Is Kitty A Risk To Your Pregnancy?
Your questionI have a cat, and heard there's a danger of me getting toxoplasmosis from her? What is toxoplasmosis, and how can I avoid it? - Robin in Bend, Oregon
The expert answers
Toxoplasma gondii (Toxoplasmosis) is a protozoan that has a complex, 3-stage life cycle that is dependent on cats, which are the only known host for the oocyst stage. The oocyst stage develops in the cat's intestine, and is excreted in feces. Human infection occurs when food is contaminated with feces or infected meat is consumed. Stray cats and domestic cats that consume raw meat are most likely to harbor toxoplasmosis. Hand washing and proper cooking of meats helps to prevent human infection.
When an infection occurs, they most commonly are asymptomatic. Symptomatic infection, although quite rare, presents in a similar fashion to mononucleosis (Mono). Immunocompromised patients (patients with HIV infection or who are taking immunosuppressants after organ transplants) are more susceptible to symptomatic infection.
The diagnosis of an acute infection is made by serologic (blood) testing for antibodies to toxoplasmosis. The initial antibody produced is called IgM, and the presence of this antibody indicates a recent infection. Later, the body produces antibodies called IgG.
Congenital infection of the fetus can occur if a woman develops acute toxoplasmosis during pregnancy. The third trimester is the period of highest fetal susceptibility to infection. Recurrent or chronic infection is unlikely to cause injury to the fetus unless the patient is immunocompromised.
Treatment of an acute infection is recommended in pregnant women and non-pregnant, immunocompromised patients. Treatment of the mother clearly has been shown to decrease the risk of congenital infection, however it does not totally eliminate its occurrence. Close follow-up of the fetus using frequent ultrasonography should be instituted, looking for signs of infection including:
- growth restriction
- calcifications within the brain
- microcephaly (small head)
- hepatosplenomegaly (organ enlargement)
- ascites (fluid accumulation in the abdomen and chest)
Amniocentesis to obtain amniotic fluid, or cordocentesis to obtain fetal blood can be performed to test for the presence of toxoplasmosis, however this is rarely done.
By far, the best treatment for toxoplasmosis is prevention of the infection. For this reason, many pregnant women are advised not to change the cat's litter box during pregnancy.