Molecular detection of Toxoplasma gondii in Tunisian free-range chicken meat and their offal

Free-range chickens are infected by Toxoplasma gondii (T. gondii) mainly when they pick-up their food from the ground. The present study was performed to estimate the molecular prevalence of T. gondii in free-range chicken meat (breast and thigh muscles) and their offal (heart and gizzard). The molecular characterization and the phylogeny of T. gondii amplicons were also investigated. Two PCRs were compared, the first targeting B1 gene and a nested PCR targeting the internal transcribed spacer ITS-1 gene. Among the 60 tested birds, 47 free-range chickens had at least one positive PCR, i.e., a prevalence of 78.3% (95% CI: 67.9-88.7%). The prevalence of T. gondii infection in muscles and organs analyzed by specific PCR targeting B1 gene (43.3%; 95% CI: 37-49.6%) was significantly higher than those analyzed for ITS-1 gene detection (15%; 95%CI: 10.4-19.5%) (p < 0.001). Heart samples had the highest T. gondii infection prevalence, as well as targeting either B1 gene (48.3%; 95% CI: 35.6-60.9%) or ITS-1 gene (21.6%; 95% CI: 11.2-32%). The present study showed that the consumption of undercooked free-range chicken meat represents a high risk for seronegative pregnant women. Our phylogenetic analysis revealed homology with wild and domestic birds and domestic mammals and a large geographic distribution.