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

Abstract

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.

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

“…Furthermore, surface antigens, targeted in serological tests, are highly similar among Sarcocystis spp. shed by opossums ( Gondim et al, 2021 ). Therefore, immunological assays that use whole merozoites as antigens, such as IFAT, and SAG-based ELISAs, may result in the false assumption that horses are seropositive for S. neurona due to seroconversion after infection with other Sarcocystis species.…”

“…The hypothesis of cross reactivity between different Sarcocystis species shed by opossums in Brazil could justify the high seropositivity observed for S. neurona in horses, despite the low number of reports on EPM in the country ( Gondim et al, 2021 ). Cross reactivity between S. neurona and S. falcatula -like has already been observed in Mongolian gerbils ( Meriones unguiculatus ) experimentally infected and tested by Western blot ( Jesus et al, 2019 ).…”

“…Serological techniques such as immunofluorescence antibody tests (IFAT), Western blot (WB), and enzyme-linked immunosorbent assays (ELISAs) based on SAGs have been used to identify the exposure of horses to S. neurona in Brazil [summarized by Gondim et al (2021) ]. Sarcocystis neurona has also been evidenced in central nervous system of horses in Brazil by means of immunohistochemistry ( Masri et al, 1992 ; Paixão et al, 2007 ; Henker et al, 2020 ) and molecular methods ( Henker et al, 2020 ).…”

Toxoplasma gondii, Neospora caninum and Sarcocystis spp. in species of naturally infected birds

“…Besides, S. falcatula and Sarcocystis neurona use Didelphis spp. as definitive hosts (Gondim et al 2021). In South America may act as definitive hosts D. albiventris, Didelphis aurita, Didelphis marsupialis, Didelphis imperfecta and Didelphis pernigra.…”

Sarcocystis sp. shed by the common boa snake (Boa constrictor) in Brazil

“…A potential problem when ITS1 is used alone as a genetic marker, is the possibility of intraspecific variation in this locus ( Gjerde and Josefsen, 2015 ). The mitochondrial gene coding for cytochrome c oxidase subunit 1 ( cox1 ) has been largely used in recent years to discriminate closely related species ( Gjerde, 2013 ; Rubiola et al, 2018 ; Gondim et al, 2021 ), as it has high interspecific variation and low intraspecific variability ( Hebert and Gregory, 2005 ). According to Hebert et al (2003) , mitochondrial genes evolve faster than those in nucleus and cox1 was considered particularly useful to resolve problems related to closely related Sarcocystis species in numerous animal hosts ( Gjerde, 2013 ).…”