Salmonella illnesses traced to pet rodents.

Hamsters and other pet rodents are probably underappreciated spreaders of salmonella bacteria, researchers say. A recent outbreak investigation linked 15 of 22 infections caused by Salmonella enterica of a type called Typhimurium to the act of handling an infected rodent or to having contact with a person who'd handled such an animal.

Salmonella is most commonly a food borne illness but has, on occasion, been linked to pets, including turtles.

The investigation began in August 2004, when researchers identified an antibiotic-resistant strain of Typhimurium in eight hamsters from a pet distributor in Minnesota. Minneapolis-based Stephen Swanson of the Epidemic Intelligence Service, a division of the Centers for Disease Control and Prevention, led the effort.

Swanson's team compared the genetic pattern of the hamster's bacterial strain with genetic patterns of bacteria obtained from sick people and recorded in a national database. The researchers identified 28 people in various states who had contracted virtually identical Typhimurium during a 10-month period. The team interviewed 22 of those patients to find out whether they'd had contact with rodents. Thirteen reported direct contact with pet rodents, while two had contact with pet owners who'd fallen ill.

Further investigation revealed that one patient's pet mouse harbored the outbreak strain, and that several hamsters from pet stores where other patients had shopped also had the drug-resistant bug.

Swanson's team reports its findings in the Jan. 4 New England Journal of Medicine.