Molecular detection of cattle Sarcocystis spp. in North-West Italy highlights their association with bovine eosinophilic myositis

Background: Cattle are intermediate hosts of six Sarcocystis species, among which Sarcocystis hominis and Sarcocystis heydorni can infect humans through the consumption of raw or undercooked meat. In addition to the zoonotic potential, there is increasing interest in these protozoa because of the evidence supporting the role of Sarcocystis spp. in the occurrence of bovine eosinophilic myositis (BEM), a specific inflammatory myopathy which leads to carcass condemnation and considerable economic losses. Actually, all the prevalence studies carried out on cattle in Italy have been based on either morphological or 18S rDNA-based molecular techniques, most likely leading to misidentification of closely related species. Therefore, there is a strong need for new data on the prevalence of the different Sarcocystis spp. in cattle in Italy and their association with bovine eosinophilic myositis. Methods: To reach our aim, individual striated muscle samples from BEM condemned carcasses (N = 54) and diaphragm muscle samples from randomly sampled carcasses (N = 59) were obtained from Northwest Italy slaughterhouses. Genomic DNA was extracted and analyzed by multiplex-PCR targeting 18S rDNA and cox1 genes. PCR products amplified using the genus-specific primer set in absence of the specific fragment for S. hirsuta, S. cruzi, S. hominis or S. bovifelis were sequenced to achieve species identification. Results: Sarcocystis DNA was detected in 67.8% of the samples from slaughter cattle and in 90.7% of the samples from BEM condemned carcasses. S. cruzi was identified as the most prevalent species in slaughter cattle (61%), followed by S. bovifelis (10.2%), S. hominis (8.5%) and S. hirsuta (1.7%). Notably, among the different Sarcocystis spp. detected, the presence of S. bovifelis and S. hominis was significantly higher in samples isolated from BEM condemned carcasses (46.3% and 40.7% respectively), while there was no statistically significant difference between the presence of S. cruzi or S. hirsuta in BEM condemned carcasses (42.6% and 1.8%, respectively) and randomly sampled carcasses. Furthermore, DNA sequence analysis revealed the presence of a putative new species in two carcasses. Conclusions: Our study contributes to updating the data on the prevalence of the different Sarcocystis spp. in cattle in Italy, highlighting the presence of three Sarcocystis spp., S. cruzi, S. hominis and S. bovifelis, in BEM lesions and allowing us to speculate on the possible role of S. hominis and S. bovifelis as the major sarcosporidian species involved in bovine eosinophilic myositis.