A continuing investigation by the CDC, several states and the US Department of Agriculture Animal and Plant Health Inspection Service has found evidence that contact with pet guinea pigs is the likely source of the salmonella outbreak.
The illnesses started between July 17, 2015, and December 15.
Most people infected with salmonella experience symptoms such as diarrhea, fever and abdominal cramps 12 to 72 hours after being exposed to the bacteria. The illness lasts about four to seven days.
Most people recover without treatment, but in some cases, the diarrhea can be so severe that patients need to be hospitalized. In rare cases, salmonella can cause death unless a patient receives prompt treatment with antibiotics.
Children younger than 5, adults older than 65 and people with weakened immune systems should take extra precautions.
The CDC said in Tuesday's announcement that this outbreak is a reminder that pet rodents such as guinea pigs can carry Salmonella bacteria even when they look healthy and clean, regardless of where they are purchased or adopted.
-- Pick the right pet. Rodents are not recommended as pets for children younger than 5, pregnant women, elderly adults or people with weakened immune systems, because these groups are at greater risk for serious illness. Pet rodents should not be kept in child care centers, schools or other facilities with children younger than 5.
-- Always wash your hands after touching, feeding or caring for pet rodents or cleaning their habitats.
-- Do not kiss, nuzzle or hold pet rodents close to your face. Never eat, drink or smoke while playing with or caring for your pet rodent.
-- Keep pet rodents, food and water bowls, and other supplies out of the kitchen or other areas where food is prepared, served or consumed.
-- Tell your health care provider that you have been around pet rodents, whether at home or away from the home, especially if you are sick or have been bitten or scratched. Some germs carried by rodents can cause serious and life-threatening illness.
-- Do not release unwanted pet rodents into the wild. Many pet retailers, pet stores, local animal shelters, zoos or animal rescues accept unwanted pets.