Since March, 93 cases of salmonella have been reported in 23 states, the Centers for Disease Control and Prevention reported. Eighteen people were hospitalized and one death is being investigated to see if it was caused by the infection.
Investigators interviewed dozens of the patients and most said they had touched chicks or ducklings before they got sick. Health officials advise washing your hands after handling live poultry.
The birds were traced to a mail-order hatchery in Mount Healthy, Ohio, north of Cincinnati. The business, Mount Healthy Hatcheries, was tied to a salmonella outbreak last year as well.
State regulators visited the business repeatedly and say it has done what the state asked.
"The place is very clean," said Erica Pitchford, a spokeswoman for the Ohio Department of Agriculture.
It's possible salmonella may have come from other businesses that supply chickens to the hatchery, she said.
A representative of the hatchery could not be reached after business hours Thursday.
The latest outbreak is different from one reported Wednesday in the New England Journal of Medicine. That one involved more than 300 cases of a different salmonella strain over eight years, and was traced to a hatchery in New Mexico.
The ability of officials to identify and trace outbreaks is improving. But there may also be a real increase in salmonella cases from chicks that's driven by the increasing popularity of backyard flocks, said Casey Barton Behravesh, a CDC veterinary epidemiologist.