Three Minnesota cases of salmonella have been linked to pet ducklings in part of a multistate outbreak that is under investigation by the U.S. Centers for Disease Control and Prevention.

The ducklings were purchased from Tractor Supply Company in Inver Grove Heights, the Minnesota Department of Health said Tuesday.

The ill Minnesotans were ages 18 to 60. All three cases were caused by Salmonella infantis, which has been previously associated with poultry. The cases occurred from late March through early April.

Dr. Joni Scheftel, public health veterinarian at the Health Department, said the outbreak underscores the importance of washing hands thoroughly after handling chicks, ducklings or other birds.

People typically contract salmonella from poultry by hand-to-mouth contact, usually after handling birds, then eating or drinking without washing their hands first. Salmonellosis can also be contracted by eating contaminated foods that have not been properly prepared and handled.

Salmonella can cause diarrhea, vomiting and fever. Some people are more susceptible to infection, including young children, pregnant women, the elderly, people on chemotherapy, diabetics and others with weakened immune systems. About 20 percent of cases reported to the Health Department go to the hospital.