(CNN) Over 220 cases of salmonella have been reported in the past month in outbreaks spanning 41 states, the US Centers for Disease Control and Prevention announced Thursday, and the agency believes that backyard poultry is to blame.

A total of 279 cases of illness have been reported in the outbreaks so far, and 40 people have been hospitalized. No deaths have been reported.

Most of those infected reported contact with chicks or ducklings from hatcheries, agricultural stores and websites. About a third of those who fell ill were children younger than 5, a group at particular risk for complications that may require hospitalization.

This is the 12th time since 2011 that the CDC has announced a salmonella outbreak tied to live poultry. Over 70 such outbreaks have been declared since 2000, according to the agency.

While most people recover without treatment after four to seven days, the bacterial infection can cause diarrhea, fever and stomach cramps. Severe diarrhea can require hospitalization.

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