Infecção por Sarcocystis spp. em ovinos e equino

Abstract

Infections by protozoa of the Sarcocystidae family have worldwide distribution and are common in ruminants, causing important economic losses. This study evaluated Sarcocystis spp., Toxoplasma gondii and Neospora caninum infections in sheep from Southwest region of Rio Grande do Sul, Brazil. Myocardium samples of 80 sheep raised on extensive system were collected. Tissue cysts were detected by direct examination and the presence of the agents was also confirmed by PCR. Macroscopic evaluation did not reveal changes, but direct microscopic examination showed cysts in 76.2% (61/80) of samples and all cysts were morphologically similar with Sarcocystis tenella or Sarcocystis arieticanis. PCR detected Sarcocystis spp. DNA in 21.2% (17/80) of samples tested and T. gondii DNA in 15% (12/80). In 6.2% (5/80) DNA of both protozoan were detected. Presence of N. caninum nucleic acids was not observed in the samples tested. All PCR-positive samples (23.7% - 19/80) were also positive by direct examination (microscopic cysts). Thus, a high occurrence of microscopic tissue cysts in sheep from the Southwest region of the state of Rio Grande do Sul was detected. Although PCR did not show a good sensitivity to identify the causative agents of these cysts, was possible to verify the presence of Sarcocystis spp. and T. gondii in cardiac muscle samples of the ovine. This may be a risk factor for animal and human contamination, not only through consumption, but also through handling the carcasses of these animals. Equine protozoal myeloencephalitis is a neurologic disease of horses, most often caused by the Sarcocystis neurona. However, the role of horses in the life cycle this parasite is not completely understood. This study attempts to elucidate the role of horses as intermediate hosts in S. neurona cycle, through occurrence of cysts in these animals and determine the antibodies frequency for Sarcocystis spp., Neospora spp. and T. gondii in slaughtered horses. Were collected 197 serum and heart samples of equines. None of the myocardium samples were detected tissue cysts, nucleic acids or histopathological changes associated to Sarcocystis spp. In antibodies detection, 146 (74.1%) serum samples were positive for studied protozoa. Antibodies against Sarcocystis spp. were detected in 36% (71/197), to Neospora spp. in 39.1% (77/197) and to T. gondii in 47,2% (93/197). Thus, the failure in detect tissue cysts, associated with antibodies anti-Sarcocystis spp. detection, increases the role of horses as accidental hosts in the cycle this protozoan, declining your participation in the epidemiology of Sarcocystis infection.