Since December 2017, the Centers for Disease Control and Prevention (CDC), several states, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS) have been investigating nine related cases of human Salmonella enteritidis infections linked to contact with pet guinea pigs. The Pet Industry Joint Advisory Council’s (PIJAC) Zoonoses Committee has been working with CDC during this ongoing investigation.

The investigation was triggered when CDC’s national laboratory network, PulseNet, identified three human cases of Salmonella that were shown to be closely related through genetic analysis, pointing to a common source of infection. From those results, CDC retroactively examined the PulseNet database and found an additional six human cases of closely related Salmonella dating back to 2015. Altogether, illnesses were identified in eight states: Colorado (2), Indiana, Iowa, Massachusetts, Michigan, New York, Virginia, and Vermont.

Following standard practice in public health investigations, officials interviewed seven people who had been infected in order to identify, or “trace back” possible sources, including food consumption and animal contact. Four people reported contact with a guinea pig or its habitat prior to becoming ill.

Salmonella isolated from a pet guinea pig owned by an ill individual was closely related genetically to the strain in several of the human cases. Together, these results point toward guinea pigs as the likely source.

Although the number of cases is small, CDC considers this an outbreak because the pattern is different than normal background levels. In this instance, the genetic similarity of Salmonella warrants further investigation. Unlike the recent multi-drug resistant Campylobacter puppy-related outbreak where widespread antibiotic resistance was found, 11 of the 13 Salmonella strains analyzed from humans and guinea pigs were not resistant to commonly used antibiotics. However, two samples, including one from a human, suggested resistance to three types of antibiotic medications.

The trace back phase of this investigation will continue as CDC, together with PIJAC and other public health agencies, work to identify the source(s) of infected guinea pigs and to pursue remedies at the breeder or distributor level. It is common for public health agencies, often at the state or local level, to interview personnel in retail pet stores and gather fecal samples for laboratory analysis. As more information is gathered, similar sampling may occur at breeding and consolidation facilities.

Most people infected with Salmonella develop diarrhea, fever, and abdominal cramps between 12 to 72  hours after infection. The illness usually lasts four to seven days, and most individuals recover without treatment. However, in some cases, diarrhea may be so severe that a person requires hospitalization.

Antibiotics may be necessary for infections that spread from the digestive system to other parts of the body. Children under five, pregnant women, senior citizens, and people with weakened immune systems run a greater risk of infection.

Pet rodents such as guinea pigs, regardless of where they are purchased or adopted, can carry Salmonella. Even an animal that appears healthy and clean can carry the Salmonella bacteria. It is found in the intestinal tract of many animals including reptiles, amphibians, rodents, live poultry, dogs, and cats (bacteria may be shed in feces). Infection may result from hand-to-mouth contact after directly handling animals, as well as after indirect contact through cleaning cages or bedding; handling food or food bowls; touching other things in the area where the animal lives; or through consumption of food/drink prepared in contaminated environments.

Practicing good pet hygiene is important. By following these guidelines, you can keep your family healthy and enjoy having pet rodents in your life while preventing illness spreading between people and pets:

Pick the right pet for you.

• Pet rodents, including guinea pigs, are not recommended for families with children younger than 5 years, 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 childcare centers, schools, or other facilities with children younger than 5 years.

Wash your hands.

• Always wash your hands immediately with soap and water after touching, feeding, or caring for pet rodents or cleaning their habitats.
• Closely supervise children and make sure they wash their hands with soap and water after handling small animals, their habitats or anything in their habitats.

Play safely.

• Do not kiss, nuzzle, or hold pet rodents close to your face. This can startle your pet and increase the chance it will bite you. Bites from pet rodents can spread germs and possibly make you sick.

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.

Be aware that pet rodents can carry germs that can contaminate surfaces in areas where they live and roam.

• You do not have to touch pet rodents to get sick from their germs.
• Make sure rodent enclosures are properly secured and safe so your pet does not get hurt or contaminate surfaces.

Clean and disinfect rodent habitats, food and water bowls, and other supplies outside your home when possible.

• If you clean rodent supplies indoors, use a laundry sink or bathtub, and thoroughly clean and disinfect the area immediately afterwards.
• Never clean rodent habitats or their supplies in the kitchen sink, other food preparation areas, or the bathroom sink.

Talk to your veterinarian about your pet rodent’s health.

• Your veterinarian can play a key role in helping you and your pets stay healthy.

Tell your healthcare 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 pet rodents can cause serious and life-threatening illness in people.

Resources:

• CDC’s posting on the investigation is available at https://www.cdc.gov/salmonella/guinea-pigs-03-18/index.html
• Updates on these cases and other zoonotic issues can be found on the PIJAC website at http://www.pijac.org/animal-welfare-and-programs/zoonotic-disease-prevention
• CDC advice on keeping people and small mammals healthy can be found at https://www.cdc.gov/healthypets/pets/small-mammals/index.html
• More information on Salmonella is available at https://www.cdc.gov/salmonella/index.html

PIJAC’s Animal Care Sheet for Guinea Pigs http://pijac.org/sites/default/files/pdfs/guineapig3Col030216.pdf