Toxoplasma gondii infection during pregnancy: a ten-year observation in the province of Trento, Italy

Abstract

The study analysed the trend of toxoplasmosis infection in pregnancy by using antenatal serological screening and the incidence of the congenital condition in newborns in the province of Trento, Italy. Data from pregnant women who gave birth at local maternity units between 2009 and 2018 were obtained. The serological test results were collected from birth attendance certificates (BACs), the main - and mandatory - source of information used to monitor pregnancies, births and neonatal health in Italy. The BAC used in the province of Trento acquires the results of serological tests for a vast range of infections in pregnancy. The data collected from the BACs were integrated with those provided by the Hospital Information System (HIS), which was also used to collect data on the trimester in which the seroconversion occurred. A total of 45,492 pregnant women were analysed, of whom 24% were foreigners. The average coverage of serological screening in pregnancy was 99.7%. Mean overall prevalence of Toxoplasma gondii infection was 21.7% (95% CI: 21.3-22.1): in Italians the prevalence was 17.9% (95% CI: 17.5-18.30) and in foreign nationals 32.7% (95% CI: 32.26-33.13). The mean annual seroconversion rate was 0.35% (95% CI: 3.0-4.2) of susceptible women and 0.27% (95% CI: 2.2-3.4) of all pregnant women who were screened. The seroconversion rate was higher amongst foreign women (0.32%, 95% CI: 3.0-3.6) than Italian women (0.24%, 95% CI: 2.1-2.8). In all, 91.0% of seroconverted women were treated during pregnancy in accordance with the anti-toxoplasma protocol. Five cases of congenital infection were identified (2 amongst Italians and 3 amongst foreign women), amounting to an overall transmission rate of 4.0% (2.3% in Italians and 8.8% in foreigners). Transmission risk ranged from 0.0% in the first trimester to 19% in the third. The incidence of congenital toxoplasmosis, over the entire study period, was 0.012% live births (0.011% in Italians and 0.016% in foreigners). Data collection on infections in pregnancy through BAC allows area-based assessment. Although the quality of the data recorded in the BAC can be considered satisfactory, it was also necessary to access other information sources. The screening coverage was very high. The prevalence of toxoplasmosis infection was found to be higher in foreign mothers than in Italians, as well as seroconversion. The extent of serological screening and the high treatment rate helped to keep the risk of infection transmission to the foetus low and to achieve a very low rate of congenital infection.