Sarcocystis calchasi sp. nov. of the domestic pigeon (Columba livia f. domestica) and the Northern goshawk (Accipiter gentilis): light and electron microscopical characteristics

The Genetic Identification of Numerous Apicomplexan Sarcocystis Species in Intestines of Common Buzzard (Buteo buteo)

The common Buzzard (Buteo buteo) was previously shown to transmit two Sarcocystis species (S. glareoli and S. microti) forming cysts in the brains of rodents. Due to a lack of research, the richness of Sarcocystis species spread by these birds of prey is expected to be much higher. A total of 30 samples of the small intestine of the Common Buzzard were collected in Lithuania and subjected to Sarcocystis species identification based on nested PCR of 28S rRNA and ITS1, following the sequencing of amplified DNA fragments. Six known Sarcocystis spp., S. cornixi, S. glareoli, S. halieti, S. kutkienae, S. turdusi, and S. wobeseri, along with three genetically distinct species (Sarcocystis sp. Rod3, Sarcocystis sp. Rod4, and Sarcocystis sp. Rod5), were identified. Phylogenetically, these three potentially new species clustered with Sarcocystis spp. characterised by a rodents-birds life cycle. Sarcocystis spp. employing rodents and birds as their intermediate hosts were detected in 66.7% and 50.0% of samples, respectively. These findings are consistent with the diet preferences of Common Buzzards. Notably, co-infections with two or more species were observed in a half of the samples. Altogether, the obtained results indicate that the Common Buzzard could serve as definitive host of various Sarcocystis species.

First report of Sarcocystis falcatula in naturally infected Razorbill auks (Alca torda) collected in Tunisian Mediterranean Sea shores

Sarcocystis spp. are apicomplexan cyst-forming parasites that can infect numerous vertebrates, including birds. Sarcosporidiosis infection was investigated in three muscles (breast, right and left thigh muscle) and one organ (heart) of four Razorbill auks (Alca torda) stranded between November and December 2022 on the shores of the Mediterranean Sea in Nabeul and Bizerte governorates, Northern Tunisia. Two of the four tested A. torda were PCR positive for 18S rRNA Sarcocystis spp. gene. Among the examined 16 muscles/organs, only one breast and one right thigh were Sarcocystis spp. PCR-positive (12.5% ± 8.3, 2/16). Our results showed a relatively high molecular prevalence of Sarcocystis spp. in Razorbill auks (A. torda). Sarcocystis spp. sequence described in the present study (GenBank number: OR516818) showed 99.56-100% identity to Sarcocystis falcatula. In conclusion, our results confirmed the infection of Razorbill auks (A. torda) by S. falcatula. Further research is needed on different migratory seabirds' species in order to identify other Sarcocystis species.

Molecular Confirmation of Accipiter Birds of Prey as Definitive Hosts of Numerous Sarcocystis Species, including Sarcocystis sp., Closely Related to Pathogenic S. calchasi

The present study aimed to test intestinal scrapings of the Northern Goshawk (Accipiter gentilis) and the Eurasian Sparrowhawk (Accipiter nisus) from Lithuania for S. calchasi and other Sarcocystis species characterised by bird-bird life cycles. The protozoan parasite Sarcocystis calchasi can cause respiratory and neurological diseases in a variety of birds; however, the distribution of this parasite is not well-examined. Sarcocystis species were identified with nested PCR and sequencing of the partial ITS1 region. Sporocysts and/or sporulated oocysts of Sarcocystis spp. were observed in 16 (100%) Northern Goshawks and 9 (56.3%) Eurasian Sparrowhawks. Four species, S. columbae, S. halieti, S. turdusi, and S. wobeseri, were confirmed in the Eurasian Sparrowhawk. Apart from the latter four species, S. calchasi, S. cornixi, S. kutkienae, and S. lari were established in the Northern Goshawk. A higher prevalence of Sarcocystis spp. and species richness in Northern Goshawks is associated with the differences in the diet of two examined Accipiter species. This study is the first report of S. calchasi in Lithuania. Furthermore, the genetically distinct species Sarcocystis spp. 23LTAcc, which is most closely related to S. calchasi, was found in three Northern Goshawks.

Fatal Sarcocystis calchasi hepatitis in a captive Indian ringneck parakeet (Psittacula krameri manillensis)

An adult Indian ringneck parakeet (Psittacula krameri manillensis) from an outdoor aviary in Sacramento, California was found dead on the nest box. Postmortem examination showed firm, enlarged, yellow‑tinged liver and splenomegaly. Multifocal to coalescing, acute necrosis with macrophages, lymphocytes, plasma cells, and periportal ductular reaction were seen on liver histology with extra- and intracellular schizonts and merozoites. A few schizonts and lymphohistiocytic inflammation were seen in the spleen. Toxoplasma gondii, Sarcocystis neurona, S. falcatula and Neospora caninum were ruled out by immunohistochemistry. PCR of the liver for Sarcocystis spp. Based on the positive amplification/PCR of ITS1 segment and sequencing of 28S rRNA fragment, S. calchasi was confirmed. The splanchnic presentation of S. calchasi in this parakeet resembles the acute infection described experimentally in domestic pigeons (Columba livia f. domestica) and cockatiels (Nymphicus hollandicus). Since large populations of red-tailed hawks (Buteo jamaicensis) and Cooper's hawk (Accipiter cooperi), the likely definitive hosts of S. calchasi in North America, inhabit the Sacramento area, their presence near outdoor aviaries may account for the source of S. calchasi infective sporocysts.

Natural infection with Toxoplasma gondii, Neospora caninum and Sarcocystis species in domestic pigeons (Columba livia domestica) in Iran

Pigeons are common birds around the world and may act as intermediate hosts of the tissue cyst-forming apicomplexan parasites Toxoplasma gondii, Neospora caninum and Sacrocystis spp. This study aimed to provide an overview on the prevalence of and exposure to these parasites in Iranian domestic rock pigeon (Columba livia domestica) through molecular, serological and histopathological examination. Blood and tissue samples (i.e., brain, heart, gizzard, neck, thigh, and pectoral muscles) were taken from 100 pigeons. Sera were screened by agglutination tests for detection of anti- T. gondii and N. caninum antibodies, genomic DNA from tissue samples were assessed by respective species-specific PCRs, and histopathological examination of tissues was carried out. A seroprevalence of 45 % to anti-T. gondii and 35 % to anti-N. caninum IgG was recorded. PCR detected T. gondii DNA in 28 pigeons. Sacrocystis spp. was detected in one animal, but sequencing of the 28 S rRNA gene product did not reveal the identity of the species. Histopathology revealed myocarditis, myositis, and gliosis in the heart, skeletal muscles, and brain, respectively. No Sarcocystis tissue-cysts were detected, but T. gondii tissue cyst-like structures in the brain (i.e., 4 %) and heart (i.e., 3 %) were found by histology. Data reported herein demonstrate that pigeons from Iran are infected with tissue cyst-forming apicomplexans, particularly T. gondii. Since domestic pigeons are in close contact with human populations, and consumption of their meat and egg is popular in different societies, control strategies for minimizing the risk of infection in both pigeons and humans are suggested.

White-tailed eagle (Haliaeetus albicilla) as the definitive host of Sarcocystis lutrae in the Czech Republic

The white-tailed eagle, Haliaeetus albicilla, has been involved in the life cycle of several Sarcocystis species as the intermediate and definitive host. To date, it has been supposed that the eagle might play the role as the definitive host for S. Lutrae, and, herein, we tried to elucidate it based on morphometric and molecular analyses. One out of two eagles harbored oocysts (17.0−17.4 × 11.3–11.9 μm) and sporocysts (11.3–12.3 × 8.3–9.3 μm) in the intestinal mucosa, whose sequences at 18S rRNA, 28S rRNA, ITS1, and cox1 showed similar identity (97.64–100%) to published sequences of S. lutrae from other hosts. The presence of sporulated oocysts in the lamina propria of villi confirms that S. lutrae truly infects the white-tailed eagle. The white-tailed eagle is confirmed as the definitive host of S. lutrae in the Czech Republic.

A novel RFLP method for identification of morphologically similar avian Sarcocystis species

Protozoans of genus Sarcocystis are widespread parasites infecting mammals, birds, and reptiles. Morphology of their sarcocysts is an important criterion for species identification. However, as more and more morphologically similar Sarcocystis species are being found and described, additional methods for their routine diagnostics are needed. We investigated restriction fragment length polymorphism (RFLP) as potential alternative to sequencing data analysis for the identification of Sarcocystis species using birds as an intermediate host. The internal transcribed spacer 1 (ITS1) region sequences of seventeen Sarcocystis species (S. albifronsi, S. anasi, S. calchasi, S. columbae, S. cornixi, S. corvusi, S. cristata, S. halieti, S. falcatula, S. fulicae, S. kutkienae, S. lari, S. lindsayi, S. rileyi, S. turdusi, S.wenzeli, and S. wobeseri) of interest were analysed and five best-fitting endonucleases generating most informative restriction fragments were selected for routine testing. In general, RFLP analyses are always inconclusive as they target very short DNA sequences. However, it can be an irreplaceable technique when fast and cheap identification and discrimination of known species are required, which was our main goal and preliminary results indicate that RFLP could be successfully used when identifying closely related avian Sarcocystis species with just two nucleases.

Molecular characterization of Sarcocystis spp. in seabirds from southern Brazil

Sarcocystis spp. are cyst forming apicomplexan parasites that infect many vertebrates including birds. Sarcocystis spp. infection was investigated in tissue samples (pectoral muscles, heart, and brain) of 47 dead seabirds collected from the coastline of Santa Catarina State SC - Brazil, between August 2019 and March 2020. A portion of each tissue was fixed in 10% buffered formalin for histopathologic analysis while DNA was extracted from another portion and screened using nested-PCR targeting ITS1. Based on molecular analysis, Sarcocystis spp. were identified in 15/47 (31.9%) seabirds of five species, kelp gull (Larus dominicanus), manx shearwater (Puffinus puffinus), neotropic cormorant (Phalacrocorax brasilianus), brown booby (Sula leucogaster) and great skua (Stercorarius skua). Microscopically visible sarcocysts were observed only in the pectoral muscle of four seabirds 8.5% (4/47), while in one brown booby, sarcocysts were seen in both pectoral and cardiac muscles. Two types of sarcocysts, thin walled (≤1 μm) and thick-walled (≥ 2 μm) were identified. Based on ITS1 sequence comparison, S. halieti, S. falcatula and three not yet described Sarcocystis spp. were detected. Phylogenetically, S. falcatula isolates were classified as two distinct clusters. This is the first confirmation of S. halieti in seabird's species in South America and S. falcatula in birds of the order Charadriiformes. Further molecular studies are needed to understand the epidemiology of the Sarcocystis spp. infection and its impact on the health of seabirds.

Fatal Sarcocystis calchasi-associated meningoencephalitis in 2 captive vulturine guineafowl

Two captive vulturine guineafowl (Acryllium vulturinum) were presented with lethargy, hyporexia, weight loss, and progressive neurologic signs. One of the guineafowl was seropositive for Sarcocystis falcatula (1:50 dilution). Both guineafowl died within 5 d of presentation. Histologic examination revealed nonsuppurative meningoencephalitis with gliosis, associated with occasional schizonts in the neuropil. Using fresh-frozen brain tissue, PCR was performed to amplify the ITS1 RNA region and portions of the 18S ribosomal RNA gene (18S gene) and the 28S ribosomal RNA gene (28S gene). Analysis of nucleic acid sequences from the resulting amplicons indicated that Sarcocystis calchasi was the likely cause of disease. To our knowledge, S. calchasi-associated disease has not been reported previously in the order Galliformes.

Morphological and molecular identification of Sarcocystis sp. from the little grebe, Tachybaptus ruficollis (Aves: Podicipediformes), for the first time in Egypt

Background

In Egypt, studies of sarcocystosis in migratory and wading birds specially Podicipediformes are scarce. Therefore, the occurrence of Sarcocystis spp. in the little grebe, Tachybaptus ruficollis (Podicipediformes: Podicipdidae) was investigated in Qena province, Upper Egypt. During the period from September 2017 to March 2018, muscle specimens of esophagus from 25 little grebes were examined for the occurrence of Sarcocystis spp. using light microscopy, transmission electron microscopy (TEM) and molecular tools including conventional PCR and phylogenetic analysis with both 18S rRNA and 28S rRNA genetic loci.

Results

Sarcocystis spp. were identified in 84.0% (21/25) of the T. ruficollis esophageal muscle samples by morphological analysis; each was long, ribbonlike and extended along the muscle fibers. TEM revealed a characteristic thin and wavy cyst wall and an undulating vacuolar membrane with villar protrusions of slightly variant sulci and gyri, as well as several septated compartments filled with bradyzoites. The applied 18S rRNA and 28S rRNA were not enough variable for the identification of Sarcocystis species.

Conclusion

This study is the first to report the occurrence of Sarcocystis sp. in little grebes in Egypt. Further studies are required to identify Sarcocystis spp. in various wild birds by ITS1 region in Egypt.

Graphical abstract

Investigations on Sarcocystis species in the leg muscles of the bird family Corvidae in Lithuania

Although three species of Sarcocystis, S. cornixi, S. corvusi and S. kutkienae, have been described in corvids, molecular studies of sarcocysts isolated from these birds are incomplete. Leg muscles of 83 corvids, 35 hooded crows (Corvus cornix), 21 western jackdaws (Coloeus monedula), 11 rooks (Corvus frugilegus), 9 common ravens (Corvus corax), 4 common magpies (Pica pica) and 3 Eurasian jays (Garrulus glandarius), from Lithuania were examined for the presence of Sarcocystis spp. in the present study. In methylene blue-stained squashed samples, sarcocysts were detected in 26 birds (31.0%). Under a light microscope, two morphological types of sarcocysts were distinguished (type A and type B). Sarcocysts of type A had a smooth and thin (about 1 μm) cyst wall, while cysts of type B were characterised by a thicker (1.4-2.5 μm) cyst wall. Based on ITS1 sequence comparison, sarcocysts of type A were identified as S. halieti and Sarcocystis sp. ex Corvus corax, whereas cysts of type B belonged to S. kutkienae and S. cornixi. Furthermore, it was demonstrated that a single bird could host two different Sarcocystis spp. Sarcocystis halieti was detected in corvids for the first time in the common raven and the hooded crow. Also, this study presents the first evidence of S. kutkienae in the hooded crow and the common magpie, and S. cornixi in the western jackdaw. Sarcocystis sp. ex Corvus corax was genetically characterised using almost complete 18S rDNA, partial 28S rDNA and complete ITS1 sequences. Sarcocystis sp. ex Corvus corax clustered together with S. columbae, S. corvusi and S. halieti in phylogenetic trees reconstructed using 28S rDNA and ITS1 sequences.

Sarcocystis calchasi in a captive Patagonian conure (Cyanoliseus patagonus) in Finland

Sarcosystis calchasi is an emerging pathogen causing encephalitis in many avian species and has been documented in North America, Germany and Japan. In November 2019, a captive Patagonian conure (Cyanoliseus patagonus), kept in a zoological aviary in Finland, was euthanized due to acute respiratory distress. At necropsy, histopathological examination revealed numerous parasitic tissue cysts in the skeletal muscles and myocardium, chronic moderate multifocal lymphoplasmacytic and histiocytic meningoencephalitis and acute moderate multifocal purulent pneumonia caused by aspiration of foreign material. By light and transmission electron microscopy, tissue cysts had structures typical of Sarcocystis organisms. The ultrastructure of the cyst wall was compatible with S. calchasi and Sarcocystis columbae. S. calchasi-specific semi-nested polymerase chain reaction testing resulted in amplification of the internal transcribed spacer (ITS) gene, which had 100% identity with S. calchasi ITS sequences. This is the first report of S. calchasi in Fennoscandia and of a naturally-occurring S. calchasi infection in a captive psittacine bird in Europe. Our finding suggests that captive psittacine birds kept in outdoor facilities may be at risk of S. calchasi infection throughout the Holarctic.

The Role of Birds of the Family Corvidae in Transmitting Sarcocystis Protozoan Parasites

Simple Summary

Members of the genus Sarcocystis are protozoan parasites that infect mammals, birds, and reptiles. Sarcocystis spp. have an obligatory two-host prey-predator life cycle. Sarcocysts form in the muscles and central nervous system of the intermediate host, while oocysts and sporocysts develop in the small intestine of the definitive host. There is a lack of studies on omnivorous birds of family Corvidae as potential definitive hosts of Sarcocystis spp. Until now, only S. ovalis has been confirmed to be transmitted via corvids. In the current study, 91 small intestine samples from six corvid species from Lithuania were examined for the presence of Sarcocystis spp. that use birds, carnivorous mammals, and cervids as intermediate hosts. Oocysts of Sarcocystis spp. were observed in 43 samples (47.3%) using a light microscope. Based on molecular methods, 11 Sarcocystis spp., (S. columbae, S. cornixi, S. halieti, S. kutkienae, S. lari, S. turdusi, S. wobeseri, S. arctica, S. lutrae, S. ovalis, and S. oviformis) were identified. These results indicate that corvids may transmit some species of Sarcocystis that use birds and mammals as intermediate hosts.

Abstract

Members of the family Corvidae are ecologically flexible omnivorous birds, particularly adaptive to urban habitats, and living in proximity to humans; these birds may serve as definitive hosts (DH) for Sarcocystis spp., but research about this is lacking. In the present study, intestinal samples from 91 corvids collected in Lithuania were molecularly tested by species-specific PCR targeting the ITS1 and cox1 genes and subsequently sequenced for the presence of Sarcocystis spp. Under a light microscope, oocysts of Sarcocystis spp. were observed in 43 samples (47.3%), while molecular methods, detected Sarcocystis spp. in 77 birds (84.6%). Eleven Sarcocystis spp. (S. columbae, S. cornixi, potentially pathogenic S. halieti, S. kutkienae, S. lari, S. turdusi, S. wobeseri, S. arctica, S. lutrae, S. ovalis, and S. oviformis) were identified in the intestinal samples from six corvid species from Lithuania. Infections with multiple Sarcocystis spp. were detected in 79.2% of the infected corvid birds. Three of the identified Sarcocystis spp. use corvids as intermediate hosts (IH); therefore, corvids may serve as IH and DH of the same Sarcocystis species. Based on molecular results and on corvid diet, omnivorous corvids may play an important role in transmitting Sarcocystis spp.

Molecular identification of Sarcocystis wobeseri-like parasites in a new intermediate host species, the white-tailed sea eagle (Haliaeetus albicilla)

A reintroduced white-tailed sea eagle (Haliaeetus albicilla) in moderate body condition was found dead and submitted for post-mortem examination. There were no signs of disease on gross pathological examination. Histopathological examination however revealed the presence of encysted protozoan parasites in pectoral and cardiac muscle sections. Polymerase chain reaction amplification of extracted genomic DNA and sequencing of four regions: the 18S rDNA, 28S rDNA, internal transcribed spacer (ITS) 1, and RNA polymerase B (rpoB) loci, confirmed the presence of a Sarcocystis species in pectoral and cardiac muscle which appeared phylogenetically similar to Sarcocystis wobeseri. This is the first report of S. wobeseri-like infection in a white-tailed sea eagle revealing a new intermediate host species for this parasite.

Molecular Characterization of New Haplotype of Genus Sarcocystis in Seabirds from Magdalena Island, Southern Chile

Simple Summary

Sarcocystidae is a family of apicomplexan protozoa highly prevalent in vertebrates. The definitive hosts of sarcocystids eliminate oocysts or sporocysts that infect intermediate hosts. After infection, mature tissue cysts (sarcocysts) develop in intermediate hosts, mostly in muscle and neurological tissues. Sarcocysts are infectious for definitive hosts, which acquire them through carnivorous or scavenging habits. Intermediate hosts and definitive hosts are the natural hosts of sarcocystids in which infections are usually mildly or not symptomatic. In 2017, muscular and neurological tissues of 22 birds from Magdalena Islands, southern coast of Chile, were screened for the presence of DNA of sarcocystids. DNA of organisms of the genus Sarcocystis was identified in two Chilean skuas (Stercorarius chilensis). The genetic makeup of the parasite detected in skuas was unprecedented and probably represent a new species in the genus. It is well known that Sarcocystis may cause severe infections in aberrant hosts, which are susceptible animals that do not behave as natural hosts for the parasite and have low resistance to the infection, thus more studies are needed to characterize this parasitosis in skuas and other hosts to understand the epidemiology of the infection and its impact on the health of marine fauna.

Abstract

Evidence of sarcocystid infection was investigated in samples of 16 penguins (Spheniscus. magellanicus), four Dominican gulls (Larus dominicanus) and two Chilean skuas (Stercorarius chilensis) found in Madalenas Islands, Chile, in 2017. Samples of skeletal muscle, cardiac muscle and brain from all birds were screened by a pan-sarcocystid nested-PCR targeting a short fragment of the gene encoding the small ribosomal unit (nPCR-18Sa). The only two positive samples by nPCR-18Sa, both from skuas, were tested by a nested-PCR directed to the internal transcribed spacer 1 (nPCR-ITS1), also a pan-sarcocystidae nested-PCR, and to a nested-PCR directed to the B1 gene (nPCR-B1), for the exclusive detection of Toxoplasma gondii. The two nPCR-18Sa-positive samples were nPCR-ITS1-positive and nPCR-B1-negative. The nPCR-ITS1 nucleotide sequences from the two skuas, which were identical to each other, were revealed closely related to homologous sequences of Sarcocystis halieti, species found in seabirds of northern hemisphere. Larger fragments of genes encoding 18S and partial sequences of genes coding for cytochrome oxidase subunit 1 were also analyzed, corroborating ITS1 data. The haplotypes found in the skuas are unprecedent and closely related to species that use birds as the definitive host. Further studies need to be carried out to detect, identify and isolate this parasite to understand the epidemiology of the infection and its impact on the health of marine fauna.

Unique report of two Sarcocystis species from Egyptian domestic chicken (Gallus gallus) – new host and locality

Sarcocystis is an intracellular protozoan parasite in the phylum Apicomplexa. It is widely distributed all over the world. There are scarce reports about chicken Sarcocystis. From February 2016 to January 2018, a total number of 630 chicken carcasses, intestines and viscera were collected from different chicken markets in Menoufia and Gharbia Governorates, Middle region of the Nile Delta, Egypt and carefully inspected. Macroscopic and microscopic cysts of Sarcocystis spp. were found in the intestinal wall and mesentery of 5 birds. Histopathological sections revealed the presence of two shapes of the macroscopic cysts (oval and kidney shape). Their wall was striated and characterised by the presence of radial septa. It had compartments mostly of hexagonal shape, containing both bradyzoites and metrocytes in the periphery. The bradyzoites were banana-shaped and measured 20–30 × 8–10 μm with centrally or posteriorly located nuclei. Microscopic cysts of Sarcocystis spp. were detected in-between muscle bundles, with variable shapes (spindle and oval).

Molecular and morphological description of Sarcocystis kutkienae sp. nov. from the common raven (Corvus corax)

Until now, two Sarcocystis species, S. cornixi and S. corvusi, were known to employ members of the family Corvidae as intermediate hosts. Between 2013 and 2019, having examined leg muscles of 23 common ravens in Lithuania, sarcocysts were detected in 18 birds (78.3%). Using light microscopy, transmission electron microscopy (TEM), and molecular analysis (three genetic loci, 18S rDNA, 28S rDNA, and ITS1), sarcocysts found in the common raven were described as a new species S. kutkienae. Under a light microscope, the observed sarcocysts were ribbon-shaped (1500-8147 × 53-79 μm) and had a wavy striated cyst wall that reached up to 1.5 μm. Lancet-shaped bradyzoites were 7.7 × 2.2 μm (6.1-9.0 × 1.2-3.0 μm) in size. Ultrastructurally, the sarcocyst wall was 1.5-1.8 μm in thickness and had conical-like protrusions with minute invaginations of a parasitophorous vacuolar membrane. The cyst wall was type 1e-like. Limited genetic variability was observed between the 18S rDNA and 28S rDNA sequences of S. kutkienae and other Sarcocystis spp. using birds as intermediate hosts. In contrast, S. kutkienae could be clearly identified by comparing sequences. At this locus, sequences of S. kutkienae shared the highest similarity (89.5-89.7%) with those of S. cornixi. Phylogenetic analysis showed that S. kutkienae was most closely related to Sarcocystis spp. that employs birds as intermediate and definitive hosts. The issue relating to which species might serve as definitive hosts of S. kutkienae in Lithuania is addressed.

Emerging and Re-emerging Diseases of Selected Avian Species

Emerging infections and re-emerging diseases in birds can be caused by numerous factors and need to be recognized and understood. This article introduces and summarizes author-selected emerging and re-emerging diseases of avian species. These diseases hold significance as they relate to scientific research, disease recognition and identification, avian welfare aspects, and ecosystem health. Some are significant in human health and others affect production medicine. These and many others remain important pathogens of worldwide consequence.

Protozoal encephalitis associated with Sarcocystis calchasi and S. falcatula during an epizootic involving Brandt's cormorants (Phalacrocorax penicillatus) in coastal Southern California, USA

Between March and May 2019, wildlife rehabilitation centers along coastal southern California admitted increased numbers of Brandt's cormorants (Phalacrocorax penicillatus) with neurological disease including head tilt, nystagmus, torticollis, tremors, paresis, paralysis, and ataxia. Seven cormorants from Los Angeles County and one cormorant from Orange County were submitted for postmortem examination. Gross findings included thin to fair body condition, generalized congestion/hyperemia, nematode parasites in the ventriculus, and diarrhea in the seven birds from Los Angeles County while the one bird from Orange County had icterus. Histologic examination revealed sarcocysts in the adductor muscles and meningoencephalitis characterized by coalescing infiltrations of macrophages, lymphocytes and plasma cells with severe perivascular cuffing and gliosis in all eight cormorants. Rare to few numbers of schizonts were seen in the cerebrum of the seven cormorants from Los Angeles County whereas the cormorant from Orange County had numerous schizonts in various stages of development in the cerebrum, cerebellum, and brainstem. All eight birds were positive for the generic Sarcocystis spp. 28S PCR. The seven cormorants from Los Angeles County tested positive for the S. calchasi-specific ITS1 and confirmed by sequencing, while the analysis of the 28S sequence in the cormorant from Orange County showed a 100% homology to S. falcatula. This bird also was positive by immunohistochemistry for Sarcocystis spp. using a polyclonal antibody that detects S. falcatula and S. neurona. This report demonstrates for the first time that seabirds such as Brandt's cormorants may be intermediate or dead-end hosts for S. calchasi and/or S. falcatula, and that S. calchasi can cause epizootic infection in a seabird.

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Neurological disease in Brandt's cormorants along southern California coast.

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Brandt's cormorants with protozoal encephalitis assocated with Sarcocystis spp.

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Brandt's cormorants may be intermediate hosts for S. calchasi and S. falcatula.

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Transmission of terrestrial protozoal pathogens to seabirds.

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Lifecycles of S. calchasi and S. falcatula in marine environment needs research.

Molecular identification of four Sarcocystis species in the herring gull, Larus argentatus, from Lithuania

Background

Birds of the family Laridae have not been intensively examined for infections with Sarcocystis spp. To date, sarcocysts of two species, S. lari and S. wobeseri, have been identified in the muscles of gulls. The aim of the present study was to evaluate the species richness of Sarcocystis in the herring gull, Larus argentatus, from Lithuania.

Methods

In the period between 2013 and 2019, leg muscles of 35 herring gulls were examined for sarcocysts of Sarcocystis spp. Sarcocystis spp. were characterised morphologically based on a light microscopy study. Four sarcocysts isolated from the muscles of each infected bird were subjected to further molecular examination. Sarcocystis species were identified by means of ITS1 sequence analysis.

Results

Sarcocysts were detected in 9/35 herring gulls (25.7%). Using light microscopy, one morphological type of sarcocysts was observed. Sarcocysts were microscopic, thread-like, had a smooth and thin (about 1 µm) cyst wall and were filled with banana-shaped bradyzoites. On the basis of ITS1 sequences, four Sarcocystis species, S. columbae, S. halieti, S. lari and S. wobeseri, were identified. Furthermore, it was demonstrated that a single infected herring gull could host two Sarcocystis species indistinguishable under light microscopy.

Conclusions

Larus argentatus is the first bird species found to act as intermediate host of four Sarcocystis spp. According to current knowledge, five species, S. falcatula, S. calchasi, S. wobeseri, S. columbae and S. halieti can use birds belonging to different orders as intermediate hosts.

High prevalence of Sarcocystis calchasi in racing pigeon flocks in Germany

The apicomplexan parasite Sarcocystis calchasi (Coccidia: Eimeriorina: Sarcocystidae) is the causative agent of Pigeon Protozoal Encephalitis (PPE) and infects birds of the orders Columbiformes, Piciformes and Psittaciformes. Accipiter hawks (Aves: Accipitriformes) are the definitive hosts of this parasite. Infections of S. calchasi have been detected in Germany, the United States and Japan. However, the prevalence of the parasite in racing pigeon flocks has not yet been determined. Here, the first cross-sectional prevalence study to investigate S. calchasi in pigeon racing flocks was accomplished including 245 pigeon flocks across Germany. A total of 1,225 muscle biopsies, were taken between 2012 and 2016 and examined by semi-nested PCR for S. calchasi DNA targeting the ITS gene. Additionally, a questionnaire on construction of the aviary as well as management and health status of the flock was conducted. In 27.8% (95% C.I. = 22.3-33.8%) of the flocks, S. calchasi DNA was detected in at least one pigeon. Positive flocks were located in 15 out of 16 federal states. A significant increase of infected racing pigeons was seen in spring. Half-covered or open aviary constructions showed a trend of increase of the prevalence rate, while anti-coccidian treatment and acidified drinking water had no effects. The high prevalence and the geographical distribution of S. calchasi suggest a long-standing occurrence of the parasite in the German racing pigeon population. For pigeons presented with neurological signs or other symptoms possibly related to PPE, S. calchasi should be considered as a potential cause throughout Germany.

Prevalence of Sarcocystis calchasi in free-ranging host species: Accipiter hawks and Common Woodpigeon in Germany

The apicomplexan parasite Sarcocystis calchasi (S. calchasi) triggers pigeon protozoal encephalitis, a neurologic disease in columbids. Accipiter hawks have been identified as the final host, and Columbidae and Psittaciformes as intermediate hosts. In this study, 368 free-ranging Accipiter hawks and 647 free-ranging common woodpigeons were sampled in a country-wide study in order to identify the prevalence of S. calchasi in these populations. A semi-nested PCR specific for S. calchasi tested positive in 7.3% (4.9–10.5) of submitted samples from Accipiter hawks. Juvenile Accipiter hawks (13.7%; 7.7–22.0) had a significantly higher infection rate with S. calchasi than adult Accipiter hawks (5.8%; 2.7–9.3). The prevalence of S. calchasi in common woodpigeons was 3.3% (5.4–9.7). Positive pigeons were identified in 14/16 federal states, and a region-dependency was detected, with higher rates of infection in the eastern parts of Germany. The results of this study suggest that the common woodpigeon is a natural reservoir for S. calchasi. In a study of one region for four consecutive years, an increase in prevalence was not detected. Findings indicate that the parasite is not newly introduced to Germany, but rather long established. The prevalence suggests that there is a substantial risk of S. calchasi infections in other free-ranging as well as captive host species.

Morphological and genetic characterisation of Sarcocystis halieti from the great cormorant (Phalacrocorax carbo)

Having examined 19 great cormorants (Phalacrocorax carbo) hunted in Lithuania, sarcocysts were found in the muscles of two birds. Sarcocysts detected were examined using light microscopy (LM), transmission electron microscopy (TEM), and 18S rDNA, 28S rDNA, ITS1, cox1, and rpoB sequence comparison. Based on the molecular analysis, mainly of the ITS1 region, sarcocysts were identified as Sarcocystis halieti. This is the first Sarcocystis species characterised in the great cormorant. Under the LM sarcocysts were ribbon-shaped, very long and thin (the largest fragment found amounted to 6.5 × 0.1 mm) with a smooth and thin (up to 1.2 μm) cyst wall. Banana-shaped bradyzoites were 7.2 × 1.9 (6.3-8.2 × 1.4-2.4) μm. Under TEM, the cyst wall was wavy, 0.8- to 1.2-μm thick. The comparison of 12 species demonstrated cox1 and rpoB to be unsuitable for the identification of Sarcocystis spp. using birds as intermediate hosts.

Sarcocystis calchasi Outbreak in Feral Rock Pigeons ( Columba livia) in California

Twenty-two feral rock pigeons ( Columba livia) from 10 counties in California with ataxia, torticollis, and difficulty standing and flying were admitted to rehabilitation centers in late winter and spring of 2017 and died or were euthanized. Common necropsy findings included thin body condition, generalized deep red discoloration of organs, and hemorrhagic subcutaneous neck tissues. Meningoencephalitis was observed microscopically in 16 pigeons, and 3 also had protozoal schizonts in the brain. The most consistently affected regions of the brain were cerebellum and brainstem. Skeletal muscles, and less frequently the heart, contained large intrasarcoplasmic bradyzoites typically without inflammation. Fifteen of the 22 birds tested positive using pan- Sarcocystis polymerase chain reaction. The sequence of the amplicon was most closely related to S. calchasi, and the 8 subtyped sequences had 100% homology with S. calchasi. This investigation demonstrated the transcontinental and North American spread of S. calchasi causing a disease outbreak in free-ranging rock pigeons, thus warranting increased surveillance in susceptible native columbids.

Molecular identification of Sarcocystis halieti n. sp., Sarcocystis lari and Sarcocystis truncata in the intestine of a white-tailed sea eagle (Haliaeetus albicilla) in Norway

An emaciated white-tailed sea eagle (Haliaeetus albicilla) from Western Norway was found and nursed briefly before it died. The necropsy revealed that the principal cause of death was an inflammation and occlusion of the bile ducts. A secondary finding was the presence in the intestinal mucosa of numerous sporulated Sarcocystis oocysts measuring 21.8-22.8 × 16.0-17.0 μm. The aim of this study was to identify these oocysts to species level using molecular methods. Genomic DNA was extracted from 10 mucosal scrapings containing oocysts and subjected to PCR amplification and sequencing of four DNA regions: the 18S and 28S rRNA genes, the ITS1 region and the cox1 gene. DNA of three previously known Sarcocystis spp. was identified, but only two of these, Sarcocystis halieti n. sp. and Sarcocystis lari, both employing sea birds as intermediate hosts, were considered to have used the sea eagle as a definitive host and to have formed oocysts in its intestine. The third species found, Sarcocystis truncata, employs red deer as intermediate hosts and seems to use felids as definitive hosts based on its phylogenetic position and prevalence. The sea eagle had probably recently ingested portions of one of the latter hosts (red deer or cat/lynx) containing stages (sarcocysts/oocysts) and thus DNA of S. truncata. The species S. halieti and S. lari could only be unambiguously separated from their most closely related congeners on the basis of their ITS1 sequences. This is the first report of Sarcocystis oocysts in sea eagles and the first identification to species level of Sarcocystis oocysts in any type of eagle. The sea eagle also acted as intermediate host of an unidentified Sarcocystis spp. as evidenced by the finding of six thin-walled sarcocysts in a histological section of cardiac muscle.

Histopathologic and Molecular Characterization of Sarcocystis calchasi Encephalitis in White-winged Doves ( Zenaida asiatica ) and Eurasian Collared Doves ( Streptopelia decaocto ), East-central Texas, USA, 2010-13

Sarcocystis calchasi is a recently described apicomplexan parasite that causes encephalitis in avian hosts. We diagnosed one White-winged Dove ( Zenaida asiatica ) and two Eurasian Collared Doves ( Streptopelia decaocto ) in Texas, US, with a history of neurologic signs with protozoal encephalitis. On histologic examination, all three doves had moderate to severe meningoencephalitis characterized by large numbers of plasma cells, lymphocytes, and macrophages with gliosis and astrocytosis. Brain sections from two doves also contained numerous Mott cells. Protozoal schizonts with rosettes or clusters of individual merozoites consistent with Sarcocystis spp. were seen within areas of inflammation. Sarcocysts were also identified in the skeletal muscle of one dove. The PCR and sequencing of brain and skeletal muscle from two doves revealed 99% identity with S. calchasi. The presence of S. calchasi in fatal cases of encephalitis in doves in Texas suggests that the geographic and host ranges of S. calchasi are broader than previously reported.

No evidence of Sarcocystis calchasi involvement in mammalian meningoencephalitis of unknown origin

Sarcocystis calchasi has recently been identified as the cause of pigeon protozoal encephalitis, PPE, a lethal brain disease in pigeons and parrots. While only avian species have been identified so far to be susceptible to this pathogen as definitive or intermediate hosts, we speculated whether mammals may be susceptible as well, as in Sarcocystis neurona and other related apicomplexan parasites. Specifically, we hypothesized its involvement in mammalian meningoencephalitis of unknown origin, MUO. A total of 143 archived formalin fixed, paraffin embedded brain samples with MUO from dogs, cats, pigs, cattle, sheep, guinea pigs, horses, goats, mice, raccoon, ferret, hamster, mink and maned wolf were examined pathohistologically and by PCR for parasitic stages or DNA, respectively, of Sarcocystis calchasi or other apicomplexan parasites. All samples had non-suppurative, lymphoplasmacytic and/or granulomatous encephalitis or meningoencephalitis typical of MUO with many similarities to PPE in pigeons. However, neither parasitic structures nor DNA of Sarcocystis calchasi or other apicomplexan parasites were detected. It thus appears that, despite histological similarities between mammalian MUO and pigeon PPE and despite seemingly high prevalence of PPE and a persistent threat by Sarcocystis calchasi in pigeons, based on histopathology and PCR there is no evidence for a role of this parasite in MUO in mammals as intermediate or aberrant hosts.

Acute, fatal Sarcocystis calchasi-associated hepatitis in Roller pigeons (Columba livia f. dom.) at Philadelphia Zoo

Four Roller pigeons (Columba livia f. dom.) at the Philadelphia Zoo died suddenly. Necropsy examination revealed macroscopic hepatitis. Microscopically, the predominant lesions were in liver, characterized with necrosis and mixed cell inflammatory response. Sarcocystis calchasi-like schizonts and free merozoites were identified in liver. Transmission electron microscopy confirmed that schizonts were in hepatocytes. A few schizonts were in spleen. PCR using S. calchasi-specific primers confirmed the diagnosis. Neither lesions nor protozoa were found in brain and muscles. This is the first report of acute visceral S. calchasi-associated sarcocystosis in naturally infected avian hosts.

Sarcocystis calchasi encephalitis in a rock pigeon

A rock pigeon (Columba livia) caught in Akihabara, Tokyo, showed neurological symptoms, such as head tilt and circling. Pathological examinations revealed abundant Sarcocystic cysts in the skeletal muscle and myocardium with mild myositis, and numerous schizonts and sarcocysts with severe multifocal granulomatous T-lymphocytic infiltration in the central nervous system. A Sarcocystis calchasi-specific gene was detected in the muscle and brain. This case indicates S. calchasi was distributed in Japan and caused severe encephalitis to rock pigeons.

Muscular sarcocystosis in two arctic foxes (Vulpes lagopus) due to Sarcocystis arctica n. sp.: sarcocyst morphology, molecular characteristics and phylogeny

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.

An outbreak of Sarcocystis calchasi encephalitis in multiple psittacine species within an enclosed zoological aviary

A total of 5 psittacine birds in an enclosed zoological exhibit, including 2 princess parrots and 3 cockatoos of 2 different species, developed severe central nervous system clinical signs over a 2–3-month period and died or were euthanized. Histologically, all birds had a lymphoplasmacytic and histiocytic encephalitis with intralesional protozoa consistent with a Sarcocystis species in addition to intramuscular tissue sarcocysts. By immunohistochemical staining, merozoites in brain and tissue cysts in muscle did not react with polyclonal antisera against Sarcocystis falcatula, Sarcocystis neurona, Toxoplasma gondii, and Neospora caninum, or with a monoclonal antibody to S. neurona. Transmission electron microscopy on sarcocyst tissue cyst walls from 2 birds was morphologically consistent with Sarcocystis calchasi. Polymerase chain reaction (PCR) amplification and sequencing of partial 18S ribosomal RNA from muscle tissue cysts and brain schizonts from 3 birds was consistent with a clade containing S. calchasi and Sarcocystis columbae but could not distinguish these closely related Sarcocystis species. However, PCR amplification and sequencing of the internal transcribed spacer 1 RNA segment in the brain from 2 birds and muscle from 2 birds specifically identified the isolates as S. calchasi. The current report documents that multiple psittacine species are susceptible intermediate hosts of S. calchasi, and that infection can cause encephalitis resulting in significant morbidity and mortality in psittacine aviaries.

Description of Sarcocystis turdusi sp. nov. from the common blackbird (Turdus merula)

Cysts of Sarcocystis species were found in 24 of 44 (54·5%) examined blackbirds (Turdus merula). Under the light microscope, only 1 morphological type of cyst was found in all birds investigated. Ribbon-shaped cysts were long (the largest fragment found amounted to 7 mm) and of different thickness (25–206 μm). A cyst wall reached up to 3·5 μm and had finger-like protrusions. Under the transmission electron microscope, a single cyst isolated from 1 blackbird was studied. The cyst wall was 2·5–4·4 μm thick, had club- or irregularly-shaped and sometimes branched protrusions that differed in size. The content of cysts was divided into large chambers by septa. Orange segment-shaped cystozoites were 6·2 × 1·4 (5·5–7·2 × 1·2–1·5) μm. This type of cyst wall has never been described in Sarcocystis species isolated from birds, thus far. The results of 18S rDNA, 28S rDNA and ITS–1 region sequences showed that S. turdusi was most closely related to S. columbae, S. calchasi, S. wobeseri, S. cornixi and Sarcocystis sp. ex Accipiter nisus parasitizing birds. Phylogenetic results suggest that predatory birds are the most probable definitive hosts of S. turdusi.

Description of Sarcocystis anasi sp. nov. and Sarcocystis albifronsi sp. nov. in birds of the order Anseriformes

On the basis of the already published morphological, 18S rDNA, 28S rDNA data (Kutkienė et al., Parasitol Res 99:562-565, 2006; Parasitol Res 102:691-696, 2008; Parasitol Res 104:329-336, 2009), and ITS-1 region investigation results of sarcocysts presented in this paper, Sarcocystis albifronsi sp. nov. from the white-fronted goose (Anser albifrons) and Sarcocystis anasi sp. nov. from the mallard duck (Anas platyrhynchos) are described.