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.

Sarcocystis neurona and related Sarcocystis spp. shed by opossums (Didelphis spp.) in South America / Sarcocystis neurona e Sarcocystis spp. relacionados, excretados por gambás (Didelphis spp.) na América do Sul

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.

Resumo Parasitos protozoários do gênero Sarcocystis são coccídios heteroxenos formadores de cistos, que infectam variadas espécies animais e compreendem cerca de 200 espécies descritas. Pelo menos quatro Sarcocystis spp. (S. falcatula, S. neurona, S. lindsayi e S. speeri) utilizam gambás (Didelphis spp.) como hospedeiros definitivos; e duas delas, S. neurona and S. falcatula são conhecidas por causarem doença em equinos e aves, respectivamente. Gambás didelfídeos são restritos ao continente americano, contudo são distribuídos de forma heterogênea nas Américas. Cinco Didelphis spp. são distribuídos na América do Sul (D. aurita, D. albiventris, D. marsupialis, D. imperfecta e D. pernigra), enquanto somente uma espécie (D. virginiana) é encontrada na América do Norte. Trabalhos conduzidos, nas últimas décadas, mostram que Sarcocystis spp. derivados de Didelphis spp. sul-americanos possuem diferenças biológicas e genéticas, quando comparados a Sarcocystis spp. excretados pelo gambá norte-americano D. virginiana. O objetivo desta revisão é discutir a situação peculiar das espécies de Sarcocystis na América do Sul com um foco especial em diagnóstico, epidemiologia e infecções animais, assim como nas características genéticas desses parasitos.

First molecular characterization of Sarcocystis neurona causing meningoencephalitis in a domestic cat in Brazil.

Sarcocystis neurona is the main agent associated with equine protozoal myeloencephalitis (EPM). Apart from horses, S. neurona has been occasionally described causing neurologic disease in several other terrestrial animals as well as mortality in marine mammals. Herein, we describe the clinical, pathological, and molecular findings of a fatal case of S. neurona-associated meningoencephalitis in a domestic cat. The causing agent was analyzed by multilocus genotyping, confirming the presence of S. neurona DNA in the tissue samples of the affected animal. Significant molecular differences were found in relation to S. neurona isolates detected in other regions of the Americas. In addition, the parasite was identical to Sarcocystis sp. identified in opossum sporocysts in Brazil at molecular level, which suggests that transmission of. S. neurona in Brazil might involve variants of the parasite different from those found elsewhere in the Americas. Studies including more samples of S. neurona would be required to test this hypothesis, as well as to assess the impact of this diversity.

Multilocus characterization of Sarcocystis falcatula-related organisms isolated in Brazil supports genetic admixture of high diverse SAG alleles among the isolates.

In a previous study in Brazil, six isolates of Sarcocystis spp. recovered from budgerigars fed sporocysts excreted by opossums of the genus Didelphis were characterized by means of sequencing fragments of gene coding cytochrome B (CYTB), internal transcribed spacer 1 (ITS1), and surface antigen genes (SAG2, SAG3 and SAG4). The isolates shared identical ITS1 and CYTB sequences, but differed at SAG2, SAG3 and SAG4: three allele variants of SAG2, 3 allele variants of SAG3 and 2 allele variants of SAG4 were encountered in three multilocus genotypes (MLGs) (MLG1, MLG2, and MLG3). At ITS1 and CYTB, all the isolates from budgerigars were identical to the Sarcocystis falcatula-like isolate 59-2016-RS-BR that was detected in a barefaced ibis (Phimosus infuscatus) causing necrotizing meningoencephalitis in Brazil. At ITS1 locus, all the above isolates were clearly distinct from Sarcocystis neurona, Sarcocystis falcatula, Sarcocystis lindsayi, and Sarcocystis speeri, the four known species of Sarcocystis that use opossums of the genus Didelphis as definitive hosts. Here, we replicated the experiment above to identify additional MLGs or other species of Sarcocystis. Fifteen budgerigars were experimentally infected with sporocysts of Sarcocystis spp. from 12 opossums of the genus Didelphis. All the birds died 9-19 days after infection and tissue samples containing merozoites and schizonts of Sarcocystis spp. were recovered. Fractions of sequences coding for 18S ribosomal RNA gene (18S), CYTB, ITS1, SAG2, SAG3 and SAG4 were PCR amplified and sequenced from the infected lungs. In addition, fractions of 18S, SAG2, SAG3 and SAG4 were sequenced from the isolate 59-2016-RS-BR and fractions of 18S were sequenced from the six isolates from budgerigars described above. From the results, all the isolates shared identical 18S, ITS1 and CYTB sequences. Among the 15 new isolates from budgerigars, three allele variants of SAG2, 3 allele variants of SAG3 and 2 allele variants of SAG4 were encountered in five MLGs, of which four were novel (MLG1, MLG4, MLG5, MLG6 and MLG7). Isolate 59-2016-RS-BR was assigned to an eighth MLG (MLG8). Molecular data pointed that Sarcocystis assigned to MLGs 1 to 8 are variants of the same species, but the SAG-based trees of the isolates conflicted, which supports genetic admixture among them. The sarcocystinae studied have high diversity of SAG alleles per locus and the correlation of such an abundant variety of SAG alleles to host specificity and pathogenicity needs to be assessed. Remains to be elucidated if the parasites studied here and S. falcatula are variants of the same species that have diverged to the point of possessing differences at ITS1 level, but that are still capable of exchanging genes.

Seroprevalence and risk factors for Neospora caninum infection in cattle from the eastern Antioquia, Colombia.

Bovine neosporosis is a parasitic disease with worldwide distribution that causes important economic losses. Because of the limited information on the occurrence of Neospora caninum infection in Colombia, this study aimed to determine the seroprevalence and identify the risk factors associated with this infection in cattle in Antioquia, which is the largest milk-producing state in the country. We collected 1,038 blood samples from Holstein, Jersey and crossbred cows from 31 farms. An epidemiologic questionnaire was given to all the owners. A commercial ELISA kit was used as the diagnostic technique. The occurrence of anti-N. caninum antibodies was determined to be 28.3% (294/1038), and 100% of the screened farms were positive, indicating that all the properties had at least one positive animal. The seropositivity within each farm ranged from 5.5% to 50%. A multivariable logistic regression model identified the following as significant risk factors: history of abortion (OR = 5.33, p < 0.001), replacement with cattle purchased outside the farm (OR = 1.54, p < 0.05), age (OR = 1.7, p < 0.01) and poor hygienic practices associated with manual milking (OR = 1.69, p < 0.01). The latter two factors suggest that horizontal transmission is an important route of infection. This study is the first to report the seroprevalence of and risk factors for N. caninum infection in Antioquia and allows us to conclude that N. caninum is widely distributed in this region.