Brazilian Horses from Bahia State Are Highly Infected with Sarcocystis bertrami

SIMPLE SUMMARY: Sarcocystis bertrami is a protozoan parasite that infects horses. Equine meat containing the parasite, when consumed raw or undercooked, is suspected to cause gastrointestinal disorders in humans. Brazil exports horse meat for the European and Asian markets; however, there is no report in the country about the occurrence of S. bertrami. Herein, we obtained tissues from 51 horses destined for human consumption, which were examined for S. bertrami using morphologic and molecular methods. The parasite was observed in 100% of the examined horses. To the best of our knowledge, this is the first confirmation of S. bertrami in Brazilian and South American horses. Further studies are necessary to evaluate the impact of this parasite on animal and human health. ABSTRACT: The protozoan Sarcocystis bertrami (syn. Sarcocystis fayeri) infects horses and has dogs as definitive hosts. Herein we aimed to detect S. bertrami in Brazilian horses destined for human consumption and to determine the frequency of infection in the examined animals. Muscle fragments from 51 horses were collected in a slaughterhouse in Bahia State during three different seasons of the year. Samples from six tissues from each animal were prepared for macroscopic and microscopic evaluation, using tissue grinding, squash and histology. Sarcocystis sp. was observed in 100% of the examined horses. Selected samples were processed for transmission electron microscopy (TEM). Species identification was confirmed using a PCR targeted to the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). Histological examination revealed sarcocysts with variable sizes and shapes, and dispersed within the muscle fibers. When observed by TEM, the sarcocyst wall was wavy and covered by an electrodense layer. The villar protrusions were digitiform and bent. To our knowledge, this study is the first morphological and molecular confirmation of S. bertrami in horses in Brazil and South America.