Contaminated dry dog food was the cause of an outbreak of Salmonella infections affecting people in 19 states, public health officials reported in the Morbidity and Mortality Weekly Report, a publication of the U.S. Centers for Disease Control and Prevention.

These findings point out that although it is somehow surprising, dry pet food may be a source of human infections, especially in children. There hasn’t been any research with this result before.

"This is the first time human illness has been linked to dry dog food," said Centers for Disease Control and Prevention epidemiologist Dr. Casey Barton Behravesh, co-author of the report, as quoted by the Washington Post.

It hasn’t been yet discovered how the Salmonella bacteria got into the dog food, but specialists are trying to discover the source.

The cases of infections with Salmonella from dry dog food were registered in 2006 and 2007. Almost 70 people, most of them living in the Northeast, were contaminated by dog food produced by Mars Petcare at its Pennsylvania plant. 40% of the people infected were children, according to the report, published in the May 16 issue of the CDC's Morbidity and Mortality Weekly Report.

Mars Petcare withdrew the infected products and suspended operations between July and November for cleaning and disinfection.

The CDC made some recommendations in order to prevent Salmonella infections. The pet owners should wash their hands immediately after handling pet food. The agency also urges 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.