Detection of Toxoplasma gondii in faeces of privately owned cats using two PCR assays targeting the B1 gene and the 529-bp repetitive element

Toxoplasma gondii infection is a worldwide parasitic zoonosis with a high-health risk for humans. The key epidemiological role played by felids is related to oocyst shedding. The present study compared two amplification protocols for the molecular diagnosis of Toxoplasma infection in owned cats. A total of 78 owned cats referred to an Italian university-teaching hospital and exposed to various T. gondii-associated risk factors were sampled for blood and faeces. Faecal specimens were processed by flotation and tested using 2 copro-PCRs targeting the widely used B1 gene and the 529-bp repetitive element (RE). The sera were tested by the indirect immunofluorescent antibody test (IFAT) for the detection of immunoglobulins against T. gondii. Sixteen faeces (20.52%) tested positive for T. gondii DNA; 12 samples were positive only at B1-PCR, two at 529-bp RE-PCR and two at both genetic targets (overall agreement = 82.11%). The amplicons obtained were sequenced, and the Basic Local Alignment Search Tool analysis showed a high homology with the T. gondii strains available in reference databases. Two stool samples were microscopically positive for T. gondii-like oocysts and also tested positive by both B1 and 529-bp RE-PCRs. Thirty-three (42.3%) sera tested positive for antibodies; of which, seven were found to have T. gondii DNA-positive results using the B1 genetic target (overall agreement = 57.77%). The amplification sets targeting B1 and 529-bp RE showed substantially different yields. Further research is needed to better understand the significance and the sensitivities of using these multi-copy-targeted molecular methods from cat faeces before being used for routine diagnosis.