CDC declares end to Salmonella outbreak traced to backyard flocks

This year's outbreak of Salmonella infections traced to backyard poultry flocks has been declared over by the Centers for Disease Control and Prevention.

A total of 1,253 people were infected with the outbreak strains of Salmonella Altona, Enteritidis, Indiana, Infantis, Kedougou, Mbandaka, and Saintpaul. The sick people were reported from 46 states and Puerto Rico. A third of the patients required hospitalization, and there were two deaths reported. 

One in five of the patients were children younger than 5 years old. Overall, patient ages ranged from less than 1 year to 99 years old with a median age of 36. 

Most of the sick people or their caregivers reported the chicks and ducklings for their backyard flocks were purchased at agricultural retail stores, but some bought the birds from people they knew, directly from hatcheries or from local farms.

The CDC reports that eight hatcheries were identified as having sold infected birds, but the agency has not named those hatcheries. 

Investigators in Idaho, Michigan, Minnesota, Ohio, Oregon and Tennessee collected samples from backyard poultry or from the inside of boxes used to ship live poultry from hatcheries to retail stores. Whole genome sequencing showed that the Salmonella Enteritidis, Mbandaka, Kedougou, and Saintpaul found in these samples were the same strains as those found in sick people.

Some of the Salmonella strains detected in outbreak patients were found to be resistant to antibiotics.

The CDC sequenced 1,253 human isolates. There were 670 resistant to fosfomycin, 184 to nalidixic acid, 152 to tetracycline, 53 to streptomycin, 40 to gentamicin, 24 to sulfisoxazole, and smaller numbers to ampicillin, ceftriaxone, ceftiofur, amoxicillin-clavulanic acid and cefoxitin. Another 185 were predicted nonsusceptible to ciprofloxacin.

The CDC first reported the outbreak on April 13 when there was a total of 34 patients. At that time only 13 states were reporting outbreak patients, with 13 requiring hospitalization. The April 13 report showed illnesses started on Feb. 26.

There were likely many more outbreak patients than were included in the official count. This is because some sick people don’t seek medical attention and others are not specifically tested for Salmonella. The CDC estimates for every confirmed patient in a Salmonella outbreak there are 29 who go undetected.

This year’s outbreak marked the second largest the CDC has recorded. The highest patient count was in 2020, the year of the COVID-19 outbreak when many people were staying home and had backyard flocks as a source of entertainment.