WEDNESDAY, May 21, 2008 (HealthDay News) -- An outbreak of human Salmonella infection, which occurred as far back as 2006, has been traced to contaminated dry dog food, the first time such a link has been uncovered, according to U.S. officials.
And, Salmonella infections in humans from dry dog food may be an under-recognized source of illness in people, especially young children, officials from the U.S. Centers for Disease Control and Prevention said.
"This is the first time human illness has been linked to dry dog food," said CDC epidemiologist Dr. Casey Barton Behravesh, who co-authored a report on the finding.
The CDC isn't sure how the Salmonella bacteria got into the dog food, Barton Behravesh said. "There are a number of possible ways that that could happen, and that's something we are still trying to figure out," she said, adding that there have been previous cases of people contracting Salmonella infection from contaminated pet treats.
The incidents of people becoming infected with Salmonella from dry dog food occurred in 2006 and 2007. An estimated 70 people, mostly in the Northeast, were infected by dog food produced by Mars Petcare at its Pennsylvania plant. About 40 percent of those infections involved infants, according to the report, published in the May 16 issue of the CDC's Morbidity and Mortality Weekly Report.
Most of the cases occurred in Pennsylvania (29), New York (nine) and Ohio (seven). There were also reported cases in Alabama, California, Illinois, Iowa, Kentucky, Michigan, Minnesota, North Dakota, North Carolina and Virginia.
Among the 61 people whose ages were available, the median age was 3 years, and 24 were less than 1 year old. Of the 38 people for whom clinical information was available, 15 (39 percent) had bloody diarrhea. For the 45 persons whose hospitalization status was known, 11 (24 percent) had to be hospitalized. No deaths were reported, according to the report.
No pets became ill. However, Salmonella was identified in feces samples from dogs that ate the dry food. In addition, Salmonella was found in open bags of the pet food fed to the dogs and in unopened bags of dog food made in the Pennsylvania plant, the CDC said.
Mars Petcare voluntarily recalled some bags of the two brands of food involved, but neither of the recalled brands was related to human illness, the CDC said.
Infection with the Salmonella bacteria produces an illness called salmonellosis. According to the CDC, most infected people develop diarrhea, fever, and abdominal cramps within 12 to 72 hours. The illness typically lasts four to seven days, and most people recover without treatment. But, for some, the diarrhea may be so severe that they need to be hospitalized. In these patients, the infection can spread from the intestines to the blood stream, and then to other parts of the body, leading to death unless antibiotics are administered promptly. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.
Salmonella infection typically comes from undercooked eggs, poultry, or meat, but can also result from direct contact with farm animals, reptiles and pets. To prevent infection, the CDC recommends washing your hands immediately after handling the food, including dry dog food.
"The most important thing is to wash your hands right after you handle any dry dog food, any other pet food, pet treats, even supplements or vitamins," Barton Behravesh said. "In addition, keep infants and other young children away from pet food, because kids tend to want to see what their dogs are eating and grab at the pet food and play with it or even put it in their mouth."
One expert thinks contamination of pet food is likely to become more commonplace.
"There have been problems with pet foods before," said Dr. Pascal James Imperato, chairman of the department of preventive medicine and community health at the State University of New York Downstate Medical Center in New York City.
"If the food had any animal product in it, there could have been contamination, or if it was being processed in a plant where they were also processing animal product, then contamination can easily occur," he said.
Imperato said the way food is produced makes it more likely that contamination will occur.
"There is greater industrialization of the production of food products, both for humans and animals, and these are complex processing systems. Therefore, there is greater opportunity for contamination," Imperato said. "We are likely to see many more of these problems."
For more on salmonella, visit the U.S. Centers for Disease Control and Prevention.