Pregnancy peril from cats is exaggerated


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, pregnant women are always 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 flu-like 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 preterm labor.

Bernstein told her caller that there was no need for her to part with the cat if she followed a few simple precautions: Wear a surgical mask and gloves when cleaning the litter box, or, better yet, have her husband do it.

Although 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.

And some experts go so far as to say that cats have been unfairly singled out for spreading this highly infectious disease, when in fact they carry little blame.

“The chance 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.

As proof, he points to a study done in six European cities and published in the July 2000 issue of the British Medical Journal. It found, he says, “no association between toxoplasmosis and having a cat, litter box 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% of infections), contact with soil (6% to 17%), and travel outside Europe and North America. “Contact with cats,” the study concluded, “was not a risk factor.”

But many doctors still focus on them. A report in the December issue of Contemporary OB/GYN magazine found that of the 1,459 doctors responding, 1,364 advised that their cat-owning patients not clean the litter box. But only 1,101 mentioned avoiding raw or undercooked meat, and only 888 recommended gloves for gardening -- even though those activities represented a greater risk of infection.

Feline scapegoating started, Richards explains, when “it was discovered that cats shed infectious stages of toxoplasmosis in their stool. It’s from that that all this fear arose.”

Cats can become infected with toxoplasmosis by eating or licking cat feces that contain the parasite egg, or oocyst.

But Richards says that scenario is “unlikely” and suggests 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 explains. “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 litter box -- always with gloves if a woman is pregnant -- lowers the negligible risk even further.

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