Serosurvey of Toxoplasma gondii, Neospora caninum and Sarcocystis neurona in raptors and risk factor analysis

Global prevalence and risk factors associated with Toxoplasma gondii infection in wild birds: A systematic review and meta-analysis

A systematic review and meta-analysis were performed to identify the global prevalence and factors associated with Toxoplasma gondii infection in wild birds. Six bibliographic databases (Chinese National Knowledge Infrastructure, VIP Chinese Journal Database, Wanfang Data, PubMed, Web of science and ScienceDirect) were searched from inception to February 2023. The search yielded 1220 records of which 659 articles underwent full-text evaluation, which identified 49 eligible articles and 16,030 wild bird samples that were included in the meta-analysis. The estimated pooled global prevalence of T. gondii infection in wild birds was 16.6%. Out of the variables tested, publication year after 2020 and climate type were significantly associated with T. gondii infection (P<0.01). Our data indicate that the prevalence of T. gondii in wild birds can be influenced by epidemiological variables. Further research is needed to identify the biological, environmental, anthropogenic, and geographical risk factors which impact the ecology and prevalence of T. gondii in wild birds.

The Dangerous Side of Being a Predator: Toxoplasma gondii and Neospora caninum in Birds of Prey

Toxoplasma gondii and Neospora caninum are apicomplexan protozoa of major concern in livestock and T. gondii is also considered one of the major threats and a public health concern. These protozoa have a wide range of intermediate hosts, including birds. The present work aimed to assess the prevalence of these cyst-forming parasites in migratory and sedentary birds of prey. The skeletal muscle and myocardium of 159 birds of prey from Central Italy, belonging to 19 species and recovered across 6 Wildlife Recovery Centers/Care structures along the Italian migratory route, were collected specifically for molecular (PCR) and for histopathological analysis to detect T. gondii and N. caninum. For the molecular analysis, genomic DNA was extracted. The DNA was tested by sequence typing, targeting GRA6, 529 bp repeated element, B1, PK1, BTUB, SAG2, alt.SAG2, and APICO genes for T. gondii and to end-point PCR targeting NC5 gene for N. caninum. Thirty-seven out of the one hundred and fifty-nine analyzed samples tested positive for T. gondii with a prevalence of 23.27% and nine for N. caninum, with a prevalence of 5.66%. Thirty-two sequences were obtained from the thirty-seven isolates of T. gondii. Among these, 26 presented alleles compatible with type I strain in 1 or more loci, 4 with type II strain and 2 consisted of atypical strains. Toxoplasma gondii genetic variability in birds of prey confirms previous findings of wildlife as reservoirs of atypical strains. Results from the histology showed few protozoal tissue cysts in skeletal muscle (n. 4) and hearts (n. 2).

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 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.