Investigação de anticorpos contra Sarcocystis neurona e Sarcocystis cruzi em equinos

Reactivity against Sarcocystis neurona and Sarcocystis falcatula-like in horses from Southeastern and Midwestern Brazil

Equine protozoal myeloencephalitis (EPM) is a neurological disease caused by Sarcocystis neurona. Immunofluorescence antibody tests (IFATs) have been widely used to identify exposure of horses to S. neurona in Brazil. Here we used IFAT to search for IgG antibodies against Sarcocystis falcatula-like (Dal-CG23) and S. neurona (SN138) in sera from 342 horses sampled in Campo Grande, Mato Grosso do Sul state (Midwestern), and São Paulo, São Paulo state (Southeastern), Brazil. The 1:25 cutoff value was chosen to maximize sensitivity of the test. IgG antibodies against S. neurona were detected in 239 horses (69.88%), whereas IgG antibodies against S. falcatula-like were detected in 177 horses (51.75%). Sera from 132 horses (38.59%) reacted against both isolates. Absence of reactivity was evidenced in 58/342 horses (16.95%). The lower cutoff used, and the presence of opossums infected with S. falcatula-like and Sarcocystis spp. in the regions where the horses were sampled, might justify the high seroprevalence observed here. Owing to the similarity among antigens targeted in immunoassays, reports on S. neurona-seropositive horses in Brazil may also derive from the exposure of horses to other Sarcocystis species. The role of other Sarcocystis species in causing neurological diseases in horses in Brazil remains unclear.

Sarcocystis neurona and related Sarcocystis spp. shed by opossums (Didelphis spp.) in South America

Protozoan parasites of the genus Sarcocystis are obligatory heteroxenous cyst-forming coccidia that infect a wide variety of animals and encompass approximately 200 described species. At least four Sarcocystis spp. (S. falcatula, S. neurona, S. lindsayi and S. speeri) use opossums (Didelphis spp.) as definitive hosts, and two of them, S. neurona and S. falcatula, are known to cause disease in horses and birds, respectively. Opossums are restricted to the Americas, but their distribution in the Americas is heterogeneous. Five Didelphis spp. are distributed in South America (D. aurita, D. albiventris, D. marsupialis, D. imperfecta and D. pernigra) whereas just one opossum species (D. virginiana) is found in North America. Studies conducted in the last decades show that Sarcocystis spp., derived from South American Didelphis spp., have biological and genetic differences in relation to Sarcocystis spp. shed by the North American opossum D. virginiana. The aim of this review was to address the peculiar scenario of Sarcocystis species shed by South American opossums, with a special focus on diagnosis, epidemiology, and animal infections, as well as the genetic characteristics of these parasites.

Low prevalence of infection by Sarcocystis neurona in horses from the State of Alagoas, Brazil

The aim of this study was to determine the prevalence of infection by Sarcocystis neurona in horses and identify potential risk factors. Were analyzed 427 samples from 36 farms in 21 municipalities in the Alagoas State, Brazil. Presence of anti-S. neurona antibodies was diagnosed by indirect immunofluorescence antibody test (IFAT) and was confirmed using the immunoblot test. Risk factors were assessed through investigative questionnaires on animal management on the farms. The prevalence of anti-S.neurona antibodies was 2.8% (confidence interval, CI: 1.5-4.9%) from IFAT and 1.6% (CI:0.8-3.34%) from immunoblot, and there were positive horses on 16.6% of the studied farms. None of the variables studied presented associations with serological status for S. neurona. This is the first report on infection by S. neurona in horses reared in Alagoas, Brazil showing a low exposure to S. neurona in this region, but with significant numbers of foci.