RATIONALE: Congenital toxoplasmosis is an infection caused by the parasitic organism Toxoplasma gondii, and it may be passed from an infected mother to her unborn child. The mother may have mild symptoms or no symptoms; the fetus, however, may experience damage to the eyes, nervous system, skin, and ears. The newborn may have a low birth weight, enlarged liver and spleen, jaundice, anemia, petechiae, and eye damage. Giving the antiparasitic drugs pyrimethamine and sulfadiazine is standard treatment for congenital toxoplasmosis, but it is not yet known which regimen of pyrimethamine is most effective for the disease.