Toxoplasma gondii outbreak in southern Brazil: heterogeneity of the serological humoral response in pregnant women and outcomes in newborns.

The aim of the study was to describe the heterogeneity of the humoral immune response and pregnancy outcomes in infected women during an outbreak of toxoplasmosis. Forty-two pregnant women referred to the University Hospital of Santa Maria (HUSM), RS, Brazil in 2018 and 2019, were evaluated. Clinical symptoms were reported in 33.3% of the patients. The majority (64.3%) of symptomatic pregnant women had anti T. gondii IgM antibodies index >7.0. Considering asymptomatic pregnant women, 46.4% presented antibodies IgM index below 3.0. Anti T. gondii IgG low avidity antibodies are present in 23.5% of pregnant women with a IgM index <3.0. Three newborns had the congenital form of the infection, and of these, only 1 had a positive IgM result. The serological response detected at the time of diagnosis of the infection is heterogeneous, which can make it difficult to interpret the tests, due to the presence of non-classical serological profiles.