Morphology, Molecular Characteristics, and Demonstration of a Definitive Host for Sarcocystis rommeli from Cattle (Bos taurus) in China

The Occurrence and Meta-Analysis of Investigations on Sarcocystis Infection among Ruminants (Ruminantia) in Mainland China

Sarcocystis is a zoonotic pathogen that threatens public health and the quality of food safety. To determine the Sarcocystis spp. prevalence in ruminants (Ruminantia) in China, we conducted a systematic review and meta-analysis. Data were collected from English databases (PubMed and Web of Science) and Chinese databases (Chinese Web of knowledge (CNKI), Database for Chinese Technical Periodicals (VIP) and Wan Fang databases). A total of 20,301 ruminants from 54 publications were evaluated. The pooled prevalence of Sarcocystis spp. among ruminants in mainland China was 65% (95% CI: 57-72%). Our results indicate that sarcocystosis is prevalent in ruminants, which show significant geographical differences. Therefore, it there is a need for continuous monitoring of infections of Sarcocystis spp. in ruminants to reduce the threat to human health and economic losses to the animal industry.

Bovine sarcocystosis: Sarcocystis species, diagnosis, prevalence, economic and public health considerations, and association of Sarcocystis species with eosinophilic myositis in cattle

Infections by Sarcocystis in cattle are ubiquitous worldwide. There is considerable debate concerning the identity of Sarcocystis spp. in cattle. Proper diagnosis of Sarcocystis spp. is important to assess their economic and public health importance. Currently there are seven named species: Sarcocystis hirsuta, Sarcocystis cruzi, Sarcocystis hominis, Sarcocystis bovifelis, arcocystis heydorni, Sarcocystis bovini and Sarcocystis rommeli. Additionally, there are unnamed Sarcocystis spp. Two species, S. hominis and S. heydorni, are zoonotic. One out of seven species (S. hirsuta, contracted from cats) forms macroscopic cysts which can be visible during carcass inspection. Current molecular characterization is based on DNA extracted from sarcocysts from naturally infected cattle because DNA was not characterized from tissues of experimentally infected cattle or feces of experimentally infected definitive hosts. Sarcocystis cruzi (transmitted via canids) is recognized as the most pathogenic species and it causes abortion, low milk yield, poor body growth, and outbreaks of clinical sarcocystosis and death. Additionally, Sarcocystis infections have been linked to an inflammatory condition of striated muscles termed bovine eosinophilic myositis (BEM). Cattle affected by BEM appear clinically normal. Diagnosis of BEM at slaughter occurs when inspecting the carcass surface, or once the carcass has been divided into prime cuts or quarters. Sex and breed have no apparent influence on prevalence of BEM. The condition evidently occurs with equal frequency in steers, cows, and heifers. Virtually all striated muscles can be affected including skeletal muscles, the muscles of the eye, larynx, and the heart. In the USA, regulations require condemnation of BEM-affected parts, or (in severe cases) the entire carcass. These aesthetic considerations result in economic losses. Cattle experimentally infected with Sarcocystis did not have BEM at slaughter. Here, we review the status of Sarcocystis spp. and BEM in cattle including prevalence, lesions, epidemiology, and association of BEM with different species of Sarcocystis.

Redescription, deposition of life-cycle stage specimens of Sarcocystis bovifelis Heydorn, Gestrich, Mehlhorn and Rommel, 1975, and amendment to Sarcocystis hirsuta Moulé, 1888

There is considerable debate concerning the life cycles and taxonomy of Sarcocystis species in cattle. Of the 8 species of Sarcocystis named from cattle, 2 (Sarcocystis cruzi and Sarcocystis heydorni) are morphologically distinctive because their sarcocysts are microscopic and the sarcocyst wall is thin (<0.5 μm thick). The sarcocysts of the remaining species (Sarcocystis hirsuta, Sarcocystis hominis, Sarcocystis bovini, Sarcocystis bovifelis, Sarcocystis sinensis, Sarcocystis rommeli) have thick (5–8 μm) walls indistinguishable by light microscopy, alone. To provide needed clarity, I herein review the history, nomenclature and life cycle of S. bovifelis (originally named by Heydorn and associates from Germany), redescribe it and deposit specimens of its various life-cycle stages at a museum for future reference. I also provide means to distinguish this parasite from S. hirsuta. Cats are the definitive hosts for both S. bovifelis and S. hirsuta. The sarcocysts of S. bovifelis are microscopic, its sarcocyst wall is type 10g, it has 2 schizogonic stages in blood vessels and sarcocysts are formed between 25 and 30 days post-inoculation in striated muscles, but not in the heart. Sporulated oocysts are 17.1 × 12.7 μm and sporocysts are 12.8 × 8.4 μm. The sarcocysts of Sarcocystis hirsuta are macroscopic, up to 7 mm long, its wall is type 18. Nothing is known of the development of S. hirsuta in cattle tissues and in cat intestine. Size of its oocysts and sporocysts is uncertain.

Molecular identification of four Sarcocystis species in cattle from Lithuania, including S. hominis, and development of a rapid molecular detection method

Background

Six Sarcocystis species are known to use cattle (Bos taurus) as the intermediate host, two of which, S. hominis and S. heydorni, are zoonotic. There is a need for a method that will enable rapid identification of the Sarcocystis species in cattle.

Methods

The diaphragm muscles of 102 cattle from Lithuania were examined for the presence of Sarcocystis spp., using two different methods for species identification. Individual sarcocysts were isolated from squash preparations of the diaphragm muscle under the light microscope, followed by genetic characterisation of excised cysts using sequence analysis of the 18S rRNA (18S rRNA) and cytochrome c oxidase subunit I (cox1) genes. The same cattle muscle samples were digested and species-specific PCR analyses targeting cox1 were developed to identify the Sarcocystis isolates to the species level.

Results

Under the light microscope, sarcocysts were detected in 87.3% of animals, and Sarcocystis infection was verified in all digested samples. Three species, namely S. cruzi (n = 20), S. bovifelis (n = 23) and S. hirsuta (n = 6), were identified by DNA sequence analysis of isolated sarcocysts. Based on sequence analysis of cox1, the level of genetic variability depended on Sarcocystis species and geographical location. Four Sarcocystis species, S. cruzi (96.1%), S. bovifelis (71.6%), S. hirsuta (30.4%) and S. hominis (13.7%), were confirmed in the digested samples. In individual samples, the most common finding was two species of Sarcocystis (44.1%), followed by three species (26.5%), a single species (24.5%) and four species (4.9%).

Conclusions

Although examination of tissue preparations under the light microscrope did not detect any sarcocysts belonging to S. hominis, this species was identified in the digested samples subjected to a cox1-specific PCR analysis. These results demonstrate the need for effective molecular diagnosis techniques to detect Sarcocystis spp., which may be present at a lower prevalence and not detectable among the limited number of sarcocysts identified individually under the light microscope.

Anti-Sarcocystis Antibodies in Lambs Deprived of Colostrum

INTRODUCTION

The objective of this study was to evaluate the presence of anti-Sarcocystis spp. specific IgG antibodies in serum samples from precolostral lambs to determine the occurrence of transplacental transmission of Sarcocystis spp. in sheep.

METHODS

Blood samples were collected from 80 ewes and their respective lambs, immediately after lambing and before colostrum ingestion, respectively. The presence of anti-Sarcocystis spp. IgG was evaluated in serum samples using the indirect fluorescent antibody test (IFAT). Positive samples of the lambs were submitted to titration and IFAT to detect anti-T. gondii and anti-N. caninum specific IgG.

RESULTS

Anti-Sarcocystis spp. IgG was detected in 62.5% of the ewes (50/80) and in 4% of the lambs of the seropositive ewes (2/50). None of the lambs from seronegative ewes were positive. The final titers of the positive lambs were 80. No cross reaction was detected among the positive samples to anti-Sarcocystis spp., anti-N. caninum, and anti-T. gondii IgG. The detection of anti-Sarcocystis spp. antibodies in serum samples of lambs deprived of colostrum suggests transplacental transmission of infection. Thus, the vertical transmission may be an alternative route of infection of Sarcocystis spp. also in sheep. Further studies are warranted to confirm transplacental transmission in sheep and to explain the importance of this infection pathway.

Ultrastructural and Molecular Identification of the sarcocysts of Sarcocystis tenella and Sarcocystis arieticanis Infecting Domestic Sheep (Ovis aries) from Egypt

BACKGROUND

In spite of the global economic significance of sheep production, little is known about the prevalence of various Sarcocystis spp. infecting the domestic sheep (Ovis aries) in Egypt.

MATERIALS AND METHODS

Muscle samples were collected from 175 sheep (> 2 years) slaughtered at El-Mahalla El-Kubra abattoir, Gharbia governorate, Egypt. Samples were initially examined by naked eye for the existence of macrosarcocysts. The microscopic sarcocysts were detected and identified using the light microscopy and the Transmission electron microscopy (TEM). Different microscopic species of ovine Sarcocystis were molecularly confirmed by PCR, sequence analyses and phylogeny.

RESULTS

Preliminary light microscopic inspection of the muscle specimens revealed the existence of only the microscopic sarcocysts of Sarcocystis tenella and Sarcocystis arieticanis in 152 (86.8%) out of the175 examined animals. Sarcoysts of S.tenella had striated thick cyst wall that amounted from 3.5-5.5 μm in thickness whereas, S.arieticanis sarcocysts had a thin cyst wall that ranged from 1-3 μm in thickness. S.tenella sarcocysts were detected in 115 sheep (65.7%), and were more prevalent than those of S.arieticanis, observed only in 68 sheep (38.8%). No macroscopic sarcocysts were observed in any of the examined carcasses. Transmission electron microscopy (TEM) of the cyst wall of S.tenella revealed the existence of the short stubby villar protrusions (VP) with the characteristic disk-like structures at the tips of the (VP). While, TEM of S.arieticanis showed that the cyst wall had elongated tubular protrusions that measured approximately 5-7 μm in length. Each (VP) consisted of a dome-shaped base (0.3-0.9 μm in diameter), a relatively thick middle portion (0.1-0.3 μm) in width, and a thin hair-like distal portion that measured about (0.03 x 1-4.5 μm).

CONCLUSION

Comparative analyses of the sequences of the four genetic markers (18S rRNA, 28S rRNA, mitochondrial cox1 and ITS-1) for S.tenella and S.arieticanis isolates detected herein, revealed genetic variations of 95% and 95- 96% among the different isolates on the level of the 18S rRNA and 28S rRNA, respectively. Whereas, the cox1 and ITS-1 shared sequence identities of 76-78% and 70-73%, respectively. S.tenella was strongly related to S.capracanis infecting goats (Capra hircus). Sequence identity of 98% on the level of 18S rRNA, 28S rRNA genes was observed between the currently identified isolates of S.tenella and the formerly GenBank deposited isolates of S.capracanis. While, cox1 sequences shared identities of 92-93%. Furthermore, S.arieticanis isolates identified here were closely related to the formerly published sequences of S.hircicanis. The 18S rRNA and 28S rRNA sequences of S.arieticanis shared 98% and 94-95% identities with those of S.hircicanis, respectively. However, 87-88% homologies were observed between the cox1 sequences of S.arieticanis and S.hircicanis. Consequently, cox1 and ITS-1 gene sequences act as better genetic markers than 18S rRNA and 28S rRNA sequences for the characterization of ovine Sarcocystis spp. Maximum parsimony analyses based on the sequences of three genetic markers, (18S rRNA, 28S rRNA and mitochondrial cox1), yielded the same placement of the currently identified isolates of the two taxa (S.tenella and S.arieticanis) within a clade of Sarcocystis species with carnivorous animals as known, or assumed, final hosts.

Molecular identification of Sarcocystis spp. in cattle: partial sequencing of Cytochrome C Oxidase subunit 1 (COI)

Sarcocystis spp. are protozoan parasites with an obligatory two-host life cycle, with herbivores as intermediate hosts and carnivores as definitive hosts. Cattle are intermediate hosts for several species of Sarcocystis: indeed, in addition to S. cruzi, S. hirsuta and S. hominis, at least four new species were recently identified in bovine muscle: S. bovifelis, S. rommeli, S. bovini and S.heydorni. Since is not possible to unambiguously discriminate between S. hominis and the new species either morphologically or by the analysis of the 18S ribosomial (rRNA) gene, the aim of the present study was to use molecular techniques to discriminate cattle Sarcocystis species, taking advantage of the higher discriminative power of the Cytochrome C Oxidase subunit I mitochondrial (mtDNA COI) gene. Therefore, 119 bovine muscle samples were tested to identify S. hominis-like sarcocystis using a multiplex PCR of the 18S rRNA gene; later, positive samples were tested using a newly designed primer set for the PCR amplification of COI gene. Species identification was achieved by sequencing the amplified products: 16 sequences were confirmed to belong to S. bovifelis, while 12 sequences didn't constitute the best BLAST match of any of the published sequences, allowing to speculate the possible presence of S. hominis. This study confirms the higher discriminatory power of COI mitochondrial gene; besides, our work provides the first report of S. bovifelis in Italy.

Prevalence and molecular characterization of Sarcocystis infections of retail beef products from central China

Cattle are the intermediate hosts for five Sarcocystis species including S. hominis and S. heydorni, which also infect humans. To investigate the prevalence of Sarcocystis infections in beef products from 17 cities in the Henan Province of central China, 62 raw beef samples from markets were collected and analyzed for Sarcocystis presence via muscle squashing microscopic observation, histological section examination, and molecular characterization with 18S rRNA gene sequencing. Sarcocystis were detected in a total of 20 of the meat samples. Four species were identified that comprised S. cruzi, S. rommeli, S. heydorni, and S. hirsuta, with S. cruzi as the dominant species. In addition, seven of the 20 infected samples were infected with two or three species. Analysis of the 18S rRNA sequences recovered from these samples suggested very little genetic diversity within each species. This study represents the first molecular identification of Sarcocystis species infection in retail beef products from China. These findings will provide valuable information for evaluating the potential public health risk of bovine Sarcocystis species infections and the control of sarcocystosis in cattle.

Sarcocystis species identification in cattle hearts destined to human consumption in southern Brazil

Sarcocystis spp. are ubiquitous protozoan parasites that can form cysts in striated muscle and CNS of cattle. Cattle hearts are commonly infected by microscopic sarcocysts. Humans can get infected by consuming cattle meat containing the zoonotic parasites Sarcocystis hominis and Sarcocystis heydorni. However, bovine myocardium is generally infected by Sarcocystis cruzi. The aims of this study were to investigate the occurrence of sarcocysts and the identity of Sarcocystis species present in cattle hearts destined to human consumption in the Central region of the Rio Grande do Sul state, southern Brazil. A total of 314 cattle myocardium samples collected from a local abattoir were microscopically examined for the presence of sarcocysts. The sarcocysts isolated from 134 of these samples (ten sarcocysts per sample) were subjected to DNA extraction and PCR amplification. The PCR-amplified DNA fragments were digested with the restriction enzymes BclI and RsaI (PCR-RFLP) for differentiation among S. cruzi, S. hirsuta, and S. hominis. Sarcocystis species identification was confirmed using DNA sequencing of the cox1 mitochondrial DNA. Sarcocysts were detected in all the bovine myocardium samples. PCR-RFLP analysis resulted in successful amplification of 78 of the 134 samples tested. Only the S. cruzi DNA restriction pattern was identified from all of the 78 amplified samples. DNA sequencing also confirmed the presence of S. cruzi DNA. In conclusion, all myocardium samples evaluated were infected with microscopic sarcocysts. S. cruzi was the only species detected infecting the cattle hearts.

First isolation of Sarcocystis caninum sarcocysts from two domestic dogs (Canis familiaris) from China

The presence of Sarcocystis cysts in the muscle tissue of domestic dogs (Canis familiaris), which normally serve as definitive hosts, is unusual and infrequent. Here, S. caninum sarcocysts were identified for the first time in two of 37 dogs (2.7%) from China. Examination using light microscopy found that the S. caninum sarcocysts were up to 1520 μm long and up to 147 μm wide and contained numerous 1.5-3.3 μm wedge-like villar protrusions (vp). Transmission electron microscopy revealed that the sarcocysts had pleomorphic vp that closely resembled those of "type 9c." Five loci, 18S rDNA, 28S rDNA, mitochondrial cox1, ITS1 and ropB, were sequenced and characterized in S. caninum sarcocysts. The sequences of the five loci shared similarities of 99.9-100%, 99.0-100%, 99.4-100%, 99.6-100%, and 99.7-100%, respectively, with those of S. arctica. Phylogenetic analysis based on the sequences of 28S rDNA and mitochondrial cox1 indicated that S. caninum and S. arctica are closely related to Sarcocystis species that use a raptorial bird as their definitive host.

High prevalence of Sarcocystis spp. infections in cattle (Bos taurus) from central China

Myocardium and diaphragm samples of cattle (n = 521) from HeNan Province (China) were screened for Sarcocystis sarcocysts by histological examination, pepsin digestion, and molecular assays. Morphology and molecular assays were used for identification. The prevalence of Sarcocystis infection in cattle was 41.5% (216/521). Histological examination identified sarcocysts in the myocardium (49.4%, 200/405) and diaphragm (13.8%, 16/116) of cattle. Two species were identified, namely S. cruzi (41.3%, 215/521) and S. hominis (0.2%, 1/521). The findings of the present study indicate a high prevalence of S. cruzi infection in cattle from central China.

First molecular characterization and morphological aspects of Sarcocystis fusiformis infecting water buffalo Bubalus bubalis in Egypt

Fresh muscle samples from water buffalo (Bubalus bubalis) aged 2-15, from Giza Province, Egypt; were examined for Sarcocystis infection. Macroscopic ovoid sarcocysts embedded in the muscle tissues of the examined buffaloes were detected; they measured 152-230 (210 ± 7) μm in length and 37-119 (95 ± 3) μm in width. The esophagus was the most infected organ followed by the diaphragm, and tongue, while the heart muscles were the least infected. The cyst cavity was compartmentalized by septa derived from the ground substance located under the primary cyst wall. Using transmission electron microscopy, the primary cyst wall bordered sarcocysts were determined to be 0.08-0.22 μm in thickness, raised from the parasitophorous vacuolar membrane, and surrounded by a secondary cyst wall of host origin. The primary cyst wall had irregular wall folds with numerous cauliflower-like projections of variable sizes and shapes accompanied by knob-like electron-dense elevations. 18S rRNA gene expression studies confirmed that the present parasite isolates belonged to the genus Sarcocystis. The sequence data showed significant identities (>90%) with archived gene sequences from many Eimeriidae organisms, and a dendogram showing the phylogenetic relationship was constructed. The most closely related species was Sarcocystis fusiformis KR186117, with an identity percentage of 98%. The recovered sequences were deposited in the GenBank under the accession number MG572125. The present study, to our knowledge, is the first collective ultrastructural and molecular study that confirmed the taxonomy of sarcocysts isolated from water buffaloes in Egypt as Sarcocystis fusiformis.