Seroepidemiology of Toxoplasma gondii in blood donors in Portugal

Infection with the protozoan parasite Toxoplasma gondii is prevalent in animals and humans worldwide. The present study aimed to evaluate the prevalence of antibodies to T. gondii and associated risk factors among blood donors in Portugal. Serum samples were tested for the presence of anti-T. gondii immunoglobulin (Ig) G by a modified agglutination test (MAT). A written standardized questionnaire was used to collect sociodemographic and behavioural data from the blood donors. Out of 520 participants (median age: 39.5 years; interquartile range: 29.0-47.0), who attended blood collection sessions promoted by the Portuguese Institute for Blood and Transplantation (IPST), 198 (38.1%) were positive for anti-T. gondii IgG (95% confidence interval [CI]: 33.9-42.4%). Multiple logistic regression analysis revealed that ages of 46-55 years (odds ratio [OR] = 6.72; 95% CI = 3.40-13.28), and of 56 - 65 years (OR = 4.34; 95% CI = 1.73-10.86), having a lower education level (OR = 2.55; 95% CI = 1.45-4.49), living in the North (OR = 2.14; 95% CI = 1.25-3.65) and in the Centre regions (OR = 2.54; 95% CI = 1.36-4.76) of Portugal, and drinking water from untreated sources (OR = 2.46; 95% CI = 1.12-5.39) were risk factors for seropositivity to T. gondii. This study provides the first data on the seroprevalence of T. gondii in blood donors in Portugal, as well insights to sociodemographic and behavioural risk factors as the basis for future prevention programs.