My wife is two months pregnant. We have two cats. We are trying to decide if we should keep them. Is it safe to keep the cats? What kind of diseases can be passed along to the baby?

--Tom

Cats may transmit an infection called toxoplasmosis through their feces. Outdoor cats who hunt are more likely to have toxoplasmosis than are strictly indoor cats. A person may also contract toxoplasmosis through eating infected raw or undercooked meat. If a woman is infected with toxoplasmosis for the first time during pregnancy, the infection may reach the baby; this happens in up to five pregnancies in every 1,000. Toxoplasmosis in the baby may cause miscarriage, calcifications in the brain with resultant seizures or mental retardation, eye problems, anemia, liver disease and low birthweight.

However, if a woman is immune to toxoplasmosis before pregnancy, then the baby is protected. One-third of American women are already immune to toxoplasmosis, and that percentage is higher in longtime cat owners. The ideal situation is for all cat owners who are contemplating pregnancy to be tested for immunity to toxoplasmosis before conceiving; this is done by a simple blood test. If a woman, such as your wife, is already pregnant and tests positive for toxoplasmosis, it can be difficult to determine whether she was infected during the pregnancy or before it; a series of blood tests over the course of a few weeks may be necessary. If a woman has been infected during pregnancy, an antibiotic called spiramycin can reduce the chance of the baby being infected. Amniocentesis, a test that involves withdrawing some amniotic fluid from around the baby, may also be done to look for infection.

If a pregnant woman is not immune to toxoplasmosis, she should avoid cat feces. Because the infection can be transmitted through the dust associated with the litter box, she should not change the litter. Ideally, the litter box should be placed well out of her way and changed by you -- the husband -- daily. Using of one of the clumping types of litter may help as well. Contact with the cats themselves is not harmful; cats tend to be very fastidious and rarely if ever roll around in their own wastes.

Once the baby is born, the cats, like any other pets, should not be left with the child unsupervised. You might place a screen door on the baby's room -- this way mom and dad can easily peek in and hear baby, and the pets can roam as usual in the rest of the house.