A Case of Bovine Eosinophilic Myositis (BEM) Associated with Co-Infection by Sarcocystis hominis and Toxoplasma gondii

SIMPLE SUMMARY: In this study, a peculiar case of bovine eosinophilic myositis (BEM) observed in a beef cattle is described. BEM is a specific inflammatory myopathy, often associated with Sarcocystis spp., with multifocal gray-green lesions that can lead to considerable economic losses and public health issues. Through histological, molecular, and serological analyses, we confirmed the first detection of T. gondii DNA in a case of BEM, associated with the coinfection by S. hominis. Molecular results highlighted DNA of both pathogens within the lesion, in healthy muscle and or in the meat juice pellets, drawing attention to the possible role that a co-infection of T. gondii with Sarcocystis sp. may play in evoking BEM lesions. ABSTRACT: Bovine eosinophilic myositis (BEM) is a specific inflammatory myopathy, often associated with Sarcocystis spp., with multifocal gray-green lesions leading to carcass condemnation with considerable economic losses. Here is described a peculiar case of BEM that occurred in an adult (16 month) cattle, born in France, bred, and slaughtered in Italy at the end of 2021. On inspection, muscles showed the typical multifocal gray-green lesions that were sampled for, cytological, histological, and molecular investigations, while meat juice was subjected to IFAT for Toxoplasma IgG. Genomic DNA was extracted from lesions, portions of healthy muscle and from meat juice pellet and analyzed by PCR targeting 18S rDNA, COI mtDNA and B1 genes, and sequenced. The cytology showed inflammatory cells mostly referable to eosinophils; at histology, protozoan cysts and severe granulomatous myositis were observed. A BEM lesion and meat juice pellet subjected to PCR showed, concurrently, sequences referable both to S. hominis and T. gondii. Meat juice IFAT resulted negative for T. gondii IgG. Our findings highlight the first detection of T. gondii DNA in association with S. hominis in a BEM case, suggesting a multiple parasite infection associated with this pathology, although the actual role of T. gondii infection in the pathophysiology of the diseases should be clarified.