Full Year of Treatment Helps Infants and Children with Toxoplasmosis

The first long-term study shows that treatment with pyrimethamine and sulfadiazine (two anti-parasitic drugs) during the first year of life leads to a lasting reduction in brain and eye damage for children with congenital toxoplasmosis.

In the May 15 issue of the journal Clinical Infectious Disease, researchers report that a treatment they defined - now considered the standard of care because it improves early outcomes - resulted in normal longer-term neurologic outcomes for all patients born with the infection who did not already have severe brain involvement.

Even for many patients born with moderate or severe neurologic disease, the treatment was able to resolve symptoms within a few weeks. Seventy-two percent of those patients had normal long-term cognitive outcomes.

By demonstrating the benefits of diagnosing and treating the infection, these findings have renewed the call for comprehensive screening for this acute parasitic infection in pregnant women and newborns.

"We now know that we can improve longer-term outcomes if we treat the acute infection early," said study author Rima McLeod, M.D., professor of infectious diseases and medical director of the Toxoplasmosis Center at the University of Chicago, "but to treat it early we have to detect it early and we know we are missing many infants who would benefit."

According to the Centers for Disease Control and Prevention, approximately 85 percent of women of childbearing age in the United States are at risk of acquiring the infection for the first time during gestation and transmitting the infection to their fetus. The Toxoplasma gondii parasite infects humans through undercooked, infected meat; through T. gondii oocysts found in cat litter; or when a newly infected pregnant woman transmits the parasite to her fetus.

Most people have no recognized symptoms. The immune system usually keeps the parasite from causing acute illness. If the infection is acquired for the first time while a woman is pregnant, however, it can cause serious problems for the fetus, including severe eye and brain damage.

The National Collaborative Chicago-Based Congenital Toxoplasmosis Study followed 120 infants from the United States and Canada who had been diagnosed with toxoplasmosis soon after birth and were referred, between 1981 and 2004, for treatment and periodic evaluation by the study team. Eighty percent of these infants (96/120) had clinical abnormalities at birth, often severe.

Patients were treated with pyrimethamine at one of two different dose levels and sulfadiazine for one year and then followed periodically. Follow-up evaluations assessed neurologic status, including movement abnormalities and cognitive function, vision, including the development of new lesions in the eye, and hearing loss.

The authors emphasize that the median age of these children is about 10 years and longer follow up into adulthood is needed to determine whether these current favorable outcomes are sustained.