A Case of Congenital Toxoplasmosis in an Infant Discovered Through Visual Impairment During a Health Check-up

Toxoplasmosis is an infectious disease transmitted by ingestion of inadequately cooked meat, etc. If a woman is infected with Toxoplasma gondii for the first time during pregnancy, the fetus is at risk of congenital toxoplasmosis (via placental infection). We herein report on a patient who was born to a mother with a negative toxoplasma antibody test at an early stage of pregnancy, and was later diagnosed as having congenital toxoplasmosis based on decreased visual acuity at a medical check-up. A 3-year-old boy presented to our hospital with suspected low vision in the right eye. Fundus examination showed macular scarring in the right eye with accompanying reduced visual acuity. Both mother and child were positive for toxoplasma antibody IgG and negative for IgM, and the child was diagnosed as having congenital toxoplasmosis based on characteristic fundus findings. While being followed closely without treatment, retinochoroiditis of the left eye developed at the age of 4 years and 6 months, and treatment with pyrimethamine, sulfadiazine, leucovorin, and steroid was then started at another institution. This treatment improved visual acuity and fundus findings in the left eye. Congenital toxoplasmosis is an infectious disease in which early diagnosis and early treatment are beneficial. No therapy, however, has yet been established for children with non-apparent disease at birth and whose diagnosis was made after infancy, such as the child in our present report. Taking these factors into consideration, antibody tests during the prenatal check-up are important in order not to overlook potentially treatable pregnant women or infants, though the usefulness of antibody screening tests in all pregnant women has not been established in Japan. A thorough review of antibody screening tests in pregnant women, given circumstances such as the recent changes in food culture and internationalization,would appear to be warranted.