Screening and prevention of congenital toxoplasmosis: An effectiveness study in a population with a high infection rate

Objectives: Secondary prevention of congenital toxoplasmosis has been attempted by screening pregnant women or by screening neonates. We compared the results of these two approaches, in order to evaluate the effectiveness of these strategies and of the antibiotic treatment of infected women. Methods: A prenatal serological screening program for toxoplasmosis enrolled 8061 pregnant women; 9730 neonates were screened during the same period. Results: Out of 5288 susceptible pregnancies, 188 were identified as infected by Toxoplasma gondii (35/1000). The transmission rate was 11.3%, with a higher rate for neonates exposed in the last trimester (relative risk 10.6); four neonates were affected. Out of 9730 screened neonates, four tested positive (0.4/1000) and one was affected. Out of a total of 163 exposed neonates, 12 were clinically affected. The rate of clinical sequelae was 31.6 % among those infected and 7.4% among all exposed to infection; neonates born of women who had not been treated were more likely to be affected than treated neonates (odds ratio 4), but after adjustment for trimester of infection no significant association was found. Conclusions: Neonatal screening for toxoplasmosis seems to be less effective than pregnancy screening. Observational data do not support the effectiveness of treatment during pregnancy to prevent clinical disorders.