Tainted Pet Food Linked to Rare Salmonella Infection

Young Children, in Particular, Are at Risk of Salmonella Infection From Direct or Indirect Contact With Pets

By Katrina Woznicki
WebMD Health News

Reviewed By Laura J. Martin, MD

Aug. 9, 2010 -- Pet food can be a source of salmonella infection, and millions of families, particularly young children, may be at risk of becoming sick if pet food is not properly handled and stored in the home, according to research conducted by the CDC and several state departments of health.

Human salmonella infections linked to dry pet food had not been reported prior to a three-year outbreak in 2006-2008. Overall, Salmonella enterica causes 1.4 million illnesses and 400 deaths every year nationwide. Although the most common source of human infection is ingestion of contaminated water or food, infection can also occur through direct or indirect contact with pets.

One type of Salmonella enterica is called Salmonella Schwarzengrund, which is not common and accounts for only 0.4% of all human salmonella infections per year. Federal and state researchers examined a multistate outbreak of Salmonella Schwarzengrund that occurred from 2006 to 2008. They conducted one case-controlled study to evaluate household exposures to pet food and a second study to examine the risk factors for transmitting salmonella among children. In the United States, 37% of households have dogs and 32% have cats, and many pets are fed dry pet food, which includes animal ingredients such as liver, beef, or fish.

Researchers compared households where there was a case of infection to geographically matched households where there was no infection.Participants were interviewed and also filled out questionnaires about their contact with animals, use of pet food, brand of pet food used, and pet-feeding practices.

Salmonella in Pet Food

Among the researchers' findings:

• More than 23,000 tons of dry dog and cat pet foods from more than 100 different brands were recalled between 2006 and 2008.
• Seventy-nine patients infected with Salmonella Schwarzengrund in 21 states were identified during the study period; nearly half, 48%, were children aged 2 or younger. Symptoms included bloody diarrhea and fever. Some patients were hospitalized. No deaths were reported.
• Illnesses among infants were significantly associated with feeding pets in the kitchen, but, interestingly, there was no association between salmonella contamination and children putting pet food in their mouths.
• Illness in case households was strongly associated with contact with a dog.
• In 2007, scientists isolated the Salmonella Schwarzengrund strain from 38% of dog fecal samples and from 9% of dry dog foods tested from nine case households in Pennsylvania. Environmental samples taken from the manufacturer later confirmed a match in the outbreak strain. The manufacturer closed its plant in October 2008.

The results were published in the September issue of Pediatrics and were released today online.

The researchers note that dry pet food has a long shelf life and that Salmonella Schwarzengrund may have remained in some households even after the pet foods were recalled. According to the report, since 2006 the FDA has announced at least 13 recalls of 135 pet food products due to salmonella contamination.

The authors recommend that pet owners and their families regularly wash their hands after interacting with pets and pet food products and routinely keep a pet's food and water bowls cleaned and disinfected. The bowls should not be cleaned in the same kitchen sinks or bathtubs where children are bathed, the researchers said, because of the risk of cross contamination.

SOURCES: News release, American Academy of Pediatrics.

Behravesh, C. Pediatrics, published online Aug. 9, 2010.

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