On April 6, 2012, the United States Food and Drug Administration announced a voluntary recall of Diamond Naturals Lamb Meal and Rice dry dog food. Since the initial recall, several other brands of food manufactured in a South Carolina plant have been voluntarily recalled for possible Salmonella contamination. Voluntary recalls of pet food are not uncommon, but this recall is unusual. Illness in humans, not dogs, prompted the recall.

Outbreak investigation

Scientists at the Centers for Disease Control checked the genetic fingerprint of the Salmonella found in the dog food against a national database of foodborne infections and found people infected with an identical bacterium. Because the Salmonella isolated from the dog food and the people is a rare type, the humans were interviewed to determine if there was a common source of infection. These interviews revealed many of the infected people had been exposed to dogs and the brand of dog food included in the initial recall. Subsequent recalls have all involved food manufactured in the same facility.

Why did people get sick?

This medical mystery seemed backwards to me. I could understand if my dog and I both got sick from some food I slipped her at the table, but I would suspect hardly any of us grab a handful of tan nuggets from our dog’s bowl as a quick snack.

So to help me understand, I called my sister, Mary Hohenhaus, MD, FACP, who is also a board certified internist (but for people) with Brigham and Women’s Physicians Organization in Boston.

The other Dr. Hohenhaus says:

Salmonella bacteria are a leading cause of infectious gastroenteritis in humans – more than a million cases in the U.S. each year. Symptoms include diarrhea, cramping, and fever starting anywhere from 12 to 72 hours after exposure.

Catching Salmonella is easy only if the bacteria can find their way into your mouth. I use a scoop to measure out dry food for my cat, but I could just as easily grab a handful of kibble for Sam’s bowl – and if the next thing I did was grab a handful of grapes for my breakfast, I could be in trouble.

Food and water contaminated with animal feces are a common source of Salmonella infection. Outbreaks have been associated with meat, eggs, dairy products, and fresh produce, as well as processed foods. Pet birds and reptiles can carry Salmonella without appearing ill. Feces from infected humans are another source.

Many infections are mild and don’t come to medical attention. Most people get better within a week just with extra fluids and rest. Children, the elderly, and people whose immune systems don’t work well are more likely to have severe cases of Salmonella, where the bacteria enter the bloodstream. These people need intravenous fluids, antibiotics and close monitoring in a hospital.

This current outbreak is a good reminder that Salmonella can show up in some surprising and unexpected places. It also reminds us that contaminated foods look, smell, and taste perfectly normal. The best protection against Salmonella and many other infections is common sense: keep your hands clean (and out of your mouth) and practice food safety.

When should you wash? After using the toilet, before preparing food, and any time your hands are visibly soiled are a must. Don’t forget to wash after playing with pets, not just after poop-scooping. A pocket-sized bottle of hand sanitizer is a great addition to your daily walk with Fido.

In the kitchen, wash utensils and work surfaces thoroughly after handling raw meat and eggs and before preparing produce – especially important if fruits and vegetables will be served raw. Thoroughly cook meat and eggs, and be sure to serve hot foods hot and cold foods cold. For more information click here.

This Dr. Hohenhaus is worried about dogs

Although the Salmonella cases making the news are human, dogs can also contract Salmonella after eating tainted food. Veterinarians in New York City are required to report certain diseases to the Department of Health and Mental Hygiene just like physicians are. We report zoonotic diseases, diseases transmitted between animal and humans, which include: Salmonellosis, tuberculosis, Rocky Mountain spotted fever, and leptospirosis.

I contacted one of my colleagues at the New York City Department of Health and Mental Hygiene, Dr. Sally Slavinski, Assistant Director Zoonotic, Influenza and Vector-borne Disease Unit, and she says no canine cases associated with this recall have been reported to the DHMH. I do have veterinary colleagues out of state who have seen a smattering of dogs they believe contracted Salmonellosis from the recalled foods.

Prevention in pets

For tips on preventing foodborne infections in your pets, click here.