2021 Salmonella Outbreak Linked to Wild Songbirds – Investigation Details
Posted August 23, 2021
This outbreak investigation is over. Wild birds can carry Salmonella and make people sick. Always take steps to stay healthy around wild birds and bird feeders.
CDC and public health officials in several states collected different types of data to investigate a multistate outbreak of Salmonella Typhimurium infections in people.
Epidemiologic and laboratory data showed that contact with wild songbirds and bird feeders made people sick in this outbreak.
As of May 28, 2021, this outbreak is over.
Epidemiologic Data
As of May 28, 2021, a total of 29 people infected with the outbreak strain of Salmonella Typhimurium were reported from 12 states (see map). Illnesses started on dates ranging from December 26, 2020, to April 29, 2021 (see timeline).
Sick people ranged in age from 21 days to 89 years, with a median age of 13 years, and 54% were female. Of 27 people with information available, 14 were hospitalized. No deaths were reported.
State and local public health officials interviewed people about the animals they had contact with in the week before they got sick. Of the 21 people interviewed, 13 (62%) reported owning a bird feeder and 4 (19%) people reported contact with a sick or dead wild bird. Fifteen people had pets that had access to or contact with wild birds.
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 gastrointestinal illnesses. DNA fingerprinting was performed on bacteria using a method called whole genome sequencing (WGS).
WGS showed that bacteria from sick people’s samples were 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 was closely related to bacteria from sick people.
WGS of bacteria isolated from 26 people’s samples and 17 animal samples did not predict any antibiotic resistance.
Public Health Actions
Clean your bird feeder and bird bath at least monthly. You may need to clean them more often as bird poop and other dirt builds up on your feeder. Keep pets away from bird feeders and bird baths and the areas under them. Never handle wild birds with your bare hands.
If you find a sick bird, call your state wildlife agency or wildlife rehabilitator. If you find a dead bird, check with your state wildlife agency for information about reporting dead birds in your area.
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 agency or wildlife rehabilitator. If you find a dead bird, check with your state wildlife agency for information about reporting dead birds in your area.
