Molecular identification targeting cox1 and 18S genes confirms the high prevalence of Sarcocystis spp. in cattle in the Netherlands

Molecular identification of Sarcocystis species in wild boar (Sus scrofa) and pigs (Sus scrofa domesticus) in Brazil

Sarcocystis spp. are protozoan parasites that form cysts in the organs and musculature of various animal species. The species Sarcocystis miescheriana and Sarcocystis suihominis are pathogenic to pigs and wild boars (Sus scrofa), acting as intermediate hosts, while humans are the definitive host for S. suihominis. To date, there have been no reports of the identification of these coccidian species in Sus scrofa in Brazil. Therefore, in this study, we conducted the first molecular identification of Sarcocystis species using PCR-RFLP and sequencing. A total of 210 samples were analyzed, of this total, 67 tested positive for Sarcocystis spp., representing 31.9% of the total samples assessed. Out of the total positive samples, 55 (82.1%) were identified as S. miescheriana and 8 (11.9%) as S. suihominis, a zoonotic species. Additionally, other species related to bovines, such as S. cruzi and zoonotic S. hominis, were detected in 3.0% of the samples, serving as contaminants in the pork products. The presence of S. suihominis in swine and wild boar samples is concerning due to the zoonotic risk and potential environmental contamination, as humans act as definitive hosts, also for the presence of S. hominis as a bovine contaminant in pork sausages. Furthermore, we confirmed the efficacy of the PCR-RFLP technique as a reliable tool for the identification of Sarcocystis species, demonstrating its potential use in laboratories for molecular diagnosis and rapid identification of these parasites, aiming to protect public health and ensure food safety.

Detection of Sarcocystis hominis, Sarcocystis bovifelis, Sarcocystis cruzi, Sarcocystis hirsuta and Sarcocystis sigmoideus sp. nov. in carcasses affected by bovine eosinophilic myositis

Bovine eosinophilic myositis is an inflammatory myopathy characterized by multiple focal or diffuse grey to green patches leading to condemnation of affected carcasses. Although its etiology is still uncertain, there is evidence that Sarcocystis species may play a role in the development of eosinophilic myositis. The goal of the present study was to identify Sarcocystis spp. in intralesional and extralesional tissues of condemned cattle carcasses, in order to evaluate the possible role of different bovine Sarcocystis spp. in the etiology of bovine eosinophilic myositis. Muscle samples (n = 100) of 26 affected carcasses were collected in Northern Italy. One to five samples with lesions and two aliquots of tissue without lesions were collected from each carcass; lesions were grossly categorized in green focal lesions and green diffuse patches. Genomic DNA was extracted and analyzed by multiplex-PCR targeting different Sarcocystis spp. Unidentified species were characterized morphologically (light microscopy, histology), ultrastructurally (scanning and transmission electron microscopy) and on the molecular level (complete 18S rRNA gene and partial cox1 gene sequencing). A bovine eosinophilic myositis prevalence of 0.017% was visually assessed by routine carcass inspection between 2014 and 2019 in Italy (184/1,108,150 slaughtered cattle). Out of 26 carcasses, 25 revealed the presence of at least one Sarcocystis species (96.2%). The presence of Sarcocystis spp. DNA was significantly more frequent in intralesional than in extralesional samples. Considering the different species, Sarcocystis bovifelis and Sarcocystis hominis were significantly more frequent in intralesional (41.7% and 50%, respectively) than in extralesional samples (1.9% and 15.4%, respectively), while there was no significant difference between the presence of Sarcocystis cruzi and Sarcocystis hirsuta in intralesional (27.1% and 2.1%, respectively) and extralesional (30.8% and 1.9%, respectively) samples. The presence of an unnamed Sarcocystis sp. showing thick-walled (3.7-5.4 μm) cysts with densely packed, flattened, undulating and narrow protrusions, which showed an S-shape in side view, was recorded in the diaphragm of two carcasses. Genomic DNA from individual sarcocysts isolated from the diaphragm was successfully amplified and further sequenced. Sequence comparison revealed <94.6% and 83.4% identity at 18S rRNA and cox1 genes, respectively, with other named Sarcocystis spp., while the phylogenetic analysis clearly separated the unnamed Sarcocystis sp. from the other Sarcocystis spp. using cattle as intermediate hosts. The present study contributes to the understanding of the importance of different Sarcocystis spp. in the pathogenesis of bovine eosinophilic myositis. The results emphasize the association of Sarcocystis hominis and Sarcocystis bovifelis with bovine eosinophilic myositis and highlight the presence of a new Sarcocystis sp. using cattle as intermediate hosts. The name Sarcocystis sigmoideus sp. nov. is proposed for the newly described Sarcocystis species.

Morphological, ultrastructural, genetic characteristics and remarkably low prevalence of macroscopic Sarcocystis species isolated from sheep and goats in Kurdistan region, Iraq

Introduction

Sarcocystis is a genus of cyst-forming parasites that infest both humans and livestock. Some parasites cause clinical and subclinical diseases in their hosts, resulting in economic losses.

Methods

Esophagus, diaphragm, and skeletal muscle from slaughtered sheep and goats were examined macroscopically, microscopically, and ultrastructurally and subjected to DNA analysis.

Results

We isolated macrocysts of S. gigantea and of S. caprafelis moulei from naturally infected sheep (Ovis aries) and goats (Capra hircus). The macrocyst wall thickness was 18.9 µm in sheep and 15.3 µm in goats, and consisted of an inner Periodic acid Schiff- (PAS) negative primary wall and an outer glycoconjugates containing i.e. PAS-positive secondary wall. The walls inner surface was compartmentalized and filled with bradyzoites. In S. gigantea the bradyzoites were approximently 12.3 x 2.6 µm in size, while in S. caprafelis moulei they were 13.9 x 4.4 µm. Ultrastructurally, both species have nearly identical morphology: cauliflower-like protrusions with numerous microtubules and often dendritic-like filaments, branching from the primary wall. The 18S rRNA gene in S. gigantea was 85.9% identical to that in S. medusiformis and 80.4% to the S. caprafelis moulei gene. The 28S rRNA gene in S. gigantea was 94.6% identical to that in S. medusiformis and 97.3% to the S. caprafelis moulei.

Conclusion

This study is the first to (i) detail the ultrastructure of the macrocyst wall of S. caprafelis moulei, (ii) identify S. medusiformis in Iraqi sheep, and (iii) compare the prevalence of macroscopic Sarcocystis at different time periods within the same region. A positive finding was the reduction of macroscopic sarcocystosis occurrences (0.01% in sheep and 0.02% in goats) compared to our previous data from 1992 (4.1%: sheep, 33.6%: goats).

Sarcocystis Species Richness in Sheep and Goats from Lithuania

Contradictory data is available on the intermediate host specificity of Sarcocystis spp. in farm animals. Therefore, the current work aimed at molecularly testing samples of sheep and goats reared in Lithuania to identify Sarcocystis species described in other intermediate hosts but suspected to be non-canonical parasites to these small ruminants. For this purpose, muscle samples from 47 domestic sheep and nine goats were examined. Sarcocystis species were identified using direct and nested PCR targeting cox1 and sequencing of positive amplified products. Along with the detection of the canonical Sarcocystis spp. in their respective intermediate hosts, the DNA of S. capracanis and S. morae was detected in sheep, although these species were previously thought to be specific to goats and deer, respectively. In addition, DNA from S. arieticanis and S. tenella was found in goats, even though these two species were believed to be sheep-specific. Notably, under light microscopy, only sarcocysts of S. capracanis specific to goats were observed. Thus, future research on the life cycle and host-specificity of Sarcocystis spp. examined is warranted.

The Value of Current Ante Mortem Meat Inspection and Food Chain Information of Dairy Cows in Relation to Post Mortem Findings and the Protection of Public Health: A Case for a More Risk-Based Meat Inspection

In this study, the contribution of the ante mortem (AM) inspection and the food chain information (FCI) to ensuring meat safety and public health was investigated, by evaluating the slaughterhouse findings of 223,600 slaughtered dairy cows in the Netherlands. The outcome of this study was that the ante mortem (AM) and post mortem (PM) inspections have a substantial overlap, and that with regard to food safety and public health in over 99% of cases the PM could even be omitted on the basis of the AM. In this study, the data provided by the dairy farmers on the current FCI forms contributed little to nothing with regard to the outcomes of AM and PM inspection. It is concluded that current meat inspection procedures need an update and a more risk-based approach needs to be adopted. Regarding this, the AM inspection of dairy cattle should remain, because it plays an important role in ensuring food safety (e.g., by preventing contamination of the slaughter line by excessively dirty animals, or animals with abscesses), monitoring animal welfare and in detecting some important notifiable diseases. The PM inspection, however, could in many cases be omitted, provided there is a strict AM inspection complemented by a vastly improved (automated) way of obtaining reliable FCI.

A Case of Bovine Eosinophilic Myositis (BEM) Associated with Co-Infection by Sarcocystis hominis and Toxoplasma gondii

Bovine eosinophilic myositis (BEM) is a specific inflammatory myopathy, often associated with Sarcocystis spp., with multifocal gray-green lesions leading to carcass condemnation with considerable economic losses. Here is described a peculiar case of BEM that occurred in an adult (16 month) cattle, born in France, bred, and slaughtered in Italy at the end of 2021. On inspection, muscles showed the typical multifocal gray-green lesions that were sampled for, cytological, histological, and molecular investigations, while meat juice was subjected to IFAT for Toxoplasma IgG. Genomic DNA was extracted from lesions, portions of healthy muscle and from meat juice pellet and analyzed by PCR targeting 18S rDNA, COI mtDNA and B1 genes, and sequenced. The cytology showed inflammatory cells mostly referable to eosinophils; at histology, protozoan cysts and severe granulomatous myositis were observed. A BEM lesion and meat juice pellet subjected to PCR showed, concurrently, sequences referable both to S. hominis and T. gondii. Meat juice IFAT resulted negative for T. gondii IgG. Our findings highlight the first detection of T. gondii DNA in association with S. hominis in a BEM case, suggesting a multiple parasite infection associated with this pathology, although the actual role of T. gondii infection in the pathophysiology of the diseases should be clarified.

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.

Molecular detection of Sarcocystis cruzi in three beef carcases with eosinophilic myositis lesions and in unaffected beef from animals in the same herd

Eosinophilic myositis in bovine striated muscle thought to be caused by a hypersensitivity reaction to the degradation of Sarcocystis tissue cysts, is a rare reason for carcase condemnation in the United Kingdom. This paper describes the identification of Sarcocystis cruzi associated with lesions of generalised eosinophilic myositis in three English beef carcases, by gross and histopathological examination followed by PCR with subsequent sequencing. Samples from two unaffected animals were also examined. Although sarcocystosis caused by S.cruzi is not considered a public health risk, the clinically affected carcases were deemed unfit for human consumption due to the extensive lesions affecting meat quality. We believe this to be the first report from the UK describing the molecular-based identification of Sarcocystis cruzi in meat affected and unaffected with eosinophilic myositis.

Molecular Epidemiology, Species Distribution, and Zoonotic Importance of the Neglected Meat-Borne Pathogen Sarcocystis spp. in Cattle (Bos taurus): A Global Systematic Review and Meta-analysis

BACKGROUND

Sarcocystis species are diverse apicomplexan parasites, though only two zoonotic species (S. hominis and S. heydorni) circulate between cattle and humans. Due to the importance of cattle in the human food chain and to prevent the consequences of parasitosis in humans, the first global systematic review and meta-analysis on molecular epidemiology, species distribution, and zoonotic significance of Sarcocystis infection in cattle was performed.

METHODS

For this aim, four international English databases (PubMed, Scopus, Google Scholar, and Web of Science) were systematically searched till 20th September 2021, and random-effect models were drawn to calculate total estimates and their 95% confidence intervals (CIs).

RESULTS

Finally, 44 papers from 21 countries were qualified for this review which examined 8526 cattle regarding Sarcocystis infection, rendering a total prevalence of 62.7% (95% CI 53-71.5%). Globally, 12 Sarcocystis spp. have been reported from cattle, including S. cruzi, S. hominis, S. hirsuta, S. rommeli, S. heydorni, S. bovifelis, S. bovini, S. sinensis, S. gigantea, S. fusiformis, S. hjorti and S. tenella. Among them, S. cruzi (37 studies), S. hominis (22 studies) and S. hirsuta (19 studies) were the 3 most common species, with 76.4% (95% CI 64.8-85%), 30.2% (95% CI 19.3-44%) and 8.7% (95% CI 3.8-18.6%), respectively. However, molecular identification was not performed in 48.4% (95% CI 27.3-70.1%) of the positive samples.

CONCLUSION

Despite the zoonotic significance of Sarcocystis spp., particularly S. hominis, the epidemiology and distribution of Sarcocystis infection in cattle remains unclear and demands more extensive researches around the world.

M. Bulla-Castañeda DMBC, López Buitrago HA, Díaz Anaya AM, Madeira de Carvalho LM, Pulido-Medellín MO. Sarcocystis spp., a parasite with zoonotic potential

Sarcocystosis infection is caused by protozoan cysts of genus Sarcocystis spp. where S. hominis, S. heydorni (bovines) and S. suihominis (porcine) are the most relevant for humans because of their zoonotic potential. S. cruzi, S. suihominis and S. ovicanis represent the most pathogenic species for cattle, pigs and sheep respectively. This infection has a worldwide importance due to its high transmission; besides to represent a zoonosis, it generates great economics losses. The main diagnostic methods for this disease are artificial digestion, PCR, indirect ELISA, and compression analysis. It’s important to highlight few studies on Sarcocystis spp., especially the ones involving the pursuit of effective treatments to control the infection for both humans and animals, however, some studies have reported that treatments such as cotrimoxazole and albendazole with or without prednisone are effective in counteracting symptoms in humans, considering the lack of reports about Sarcocystis spp. prevalence in Colombia.

Sarcocystis cruzi infection in free-living European bison (Bison bonasus bonasus L.) from the Białowieża Forest, Poland - A molecular analysis based on the cox1 gene

European bison are susceptible to a range of pathogens which may influence their health, and hence, to ensure their protection, it is essential to provide effective monitoring of potential exposure. This study presents the first molecular confirmation of Sarcocystis cruzi infection in European bison based on PCR amplification of the cytochrome c oxidase subunit I (cox1) gene. A sample of heart tissue taken from one fifteen-year-old European bison cow was examined by light microscopy for the presence of heart sarcocysts. The genomic DNA isolated from any identified sarcocysts was subjected to PCR to amplify cox1 gene sequences, and the obtained amplicons were sequenced by Sanger dideoxy sequencing. Two partial cox1 sequences were obtained; they were identified as S. cruzi and deposited in the GenBank™ database under the accession numbers MW490605 and MW490606. BLAST analysis found them to demonstrate the closest similarity to S. levinei (MH255771-MH255779 and KU247874-KU247884), sharing an identity of 93.14-93.8 %. This is the first report to identify sarcocysts isolated from heart tissue of infected European bison living in the Białowieża forest to species level using cox1 analysis. Our findings confirm that the European bison is a natural intermediate host for S. cruzi. As such, coordinators of future conservation programmes should consider the impact of these diseases on reintroduced animals.

Sarcocystis species in bovine carcasses from a Belgian abattoir: a cross-sectional study

BACKGROUND

Sarcocystis species are obligatorily heteroxenous parasites, of which some are zoonotic, representing a public health and economic impact. This study investigated the occurrence of Sarcocystis spp. in cattle sampled from a Belgian slaughterhouse.

METHODS

A total of 200 carcasses were included in the study, sampled during 10 sampling days. The sedimentation method was applied to isolate the sarcocysts from both heart and diaphragm muscles collected from each carcass. Multiplex PCR, PCR-RFLP as well as cox1 gene sequencing techniques were applied serially on collected sarcocysts for species identification.

RESULTS

Sarcocystis spp. were detected in 64% (128/200; 95% CI 57-71%) of the sampled carcasses. Female dairy cattle presented the highest Sarcocystis occurrence rate (91%) as well as the highest Sarcocystis species diversity compared to female beef and male beef. Sarcocystis spp. were detected more often in the heart muscles than in the diaphragm among female beef (p < 0.001) and dairy carcasses (p = 0.001), while in male carcasses no significant difference was observed (p = 0.763). The effect of age was not significant in male carcasses (p = 0.872), while the odds of finding sarcocysts significantly increased with age (p = 0.003) within both types of female carcasses. S. cruzi was the most prevalent species and was found in 56.5% (113/200) of the carcasses, followed by S. hominis (21.0%, 42/200), S. bovifelis (12.5%, 25/200), S. bovini (2.0%, 4/200), S. hirsuta (1.5%, 3/200) and S. heydorni (0.5%, 1/200). Six different species were detected in the diaphragm, while only two species were recovered from the heart. S. cruzi was the most prevalent species in heart, while in the diaphragm, this was S. hominis.

CONCLUSIONS

The detection of S. hominis in 21% of the sampled carcasses presents a potential food safety issue, and further research is warranted into controlling this infection.

Molecular detection of cattle Sarcocystis spp. in North-West Italy highlights their association with bovine eosinophilic myositis

Background

Cattle are intermediate hosts of six Sarcocystis species, among which Sarcocystis hominis and Sarcocystis heydorni can infect humans through the consumption of raw or undercooked meat. In addition to the zoonotic potential, there is increasing interest in these protozoa because of the evidence supporting the role of Sarcocystis spp. in the occurrence of bovine eosinophilic myositis (BEM), a specific inflammatory myopathy which leads to carcass condemnation and considerable economic losses. Actually, all the prevalence studies carried out on cattle in Italy have been based on either morphological or 18S rDNA-based molecular techniques, most likely leading to misidentification of closely related species. Therefore, there is a strong need for new data on the prevalence of the different Sarcocystis spp. in cattle in Italy and their association with bovine eosinophilic myositis.

Methods

To reach our aim, individual striated muscle samples from BEM condemned carcasses (N = 54) and diaphragm muscle samples from randomly sampled carcasses (N = 59) were obtained from Northwest Italy slaughterhouses. Genomic DNA was extracted and analyzed by multiplex-PCR targeting 18S rDNA and cox1 genes. PCR products amplified using the genus-specific primer set in absence of the specific fragment for S. hirsuta, S. cruzi, S. hominis or S. bovifelis were sequenced to achieve species identification.

Results

Sarcocystis DNA was detected in 67.8% of the samples from slaughter cattle and in 90.7% of the samples from BEM condemned carcasses. S. cruzi was identified as the most prevalent species in slaughter cattle (61%), followed by S. bovifelis (10.2%), S. hominis (8.5%) and S. hirsuta (1.7%). Notably, among the different Sarcocystis spp. detected, the presence of S. bovifelis and S. hominis was significantly higher in samples isolated from BEM condemned carcasses (46.3% and 40.7% respectively), while there was no statistically significant difference between the presence of S. cruzi or S. hirsuta in BEM condemned carcasses (42.6% and 1.8%, respectively) and randomly sampled carcasses. Furthermore, DNA sequence analysis revealed the presence of a putative new species in two carcasses.

Conclusions

Our study contributes to updating the data on the prevalence of the different Sarcocystis spp. in cattle in Italy, highlighting the presence of three Sarcocystis spp., S. cruzi, S. hominis and S. bovifelis, in BEM lesions and allowing us to speculate on the possible role of S. hominis and S. bovifelis as the major sarcosporidian species involved in bovine eosinophilic myositis.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04722-5.

Sarcocystidae in wild birds of southeastern Brazil

This study aimed to identify members of the Sarcocystidae family in naturally infected wild birds at a rescue center in the state of Minas Gerais, southeastern Brazil. The heart and brain of 44 wild birds were evaluated by bioassay in mice to detect T. gondii, and extracted DNA was used for nested PCR of the 18S ribosomal DNA gene to detect members of the Sarcocystidae family. The positive samples were sequenced, assembled, edited and compared with sequences deposited in GenBank. Toxoplasma gondii was isolated from six (13.6%) out of 44 birds. Toxoplasma gondii DNA was identified in 10/44 (22.7%) of the birds. The amplified sequences exhibited 100% similarity with the DNA of the ME49 strain of T. gondii. Sarcocystis DNA (99% similarity) was identified in 5/44 (11.4%) of the birds. T. gondii and Sarcocystis spp. are common in wild birds in Minas Gerais, Brazil.

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.

Prevalence and molecular analysis of Sarcocystis infections in cattle in Northwest Iran and the first global report of S. gigantea in cattle

Cattle are intermediate host for several species of Sarcocystis, including S. cruzi, S. hirsuta, and S. hominis with high prevalence worldwide. The present study aimed to determine the prevalence of Sarcocystis infection, species identification, and phylogenetic analysis of the parasite in cattle in Northwest Iran. The samples of diaphragm and esophagus from 290 cattle were collected from slaughterhouses in Northwest Iran and subjected to macroscopic, microscopic, and histopathology examinations, PCR-RFLP, sequencing and phylogenetic analyses. Tissue cysts of Sarcocystis spp. were detected in 92% of cattle by digestion and microscopic tests. Based on the PCR-RFLP and specific PCR, 87.9% and 1.03% of isolates were identified as S. cruzi, and S. hominis, respectively. Macrocyst was seen in a single sample that was identified as S. gigantea. The haplotype network exhibited the extension of the various haplotypes of S. cruzi between neighboring provinces in Northwest Iran. Heterogeneity analysis of S. cruzi 18S-rRNA sequences indicated genetic diversity among S. cruzi isolates (Haplotype diversity: 0.733-0.854) consisting 16 haplotypes; however, the nucleotide differences showed low diversity (0.01481 to 0.03351). Pair wise sequence distance matrix amongst S. cruzi sequences indicated an intra-species divergence of 0%-7.8% and identity of 92.6%-100%. Sarcocystis infection is highly prevalent in cattle in Northwest Iran, with the predominance of S. cruzi, and genetic variants of this species are unequivocally distributing in Northwest provinces. First global detection of S. gigantea in cattle reflects new insights of transmission dynamic and biology of this parasite in Iran.

Serologic reactivity of canine sera to Sarcocystis neurona and Sarcocystis cruzi antigens

Sarcocystis neurona, a coccidian parasite shed by opossums (Didelphis spp.) in the Americas, is the major cause of equine protozoal myeloencephalitis (EPM) and induces disease in other domestic and wild animal species, including domestic dogs. Sarcocystis cruzi, despite its low pathogenicity for cattle (intermediate hosts), is worldwide distributed and uses mostly dogs as definitive hosts. The aims of this study were to test serological reactivities of dog sera to S. neurona and S. cruzi antigens, and to investigate potential serological cross-reactivity to these parasites. Sera from 353 Brazilian dogs were obtained from rural areas in the municipality of Ilhéus, Bahia, and examined by immunofluorescent antibody tests (IFAT). Antigens used in serological reactions consisted of S. neurona merozoites from a North American strain (SN138), and bradyzoites of S. cruzi obtained from Brazilian bovine hearts, with parasite species identity confirmed by PCR and sequencing of the 18S gene of the rDNA. Seropositivity to S. neurona and to S. cruzi were detected in 3.39% (12/353) and 4.81% (17/353) of the dogs, respectively. Ten canine sera reacted solely to S. neurona and 15 serum samples reacted only to S. cruzi. Two serum samples were simultaneously positive for both parasites. Sera from 14 dogs that tested positive by IFAT (9 for S. neurona and 3 for S. cruzi) and from two dogs that were negative by IFAT for the two parasites, were examined by Western blot using S. neurona as antigen; these sera reacted to a great number of protein bands, including antigens on the 16 and 30 KDa positions, which encompass immunodominant antigens for S. neurona in horses. Western blot did not show any specific pattern for S. neurona infection/exposure using canine sera. Dogs act as definitive hosts for several Sarcocystis spp. that infect farm animals, including horses, sheep, goats, water buffaloes and pigs, and for this reason, should contain antibodies to a broad repertoire of Sarcocystis spp. antigens. In conclusion, low percentages of dogs from rural areas of Ilhéus, Bahia, were reactive to both S. neurona and S. cruzi antigens. It is possible that other Sarcocystis species, besides S. neurona and S. cruzi, might have contributed for the seropositivity observed in this study. IFAT was more specific than Western blot to differentiate canine serological reactions to S. neurona and S. cruzi antigens.

Molecular phylogeny of Sarcocystis fayeri (Apicomplexa: Sarcocystidae) from the domestic horse Equus caballus based on 18S rRNA gene sequences and its prevalence

Sarcocystosis is a parasitic disease caused by an intracellular protozoan parasite Sarcocystis belonging to the phylum Apicomplexa. These parasites have a requisite two-host life cycle. Recently, there are many Sarcocystis species that identified morphologically. In the present study, diaphragmatic muscle samples from the domestic horse (Equus caballus) were examined for Sarcocystis infection. The natural infection with sarcocysts was recorded to be 62·5% for only microcysts in the infected muscles. Molecular analysis using the 18S rRNA gene was conducted to swiftly and accurately identify the recovered species. Studies on the expression of the 18S rRNA gene have confirmed that the present parasite isolates belong to the Sarcocystis genus. The sequence data showed significant identities (>80%) with archived gene sequences from species within the Sarcocystidae family, and a dendrogram showing the phylogenetic relationship was constructed. The most closely related species were the previously described Sarcocystis fayeri and Sarcocystis bertrami. The current data showed that the present species was identified as S. fayeri and deposited in GenBank (accession number MF614956.1). This study highlights the importance of the genetic data in the exact taxonomy within sarcocystid species.

Sarcocystis infection in beef and industrial raw beef burgers from butcheries and retail stores: A molecular microscopic study

Sarcocystis is a genus of eucoccidian parasites, which globally infects humans and various animals. In addition to economic losses in livestock industries, the parasite is a zoonosis that infects humans through contaminated beef and pork with the parasite sarcocysts. Therefore, this study was carried out to assess Sarcocystis contamination in beef and industrial raw beef burger samples from butcheries and retail stores in Tehran, Iran. Overall, 180 samples of 90 beefs and 90 raw industrial beef burgers with at least 80% meat were randomly collected in Tehran, Iran. Samples were studied microscopically after peptic digestion. Furthermore, sample genomic DNAs were used in conventional polymerase chain reaction (PCR) to amplify approximately 900-bp fragments from 18S ribosomal DNA. Of 180 samples, 170 samples (94.4%) were microscopically and 161 samples (89.44%) were molecularly positive for Sarcocystis spp. Eucoccidial DNA fragments were detected in 161 samples (89.4%), including 78 (86.6%) beef and 83 (92.2%) beef burger samples. No significant differences were found between the beef and beef burger infestations by Sarcocystis bradyzoites using statistical analysis (P > 0.05). Statistically significant differences were seen between the sample type and the intensity of parasites in samples (P = 0.003). Furthermore, differences between the conventional PCR results (positive/negative) and the intensity of parasites in samples were statistically significant (P < 0.001). The considerable prevalence of Sarcocystis spp. in beef and beef burger samples reflects high transmission of the parasite in meat producing cattle, which is important due to food hygiene. Although the most prevalent bovine species, S. cruzi, is not a zoonosis, it is highly recommended to follow guidelines on the parasite transmission prevention due to the existence of S. hominis as a zoonotic bovine species.

Molecular differentiation of cattle Sarcocystis spp. by multiplex PCR targeting 18S and COI genes following identification of Sarcocystis hominis in human stool samples

Sarcocystis spp. are protozoan parasites which can infect a wide range of vertebrates, including humans; the latter can act as definitive hosts for two cattle Sarcocystis spp.: Sarcocystis hominis and Sarcocystis heydorni. Reports of intestinal sarcocystosis are well documented in the literature, but PCR-based methods have been scarcely used to identify Sarcocystis species in human stools, and have been limited to the molecular analysis of 18S ribosomal RNA (18S rRNA) gene sequences. Since the mitochondrial cytochrome c oxidase subunit I (COI) gene is one of the most promising tools for distinguishing between closely related Sarcocystis spp., and taking into account the lack of publicly available S. hominis COI sequences, in the present study we obtained the first partial COI sequence of S. hominis from human stool samples of patient with gastrointestinal symptoms. We designed specific COI primers to develop a multiplex PCR method for the identification of Sarcocystis spp. in cattle. The submission of the COI sequence described herein and the unambiguous identification of S. hominis through the application of the new multiplex PCR is important for determining the prevalence of this zoonotic Sarcocystis spp. in meat and the risk for consumers.