First Observations of Buzzards (Buteo) as Definitive Hosts of Sarcocystis Parasites Forming Cysts in the Brain Tissues of Rodents in Lithuania

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

The Distribution of Sarcocsytis Species Described by Ungulates-Canids Life Cycle in Intestines of Small Predators of the Family Mustelidae

PURPOSE

Using molecular techniques, we have previously shown that carnivorous mammals of the family Mustelidae might be common definitive hosts for various protozoan Sarcocystis species. In the present study we aimed to unravel whether Sarcocystis species using ungulates as intermediate hosts and canids or felids as definitive hosts can be found in intestine of mustelids.

METHODS

Small intestine samples of 93 individual mustelids of five different species from Lithuania were examined. Sarcocystis species were identified based on species-specific PCR and subsequent cox1 sequencing.

RESULTS

Six Sarcocystis species (S. arieticanis, S. bertrami, S. capracanis, S. capreolicanis, S. linearis and S. morae) defined by ungulate-canid life cycle were detected for the first time in small intestines of mustelids. By contrast, the prevalence of Sarcocystis characterised by ungulate-felid life cycle was low (3.2%). Overall, 76% of the examined animals were positive for at least one of the studied Sarcocystis species. Four species, S. arieticanis, S. bertrami, S. capracanis and S. morae were most commonly found, with the detection rate of about 40%.

CONCLUSIONS

The current finding, in addition to our previous studies, suggests that mustelids play an important role in the spread of various Sarcocystis species.

Identification of Sarcocystis and Trichinella Species in Muscles of Gray Wolf (Canis lupus) from Lithuania

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

First report of Sarcocystis halieti (Apicomplexa) in bearded vulture (Gypaetus barbatus)

At least three Sarcocystis species (S. falcatula, S. halieti and S. wobeseri-like) have been detected infecting raptorial birds. By histopathology and PCR-sequencing of the ITS1 marker, S. halieti was detected in a bearded vulture (Gypaetus barbatus) and a black kite (Milvus migrans) from the Catalonia region in North Spain. The 241 bp-long sequences obtained from the Sarcocystis organisms detected in both raptors showed 97.5-99.6% and 97.9-100% similarity with those of previously identified S. halieti; also, the phylogenetic trees generated placed the identified sequences together with other sequences of S. halieti available in GenBank. In sum, the description of the bearded vulture as a new intermediate host for S. halieti adds new insights on the complex epidemiology of the genus involving avian hosts.

Low Genetic Variability of the Tundra Vole in Lithuania

The distribution and spread of the tundra vole (Alexandromys oeconomus) in Lithuania have been documented over the last 70 years, but the genetic diversity of the species has not been studied. In this study, we examined A. oeconomus trapped in three sites in northern and western Lithuania using mtDNA sequence analysis of the cytb and control region. The western and northern sites are separated by anthropogenic landscape barriers. The western site is subject to regular spring flooding. Phylogenetic analyses of the studied individuals placed them in the Central European phylogroup, suggesting that Lithuanian A. oeconomus originated from northeastern Poland. In Lithuania, the genetic diversity of A. oeconomus at both mtDNA loci was relatively low (Hd < 0.6, π < 0.002) compared to that found in other European samples (Hd = 0.833-0.958; π = 0.00402-0.01552). Individuals analyzed in Lithuania were genetically different from samples collected in Poland and Northern Europe (ΦST > 0.15, p < 0.05). The genetic divergence between the western and northern samples of A. oeconomus in Lithuania, together with the low genetic variability among the voles studied, provides new insights into the phylogeography of the species and the influence of barriers on the colonization of the country.

Molecular identification of Sarcocystis species in sika deer (Cervus nippon) of free-ranging populations in Germany and Austria

In this study, for the first time, Sarcocystis species were identified molecularly in sika deer (Cervus nippon) that form free-ranging populations in several countries of Europe. Diaphragm muscle samples from 151 deer from 10 populations in Germany and Austria were examined for sarcocysts. By one-gram methylene-blue staining, sarcocysts were recorded in samples of 114 animals (75.5%) which originated from all populations. Sarcocysts were more often (p < 0.0001) recorded in yearling and adult deer than in calves. Infection intensity was generally low with ~ 70% of the sarcocyst positive deer harbouring ≤ 10 sarcocysts per 1-gram diaphragm muscle. Based on cox1 sequence comparison, 10 species of Sarcocystis, all previously reported parasitizing cervids, were identified: S. elongata, S. entzerothi, S. hjorti, S. iberica, S. japonica, S. linearis, S. morae, S. pilosa, S. silva and S. truncata. The prevailing S. hjorti was detected in sika deer of all 10 populations. The identification in sika deer of S. hjorti, S. iberica, S. elongata, S. linearis, S. morae and S. silva constitutes new host records. With the additional species records of this study, the highest number of Sarcocystis species, at least 16, was identified in this host.

Molecular differentiation of Sarcocystis miescheriana and Sarcocystis suihominis using a new multiplex PCR targeting the mtDNA cox1 gene in wild boars in southern Italy

The increase of wild boar populations density and their meat consumption across Europe could expose humans to a plethora of foodborne diseases as sarcocystosis, caused by the zoonotic protozoan Sarcocystis suihominis. Humans become infected by eating raw or undercooked pig (Sus scrofa domesticus) containing S. suihominis sarcocysts. Despite this, to date very few data are available on the risk of infection by this parasite to wild boar (Sus scrofa) meat consumers. Thus, the present study aimed to assess the occurrence of Sarcocystis spp. in wild boars from southern Italy, applying both histology and a new multiplex PCR assay targeting the cox1 gene. Between 2019 and 2020, 997 muscle tissues (i.e., n = 269 oesophagus, n = 277 diaphragms, n = 298 hearts, n = 153 tongues) from 311 wild boars were collected and screened by a combined histological and molecular approach. Overall, 251 (80.7%) animals tested were positive for Sarcocystis spp., and S. miescheriana whose definitive hosts are canids, was the only molecularly identified species. A statistically significant difference (p < 0.05) in the prevalence of Sarcocystis infection was found according to the wild boar age and muscle tissue. Findings outlined the low zoonotic potential of infection to humans via wild boar meat consumption in Italy and the importance of the application of new molecular methods in distinguishing different Sarcocystis species.

Trends of Eurasian Perch (Perca fluviatilis) mtDNA ATP6 Region Genetic Diversity within the Hydro-Systems of the Eastern Part of the Baltic Sea in the Anthropocene

The intraspecific genetic diversity of freshwater fish inhabiting hydro-systems of the macrogeographic area spreading from the Black to Baltic Seas requires comprehensive investigation from fundamental and practical perspectives. The current study focused on the involvement of the mtDNA ATP6 region in the adaptability and microevolution of Perca fluviatilis within phylogeographic and anthropogenic contexts. We sequenced a 627 bp fragment encompassing the ATP6 region and used it for genetic analysis of 193 perch caught in Latvia, Lithuania, Belarus, and Ukraine, representing natural and anthropogenically impacted populations. We evaluated patterns of intraspecific genetic diversity in the ATP6 region and phylogeographic trends within the studied area compared with previously established D-loop trends. Evaluation of ATP6 coding sequence variability revealed that among 13 newly detected haplotypes, only two were caused by non-synonymous substitutions of amino acids of the protein. PCoA revealed three genetic groups (I-III) based on the ATP6 region that encompassed four previously described genetic groups established based on the mtDNA D-loop. The two mtDNA regions (D-loop and ATP6) have microevolved at least partially independently. Prolonged anthropogenic impacts may generate new point mutations at the ATP6 locus, but this phenomenon could be mainly concealed by natural selection and reparation processes.

Sarcocystis spp. Macrocysts Infection in Wildfowl Species in Eastern Baltic Region: Trends in Prevalence in 2011-2022

Wildfowl meat infected with S. rileyi macrocysts is not suitable for human consumption. Ducks are among the main game birds in Europe, and S. rileyi infections cause significant economic losses. In 2011-2022, a total of 2649 anseriforms collected in Lithuania and 619 Mallards (Anas platyrhynchos) hunted in the Kaliningrad region of Russia, Belarus, and Latvia were tested for macrocysts. In Lithuania, macrocysts were detected in 206 of 2362 Mallards (8.7%) and in two of 88 (2.3%) Eurasian Teals (Anas crecca). The prevalence of macrocysts in the other three countries, Belarus (5.9%), Russia (5.0%), and Latvia (3.1%), was similar. For species identification, macrocysts isolated from 37 Mallards (21 from Lithuania, 8 from Russia, 6 from Belarus, and 2 from Latvia) were subjected to sequencing of the ITS1 region. Based on DNA analysis, S. rileyi was confirmed in all tested birds. By comparing the infection rates of macrocysts in Mallards in Lithuania, significant differences were observed in different years (p = 0.036), and a significantly higher prevalence of infection was established in November-December than in September-October (p = 0.028). Given the amount of data per decade on the prevalence of S. rileyi, awareness of infection needs to be increased.

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.

Dynamics of Polyamines, Proline, and Ethylene Metabolism under Increasing Cold in Winter Oilseed Rape

Cold stress is among the most important environmental factors reducing the yield of crops. The present study aimed to investigate the impact of increasing cold stress conditions on winter oilseed rape polyamines, proline, and ethylene metabolism in acclimated and non-acclimated winter oilseed rape. This study was carried out under controlled conditions in the laboratory. The winter oilseed rape hybrid 'Visby' was used in the experiment. Acclimated and non-acclimated plants were subjected to a two-day-long increasing cold (from -1 °C to -3 °C) treatment. HPTLC, RT-qPCR, spectral analysis, and gas chromatography methods were used to analyse the levels of polyamines, gene expression, proline, and ethylene, respectively. This study showed a decrease in putrescine, spermidine, and spermine content during cold acclimation and a decrease in putrescine and spermidine levels at sub-zero temperatures. There were intensive changes in ADC2 gene expression, proline, and ethylene levels in non-acclimated plants: a substantial increase after exposure to -1 °C temperature and a sharp decrease after exposure to -3 °C temperature. The changes in these parameters were lower or absent in acclimated plants. The phenomena observed in this study add new insights to the knowledge about the plant stress response and suggest questions to be answered in the future.

Protozoan Parasites of Sarcocystis spp. in Rodents from Commercial Orchards

Small mammals are an important group of wildlife that can transmit pathogens to humans and animals. There is a lack of comprehensive studies on the protozoan parasites of the genus Sarcocystis in agricultural areas. The aim of the current research was to evaluate the prevalence of Sarcocystis spp., and to identify the parasite species found in the skeletal muscles of rodents and insectivores from commercial orchards. A total of 679 muscle samples from small mammals, mainly rodents (n = 674), belonging to eight species were examined. Muscle samples were pooled into groups, then digested, and the presence of the Sarcocystis species was confirmed by molecular methods. The examined parasites were determined in five rodent species, Apodemus agrarius, A. flavicollis, Clethrionomys glareolus, Microtus arvalis, and M. oeconomus. The prevalence of Sarcocystis spp. was low: 2.23% in voles and 0.79% in mice. Based on a sequence comparison of cox1 and 28S rDNA, four species were identified: S. myodes, Sarcocystis cf. strixi, Sarcocystis sp. Rod1, and Sarcocystis sp. Rod2. This is the first report of S. myodes in A. agrarius, A. flavicollis, and M. arvalis. The identified species were most closely related to Sarcocystis spp., and were transmitted by predatory mammals and birds. Future studies are needed to describe the species morphologically, as well as to define the host spectrum and to evaluate their possible pathogenicity.

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.

Molecular Identification of Protozoan Sarcocystis in Different Types of Water Bodies in Lithuania

Representatives of the genus Sarcocystis are unicellular parasites having a two-host life cycle and infecting mammals, birds, and reptiles. Until now, Sarcocystis spp. have been mainly investigated in definitive and intermediate hosts. Only a few studies have been conducted on the detection of Sarcocystis parasites in water samples. The aim of this research was to examine whether the prevalence of Sarcocystis spp. parasitizing farm animals varies in different types of water bodies. Water samples (n = 150) were collected from the entire territory of Lithuania, dividing water bodies into five groups (lakes, rivers, ponds/canals, swamps, and the inshore zone of the territorial Baltic Sea area). One-liter samples were filtered and subsequently analyzed using nested PCR. At least one of the analyzed Sarcocystis spp. (S. arieticanis, S. bertrami, S. bovifelis, S. capracanis, S. cruzi, S. hirsuta, S. miescheriana, and S. tenella) was determined in all examined samples from water bodies. No significant difference in Sarcocystis spp. prevalence between different types of water sources was detected. Our research proved that selecting appropriate primers is important for the accurate identification of parasites in samples collected from water bodies.

Molecular Identification of Parasitic Protozoa Sarcocystis in Water Samples

Simple Summary

Members of the genus Sarcocystis are protozoan parasites having two-host prey–predator cycle. These parasites are widespread in farm animals. Sarcocystis species are characterized morphologically in intermediate hosts, and these parasites are identified in definitive hosts by molecular methods. Thus far, only few studies have been conducted on Sarcocystis parasites in environmental samples. The aim of the present work was to evaluate several sample preparation and polymerase chain reaction methods for the identification of several Sarcocystis species in water samples. Overall, 114 samples collected from various water sources, ponds, canals, lakes, lagoons, and rivers in Lithuania were tested for the presence of Sarcocystis spp. Based on molecular methods, eight Sarcocystis species, S. bovifelis, S. cruzi, S. hirsuta, S. arieticanis, S. tenella, S. capracanis, S. bertrami, and S. miescheriana, were identified. The main intermediate hosts of detected Sarcocystis parasites are cattle, sheep, goats, horses, and pigs. Further, more sensitive molecular techniques are needed for the development of the diagnosis of Sarcocystis species in water bodies.

Abstract

Sarcocystis parasites are among the most common parasitic protozoa in farm animals. So far, the diversity of these parasites has been mainly studied in animal carcasses by morphological or molecular methods. Research on parasitic protozoa in environmental samples is scarce due to the lack of an appropriate methodology and low concentrations of parasites. For these reasons, there is a paucity of validated methods for Sarcocystis identification from environmental samples. Therefore, the present study aims to investigate various molecular methods for Sarcocystis parasite identification in water samples. In the present study, the sample volume, sporocysts isolation, and various conventional PCR were evaluated, and species-specific primers for the identification of different Sarcocystis species have been developed. Of the methods studied, based on data the most appropriate method for the identification of analyzed Sarcocystis spp. in water bodies is nested PCR, using species-specific primers targeting the cox1 gene. Sarcocystis DNA was detected in 111 out of 114 (97.4%) samples. This paper represents the first identification of S. bovifelis, S. cruzi, S. hirsuta, S. arieticanis, S. tenella, S. capracanis, S. bertrami, and S. miescheriana by PCR and sequencing in environmental water samples. Our pilot study is useful in developing techniques for the identification of Sarcocystis species from water samples.

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.

Molecular Detection and Characterization of Intestinal and Blood Parasites in Wild Chimpanzees (Pan troglodytes verus) in Senegal

Simple Summary

Western chimpanzees are currently listed as a Critically Endangered subspecies. Human encroachment has taken a toll on this great ape due to fragmented habitat and the exchange of pathogens. This epidemiological study investigated the occurrence and genetic diversity of intestinal and blood parasites in faecal samples from wild chimpanzees living in the Dindefelo Community Nature Reserve, Senegal. We paid special attention to potential human-driven sources of infection and transmission pathways. Potential diarrhoea-causing protist parasites (e.g., Cryptosporidium spp., Giardia duodenalis, Entamoeba histolytica) were detected at low infection rates (and densities) or absent, whereas commensals (Entamoeba dispar) or protist of uncertain pathogenicity (Blastocystis sp.) were far more abundant. We detected Sarcocystis spp. in chimpanzee faeces. Blood protist parasites such as Plasmodium spp. and Trypanosoma brucei spp. (the etiological agents of malaria and sleeping sickness, respectively, in humans) were also found at low prevalences, but microfilariae of the nematode Mansonella perstans were frequently found. Molecular analyses primarily revealed host-adapted species/genotypes and an apparent absence of gastrointestinal clinical manifestations in infected chimpanzees. Zoonotic events of still unknown frequency and directionality may have taken part between wild chimpanzees and humans sharing natural habitats and resources.

Abstract

Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

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 halieti in the muscles of two species of birds of prey from Spain

BACKGROUND

Members of the genus Sarcocystis are protozoan parasites characterized by a prey-predator two-host life-cycle. Sarcocysts are formed in the muscles or central nervous system of the intermediate host (IH), while sporocysts develop in the small intestine of the definitive host (DH). Various birds of prey have been confirmed to be DH for Sarcocystis spp. Three Sarcocystis species, S. wobeseri, S. halieti and S. falcatula, have been identified in the muscles of birds of prey, of which the latter are known to be pathogenic and can cause encephalitis in various birds. The aim of this study was to identify Sarcocystis spp. in the muscles of birds of prey from Spain.

METHODS

Between 2019 and 2020, muscle tissue samples taken from 59 birds of prey admitted to the Wildlife Recovery Centre in Ilundain (Navarra, Spain) were examined for the presence of Sarcocystis spp. Sarcocysts in fresh squashed samples were morphologically characterized under the light microscope (LM). Sarcocystis spp. were identified by means of 28S ribosomal RNA and internal transcribed spacer 1 sequence analysis.

RESULTS

Microscopic examination of squashed tissue samples stained with methylene blue revealed the presence of sarcocysts in three of the 59 (5.1%) birds examined. Only one sarcocyst type was observed under the LM. Sarcocysts were thread-like (1050-2160 × 130-158 μm) and had a thin (0.7-1.4 μm) and smooth cyst wall. Septa divided the cysts into compartments filled with banana-shaped (5.9 × 1.7 μm) bradyzoites. On the basis of DNA sequence results, S. halieti was identified in the western marsh harrier (Circus aeruginosus) and the black kite (Milvus migrans) for the first time. Sarcocysts of S. halieti were shorter and wider compared to those observed in the great cormorant (Phalacrocorax carbo) and the herring gull (Larus argentatus). According to current knowledge, S. halieti may infect birds belonging to four different orders: Suliformes, Charadriiformes, Strigiformes and Accipitriformes.

CONCLUSIONS

This is the first report of S. halieti in the western marsh harrier and the black kite as IH. So far, little research has been conducted on birds of prey as IH for Sarcocystis spp. These results indicate that further studies combining morphological, histopathological, and molecular methods are required.

First description of Sarcocystis species infecting Barbary sheep (Ammotragus lervia)

Barbary sheep (Ammotragus lervia) is a North African native wild Caprinae, introduced in the 1970s in new territories such as Spain, the USA, and Mexico. Here, we describe Sarcocystis species in Barbary sheep. Sarcocysts were found in 19 out of 56 adult A. lervia in Southern Spain and characterized morphologically and molecularly. By light microscopy, sarcocysts had thin (< 1 μm) or thick (> 2 μm) walls. By transmission electron microscopy, sarcocysts with thick walls had Type 14 villar protrusions corresponding to S. tenella/S. capracanis of domestic sheep (Ovis aries) or goats (Capra hircus). Sarcocysts with thin walls had Type 7b villar protrusions that corresponded to S. arieticanis/S. hircicanis of domestic sheep or goats. Molecular analyses allowed the identification of only thick-walled Sarcocystis species. Six sarcocysts were assigned to S. tenella (99.2-100% and 95.6-100% sequence similarity within 18S rRNA and COI, respectively) and 19 sarcocysts were assigned to S. capracanis (98.5-99.8% and 97.9-99.0% sequence similarity within 18S rRNA and COI, respectively). Further studies are needed for taxonomic identification of sarcocysts in Barbary sheep because Sarcocystis species in sheep and goats are not cross transmissible despite morphological similarities.

Molecular identification of seven Sarcocystis species in red deer (Cervus elaphus) from Lithuania

The diaphragm muscles of 77 free-ranging red deer (Cervus elaphus) were examined for Sarcocystis species in Lithuania. Sarcocysts were detected in 61 out of 77 (79.2%) animals investigated. A total of 60 isolated sarcocysts were identified to species using subunit I of cytochrome c oxidase (cox1) sequence analysis. Overall, seven species, S. entzerothi, S. hjorti, S. iberica, S. linearis, S. pilosa, S. truncata and S. venatoria, were confirmed in Lithuanian red deer. Sarcocystis entzerothi was reported in red deer for the first time. Previously this species was shown to use sika deer as well as roe deer and fallow deer as an intermediate host. Based on cox1, with the addition of the current data, altogether 13 Sarcocystis species have so far been shown to use red deer as an intermediate host. Species detected in red deer demonstrated considerable differences in intraspecific genetic variation at cox1. Genetic distances between different samples of S. hjorti and S. linearis were calculated using principal coordinates analysis (PCoA), implying molecular divergence of same Sarcocystis species using different hosts in the same geographical area and divergence of those employing same intermediate host species from different areas.

Molecular identification of Sarcocystis species in diaphragm muscle tissue of European mouflon (Ovis gmelini musimon) from Austria

Previous morphological studies suggested that mouflon may have sarcocysts similar to those of sheep. However, to date, no molecular-based studies of the species of Sarcocystis infecting mouflon have been done. The present study identified Sarcocystis species in diaphragm muscle samples from 20 European mouflon (Ovis gmelini musimon). Molecular identification using the cox1 sequence analysis was performed on sarcocysts excised from muscle tissue and on DNA from digested muscle samples. Both frequency and intensity of infection in mouflon were high with 19 of 20 animals testing Sarcocystis positive and > 50 cysts per gram of tissue recovered from 10 of the 19 Sarcocystis positive animals. Molecular analysis revealed dominant Sarcocystis tenella (18/19 animals) and Sarcocystis arieticanis (1/19 animals), whose known intermediate hosts are sheep. In addition, Sarcocystis capracanis, which is known to form sarcocysts in goats, was detected in two animals. The results of this study demonstrated the digestion method to be superior over the direct isolation of sarcocysts for the molecular identification of Sarcocystis species in a certain host. Future research of Sarcocystis diversity in wild ovine and caprine species is needed.

The Role of Mustelids in the Transmission of Sarcocystis spp. Using Cattle as Intermediate Hosts

There is a lack of research on the role of mustelids in the transmission of various Sarcocystis spp. In the present study we tested the hypothesis that widespread mustelids in Lithuania could be involved in the transmission of Sarcocystis spp. using cattle as intermediate hosts. In 2016-2020, intestinal samples of 84 mustelids were examined. Sarcocystis spp. were identified by species-specific PCR targeting the cox1 gene and subsequent sequencing. Under a light microscope, oocysts/sporocysts of Sarcocystis spp. were observed in 40 samples (47.6%), while using molecular methods, they were detected in 75 animals (89.3%). Four Sarcocystis spp. were identified in the intestinal samples of American mink (Neovisonvison), Beech marten (Martes foina), European pine marten (Martes martes), European badger (Meles meles) and European polecat (Mustela putorius). The prevalence of predominant Sarcocystis spp., S. bovifelis (89.3%) and S. cruzi (73.8%) was significantly higher than that of S. hirsuta (3.6%) and S. hominis (1.2%). In an individual sample, most frequently two Sarcocystis spp. were identified (69.0%), then a single species (15.5%) and three species (4.8%). The present study provides strong evidence that mustelids serve as definitive hosts for Sarcocystis spp. using cattle as intermediate hosts.

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.

Population Structure of Fusarium graminearum Isolated from Different Sources in One Area over the Course of Three Years

Fusarium head blight (FHB) is an important crop disease worldwide and is mainly caused by members of the Fusarium graminearum species complex. F. graminearum sensu stricto is the most common cosmopolitan and predominant FHB causal agent in Europe. Thus far, the majority of studies have focused on the primary hosts (wheat and barley) of this pathogen, while the relationships between other sources of infection remain unclear. We monitored and sampled test fields over the course of 3 years and acquired 804 F. graminearum isolates from different sources: primary hosts and other plant species included in the crop rotations, weeds from the test fields, decaying plant residue, soil samples, and crop seed. Of these isolates, 73.3% had the 15-acetyldeoxynivalenol genotype and 26.7% had the 3-acetyldeoxynivalenol genotype. F. graminearum isolation rates from weeds (>50%) were much higher than from soil (< 10%) or decaying plant matter (4%). Variable number of tandem repeat markers were used for population analysis. Noticeable genetic differentiation was detected between isolates from living plants and soil biome. In contrast, absence of any noticeable division between primary and alternative plant host communities indicates the importance of weeds and other segetal plants for FHB control and prevention.

Sarcocystis spp. diversity in the roe deer (Capreolus capreolus) from Lithuania and Spain

The roe deer (Capreolus capreolus) has been identified as an intermediate host for six known Sarcocystis species, S. capreolicanis, S. entzerothi, S. gracilis, S. linearis, S. oviformis, and S. silva. In this study, we identified Sarcocystis species in the diaphragm and tongue muscles from the Lithuanian and Spanish roe deer, respectively, on the basis of a microscopic examination and DNA analysis. A total of 43 and 27 sarcocysts were isolated and characterized from the Lithuanian and Spanish roe deer, respectively. Overall six Sarcocystis species were identified in roe deer from Lithuania, and only three of them, S. gracilis, S. linearis, and S. silva were found to have infecting animals from Spain. The current paper represents first molecular results of Sarcocystis species in the Spanish roe deer. Furthermore, transmission electron microscopy examination revealed specific wall structure of sarcocysts studied, S. linearis was characterized by ribbon-like villar protrusions (vp) (type 8a), and S. oviformis was distinguished by elongated vp resembling spades or mushroom-like structures (type 39). Based on 18S rDNA and cox1 sequences, Sarcocystis species from the roe deer showed considerable intraspecific genetic variability. However, similar values of intraspecific genetic variation were estimated at both genes analysed. The highest variability was observed for S. capreolicanis and S. linearis in both genes and for S. silva at cox1. Consequently, the level of genetic variability of Sarcocystis from the roe deer varied depending on species rather than on gene analysed or geographical area.

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.

Molecular identification of two Sarcocystis species in fallow deer (Dama dama) from Lithuania

Due to the lack of molecular research conducted, little is known about Sarcocystis species diversity in the fallow deer (Dama dama). Until now, Sarcocystis jorrini and Sarcocystis morae were described to form sarcocysts in the muscles of this host. In the present study diaphragm muscle samples of free-ranging fallow deer from Lithuania were investigated for Sarcocystis species. Sarcocysts were detected in 39 out of 48 (81.3%) fallow deer examined. Under a light microscope two types of sarcocysts having hair-like and finger-like protrusions were observed. Based on DNA sequence analysis of cox1 and 18S rDNA, two species, S. morae and Sarcocystis entzerothi were identified. In prior studies, the latter species was only detected in Lithuanian roe deer (Capreolus capreolus) and in sika deer (Cervus nippon). The haplotype network of S. morae sequences specified close relationships between haplotypes found in the same country. According to current knowledge, the fallow deer is characterised by low Sarcocystis species richness as compared with other cervid species from Europe.

Sarcocystis morae (Apicomplexa) in Fallow Deer (Dama dama) from Spain: Ultrastructure and New Host Record

Members of the genus Sarcocystis are frequently found infecting members of the family Cervidae. Although Sarcocystis species are generally host specific for their intermediate hosts, species in cervids appear to be less host specific. Here, we report fallow deer (Dama dama) as a new host for Sarcocystis morae, originally described from the red deer (Cervus elaphus). Tongues of 69 legally hunted animals in Spain were tested for sarcocysts, and the species were characterized by light microscopy, ultrastructurally and molecularly. Sarcocysts were identified in 66.7% of D. dama. Sarcocysts had thin (<2 μm thick) cyst wall with hair-like villar protrusions bifurcated at their tips resembling type 8a. Genetic sequences obtained for 18S rRNA and COI reached 99.6-100% and 97.9-98.7% similarity, respectively, to those of S. morae from the red deer. The present study provides new data concerning lower level of host specificity within Sarcocystis genus for cervids.

Morphological and molecular description of Sarcocystis ratti n. sp. from the black rat (Rattus rattus) in Latvia

Rodents have been widely studied as intermediate hosts of Sarcocystis; however, only a few reports on these parasites in the black rat (Rattus rattus) are known. Having examined 13 black rats captured in Latvia, sarcocysts were found in skeletal muscles of two mammals and were described as Sarcocystis ratti n. sp. Under a light microscope, sarcocysts were ribbon-shaped, 0.9-1.3 × 0.09-0.14 mm in size and had a thin (0.8-1.3 μm) and smooth cyst wall. The lancet-shaped bradyzoites were 8.3 × 4.3 (7.5-9.3 × 3.9-4.8) μm. Under a transmission electron microscope, the cyst wall was up to 1.3 μm thick, wavy, the ground substance appeared smooth, type 1a-like. Morphologically, sarcocysts of S. ratti were somewhat similar to those of S. cymruensis, S. rodentifelis, and S. dispersa-like previously identified in the brown rat (Rattus norvegicus). On the basis of 18S rDNA, 28S rDNA, and cox1, significant genetic differences (at least 2.3, 4.5, and 5.8%, respectively) were observed when comparing S. ratti with other Sarcocystis species using rodents as intermediate hosts. While ITS1 sequences of S. ratti were highly distinct from other Sarcocystis species available in GenBank. Phylogenetic and ecological data suggest that predatory mammals living near households are definitive hosts of S. ratti.

Sarcocystis species identification in the moose (Alces alces) from the Baltic States

Various muscle tissue samples from 60 moose (Alces alces) in the Baltic region were examined for Sarcocystis species. Sarcocysts were detected in 49 out of 60 (81.7%) moose investigated. Six species, Sarcocystis alces, Sarcocystis hjorti, Sarcocystis linearis, Sarcocystis silva, Sarcocystis ovalis, and Sarcocystis sp., were identified using light microscopy (LM), and DNA sequence analysis (cox1 and 18S rDNA). Sarcocysts of S. alces, S. ovalis, and S. hjorti were studied using transmission electron microscopy (TEM); sarcocyst walls of S. alces, S. ovalis, and S. hjorti were type 25, type 24, and type 7a, respectively. Sarcocystis linearis previously found in roe deer and red deer was also shown to use moose as an intermediate host for the first time. The unknown Sarcocystis sp. was rare and might employ another main intermediate host. Phylogenetic results demonstrated that Sarcocystis sp. was most closely related to Sarcocystis tarandivulpes, using canids as definitive hosts.

Molecular identification of Sarcocystis lutrae (Apicomplexa: Sarcocystidae) in muscles of five species of the family Mustelidae

Carnivores usually act as definitive hosts of Sarcocystis species. However, the number of reports on sarcocyst formation in musculature of predators is on the increase. In the present study, muscle samples of 68 mustelids collected in Lithuania were examined for sarcocysts of Sarcocystis species. Sarcocysts were detected in diaphragm, tongue and limb muscles of ten animals (14.7%) but were not discovered in the heart. Based on 18S rDNA, 28S rDNA, cox1 and ITS1 sequence analysis, Sarcocystis lutrae was identified in three American minks (Neovison vison), two beech martens (Martes foina), three Eurasian badgers (Meles meles), one Eurasian otter (Lutra lutra) and one European polecat (Mustela putorius). The intraspecific variability of this Sarcocystis species was determined only in ITS1 region. Based on the phylogenetic analysis, no clear separation of S. lutrae by intermediate hosts or geographical locations was established. This paper represents the first identification of S. lutrae in the American mink, the beech marten and the European polecat. Current results indicate that S. lutrae is a common species in the muscles of various European mustelids.

Identification and genetic characterization of Sarcocystis arctica and Sarcocystis lutrae in red foxes (Vulpes vulpes) from Baltic States and Spain

Background

Typically, carnivores serve as definitive hosts for Sarcocystis spp. parasites; currently, their role as intermediate hosts is being elucidated. The present study aimed to identify and molecularly characterize Sarcocystis cysts detected in striated muscle of red foxes from different populations in Latvia, Lithuania and Spain.

Methods

Muscle samples from 411 red foxes (Vulpes vulpes) and 269 racoon dogs (Nyctereutes procyonoides) from Latvia, 41 red foxes from Lithuania and 22 red foxes from Spain were examined for the presence of Sarcocystis sarcocysts by light microscopy (LM). Sarcocystis spp. were identified by transmission electron microscopy (TEM) and molecular biology techniques.

Results

Sarcocystis cysts were detected in 11/411 (2.7%) Latvian, 3/41 (7.3%) Lithuanian, and 6/22 (27.3%) Spanish red foxes, however, cysts were not observed in the muscles of racoon dogs. Based on LM, TEM, 18S rDNA, 28S rDNA, ITS1, cox1 and rpoB sequences, Sarcocystis arctica and Sarcocystis lutrae cysts were identified in red fox muscles from Latvia and Lithuania, whereas only S. arctica was detected in Spain. The 18S rDNA, 28S rDNA and ITS1 sequences from the 21 isolates of S. arctica from Latvia, Lithuania and Spain were identical. By contrast, two and four haplotypes were determined based on mtDNA cox1 and apicoplast rpoB sequences, respectively. Polymorphisms were not detected between the two isolates of S. lutrae from Latvia and Lithuania. Based on phylogenetic results, S. arctica and S. lutrae were most closely related to Sarcocystis spp. using predatory mammals as intermediate hosts and to Sarcocystis species with a bird-bird life-cycle.

Conclusions

Based on current knowledge, the red fox and Arctic fox (Vulpes lagopus) could act as intermediate host for the same two Sarcocystis species. Molecular results suggest the existence of two genetic lineages of S. arctica, and such divergence relies on its geographical distribution but not on their intermediate host species.

Molecular identification of Sarcocystis rileyi sporocysts in red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) in Lithuania

Despite the fact that Sarcocystis rileyi is one of the earliest described species of the genus Sarcocystis forming macrocysts in ducks, the life cycle of this species is still unknown in Europe. Sarcocystis spp. oocysts/sporocysts were observed in faeces of four of 23 (17.4 %) and in small intestine mucosal scrapings of four of 20 (20.0 %) red foxes (Vulpes vulpes) and in small intestine mucosal scrapings of seven of 13 (53.8 %) raccoon dogs (Nyctereutes procyonoides) hunted in Lithuania. A very small number of Sarcocystis sporocysts measuring 11.9 × 8.3 μm (n = 5) was found in faecal samples, whereas considerably more sporulated Sarcocystis oocysts and free sporocysts were detected in the small intestines of red foxes and raccoon dogs. These sporocysts measured 12.9 × 8.1 μm (n = 16) and 12.1 × 8.1 μm (n = 54) in red foxes and raccoon dogs, respectively. Using species-specific PCR and subsequent sequencing, internal transcribed spacer 1 (ITS-1) region partial sequences of oocysts/sporocysts from small intestine mucosal scrapings of six raccoon dogs and three red foxes were identified as belonging to S. rileyi. The present study provides strong evidence showing that the red fox and the raccoon dog can serve as final hosts of S. rileyi in Europe; however, transmission experiments are needed for the ultimate approval.

Identification and intraspecific genetic diversity of Sarcocystis rileyi from ducks, Anas spp., in Lithuania and Finland

Macroscopic Sarcocystis cysts were detected in the muscles of 28 Mallards ( Anas platyrhynchos ), 1 Eurasian Wigeon ( Anas penelope ), and 1 Common Teal ( Anas crecca ) hunted in Lithuania and Finland. According to the sequences of the 18S rRNA gene, 28S rRNA gene, and ITS-1 region, the macrocysts examined from all 30 ducks belonged to Sarcocystis rileyi. This parasite was found in the Eurasian Wigeon and the Common Teal for the first time. All S. rileyi isolates examined were identical to each other and differed from 2 S. rileyi isolates previously reported from 2 Mallards from the United States only by 1 nucleotide substitution within the ITS-1 region.

Description of Sarcocystis lari sp. n. (Apicomplexa: Sarcocystidae) from the great black-backed gull, Larus marinus (Charadriiformes: Laridae), on the basis of cyst morphology and molecular data

A morphological type of Sarcocystis cysts found in one of two examined great black-backed gull, Larus marinus (Linnaeus) (Laridae), is considered to represent a new species for which the name Sarcocystis lari sp. n. is proposed and its description is provided. The cysts are ribbon-shaped, very long (the largest fragment found was 6 mm long) and relatively narrow (up to 75 microm). Under a light microscope the cyst wall reaches up to 1 microm and seems to be smooth. Using a computerized image analysis system, knolls, which resemble protrusions on the wall surface, are visible. Lancet-shaped cystozoites measure in average 6.9 x 1.4 microm (range 6.3-7.9 microm x 1.2-1.5 microm) in length. Observed using Transmission electron microscopy (TEM), the cyst wall is wavy and measures up to 1.2 microm in thickness. The parasitophorous vacuolar membrane has regularly arranged small invaginations. Cyst content is divided into large chambers by septa. Sarcocystis lari sp. n. has type-1 tissue cyst wall and is morphologically indistinguishable from other bird Sarcocystis species characterized by the same type of the wall. On the basis of 18S rRNA gene, 28S rRNA gene and ITS-1 region sequences, S. lari is a genetically distinct species, being most closely related to avian Sarcocystis species whose definitive hosts are predatory birds.

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.