Toxoplasmosis - A Serious Fetal Risk

Frederick R. Jelovsek MD

Is it safe to keep my cat during pregnancy? I've heard toxoplasmosis can be spread in cat litter? This is a very common question doctors are asked during antenatal care. One of our recent newsletters from the Motherisk Program had an excellent review written by Phillips, E: Toxoplasmosis - A true danger to the fetus Motherisk Newsletter 1998; 9:5-7. It answered many questions about this parasite infection caused by toxoplasma gondii:

How You Get Toxoplasmosis

Does toxoplasmosis infection occur from handling cat litter?

Human infection occurs mainly from the ingestion of raw lamb, pork or beef. Sometimes it can occur through eating poorly washed, raw vegetables contaminated with oocysts (toxoplasmosis eggs) or unpasteurized goat's milk or cheese. Rarely, it can come from eating oocysts in cat feces or even water system contamination. Inside cats have almost no exposure to toxoplasmosis, but even in that case, a non pregnant person ideally should be responsible for changing the cat litter.

What symptoms are produced by a toxoplasmosis infection?

Sometimes there are no symptoms with an infection, but when they do occur, they are mild. Tiredness, lymph node swelling, a generalized not feeling well and muscle aches are the most common, albeit nonspecific. symptoms.

What problems does toxoplasmosis infection cause for the baby?

Some babies have a classic triad of chorioretinitis (inflammation of the eye leading to blindness), hydrocephalus and calcium deposits in the brain leading to mental retardation. Others are asymptomatic at birth but develop these same problems and hearing loss in early childhood.

How often will an infected mother pass this toxoplasmosis infection to the baby?

If a mother is infected, about 30-40% of the time the infection is passed to the baby. The lowest rate of infection (15%) occurs in the first trimester but at that time there is the greatest severity of the disease resulting in abortions, stillborns and severe neurological problems. In the third trimester the infection rate is 60%, but the baby is only mildly affected. If infection occurs in the 6 months prior to pregnancy, fetal infection occurs only rarely.

Diagnose And Prevent Toxoplasmosis

How is toxoplasmosis infection diagnosed?

It is almost impossible to screen for toxoplasmosis infection. If a generalized infection is suspected, a blood test called an IgM can be drawn. The problem is that that blood level of IgM can remain elevated for up to 2 years after an infection. So you really can't tell if the infection was recent or not. Of course if the blood test is negative, that is reassuring although it can miss a very early infection. If the blood test is positive, ultrasound can be used to look for fetal infection but that is only a gross screen. Amniocentesis or fetal cord blood sampling can be performed but that is not available everywhere. A new test on amniotic fluid, PCR, is promising but not widely available.

How can I prevent getting toxoplasmosis from food?

• eat well cooked meat
• wash utensils and counters well after meat preparation
• wash hands after handling raw meat, vegetables and fruit and before eating.
• avoid contact with eyes and mucous membranes while preparing uncooked meat, raw vegetables and fruit

How can I avoid toxoplasmosis if I do have cats?

• empty cat litter daily (it takes 2-3 days for the toxoplasmosis oocysts to become infectious)
• wear gloves while handling cat litter
• wash hands after changing cat litter
• use boiling water to disinfect cat litter box
• avoid feeding cats uncooked meats
• wear gloves while gardening and wash hands well after contact with soil or sand

If you worry about toxoplasmosis or having cats, talk to your doctor.

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