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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., 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. sulamericanos 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., Facultad de Ciencias Veterinarias

Sarcocystis neurona and Neospora spp. are related protozoa that can cause equine protozoal myeloencephalitis (EPM). The present study aimed to determine the frequency of antibodies to these parasites in 649 equids (351 horses, 267 donkeys, and 31 mules) from six departments in the North and Northwest of Colombia. For this purpose, the indirect fluorescent antibody test (IFAT) was used for detecting antibodies against S. neurona and Neospora spp. with a cut-off point of 1:20 and 1:50, respectively. A binomial logistic regression model was selected to predict variables associated with exposure. The frequency of anti-S. neurona antibodies was 14.24% (95% CI: 10.84-18.44) for horses, 2.99% (95% CI: 1.39-6.04) for donkeys, and 16.13% (95% CI: 6.09-34.47) for mules. The risk for S. neurona infection was significantly lower in donkeys (OR: 0.18 [0.08-0.38]; p0.001) than horses and mules, and higher in animals with a poor body condition (OR: 2.82 [1.45-6.05]; p0.05). Additionally, older animals (12y) had a higher risk of seropositivity (OR: 5.26 [1.88-19.1]; p0.05), as well as animals that inhabit climatic conditions associated with tropical very dry forest (OR: 1.85 [1.01-3.51]; p0.05). Córdoba and Antioquia departments presented the highest seropositivity to S. neurona with 13.01 and 8.3%, respectively. The frequency of anti-Neospora spp. antibodies was 1.42% (95% CI: 0.52-3.48) for horses, 1.12% (95% CI:0.29-3.52) for donkeys and 0% (95%, CI: 0-0) for mules. Atlántico was the state with the highest seropositivity to Neospora spp. (10%). No risks associated with Neospora spp. infection were found. These findings allow us to conclude that equids from these regions of Colombia are exposed to S. neurona, but antibodies to Neospora spp. are uncommon. Further studies are necessary to explore the presence of these two agents in other areas of the country. In addition, we need to prove the importance of the above-mentioned risk factors over the susceptibility of horses to these protozoal agents and the epidemiological impact of these underdiagnosed coccidia.

Toxoplasma gondii and Neospora caninum are widespread cyst-forming coccidian parasites of the subfamily Toxoplasmatinae that infect a wide range of wild and domestic animals. Whereas T. gondii is a zoonotic disease, N. caninum is restricted to nonhuman animals. Some chiropteran species can be infected by T. gondii and present fatal toxoplasmosis. In most cases, T. gondii–infected bats are believed to remain asymptomatic and to act as an infection source to other animals. It is not known whether N. caninum can infect bats. We determined infection rates of T. gondii and N. caninum in free-living bats in the state of Bahia, Brazil. Brain samples from 97 bats of seven species, captured in 2008–15, were analyzed by PCRs for T. gondii and N. caninum. Two of the 97 samples were positive for T. gondii DNA. None of the samples were positive for N. caninum DNA, suggesting that the bats were not susceptible to N. caninum infection or that its prevalence was very low.

Sarcocystis neurona and Neospora spp. are protozoan parasites that induce neurological diseases in horses and other animal species. Opossums (Didelphis albiventris and Didelphis virginiana) are definitive hosts of S. neurona, which is the major cause of equine protozoal myeloencephalitis (EPM). Neospora caninum causes abortion in cattle and infects a wide range of animal species, while N. hughesi is known to induce neurologic disease in equids. The aims of this study were to investigate S. neurona and N. caninum in tissues from opossums in the northeastern Brazil, and to isolate Brazilian strains of Sarcocystis spp. from wild opossums for comparison with previously isolated strains. Carcasses of 39 opossums from Bahia state were available for molecular identification of Sarcocystis spp. and N. caninum in their tissues, and for sporocyst detection by intestinal scraping. In addition, Sarcocystis-like sporocysts from nine additional opossums, obtained in Sao Paulo state, were tested. Sarcocystis DNA was found in 16 (41%) of the 39 opossums' carcasses; N. caninum DNA was detected in tissues from three opossums. The sporocysts from the nine additional opossums from Sao Paulo state were tested by bioassay and induced infection in nine budgerigars, but in none of the gamma-interferon knockout mice. In vitro isolation was successful using tissues from all nine budgerigars. The isolated strains were maintained in CV-1 and Vero cells. Three of nine isolates presented contamination in cell culture and were discarded. Analysis of six isolates based on five loci showed that these parasites were genetically different from each other and also distinct from S. neurona, S. falcatula, S. lindsayi, and S. speeri. In conclusion, opossums in the studied regions were infected with N. caninum and Sarcocystis spp. and represent a potential source of infection to other animals. This is the first report of N. caninum infection in tissues from black-eared opossum (D. aurita or D. marsupialis) and white-eared opossum (D. albiventris). Brazilian opossums are probably infected by different Sarcocystis spp. distinct from S. neurona and S. falcatula, or present a high level of genetic recombination.

Sarcocystis spp. are cyst-forming coccidia that infect numerous animals species, including several livestock species. Despite the importance of sheep and goat production in Brazil, little it is known about the Sarcocystis species that infect small ruminants in the country and their potential impact on meat condemnation due to the presence of macroscopic cysts of the parasite. The aims of the present study were to determine the frequency of infection by Sarcocystis spp. in goats and sheep intended for human consumption in Bahia State, Brazil, as well as to identify the parasite species in selected samples. The entire tongue, esophagus, and heart were collected from 120 goats and 120 sheep. Tissues were examined for Sarcocystis spp. by macroscopic evaluation, light microscopy, electron microscopy, and molecular tests. Microscopic cysts of Sarcocystis spp. were detected in 95.8 % of sheep and 91.6 % of goats. Using either transmission electron microscopy or partial sequencing of the 18S region of the ribosomal DNA (rDNA) for species identification, Sarcocystis tenella and Sarcocystis arieticanis were observed in sheep and Sarcocystis capracanis in goats. Macroscopic cysts were not detected in the analyzed samples. We concluded that goats and sheep destined for human consumption in Bahia possess high frequencies of Sarcocystis infection. Carcass condemnation due to Sarcocystis macrocysts seems to be rare in the studied region. S. arieticanis and S. capracanis were confirmed for the first time by electron microscopy or by molecular tests in small ruminants from Brazil.