Salmonella outbreak traced to tainted dog food

NEW YORK (Reuters Health) - Contaminated dry dog food was the source of an outbreak of Salmonella infections affecting people in 19 states, public health officials report in the Morbidity and Mortality Weekly Report, a publication of the U.S. Centers for Disease Control and Prevention.

This investigation, the first one to identify dry dog food as the source of human Salmonella infections, demonstrates that dry pet food may be contaminated with Salmonella and be an under-recognized source of human infections, especially in young children, the investigators say.

The first three cases of infection reported in Pennsylvania in May, 2006, involved identical strains of Salmonella. By October, 2007, a total of 70 laboratory-confirmed human cases of the outbreak strain had been reported to the CDC.

According to Dr. A. Ferraro, at the Pennsylvania Department of Health, and colleagues, the largest numbers of reported cases were in Pennsylvania (29 cases), New York (9 cases), and Ohio (7 cases). Roughly 40 percent of infected individuals were infants.

A multistate case-control study, as well as cultured specimens of dog stool and bags of dry dog food, implicated a manufacturing plant in Pennsylvania, which produces approximately 25 different brands of dry pet food.

An inspection of the plant turned up one isolate of the outbreak strain on an environmental surface and two isolates in two brands of dry dog food. The manufacturer recalled these two brands, but only in the sized bags from which the bacteria were isolated, and suspended operations between July and November for cleaning and disinfection.

The limited recall by the manufacturer means that contaminated dry pet food is almost certainly still present in many homes, the CDC notes.

To prevent Salmonella infections, the CDC urges pet owners to wash their hands immediately after handling pet food. The agency also recommends that infants be kept away from pet feeding areas and that children younger than 5 not be allowed to touch or eat pet food, treats, or supplements.

SOURCE: Morbidity and Mortality Weekly Report, May 16, 2008.