Enterohemorrhagic Escherichia coli (EHEC) may cause severe disease in humans. Cattle and small ruminants are the major natural reservoirs of this food-borne pathogen. Infection in humans has also occurred after direct contact with cows, goats, sheep, and deer. Domestic dogs and cats are rare EHEC carriers, but no human EHEC infections associated with pet contact have previously been reported. In this case, a 2-year-old girl with bloody diarrhea and vomiting tested positive for EHEC serotype O145:H-. The source of infection was investigated. The family did own an indoor cat that was fed only canned cat food. The cat had no history of gastrointestinal disease. Repeated stool samples from the cat grew a strain of EHEC O145:H- that had a pathogenicity gene pattern identical to that of the girl's isolate. The cat was given probiotics in a treatment attempt. After 3 months, the cat's stool was still positive for EHEC, but the girl had spontaneously stopped excreting EHEC. The cat stopped shedding EHEC after treatment with an autovaccination of heated inactivated EHEC. There are several possibilities of the infection process, including the possibility that the girl contacted EHEC from her cat or that the cat acquired the infection from the girl. The risk for food-borne infection for the cat is very unlikely because the cat ate only canned food.

COMMENTARY: This case illustrates that domestic animals may serve as reservoirs for EHEC and should be included in investigations of outbreaks. It is important to note that the girl may have been the source of infection for the cat rather than vice versa. Another important point is that autovaccination may be helpful in treating animals with EHEC.

Enterohemorrhagic Escherichia coli excretion by child and her cat [Letter]. Busch U, Hörmansdorfer S, Schranner S, et al. EMERG INFECT DIS 13:348-349, 2007.