonella Typhimurium have been reported from eight states (see map). Illnesses started on dates ranging from December 26, 2020, to March 16, 2021 (see timeline).

Sick people range in age from 2 months to 89 years, with a median age of 16 years, and 63% are female. Of 17 people with information available, 8 have been hospitalized. No deaths have been reported.

Wild songbirds, such as pine siskins, can be found throughout the United States, so this outbreak may not be limited to the states with known illnesses. The true number of sick people in an outbreak is likely much higher than the number reported 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 2 to 4 weeks to determine if a sick person is part of an outbreak.

State and local public health officials are interviewing people about the animals they had contact with in the week before they got sick. Of the 13 people interviewed, 9 (69%) reported owning a bird feeder and 2 (15%) people reported contact with a sick or dead wild bird. Ten people have pets that had access to or contact with wild birds.

Laboratory Data

Public health investigators are using the PulseNet system to identify illnesses that may be 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).

WGS showed that bacteria from sick people’s samples are closely related genetically. This means that people in this outbreak likely got sick from contact with the same source.

Officials in Oregon and Washington collected samples from sick or dead wild pine siskin birds. WGS analysis showed that the Salmonella from the pine siskins are closely related to bacteria from sick people.

WGS of bacteria isolated from 14 people’s samples and three animal samples did not predict any antibiotic resistance. Standard antibiotic susceptibility testing by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory is currently underway.

Public Health Actions

On April 1, 2021, CDC issued an investigation notice about this outbreak to remind people to not touch or hand-feed wild birds with bare hands and always wash hands after touching wild birds, bird feeders and bird baths. Clean and disinfect bird feeders and bird baths weekly or when they are visibly dirty. If you find a sick bird, call your state wildlife agencyexternal icon or wildlife rehabilitatorexternal icon. If you find a dead bird, check with your state wildlife agencyexternal icon for information about reporting dead birds in your area.

Previous Updates

Laboratory and Traceback Data

Connecticut officialsexternal icon collected samples of El Abuelito brand Hispanic-style fresh and soft cheeses for testing from a store where a sick person reported buying these types of cheeses. On February 16, testing results showed that samples of El Abuelito brand queso fresco cheese were contaminated with Listeria monocytogenes. Whole genome sequencing (WGS) is currently being conducted to see if the Listeria bacteria in the product are closely related to the Listeria bacteria from sick people in this outbreak.

Public Health Actions

Do not eat, sell, or serve any El Abuelito brand queso fresco cheese. FDA and state partners are working with El Abuelito to recall the contaminated product and to determine if additional products should be recalled.

Until we identify which cheeses are making people sick in this outbreak, CDC continues to advise people at higher risk for severe Listeria illness to not eat Hispanic-style fresh and soft cheeses (including El Abuelito brand queso fresco cheese) and to contact their healthcare provider right away if they have any symptoms of severe Listeria illness after eating Hispanic-style fresh and soft cheeses.