Understanding Zoonoses

The health benefits of pet ownership are widely touted. Cat owners enjoy lower blood pressure. Dogs can alert their owners of impending seizures and heart attacks. While the health benefits of being with pets far outweigh the disadvantages, it's a good idea for pet owners to know about zoonoses - illnesses that can be transmitted between animals and humans.

The Centers for Disease Control (CDC) provide extensive information on zoonoses, tempering its warnings with reminders that pets are a low-level health risk for most people.

Cats

Toxoplasmosis is an illness caused by a parasite that infects most mammals. Estimates are that 60 percent of humans carry the Toxoplasma gondii. Symptoms range from none at all to flu-like aches and swollen lymph nodes. Cat litter is a culprit in the transmission of toxoplasmosis because feces become contagious after 24 hours.

If a woman contracts toxoplasmosis while pregnant, miscarriages, stillbirths and birth defects can result. In less than two percent of cases, toxoplasmosis can also cause eye infections. The CDC notes that undercooked meat is a more likely cause of toxoplasmosis than exposure to pets. Still, pregnant women should avoid cleaning the cat litter box, since the parasite can be passed through the feces. If you can't find someone to take over the chore, wear protective gloves and wash your hands thoroughly afterward.

"Cat scratch fever" may be the only zoonotic disease with its own theme song. Ted Nugent made the song a hit in 1978; the aches and fever that come from the bacteria Bortonella henselae may not be as appealing. The CDC estimates that 40 percent of cats will carry the bacteria at some point in their lives, although they will not show any symptoms. Kittens are most likely to be infected and also most likely to indulge in the rough play that leads to scratches. The CDC advises washing any cat bites or scratches immediately with running water and soap.

Dogs

Dogs who spend time outdoors can contract and communicate a range of parasites including hookworm, roundworm and tapeworm. They can also host the ticks that communicate Lyme disease and Rocky Mountain spotted fever. Worm your dogs regularly (heartworm pills are also a good general-purpose worm medication) and keep the yard free of waste. Use tick preventives to reduce the chances of your dog contracting or transmitting a tick-borne illness.

Cats, dogs and other mammals are susceptible to rabies. The disease, although deadly, is fortunately rare in the U.S. - only five Minnesotans have died of rabies since 1900. Bats are far more likely to transmit the disease than are cats or dogs. For their own safety and yours, all outdoor pets should be vaccinated. The CDC also warns against handling stray or unfamiliar animals.

A recent news article also notes that people who have recurring staph infections might consider having their cats or dogs tested and treated as well. Dogs have transmitted drug-resistant staph bacteria in several cases, and recently a German woman contracted the infection from her cat.

Reptiles

The CDC reserves its sternest warnings for reptiles in general, and turtles in particular. Turtles naturally carry salmonella, which can cause diarrhea, fever and stomach pain. While healthy adults can usually shake off the effects of salmonella after a few unpleasant days, there are high-risk groups for whom the infection can be deadly. That includes children under the age of five, who are also among the most likely to receive turtles as pets and to transmit the bacterium from their hands to their mouths. The CDC recommends that turtles not be allowed to roam freely in the house, and not be bathed in a sink, tub or other container used by humans. Turtles shouldn't be brought to childcare centers or nursing homes. Anyone who handles turtles should wash their hands thoroughly afterward.

People at risk

Many zoonotic diseases like salmonella are particularly hazardous to small children, the elderly and people with compromised immune systems. The CDC makes it clear that simple precautions can minimize the risks of pet ownership for people at risk:

• Wash hands after handling pets, especially before eating or preparing food.

• Don't give pets raw or undercooked food, or let them drink from the toilet.

• Don't adopt a pet that is under 6 months old, and be sure any animal you bring into your home is healthy.

The CDC's "Healthy Pets, Healthy People" website contains detailed suggestions for at-risk people as well as additional information on the illnesses transmitted by domestic and wild animals. Be sure to click on the "Health Benefits" link for information on the health benefits animals provide people: www.cdc.gov /healthypets.

Laura French is a freelance writer who lives in Roseville with three cats - Gracie, Tennessee Tuxedo and his pal Chumley, and Sofie, whose breed(s) will forever remain a mystery.

Dog park locations: www.startribune.com/petcentral