Neospora caninum in crows from Israel

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).

Neospora caninum in free-range chickens (Gallus gallus domesticus) from southern Brazil

Neospora caninum is an obligate intracellular parasite that can infect many domestic and wild animals, including birds. These animals are important sources for monitoring of environmental contamination, as they could become infected through sporulated oocysts; however, the real role of birds in the biological cycle of N. caninum remains uncertain. This study aimed to determine the prevalence of anti-N. caninum antibodies, evaluate associated factors, detect the parasite by molecular testing of free-range chickens from Brazil, and evaluate different techniques for its serological diagnosis. Blood samples of 366 chickens from 25 farms were collected for serological assays. The indirect fluorescent antibody test (IFAT) and the indirect enzyme-linked immunosorbent assay (ELISA) were used to detect anti-N. caninum antibodies. Chickens that tested seropositive by IFAT had their brain tissues and a pool of organs (heart, lung, and liver) submitted to PCR for molecular detection of the parasite. Out of 366 chickens, 65 (17.8%) and 163 (44.6%) were seropositive by IFAT and ELISA, respectively. Brain tissues (n=60) and the pools of organs (n=65) were negative in the PCR. Our results showed a high prevalence of antibodies in free-range chickens and that IFAT is the more sensitive technique for the detection of anti-N. caninum antibodies.

Serological evidence of exposure to Toxoplasma gondii and Neospora caninum in free-ranging Orinoco goose (Neochen jubata) in Brazil

Toxoplasma gondii and Neospora caninum are Apicomplexan intracellular protozoan parasites that affect numerous animal species, thus leading to severe diseases and economic losses, depending on the vertebrate species involved. The role of the avian species in maintaining and transmission of these coccidia has been studied for several years as they tend to serve as a potential source of infection for mammals and humans. The present study aimed to assess the serological exposure of Orinoco goose (Neochen jubata) to T. gondii and N. caninum. Between 2010 and 2013, 41 free-ranging Orinoco geese were captured in the Araguaia River, Brazil. The presence and titration of IgY antibodies to both coccidia were assayed via indirect immunofluorescent antibody test (IFAT). While IgY antibodies for N. caninum were present in 5 animals, with titers of 20, the antibodies for T. gondii were found in 35 animals, with titers ranging from 20 to 640. Considering that the Orinoco goose's meat is consumed by the local population in the studied area, it may represent an important source of T. gondii infection for humans. Due to its migratory behavior, this goose may play a pivotal role in the natural dispersion of both parasites. Furthermore, molecular studies are required for genotyping the isolates of T. gondii that occurs in this avian species.

Detection of Neospora Caninum DNA in Wild Birds from Italy

The role of avian species in the Neospora caninum life cycle has not been completely elucidated, and epidemiological data from Europe are scant. The aim of the present report was to evaluate the presence of N. caninum DNA in the tissues of 302 birds belonging to different avian species, along with IFAT titers. Forty-two out of the 302 birds (13.9%) showed low serological titers (1/50 and 1/100) against N. caninum. These data, positive for 31 animals (10.3%), were corroborated by PCR. Twenty-two hearts and eighteen brains scored positive, while nine subjects resulted had parasite DNA both in their hearts and brains. Serological data showed significantly higher results in waterfowl in respect to non-waterfowl avian species. This finding indicates a higher exposure of water birds to the parasite. These avian species, in fact, which feed directly from soil and/or water, are prone to ingest oocysts excreted by final canid hosts. The present study adds information to the state of art of N. caninum epidemiology in Italy, even if more investigations using bio-assays are needed to allow for a serological/parasitological follow-up to evaluate the real impact of the avian species in maintaining the parasite in main reservoirs.

Experimental inoculation of Neospora caninum tachyzoites in eared doves (Zenaida auriculata)

Neospora caninum is an apicomplexan parasite distributed worldwide. Although a positive association between the presence of birds and abortions in cattle associated to N. caninum has been reported, the role of the birds in the epidemiologic cycle of the parasite is unknown. To the best knowledge, no experimental studies have evaluated N. caninum in the eared dove, Zenaida auriculata. Therefore, we aimed to determine whether Z. auriculat can act as intermediate host for N. caninum. Eighteen birds were divided into four groups, G1, G2, G3, and G4 (control); G1, G2 and G3 received 2 × 10⁶ tachyzoites of NC-1 strain via different routes: subcutaneous, intramuscular, and intraperitoneal, respectively. G4 composed of three birds. Serum samples were collected weekly, and one bird each from G1, G2 and G3 was euthanized on the 7th and 14th day post-inoculation (dpi). The remaining birds were euthanized after the 28th dpi. Tissues from the doves were evaluated using histopathological analysis, PCR and dog bioassay to detect the parasite. Dogs were fed with tissues from the birds and monitored for 30 days. Serum samples were collected weekly from the dogs for serological analysis, and feces samples were collected daily until the end of the experiment for coproparasitological examinations. No dove showed clinical signs of the infection; however, all of them seroconverted after the inoculation, with stronger immunological response in the G3 birds. The lung tissue of one G3 bird showed positive PCR results; it was euthanized on the 7th dpi, and an inflammatory infiltrate was observed in the lung and kidney from this dove. The dogs did not shed oocysts or seroconverted. Our results indicate that the intraperitoneal route induced infection in the doves; however, the parasite may have been eliminated by the host, and the doves may be resistant to chronic infection.

Exposure to Neospora spp. and Besnoitia spp. in wildlife from Israel

Neosporosis and besnoitiosis, caused by cyst-forming protozoa Neospora caninum and Besnoitia besnoiti, respectively, are parasitic infestations of livestock in Israel. These parasites cause significant economic losses in cattle due to reproductive and productive disorders. Both parasites have been detected in several wild ruminant species throughout other regions of the world, while the existence of a sylvatic life cycle in Israel remains uncertain. Thus, a wide panel of 871 sera from two wild carnivores and nine wild ruminant species were tested. All sera were first analysed by MAT for an initial screening and positive samples were confirmed a posteriori by Western blot. Additionally, a complementary IFAT was used for the detection of antibodies against N. caninum. Neospora antibodies were present in six out of the 11 species investigated, whereas Besnoitia antibodies were undetected. Golden jackal, red fox, addax, Arabian oryx, Persian fallow deer, mouflon, mountain gazelle, Nubian ibex, scimitar horned oryx and water buffalo were seropositive against N. caninum infection by IFAT and/or MAT. Moreover, the presence of Neospora spp.-specific antibodies was confirmed by Western blot in golden jackal (6/189; 3.2%), red fox (1/75; 1.3%), Persian fallow deer (13/232; 5.6%), mouflon (1/15; 16.7%), Nubian ibex (22/55; 40%) and water buffalo (12/18; 66.7%). Addax (1/49) and water buffalo (1/18) were MAT-seropositive against B. besnoiti but were seronegative by Western blot. Hence, Neospora sylvatic cycle is present in Israel and may cross over to a domestic life cycle. In contrast, wildlife species investigated are unlikely to present a risk of transmitting Besnoitia to livestock in Israel.

Neospora caninum in birds: A review

Neospora caninum is an obligate intracellular protozoan parasite that infects domestic and wild animals. Canids are considered to be definitive hosts since they may shed oocysts into the environment through their feces. The disease is recognized as one of the major causes of bovine abortion worldwide, leading to important economic losses in the dairy and beef cattle industries. Previous studies have reported N. caninum infection in different species of birds; infection in birds has been associated with increased seroprevalence and reproductive problems in dairy cattle. Although the role of birds in the epidemiological cycle of neosporosis is unknown, birds are exposed to infection because they feed on the ground and could thus contribute to parasite dissemination. This review is focused on the current state of knowledge of neosporosis in birds.

Survey of Neospora caninum in eared doves (Zenaida auriculata) in Southern Brazil

Neosporosis is an infectious disease caused by Neospora caninum, a protozoan parasite that has worldwide distribution and is responsible for enormous economic losses in cattle. Birds are considered a good bioindicator of environmental contamination, since they feed on the ground, being exposed to N. caninum oocysts. The aim of this study was to determine the occurrence of antibodies against N. caninum and to verify the presence of parasite DNA in brain from free-ranging eared doves (Zenaida auriculata) from Southern Brazil. For this purpose, blood and brain samples were collected from 249 doves for ELISA and PCR analysis respectively. The prevalence of N. caninum antibodies in doves was 31.72% (79/249) and detection of parasite DNA was not observed in none of birds. This is the first report of antibodies against N. caninum in doves Z. auriculata, what show us that these birds had previously contact with the parasite but since no N. caninum DNA was detected, more studies should be performed to elucidate the real importance of doves in the epidemiologic cycle of the N. caninum.

In contrast to Toxoplasma gondii, Neospora caninum tachyzoites did not sustain multiplication in vitro at increased incubation temperatures

Neospora caninum and Toxoplasma gondii are coccidian parasites that infect a wide range of mammalian and avian species. While viable T. gondii has been in vitro isolated in natural infections from wild and domestic birds, attempts to isolate N. caninum from naturally-infected birds were unsuccessful. We speculate that body temperatures of birds, which are usually higher than those of mammals, may impair the multiplication of N. caninum. In contrast to N. caninum, T. gondii can grow in vitro at temperatures higher than 37°C. To test the hypothesis that N. caninum tachyzoites are impaired to grow in vitro at high temperatures, three strains of N. caninum (NC-1, NC-Liverpool, and NC-Bahia) and three of T. gondii (RH, ME-49 and NED) were cultivated at gradually increasing temperatures starting at 37°C up to 41.5°C. A permanent chicken cell line was chosen for the study. Parasites were observed microscopically and their presence in culture was evaluated by species-specific conventional PCRs. In a second experiment, growth rates of T. gondii (RH strain) and N. caninum (NC-1 strain) were evaluated after direct passage of tachyzoites from 37°C to 41.5°C, and quantified by real-time PCR. In addition to comparisons between N. caninum and T. gondii, growth rates of three T. gondii strains were compared at high temperatures. Neospora caninum tachyzoites could not sustain multiplication at temperatures between 39°C and 41.5°C. Toxoplasma gondii tachyzoites continued to multiply at the same experimental conditions. Direct passage of N. caninum tachyzoites from 37°C to 41.5°C caused a significant decrease in the number of parasites during 96h of observation, while T. gondii had a significant increase in the number of stages after the same period of time. T. gondii RH strain (clonal type I) presented a different growth rate at 41.5°C when compared with type II and type III strains. In conclusion, multiplication of N. caninum tachyzoites in vitro was inhibited at temperatures similar to those of chickens, what may be one of the reasons that isolation of the parasite is difficult in avian species. In contrast to N. caninum, T. gondii continued to grow at 41.5°C.

Canine neosporosis: perspectives on pathogenesis and management

Canine neosporosis is a worldwide disease caused by the obligate intracellular parasite protozoan Neospora caninum, manifesting mainly neurological symptoms. N. caninum has a heteroxenous life cycle and affects a wide range of warm-blooded animals. The domestic and wild canids are the definitive host of the parasite. They shed oocysts after ingestion of tissue cysts from infected intermediate hosts (ovine, equine, bovine, canine, and many other species), containing bradyzoites, or oocyst-contaminated water and food. The presence of dogs in farms is considered a risk factor for production animals. A wide range of diagnostic methods are currently available, but the most used is serology, ie, indirect fluorescent antibody test specific to the antibody detection in blood serum samples. No vaccine is available, but control strategies should be focused on the vertical and horizontal transmission of the parasite, ie, avoid feeding dogs with raw or undercooked meat, and taking care with water for human and animal consumption. No medicines to control the transplacental transmission are available yet.