Feline risk to pregnancies manageable

The woman called with a bittersweet announcement.

The good news: She was pregnant.

The bad news: She was returning the kitten she had bought from Joan Bernstein, who breeds Tonkinese cats in Center Moriches, N.Y.

Along with admonitions to avoid alcohol and hot tubs – individually or in tandem – pregnant women invariably are warned about contact with cats because of the concern that feline feces can transmit toxoplasmosis.

According to the Centers for Disease Control and Prevention, more than 60 million Americans carry the Toxoplasma gondii parasite. Those with healthy immune systems often do not notice, exhibiting mild, flulike symptoms or none at all.

But an active toxoplasma infection during pregnancy can cause blindness and brain damage in the unborn infant, as well as stillbirth or pre-term labor.

Bernstein told her caller that despite what her doctor had recommended, there was no need to part with her cat if a few simple precautions were followed: Wear a surgical mask and gloves when cleaning the litterbox – or, better yet, have her husband do it.

While the current conventional wisdom among doctors is that pregnant women who take adequate precautions against toxoplasmosis need not give up their cats, some women still get that unfortunate message.

“The chances of a pregnant woman catching toxoplasmosis from her cat is extremely rare,” says veterinarian James Richards, director of the Feline Health Center at the College of Veterinary Medicine at Cornell University in Ithaca, N.Y.

He points to a study in six large European cities and published in the July 2000 issue of the British Medical Journal. It found, he says, “absolutely no association between toxoplasmosis and having a cat, litterbox cleaning or having a cat that hunts.”

Instead, the study concluded that the main risk factors for acute toxoplasmosis infection were eating undercooked lamb, beef or game (30 to 63 percent of infections), contact with soil (6 to 17 percent), and travel outside Europe and North America.

“Contact with cats,” the study concluded, “was not a risk factor.”

Still, many physicians continue to focus primarily on them. A report in the December issue of Contemporary OB/GYN magazine found that, of the 1,459 physicians responding, 1,364 recommended that their cat-owning patients not clean the litterbox. But only 1,101 mentioned avoiding raw or undercooked meat and only 888 recommended wearing gloves while gardening, even though those activities represented a greater risk of infection.

Cats can become infected with toxoplasmosis by eating or inadvertently licking cat feces that contain the parasite, or oocyst. But Richards believes that scenario is “unlikely,” suggesting that predation – killing and eating infected mice, birds and other small animals – is the main way cats get infected. So keeping a cat indoors dramatically cuts down the risk of transmission. Even then, the window for passing the disease on to humans is a relatively small one.

“Once cats are infected, they will for a short period shed these toxo-organisms in their stool – maybe for a week or two,” Richards says. “And the instant they are shed, they are not infectious. They have to mature for a day or more before they are.”

Which means that frequent cleaning and scooping of a litterbox – always with gloves if a woman is pregnant – lowers the negligible risk even further.

Casual contact with an infected cat is not considered particularly dangerous, as the parasite is not usually carried on the fur.

As for keeping cats free of infection to begin with, “don’t let them hunt, and don’t let them eat raw meat,” Richards advises.