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Toxoplasmosis and Pregnancy

Toxoplasmosis is an infection caused by the protozoan parasite Toxoplasma gondii that can threaten the health of an unborn child if a woman becomes infected with Toxoplasma for the first time while she is pregnant.

The infection is usually contracted by handling soil or cat litter that contains cat feces infected with the parasite. Cats generally pick up these organisms when they hunt and eat infected prey. Healthy cats rarely get sick themselves from the parasite, but when they are infected for the first time, they can shed it in their feces. It can also be contracted from eating undercooked meat from animals infected with the parasite or from uncooked foods that have come in contact with contaminated meat. Cats excrete the pathogen in their feces for a number of weeks after contracting the disease, generally by eating an infected rodent. Even then, cat feces are not generally contagious for the first 1-3 days after excretion, after which the cyst matures and becomes potentially pathogenic. Studies have shown that only about 2% of cats are shedding oocysts at any one time, and that oocyst shedding does not recur even after repeated exposure to the parasite.

With rare exception, women who have been infected at least 6 to 9 months before conception develop immunity to and do not pass it on to their baby. If you have been infected with Toxoplasma once, you usually will not become infected again.A positive antibody titer indicates previous exposure and immunity and largely ensures the unborn baby’s safety. A simple blood draw at the first pre-natal doctor visit can determine whether or not a woman has had previous exposure and therefore whether or not she is at risk. If a woman receives her first exposure to toxoplasmosis while pregnant, the baby is at particular risk. According to the Organization of Teratology Information Services (OTIS), when the mother gets infected between weeks 10-24 of pregnancy, the risk for severe problems in the newborn is about 5-6%. Effects on the baby include premature birth, low birth weight, fever, jaundice, abnormalities of the retina, mental retardation, abnormal head size, convulsions, and brain calcification. During the 3rd trimester, a fetus has an increased risk of becoming infected, but the risk of damage to the fetus is decreased since most of the important development has already occurred.

Now that you have an understanding of the risks involved if a pregnant woman is exposed to and subsequently contracts toxoplasmosis during the initial stages of her pregnancy, you can understand why I have a problem with the recommendations made by OB/GYNE doctors to their pregnant patients. Many of my clients schedule an office visit after learning of their pregnancy because they are scared to death that the family cat will cause the death or disfigurement of their unborn child and that they need to get rid of their cats while they were pregnant, or at the very least have their cat tested for toxoplasmosis. These recommendations drive me absolutely crazy! To recommend that a pregnant woman get rid of her cat(s) is taking the easy way out. It might take a bit of effort and time for a doctor to explain the real risks of toxoplasmosis and how to reduce them, but that is exactly what needs to be done to protect babies as well as prevent unnecessary suffering for mothers, families, and family pets.

These are the facts:
1. People become infected with toxoplasmosis when they inadvertently eat the parasite. The risk of contracting toxoplasmosis from ingesting cat feces is much lower than it is from handling and eating undercooked pork. So if doctors are going to counsel that pregnant women “get rid” of anything, it should actually be pork, not their pet cats.

2. If anybody is going to be tested for toxoplasmosis, it should be the pregnant woman, not the cat. A cat will come up positive if it has been exposed to the parasite at any point in its life, but it only poses a risk if it is shedding the parasite in its feces, which generally occurs for a very short period. Therefore, a positive feline test is meaningless in this situation. Testing a pregnant woman, on the other hand, can be helpful. If her test is positive already, perfect. She has been infected in the past and even if she is exposed again during her pregnancy her unborn child will not be affected. If she is negative, then she should take precautions.Pregnant women can protect themselves and their babies from toxoplasmosis by following these simple rules:

  • Cook foods at safe temperatures and use a food thermometer to ensure that meat is cooked thoroughly.
  • Peel or thoroughly wash fruits and vegetables before eating.
  • Wash cutting boards, dishes, counters, utensils and hands with hot, soapy water after they have come in contact with raw foods.
  • Wear gloves when gardening and during any contact with soil or sand because it might contain cat feces. Wash hands thoroughly after coming in contact with soil or sand.
  • Avoid changing cat litter if possible. Better yet, get someone else in the household to change the litter box. If a pregnant woman does have to clean out the litter boxes, she should scoop them at least once daily. The parasite must spend 24 to 48 hours outside of the cat’s body before it is capable of causing an infection, so frequently cleaning the box will virtually eliminate the chances of disease transmission. If you must do it, wear gloves and wash your hands thoroughly afterward. Keep your cat inside and do not handle stray or adopted cats. Do not feed your cat raw or undercooked meats.

In my experience, I have never had a client contract toxoplasmosis, let alone pass it on to their unborn child. In fact, I have never known a female veterinarian that tested positive for exposure to toxoplasmosis. These women have subsequently become pregnant and all have given birth to happy, healthy children, all the while continuing to work in a veterinary practice throughout the majority of their pregnancies. The risk of toxoplasmosis causing birth defects in an unborn child because there is a cat in the household is, therefore, tremendously overblown. While there is always a potential risk, following simple precautions and employing common sense should eliminate the fear that your pet cat is a danger to your unborn child.