Genetic characterization of Toxoplasma gondii from industrial pigs bred in the "Food Valley" (Italy)

A significant association between human toxoplasmosis and the consumption of raw or undercooked meat or its products from pigs and other farm animals is registered worldwide. Toxoplasma gondii Type I, Type II, Type III, and atypical strains have been described. These lineages differ in their pathogenicity and prevalence in humans. Since there is little information on the genetic characterization of T. gondii in industrially-reared pigs, the aim of this study was to isolate and genotype T. gondii from pigs specifically bred for ham production. Diaphragm and heart samples were collected from 103 pigs in 2 slaughterhouses in Abruzzo Region (Italy), giving a total of 206 samples. After DNA extraction, the samples were subjected to High Resolution Melting (HRM) assay coupled with next generation EvaGreen® Real Time PCR assay to detect T. gondii DNA using the B1 locus gene. Positive samples were sequenced for confirmation. Out of 103 animals, 14 (3.6%, 95% C.I.=7-20.2%) were positive to T. gondii with 12/206 (5.8%, 95% C.I.=2.6-9%) heart samples and 2/206 (1%, 95% C.I.=0-2.3%) diaphragm samples harboring the parasite DNA. According to HRM analysis coupled with melting curves and temperatures, Type I, Type II and Type III were detected in 14 samples: Type I was detected in two heart and two diaphragm samples, Type II in six and Type III in four heart samples. The heart was the most contaminated organ, with all three T. gondii types detected. This is the biggest large-scale study in Italy on the genetic characterization of T. gondii in pigs. The use of a very innovative and specific molecular tool (HRM assay), has highlighted T. gondii lineages circulating in industrial pigs in Italy. Detection of the most pathogenic type (Type I) provides evidence that conditions in industrial breeding systems are still insufficient to guarantee 'Toxoplasma-free pork', at least for pigs bred for ham production in the examined area