A least 25 people in 11 states have become sick from human Salmonella serotype Altona after handling their backyard chicks and ducklings, according to the Centers for Disease Control and Prevention.

The CDC says a traceback investigation implicates a national mail-order hatchery, Feed Store Chain A, which supplies poultry for people raising flocks at home for fresh eggs, as the source of the birds.

Seven people have been infected with the outbreak strain of Salmonella in Ohio; four in North Carolina; three in Kentucky; two in Maryland, Pennsylvania and Tennessee; and one in Indiana, Minnesota, New York, Vermont and Virginia, the CDC said.

Laboratory testing this month confirmed Salmonella Altona bacteria matching the outbreak strain in three samples collected from a chick and the yard of an ill person’s household in Ohio, as well as from three samples collected from chick and duckling displays at two locations of Feed Store Chain A in North Carolina.

Sixteen of 21 case patients interviewed said they had contact with chicks, chickens, ducks, ducklings, geese, and turkeys prior to becoming ill. Of those who could recall the type  poultry, all 16 identified chicks, ducklings, or both, and 14 reported purchasing their chicks and ducklings from multiple locations of Feed Store Chain A.

Onset of their illnesses was between February 25 and April 25, 2011. The case patients range in age from less than one year old to 84 years old; the median age is 8 years. Among the 21 patients with available information, 8 (38 percent) were so sick they had to be  hospitalized.

Illnesses that occurred after April 20 might not yet be reported, the CDC warned, because of the time it takes between when a person becomes ill and when the illness is reported.

The PulseNet system, the national surveillance network of public laboratories coordinated by CDC, is being used to track cases of illness that may be part of the outbreak, and the CDC said it is working with state public health and agriculture officials and the U.S. Department of Agriculture’s (USDA) National Poultry Improvement Plan (NPIP) to investigate the outbreak.