CDC Declares End to Year's Largest Backyard-Poultry Salmonella Outbreak

The nation's biggest outbreak of Salmonella tied to pet chicks and ducklings this year is over, federal health officials said this week, after seven strains of the bacteria sickened more than 1,250 people across 46 states and Puerto Rico and killed two.

The Centers for Disease Control and Prevention closed its investigation on September 24, more than five months after it first warned the public in April, and Food Safety News reported the closure on Tuesday. The final count makes it the second-largest backyard-poultry Salmonella outbreak the agency has tracked since at least 2019, trailing only a 1,722-case outbreak during the pandemic spring of 2020, when stay-at-home orders drove a surge in backyard flock ownership.

The numbers

CDC's final tally put the outbreak at 1,253 confirmed illnesses, with onset dates stretching from January 20 through August 6. Of the 812 patients for whom hospitalization status was known, 256 — about one in three — were admitted. Two people died, one in Georgia and one in Washington state. Because Salmonella infections that resolve on their own are rarely tested or reported, the true number of illnesses was almost certainly far higher.

Investigators matched seven distinct outbreak strains — Altona, Enteritidis, Indiana, Infantis, Kedougou, Mbandaka and Saintpaul — to birds traced back to eight hatcheries, which the agency did not name publicly. Whole genome sequencing of poultry samples collected in Idaho, Michigan, Minnesota, Ohio, Oregon and Tennessee matched the strains making people sick, giving investigators their strongest evidence yet linking specific flocks to the human cases. Testing also found the strains carried significant drug resistance: 670 isolates were resistant to fosfomycin, 184 to nalidixic acid and 152 to tetracycline, with 185 isolates predicted to be non-susceptible to ciprofloxacin, an antibiotic commonly used to treat severe Salmonella infections in adults.

How the outbreak grew

The CDC first flagged the outbreak on April 23, when an initial public notice counted 34 illnesses across 13 states, a typical seasonal pattern tied to the spring rush of chick and duckling sales at feed stores and through mail-order hatcheries. By May 14, that case count had climbed more than fivefold, to 184 people in 31 states, and the agency's updated tally showed 53 hospitalizations and the outbreak's first death, in Washington state.

The outbreak kept expanding through the summer rather than tapering off, reaching 513 cases by mid-June, 814 by late July and 1,061 by late August, according to case counts tracked independently by infectious-disease researchers at the University of Minnesota as the investigation progressed. Of 823 patients interviewed, 582 — 71 percent — reported contact with backyard poultry before falling ill. The Saintpaul strain, the largest single piece of the outbreak, showed an unusual pattern: 81 percent of patients infected with it reported contact with chicks or chickens, but 44 percent specifically reported contact with ducklings or ducks, a species investigators said is less commonly implicated in these outbreaks but carries Salmonella just as readily.

Who was affected

The median patient age was 36, but 22 percent of those sickened were children under 5 — the age group CDC considers at highest risk of severe illness from Salmonella, along with adults over 65 and people with weakened immune systems. Fifty-six percent of patients were female. Outbreak trackers following the case count through late summer noted that most patients had bought birds from agricultural retail stores, though some got them from hatcheries directly, from local farms or from other individuals.

The actual number of ill people is likely much higher than the number reported because many people recover without medical care and are not tested for Salmonella.

That standard CDC caveat, repeated on outbreak pages for years, underscores a persistent challenge for investigators: most people who get a mild case of Salmonella from touching a backyard flock never see a doctor, so case counts almost always understate the real toll. CDC's guidance for owners has stayed consistent across the outbreak:

• Wash hands with soap and water immediately after touching birds, their eggs or anything in the area where they live
• Don't let children younger than 5, adults over 65 or people with weakened immune systems handle chicks or ducklings
• Keep poultry and their supplies outside the house, and don't let birds inside, especially in the kitchen
• Don't kiss or snuggle backyard poultry, and don't eat or drink around the area where they're kept
• Collect eggs often, throw away cracked ones, and cook eggs and poultry meat until they reach an internal temperature of 160 degrees Fahrenheit

What happens next

CDC's closure of the investigation does not mean the underlying risk has gone away. These outbreaks track the calendar of backyard flock ownership: sales of chicks and ducklings climb every spring as hatcheries ship orders ahead of Easter and the start of warm weather, and illnesses tend to follow within weeks as new, often first-time owners bring birds into households that include young children. This year's outbreak was the largest since the 1,722-case investigation CDC closed in 2020, when pandemic lockdowns drove a surge in first-time flock ownership, and it adds to a run of sizable backyard-poultry outbreaks the agency has tracked nearly every year since. The agency said it will continue working with state health departments, agricultural retailers and hatcheries on biosecurity practices in the meantime. Because the eight hatcheries linked to this year's strains were not named publicly, consumers have no way of knowing whether the same suppliers will be shipping chicks and ducklings again next spring, when the next seasonal wave of cases is most likely to begin.

For now, CDC considers the investigation closed and is not recommending that current flock owners take any specific action beyond the standard hygiene practices it recommends year-round. Feed stores and hatcheries that supply backyard poultry are encouraged, but not required, to adopt additional safeguards, including sourcing birds from suppliers that participate in voluntary salmonella-monitoring programs and providing hand-washing stations near point-of-sale displays where customers handle chicks before buying them.