THURSDAY, Nov. 6 (HealthDay News) -- Eight more cases of people becoming infected with salmonella traced to dry dog food have been identified, U.S. health officials said Thursday.
The outbreak, which started in 2006, marks the first time that dry dog food has been confirmed as a source of the bacterial infection in people.
As of Oct. 31, 79 cases of salmonella Schwarzengrund had been reported in 21 states. Most of the cases involved children 2 years old and younger, according to the federal Centers for Disease Control and Prevention.
"We have been following an outbreak of illness due to a specific strain of salmonella. And in 2007, we linked those human illnesses with contaminated pet food produced at one Pennsylvania pet food plant," said report co-author Dr. Casey Barton Behravesh, a CDC epidemiologist. "In 2008, we have identified eight additional cases."
The dog food has been traced to a Mars Petcare U.S. plant in Everson, Pa. On Sept. 12, the company announced a recall of approximately 23,109 tons of dry dog and cat food sold under 105 brand names. The plant is now closed, the CDC said in the Nov. 7 issue of its Morbidity and Mortality Weekly Report.
Despite the recall and the plant closing, Barton Behravesh said the threat of more infections exists. "The issue is that since dry pet food has a one-year shelf life, it is possible that contaminated products from even our 2007 recall could still be in the homes of ill persons and could lead to additional illness," she said.
In late 2007, the plant was shut down for several months for remodeling, cleaning and disinfection, Barton Behravesh said.
"There was a three-month period with no new cases, then cases started again. Contamination was found in the plant again, so it is possible that some of the newer food could be causing the recent increase in cases. As of Oct. 1, the plant was permanently closed," she said.
Barton Behravesh said people should check their dry pet food to see if it was made by Mars Petcare U.S. If it was, they should check the company's Web site to see if their food was part of the recall.
There's a good chance more cases will occur, Barton Behravesh said.
Young children are particularly vulnerable, because they're more likely to get sick from small doses of salmonella, Barton Behravesh said. The primary cause of infection was feeding a pet in the kitchen, she said.
Barton Behravesh noted that no animals have gotten sick during the outbreak. "However, we did find this germ in stool samples from some pets in case households," she said. "That shows that a perfectly happy, healthy pet could be shedding this germ from contaminated food. That could also lead to some routes of contamination in the household," she said.
Dr. Pascal James Imperato, dean and Distinguished Service Professor of the Graduate Program in Public Health at SUNY Downstate Medical Center in Brooklyn, N.Y., thinks there will be more outbreaks of salmonella from contaminated pet food.
"Human salmonella infections associated with dry pet foods are likely to be a continuing problem in the United States," he said. "Fortunately, the annual number of such cases has been small."
People can take a few simple steps to protect themselves from salmonella infection from pet food, Imperato said.
"These include regular washing of pet feeding bowls to prevent bacterial growth; the thorough washing of hands with soap and warm water for at least 20 seconds after handling dry pet foods, including pet treats; and scrupulously avoiding contact between dry pet foods and foods consumed by humans and food preparation surfaces and utensils," he 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 bloodstream, 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.
For more on salmonella, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Casey Barton Behravesh, D.V.M., epidemiologist, U.S. Centers for Disease Control and Prevention, Atlanta; Pascal James Imperato, M.D., dean and Distinguished Service Professor, Graduate Program in Public Health, SUNY Downstate Medical Center, Brooklyn, N.Y.; Nov. 7, 2008, Morbidity and Mortality Weekly Report