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Multistate Outbreak of Human Salmonella Infections Caused by Contaminated Dry Dog Food — United States, 2006–2007

This is a first.   Dry dog food did cause a Salmonella outbreak in humans.  That according to today’s Morbidity and Mortality Weekly Report, published by the Centers for Disease Control and Prevention.

Further,  dry dog food may be an under-recognized source of illness in people, especially small children, according to the CDC report.

FIGURE 1. Number of cases* of Salmonella Schwarzengrund
infection associated with contaminated dry dog food, by state
-- United States, January 1, 2006-December 31, 2007

Here’s some of what MMWR said:

During January 1, 2006–December 31, 2007, CDC collaborated with public health officials in Pennsylvania, other states, and the Food and Drug Administration (FDA) to investigate a prolonged multistate outbreak of Salmonella enterica serotype Schwarzengrund infections in humans. A total of 70 cases of S. Schwarzengrund infection with the outbreak strain (XbaI pulsed-field gel electrophoresis [PFGE] pattern JM6X01.0015) were identified in 19 states, mostly in the northeastern United States. This report describes the outbreak investigation, which identified the source of infection as dry dog food produced at a manufacturing plant in Pennsylvania. This investigation is the first to identify contaminated dry dog food as a source of human Salmonella infections. After handling pet foods, pet owners should wash their hands immediately, and infants should be kept away from pet feeding areas.

On May 8, 2007, the Pennsylvania Bureau of Laboratories reported three cases of S. Schwarzengrund infection with indistinguishable PFGE patterns to CDC’s PulseNet.* On June 9, 2007, after PulseNet identified cases in Ohio and other states, CDC’s OutbreakNet team was notified of a potential multistate outbreak of S. Schwarzengrund infections. During June 2007, the Pennsylvania Department of Health (PADOH) interviewed persons identified by PulseNet as infected with the outbreak strain of S. Schwarzengrund. These initial interviews suggested exposure to dogs or dry dog food as a possible source of infection. Thirteen infected persons from Pennsylvania were questioned about dog-related exposures: eight (62%) owned one or more dogs, and the other five reported regular contact with a dog. Seven of the eight persons who owned dogs were able to recall the types of dog food they had purchased recently. Several brands had been purchased, but persons in the households of six patients recalled purchasing dog food products made by manufacturer A. These interviews suggested exposure to dogs or dry dog foods as a possible source of infection.

PADOH collected dog stool specimens and opened bags of dry dog food from the homes of the 13 Pennsylvania patients. The outbreak strain of S. Schwarzengrund was isolated from five of 13 dog stool specimens and two of 22 dry dog food specimens collected from the homes. The contaminated dry dog food bags were two different brands (brand A and brand B), both produced by manufacturer A at plant A in Pennsylvania.

In July 2007, the Ohio Department of Health also interviewed persons infected with the outbreak strain of S. Schwarzengrund and collected two dog stool specimens from one patient’s home. The outbreak strain of S. Schwarzengrund was isolated from one of the dog stool specimens. The dog recently had been fed brand A dry dog food, but the bag of dog food was no longer available for testing.

Go here for the rest of MMWR, go here.  There also a Washington Post story here.