They carry risks

I’m a soft touch when it comes to pets. We’ve got two fish, two dogs, a horse and, until recently, we also shared our backyard with three chickens. But I decided to draw the line when my children pleaded for a chinchilla after a friend of theirs had gotten one. I didn’t want the responsibility of caring for yet another animal and didn’t think a chinchilla would make an ideal pet.

Indeed, chinchillas are among a long list of animals that many veterinarians advise against keeping as household pets because they pose a health risk to the people who own them. Certain infectious illnesses, called zoonotic diseases, can be transmitted from animals to humans. While infected animals may appear healthy, some of these diseases can have potentially devastating consequences on humans.

In spite of the veterinarians’ concern, the demand for unusual pets is growing. Surveys conducted by the American Pet Products Manufacturers Assn. show that between 1994 and 2004 the number of households with reptiles nearly doubled, from 2.8 million to 4.4 million; the number of households with small animals, such as rabbits and guinea pigs, climbed from 4.7 million to 5.7 million.

Topping the list of troublesome pet choices are turtles. Turtles carry salmonella bacteria and sporadically shed them in their feces. Humans become infected when they come into contact with infected feces (when they are holding the animal, for instance) and then touch their mouth or handle food. Even contact with contaminated surfaces, in the absence of the animal itself, can result in infection.

Most states now ban the sale of small turtles because of the threat of salmonella transmission. In California, pet stores are allowed to sell larger turtles but must inform customers about the salmonella risk. Other reptiles -- lizards and snakes, for example -- and amphibians such as frogs, toads and salamanders also can transmit the bacteria.

The Centers for Disease Control and Prevention estimates that more than 70,000 Americans contract salmonella from contact with reptiles and amphibians each year. Typically, these infections cause several days of severe diarrhea, fever and abdominal cramps.

Most cases resolve themselves without treatment. In some cases, however, serious -- even life-threatening -- complications develop.

To help protect against salmonella, the CDC recommends that reptiles be kept out of homes with children younger than 5 or individuals with weakened immunity, including the elderly. (These individuals are most likely to become sick if exposed to salmonella and are at greatest risk of suffering complications if they are infected.) The CDC also recommends that reptiles and amphibians not be kept in child care facilities, such as day-care centers or preschools -- although such pets are relatively common in these settings.

Earlier this year, the Journal of the American Medical Assn. reported on two women who died from rat-bite fever, a bacterial illness transmitted by rats and other rodents. Although infections in humans are usually caused by a rodent bite or scratch, rat-bite fever can also be contracted by handling an infected animal or by consuming food or water contaminated with its urine or feces.

(One woman described in the recent report died after being bitten by a rat in the pet store where she worked; it’s believed that the other woman was infected by one of the nine rats she kept as pets.)

Experts are most concerned about the risks posed by “exotic” animals, particularly those imported from other countries.

“Exotic animals seem to be becoming more and more popular,” says Nina Marano, associate director for veterinary medicine and public health at the National Center for Infectious Diseases. These animals can carry zoonotic diseases with them -- diseases that can spread rapidly among susceptible animals in this country and potentially lead to outbreaks in humans.

In 2003, more than 70 people developed a rare viral disease called monkeypox after touching or handling sick prairie dogs. The prairie dogs, which had been sold as pets, were infected with the virus by animals brought to the United States from Africa. Before this outbreak, monkeypox had never before been reported in the United States.

Although the importation of rodents from Africa has been stopped, many other types of animals -- from sugar gliders and wallabies to boa constrictors and parrots -- continue to be legally imported. “These animals are better off left in the wild,” says Marano.

My children eventually gave up the notion of getting a chinchilla. Ultimately, it was my husband who swayed them. He reminded them that chinchillas can live up to 10 years, which would mean they’d be cleaning cages well beyond graduation from high school.

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Don’t forget dogs, cats

Dogs and cats can give their owners a whole lot more than love and companionship. They can transmit diseases to them as well. Ringworm, a fungal infection of the skin, is perhaps the most common disease carried by dogs and cats that can be spread to humans.

Potentially more serious, however, are parasitic infections such as hookworm and roundworm. These infections are transmitted through contact with the stool of infected dogs and cats.

To prevent parasitic infections, dogs and cats should be properly dewormed when they are young and regularly monitored as adults. “Annual deworming is something that should be considered,” says Bruno Chomel, a professor at UC Davis School of Veterinary Medicine.

Also, children should not be allowed to play in areas that could potentially be contaminated with dog or cat feces. To prevent contamination in public parks, dogs should not be allowed in children’s play areas.

-- Valerie Ulene