Molecular identification of Sarcocystis halieti in the muscles of two species of birds of prey from Spain

Abstract

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. Graphical abstract

Role of three bird species in the life cycle of two Sarcocystis spp. (Apicomplexa, Sarcocystidae) in the Czech Republic

“…In Spain, after examining a congeneric bird species, the black kite M . migrans , Prakas et al (2021) found muscular sarcocysts in this host and considered it as S . halieti , which formed a sister branch to other sequences of the same species.…”

“…halieti ( Mayr et al, 2016 ). More recently, the herring gull from Lithuania ( Prakas et al, 2020 ), the black kite and the western marsh harrier from Spain ( Prakas et al, 2021 ), and the little owl ( Athene noctua [Scopoli, 1769]) from Germany ( Maier-Sam et al, 2021 ), were all reported as intermediate hosts of S . halieti ; whereas oocysts were found in the intestinal mucosa of corvid birds from Lithuania ( Juozaityté-Ngugu et al, 2021 ), as well as in the Cooper's hawk ( Accipitter cooperi [Bonaparte, 1828], the red-shouldered hawk ( Buteo lineatus [Gmelin, 1788]) and the red-tailed hawk ( B .…”

“…Similarly, Sarcocystis sp. in the Chilean skua ( Stercorarius chilensis [Bonaparte, 1857]) from Chile (see Acosta et al, 2021 ; Prakas et al, 2021 ) also formed a sister branch. Our phylogenetic analysis showed similar branching, so it is difficult to state whether these sequences belong to the same species, until more samples are molecularly obtained.…”

“…The intermediate hosts of S . halieti are the great cormorant Phalacrocorax carbo (Linnaeus, 1758), the little owl ( Athene noctua Scopoli, 1769), the western marsh harrier ( Circus aeruginosus [Linnaeus, 1758]) and the black kite ( Milvus migrans [Boddaert, 1783]) (see Gjerde et al, 2018 ; Prakas et al, 2018 , 2020 , 2021 ; Maier-Sam et al, 2021 ); whereas that in S . lari is the great black-backed gull ( Larus marinus Linnaeus, 1758) ( Gjerde et al, 2018 ; Prakas et al, 2014 , 2020 ).…”

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

“…kutkienae form sarcocysts in muscles of corvids, while S . halieti is multi-host adapted, employing birds of several different orders as IH [ 45 , 46 ]. Birds of prey are identified DH of S .…”