Sarcocystosis

Because the excreted sporocysts and/or oocysts of various species of Sarcocystis may not be discriminated morphologically, we sought to validate a diagnostic technique based on variation in the 18S rDNA sequence. Oocysts and/or sporocysts from three taxa of Sarcocystis were collected from human, feline, and canine definitive hosts that had fed upon meats infected with the muscle cysts of Sarcocystis hominis, Sarcocystis fusiformis and a species of Sarcocystis from water buffalo that could not be distinguished from Sarcocystis cruzi. Using a new collection method employing filter paper, these excreted oocysts and sporocysts were subjected to DNA extraction, as were the corresponding muscle cysts. Methods employing PCR-RFLP and DNA sequencing of a partial 18S rDNA gene (ssrRNA) sequence were then used to successfully distinguish among the three taxa. The same, unique restriction digestion pattern characterizes the tissue cysts and oocysts and/or sporocysts of each parasite taxon. The ...

Background and Aim: Sarcocystosis is a zoonotic infection caused by various species of Sarcocystis organisms with a worldwide geographic distribution. This study investigated the presence of Sarcocystis organisms in cattle and sheep slaughtered at an abattoir in Sulaimani Province in North Iraq.

Materials and Methods: A total of 130 muscle samples were collected during May, June, and July of 2020, including 80 samples from sheep and 50 samples from cattle. Samples were examined visually for macrosarcocysts. The peptic digestion method was used to analyze fresh muscle tissue samples for detecting microsarcocysts followed by microscopic examination. Furthermore, muscle samples were fixed and stained with hematoxylin and eosin for histopathological examination.

Results: In the gross examination, macroscopic cysts were not detected in both cattle and sheep; hence, all the prevalence data were obtained through microscopic observation of muscle samples. The peptic digestion method revealed the presence of banana-shaped bradyzoites in 90% and 92.5% of slaughtered cattle and sheep muscle samples, respectively. Organ-wise prevalence revealed that 95% and 92% of esophageal samples of sheep and cattle contained Sarcocystis spp., respectively. Moreover, 90% and 88% of sheep and cattle diaphragms were respectively infected. Histopathological examination of tissue sections revealed two morphologically distinct types of microsarcocysts, including thin-walled and thick-walled, in both sheep and cattle.

Conclusion: The suspected Sarcocystis spp. were Sarcocystis tenella and Sarcocystis arieticanis in sheep and Sarcocystis cruzi and Sarcocystis bovifelis or Sarcocystis hominis in cattle. Infective stages of different Sarcocystis spp. are widespread in the study area environment.

For parasites with a predator-prey life cycle, the completion of the life cycle often depends on consumption of parasitized prey by the predator. In the case of such parasite species the predator and the parasite have common interests and therefore a mutualistic relationship is possible. Some evidence of a predator-parasite mutualism was reported from spotted deer or chital (Axix axis) as a prey species, dhole or Indian wild-dog (Cuon alpinus) as the predator and a protozoan (Sarcocystis axicuonis) as the parasite. We examine here, with the help of a model, the ecological conditions necessary for the evolution and stability of such a mutualistic relationship. A two - level game theory model was designed in which the payoff of a parasite is decided not only by alternative parasite strategies but also by alternative host strategies and vice versa. Conditions for ESS were examined. A tolerant predator strategy and a low or moderately virulent parasite strategy which together constitute...

Twelve dogs were fed mutton containing small sarcocysts, and killed 1, 3, 4, 6, 7, 10, 15, 16, 17 days after infection (DAI). Beginning 13-15 DAI sporocysts 14.7 times 9.0 mum were passed in the faeces of the dogs killed 15-17 DAI. Histological examination showed that developing stages were most numerous in the subepithelial tissue at the tips of villi in the proximal third of the small intestine. Macrogametes containing tiny PAS + granules, and microgametocytes with peripheral developing microgametes were present 1 DAI. By 4 DAI oocysts, with a small nucleus and vacuolate cytoplasm were seen. Sporulation was observed 7-10 DAI. The first nuclear division resulted in 2 polar nuclei which divided laterally, resulting in 2 sporocysts each with 2 polar nuclei. This process was repeated once more to produce 4 nucleated sporozoites in each of 2 sporocysts. PAS + granules were seen at the periphery of sporulating oocysts and sporocysts. There was a large PAS + granule in the mid zone of sp...

The arctic fox (Vulpes lagopus) is a critically endangered species in Norway, and therefore, the small population is closely monitored, and most foxes found dead are subjected to necropsy. In two deceased foxes, thin-walled muscular sarcocysts were first detected in histological sections, and numerous sarcocysts were later found in frozen and thawed muscle samples from Fox 1. These sarcocysts measured 1-12 × 0.1-0.25 mm and had closely spaced, short, knob-like protrusions, giving the cysts a serrated outline. Genomic DNA was extracted from eight isolated sarcocysts (Fox 1) and two muscle samples (Fox 2) and subjected to polymerase chain reaction amplification at four loci: the nuclear 18S and 28S ribosomal RNA genes and internal transcribed spacer 1 region and the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). Both foxes were infected by the same Sarcocystis sp., which displayed little or no genetic variation at the three nuclear loci (99.9-100% identity) and slightly more variation at cox1 (99.4-100% identity). Sequence comparisons and phylogenetic analyses revealed that this species was distinct from other named Sarcocystis spp. but was closely related to various species using avian intermediate hosts and possibly identical to an unnamed species reported from two American dogs. The species described from the two arctic foxes was named Sarcocystis arctica n. sp.

Sarcocystis neurona was isolated from the brain of a juvenile, male southern sea otter (Enhydra lutris nereis) su€ering from CNS disease. Schizonts and merozoites in tissue sections of the otter's brain reacted with anti-S. neurona antiserum immunohistochemically. Development in cell culture was by endopolyogeny and mature schizonts were ®rst observed at 3 days postinoculation. PCR of merozoite DNA using primer pairs JNB33/JNB54 and restriction enzyme digestion of the 1100 bp product with Dra I indicated the organism was S. neurona. Four of four interferon-g gene knockout mice inoculated with merozoites developed S. neurona-associated encephalitis. Antibodies to S. neurona but not Sarcocystis falcatula, Toxoplasma gondii, or Neospora caninum were present in the serum of inoculated mice. This is the ®rst isolation of S. neurona from the brain of a non-equine host. 7

Sarcocystis sp. infection was investigated in 20 necropsied captive wild mammals and 20 birds in 2 petting zoos in Malaysia. The gross post-mortem lesions in mammals showed marbling of the liver with uniform congestion of the intestine, and for birds, there was atrophy of the sternal muscles with hemorrhage and edema of the lungs in 2 birds. Naked eye examination was used for detection of macroscopic sarcocysts, and muscle squash for microscopic type. Only microscopically visible cysts were detected in 8 animals and species identification was not possible. Histological examination of the sections of infected skeletal muscles showed more than 5 sarcocysts in each specimen. No leukocytic infiltration was seen in affected organs. The shape of the cysts was elongated or circular, and the mean size reached 254 × 24.5 µm and the thickness of the wall up to 2.5 µm. Two stages were recognized in the cysts, the peripheral metrocytes and large numbers of crescent shaped merozoites. Out of 40 animals examined, 3 mammals and 5 birds were positive (20%). The infection rate was 15% and 25% in mammals and birds, respectively. Regarding the organs, the infection rate was 50% in the skeletal muscles followed by tongue and heart (37.5%), diaphragm (25%), and esophagus (12.5%). Further ultrastructural studies are required to identify the species of Sarcocystis that infect captive wild animals and their possible role in zoonosis.

Four valid species of Sarcocystis have been reported from the water buffalo (Bubalus bubalis): Sarcocystis fusiformis, Sarcocystis buffalonis, Sarcocystis levinei and Sarcocystis dubeyi. Here, we redescribe structure of S. fusiformis sarcocysts by scanning and transmission electron microscopy (SEM, TEM). Twenty-one macroscopic sarcocysts from oesophagus of the water buffalo in Egypt were examined by light microscopy, SEM and TEM. The sarcocyst wall was up to 9 μm thick, depending on the section and the technique. In 5 μm paraffin-embedded sections, the sarcocyst wall was indistinct, 2-5 μm thick and appeared smooth. In 1 μm plastic-embedded sections stained with toluidine blue, the sarcocyst wall was 2.5-5.2 μm thick and had branched villar protrusions (vp)-like branches of a dead tree. By SEM, the sarcocyst wall had a mesh-like structure with irregularly shaped vp that were folded over the sarcocyst wall. On each vp there were uniform papillomatous structures that were 100 nm wide....

3Beta-hydroxysteroid-dehydrogenase (3beta-HSD) is an isoenzyme that catalyses an essential step in the synthesis of all classes of active steroid hormones. The presence of steroid hormones of the vertebrate type in invertebrates is acknowledged in addition to a group of steroid-like hormones called ecdysteroids that were present in arthropods and helminths. In the present study, 3beta-HSD was detected in the bradyzoites enclosed in sarcocysts of Sarcocystis spp. with immunohistochemistry. The results suggest that self-originating steroid hormones may play important roles in the development of Sarcocystis spp., and possibly in the regulation of the reciprocal immune interaction between the host and these parasites.