Pet chicks and ducklings seem unlikely culprits in a serious public health problem. But they’re responsible for infecting more than 900 people with salmonella this year — the highest number to date, according to the Centers for Disease Control and Prevention.

The agency is investigating multistate outbreaks of salmonella infections linked to people who keep poultry in their backyards. As the local-food movement grows across the nation, more people are raising chickens, ducks and other birds. But along with the benefits of connecting with nature and easy access to fresh eggs comes the risk of disease.

While most people who contract salmonella typically recover without treatment after a few days of diarrhea, fever and abdominal cramps, some cases require hospitalization and some can be fatal.

So far this year, 961 people in 48 states have contracted the disease from backyard birds. More than 200 people have been hospitalized, and one person in North Carolina has died. Outbreaks have been reported for several years now, but case numbers shot up sharply last year and are expected to continue to rise.