BACKGROUND: Sarcocystis is a food-borne zoonotic protozoan whose final hosts are humans, dogs, cats, and other carnivores and intermediate hosts are birds and mammals, especially humans and herbivores. Humans become infected by eating raw and undercooked meat contaminated with bradyzoites or by consuming water or food contaminated with the sporocyst stage of the parasite.
OBJECTIVE: The aim of this study was to investigate the effects of gamma radiation and electron beam on the survival rate of Sarcocystis bradyzoites in infected beef and to determine the effective dose.
METHODS: Three replicates of 100 g of infected meat were treated with different doses (0.5, 1, 1.5 and 2 kGy). As a control, 20 g of contaminated meat was stored separately at 4°C. The viability of the bradyzoites after digestion in pepsin solution was assessed, stained (trypan blue) and unstained, under a stereomicroscope. To assess survival of the bradyzoites, the irradiated meat samples were fed to 30 dogs. After 10 days, faecal samples were examined for sporocysts.
RESULTS: The results showed that the highest and lowest mortality rate of Sarcocystis bradyzoites in infected organs using electron beam at a dose of 2 kGy were 92.5% and 100%, respectively, and the lowest mortality rate at a dose of 0.5 kGy were 2.5% and 7.89%, respectively.
CONCLUSIONS: The results of statistical analysis showed that the mortality rate of Sarcocystis bradyzoites was significant between different doses of gamma ray and electron beam, so that gamma rays were better compared to electron beam in destroying Sarcocystis bradyzoites.

Sarcocystis miescheriana infection is an important cause of carcass condemnation during meat inspection. The infection can cause morbidity and mortality in domestic pigs. In this study, an 8-month-old finisher pig was presented to a local abattoir for slaughter. Multiple white nodular lesions affecting the meat were observed, resulting in the condemnation of the carcass. Consequently, half of the carcass was submitted to the necropsy diagnostic laboratory in the School of Veterinary Medicine for further evaluation. Grossly, all superficial and deep muscle groups had severe multifocal macrocysts (3 mm × 2 mm × 1 mm) on the surface and extending deep into the skeletal musculature. Histopathology revealed moderate multifocal granulomatous and eosinophilic myositis with intralesional degenerated and intact parasites. Sample genomic DNA sequence analysis of the 18S RNA gene showed 100% identity to S. miescheriana in the GenBank. This is the first report of S. miescheriana in Grenada, West Indies.

One of the defining features of apicomplexan parasites is their cytoskeleton composed of alveolar vesicles, known as the inner membrane complex (IMC) undergirded by intermediate-like filament network and an array of subpellicular microtubules (SPMTs). In Toxoplasma gondii, this specialized cytoskeleton is involved in all aspects of the disease-causing lytic cycle, and notably acting as a scaffold for parasite offspring in the internal budding process. Despite advances in our understanding of the architecture and molecular composition, insights pertaining to the coordinated assembly of the scaffold are still largely elusive. Here, T. gondii tachyzoites were dissected by advanced, iterative expansion microscopy (pan-ExM) revealing new insights into the very early sequential formation steps of the tubulin scaffold. A comparative study of the related parasite Sarcocystis neurona revealed that different MT bundling organizations of the nascent SPMTs correlate with the number of central and basal alveolar vesicles. In absence of a so far identified MT nucleation mechanism, we genetically dissected T. gondii γ-tubulin and γ-tubulin complex protein 4 (GCP4). While γ-tubulin depletion abolished the formation of the tubulin scaffold, a set of MTs still formed that suggests SPMTs are nucleated at the outer core of the centrosome. Depletion of GCP4 interfered with the correct assembly of SPMTs into the forming daughter buds, further indicating that the parasite utilizes the γ-tubulin complex in tubulin scaffold formation .

Representatives of the genus Sarcocystis are worldwide distributed apicomplexan parasites characterised by two-host prey-predator relationships. Sarcocystis spp. produce sarcocysts in the muscles and brains of intermediate hosts and develop sporocysts in the intestines of definitive hosts. Two species, Sarcocystis glareoli and Sarcocystis microti, previously assigned to the genus Frenkelia, form cysts in the brains of rodents and are transmitted through the common buzzard (Buteo buteo). In our study, brain samples of 694 small mammals caught in different regions of Lithuania were examined for Sarcocystis spp. Additionally, 10 B. buteo and two rough-legged buzzards (Buteo lagopus) were tested for sporocysts of the analysed parasites. Sarcocystis species were identified based on 28S rRNA sequence comparison. Of the eleven species of small mammals tested, Sarcocystis parasites were observed only in the bank vole (Clethrionomys glareolus). Cysts of S. glareoli were detected in 34 out of 374 C. glareolus (9.1%, 95% CI = 6.4-12.5%). Molecular investigation showed the presence of only S. glareoli in the intestines of 50% of B. buteo. Furthermore, two species, Sarcocystis sp. Rod3 and Sarcocystis sp. Rod4, were confirmed in B. lagopus. Our results demonstrate the need for further studies on Sarcocystis cycling between rodents and birds.

The genus Sarcocystis is an abundant group of Apicomplexa parasites found in mammals, birds, and reptiles. These parasites are characterised by the formation of sarcocysts in the muscles of intermediate hosts and the development of sporocysts in the intestines of definitive hosts. The identification of Sarcocystis spp. is usually carried out in carcasses of animals, while there is a lack of studies on the detection of Sarcocystis species in blood samples. In the current study, blood samples of 214 yellow-necked mice (Apodemus flavicollis) and 143 bank voles (Clethrionomys glareolus) from Lithuania were examined for Sarcocystis. The molecular identification of Sarcocystis was carried out using nested PCR of cox1 and 28S rRNA and subsequent sequencing. Sarcocystis spp. were statistically (p < 0.01) more frequently detected in the bank vole (6.3%) than in yellow-necked mice (0.9%). The analysed parasites were observed in four different habitats, such as mature deciduous forest, bog, natural meadow, and arable land. Three species, Sarcocystis funereus, Sarcocystis myodes, and Sarcocystis cf. glareoli were confirmed in the bank vole, whereas only Sarcocystis myodes were found in yellow-necked mice. The obtained results are important in the development of molecular identification of Sarcocystis parasites in live animals.

Sarcocystis spp. are complex apicomplexan parasites that cause a substantial economic impact on livestock used for meat production. These parasites are present worldwide. Our study aimed to identify Sarcocystis species affecting sheep meat in southern-central Spain and to evaluate the effectiveness of freezing for parasite inactivation. A total of 210 condemned samples of sheep meat were thoroughly assessed grossly and microscopically; the presence of macro- and microcysts was confirmed. The samples were then frozen at -20 °C for various time intervals (24, 48, 72, 96, 120, and 144 h) and compared with untreated samples. Bradyzoites were isolated through pepsin digestion for subsequent molecular analysis and viability assessment, employing trypan blue and double fluorescence staining techniques. Our measurements confirmed the presence of S. tenella, S. gigantea, and S. medusiformis in Spanish domestic sheep. Freezing for 96 to 144 h resulted in a significant reduction in parasite viability, with a robust correlation observed between the two staining methods. Both stains effectively measured the viability of Sarcocystis, thereby promising future advances in meat safety.

Sarcocystis spp. are coccidian protozoans belonging to the Apicomplexa phylum. As with other members of this phylum, they are obligate intracellular parasites with complex cellular machinery for the invasion of host cells. Sarcocystis spp. display dixenous life cycles, involving a predator and a prey as definitive and intermediate hosts, respectively. Specifically, these parasites develop sarcocysts in the tissues of their intermediate hosts, ranging in size from microscopic to visible to the naked eye, depending on the species. When definitive hosts consume sarcocysts, infective forms are produced in the digestive system and discharged into the environment via feces. Consumption of oocyst-contaminated water and pasture by the intermediate host completes the parasitic cycle. More than 200 Sarcocystis spp. have been described to infect wildlife, domestic animals, and humans, some of which are of economic or public health importance. Interestingly, Old World camelids (dromedary, domestic Bactrian camel, and wild Bactrian camel) and New World or South American camelids (llama, alpaca, guanaco, and vicuña) can each be infected by two different Sarcocystis spp: Old World camelids by S. cameli (producing micro- and macroscopic cysts) and S. ippeni (microscopic cysts); and South American camelids by S. aucheniae (macroscopic cysts) and S. masoni (microscopic cysts). Large numbers of Old and New World camelids are bred for meat production, but the finding of macroscopic sarcocysts in carcasses significantly hampers meat commercialization. This review tries to compile the information that is currently accessible regarding the biology, epidemiology, phylogeny, and diagnosis of Sarcocystis spp. that infect Old and New World camelids. In addition, knowledge gaps will be identified to encourage research that will lead to the control of these parasites.

BACKGROUND: members of the genus Sarcocystis are intracellular obligate protozoan parasites classified within the phylum Apicomplexa and have an obligate heteroxenous life cycle involving two hosts. A more comprehensive understanding of the prevalence and geographic range of different Sarcocystis species in marine ecosystems is needed globally and nationally. Hence, the objective of this study was to document the incidence of Sarcocystis infection in sharks within the aquarium ecosystem of Egypt and to identify the species through the characterization of the SSU rDNA gene.
METHODS: All organs of the mako shark specimen underwent macroscopic screening to detect the existence of a Sarcocystis cyst. Ten cysts were collected from the intestine and processed separately to extract the genomic DNA. The polymerase chain reaction (PCR) was accomplished by amplifying a specific 18S ribosomal RNA (rRNA) gene fragment. Subsequently, the resulting amplicons were subjected to purification and sequencing processes.
RESULTS: Macroscopic examination of the mako shark intestinal wall sample revealed the presence of Sarcocystis cysts of various sizes and shapes, and sequencing of the amplicons from Sarcocystis DNA revealed a 100% nucleotide identity with the sequence of Sarcocystis tenella recorded from sheep in Iran; The mako shark sequence has been deposited in the GeneBank with the accession number OQ721979. This study presents the first scientific evidence demonstrating the presence of the Sarcocystis parasite in sharks, thereby documenting this specific marine species as a novel intermediate host in the Sarcocystis life cycle.
CONCLUSIONS: This is the first identification of Sarcocystis infection in sharks, and we anticipate it will be an essential study for future screenings and establishing effective management measures for this disease in aquatic ecosystems.

BACKGROUND: The geographic distribution and host-parasite interaction networks of Sarcocystis spp. in small mammals in eastern Asia remain incompletely known.
METHODS: Experimental infections, morphological and molecular characterizations were used for discrimination of a new Sarcocystis species isolated from colubrid snakes and small mammals collected in Thailand, Borneo and China.
RESULTS: We identified a new species, Sarcocystis muricoelognathis sp. nov., that features a relatively wide geographic distribution and infects both commensal and forest-inhabiting intermediate hosts. Sarcocystis sporocysts collected from rat snakes (Coelognathus radiatus, C. flavolineatus) in Thailand induced development of sarcocysts in experimental SD rats showing a type 10a cyst wall ultrastructure that was identical with those found in Rattus norvegicus from China and the forest rat Maxomys whiteheadi in Borneo. Its cystozoites had equal sizes in all intermediate hosts and locations, while sporocysts and cystozoites were distinct from other Sarcocystis species. Partial 28S rRNA sequences of S. muricoelognathis from M. whiteheadi were largely identical to those from R. norvegicus in China but distinct from newly sequenced Sarcocystis zuoi. The phylogeny of the nuclear 18S rRNA gene placed S. muricoelognathis within the so-called S. zuoi complex, including Sarcocystis attenuati, S. kani, S. scandentiborneensis and S. zuoi, while the latter clustered with the new species. However, the phylogeny of the ITS1-region confirmed the distinction between S. muricoelognathis and S. zuoi. Moreover, all three gene trees suggested that an isolate previously addressed as S. zuoi from Thailand (KU341120) is conspecific with S. muricoelognathis. Partial mitochondrial cox1 sequences of S. muricoelognathis were almost identical with those from other members of the group suggesting a shared, recent ancestry. Additionally, we isolated two partial 28S rRNA Sarcocystis sequences from Low\'s squirrel Sundasciurus lowii that clustered with those of S. scandentiborneensis from treeshews.
CONCLUSIONS: Our results provide strong evidence of broad geographic distributions of rodent-associated Sarcocystis and host shifts between commensal and forest small mammal species, even if the known host associations remain likely only snapshots of the true associations.

Apicomplexan Sarcocystis and Trichinella nematodes are food-borne parasites whose life cycle is carried-out in various wildlife and domestic animals. The gray wolf (Canis lupus) is an apex predator acting as an ecosystem engineer. This study aimed to identify the species of Sarcocystis and Trichinella found in the muscles of gray wolves in Lithuania. During the 2017-2022 period, diaphragm, heart, and hind leg samples of 15 animals were examined. Microscopical analysis showed the presence of two types of Sarcocystis parasites in 26.7% of the analyzed muscle samples. Based on the sequencing of five loci, nuclear 18S rDNA, 28S rDNA, ITS1, mitochondrial cox1, and apicoplast rpoB, S. arctica, and S. svanai were identified. The current work presents the first report of S. svanai in gray wolf. Phylogenetically, S. svanai clustered together with S. lutrae, infecting various carnivorans, and S. arctica was most closely related to S. felis from domestic cats. Trichinella spp. were found in 12 gray wolves (80%). For the first time, Trichinella species were molecularly identified in gray wolves from Lithuania. Trichinella britovi was confirmed in all of the isolated Trichinella larvae using a multiplex PCR. Gray wolves in Lithuania may serve as a major source of zoonotic pathogens due to the presence of these parasites.