Guinea pigs are relatively benign pets in terms of zoonotic diseases, but like any animal, they can carry some pathogens that are transmissible to people. This was highlighted in a poster presentation at the recent International Conference on Emerging Infectious Diseases in Atlanta. The poster (Bartholomew et al) described a CDC investigation into an outbreak of Salmonella Enteritidis infections in people in multiple states in 2010.
Here are some highlights:
- The first affected person was a child who purchased a guinea pig from a pet store. The animal looked "frail" and was housed with the child's existing guinea pig. Later that month, both guinea pigs developed diarrhea and died. Shortly thereafter, the child developed diarrhea, fever, cough, chest and back pain, a rash and some other signs. Ultimately, a Salmonella infection of the sternum was diagnosed, indicating that Salmonella had traveled from the intestinal tract to the child's bloodstream and set up an infection in the breast bone.
- The CDC investigation focused on other people who had been diagnosed with the same strain of S. Enteritidis. They identified 10 such cases who also reported guinea pig exposure, scattered over 8 US states.
- The same Salmonella strain was also identified in guinea pigs, including one from a Texas guinea pig broker, around the same time as these cases were occurring.
- Most of the affected individuals were children. Three had purchased guinea pigs from the same pet store chain as the first child. Three other affected people were employees of stores from that pet store chain.
- Testing of the environment in pet stores from that chain did not identify Salmonella. However, since sampling was done well after people got infected, it doesn't mean it wasn't there earlier.
- No common guinea pig source supplier was found, but one Pennsylvania breeder was identified as a possible source for the cases associated with that pet store chain.
This is pretty strong evidence that the infections were guinea pig-associated.
Some take-home messages:
- Any animal can be a source of potential infection, and general hygiene practices should be used all the time to reduce exposure to pet feces.
- Sick animals might mean the potential for sick people. While it's sometimes tough to convince people that testing dead animals (especially dead animals that don't cost much) is useful, it might have had a great impact on the care of the first child. If physicians knew that the child was exposed to Salmonella, they might have been able to make the diagnosis much quicker.
- Pet stores are not uncommonly implicated as sources of outbreaks, and there are also risks to their staff. Pet stores need to have good infection control, hygiene and disease reporting practices.
- The nature of pet rodent distribution, with large breeders sending animals to brokers where large numbers of animals get mixed and sent on to pet stores, creates the potential for widespread disease transmission, as has been repeatedly shown in the past.