Isolation of Neospora caninum from dairy zero grazing cattle in Israel

Spinal cord protothecosis causing paraparesis in a dog

Protothecosis, an infectious disease caused by the green algae Prototheca zopfii and P. wickerhamii, occurs sporadically in domestic animals and humans. Diagnosis of CNS protothecosis is based on neurologic signs that indicate multifocal nervous system lesions and that follow a period of chronic diarrhea and weight loss, cytologic observation of algae in fecal culture or histopathology, and detection of the agent by PCR assay of infected tissues. Here, we report a case of a paraparetic dog with CNS protothecosis that was diagnosed definitively antemortem using CSF cytology, PCR, and DNA sequencing. A 4-y-old mixed-breed dog developed progressive paraparesis that followed weight loss and diarrhea. CSF analysis revealed marked eosinophilic pleocytosis. Prototheca organisms were detected by microscopic examination of the CSF, and speciated as P. zopfii by CSF PCR and DNA sequencing. Other possible causes of paraparesis were ruled out using computed tomography, serology, and CSF PCR. The dog's condition deteriorated despite treatment, developing forebrain and central vestibular system clinical signs, and it was euthanized at the owner's request. Postmortem examination was declined. Our findings indicate that when CNS protothecosis is suspected, antemortem diagnosis can be made using CSF analysis and a PCR assay.

The Effect of Vaccination with Neospora caninum Live-Frozen Tachyzoites on Abortion Rates of Naturally Infected Pregnant Cows

Neosporosis is a major cause of abortions in cattle worldwide. Recently a live attenuated vaccine showing promising results in preventing abortions, when administered at mid-pregnancy to seropositive cows, was developed. In this study, vaccination with 2 × 10⁸ live frozen N. caninum tachyzoites (NcIs491) was used to immunize naturally infected seropositive pregnant dairy dams. The study was performed under field conditions in four herds, and a follow-up of three subsequent pregnancies was analyzed. A total of 1136 cows were serologically examined. Total seroprevalence was 41.4%, with 25.1% of the cows having titers of 1:800 or higher. Abortion rates were significantly higher in cows with high antibody titers (≥1:800) for two consecutive pregnancies. Vaccination was administered to 114 out of 285 cows with antibody titers higher than 1:800. Immunization resulted in lower abortion rates at three of the farms. Vaccine efficacy ranged from −19.8% to 75% at different farms, with overall efficacy of 28.4% in all four farms and overall efficacy of 58.2% in the three farms with positive results. Our results showed different vaccine efficacy in studied farms, suggesting that frozen live vaccination may generally be an effective method to control neosporosis in cattle.

Detection of Neospora caninum Infection in Aborted Equine Fetuses in Israel

In horses, Neospora caninum and Neospora hughesi have been associated with fetal loss, and neurological disease, respectively. This study investigated the role of Neospora spp. infection in equine abortion in Israel. The presence of anti-Neospora spp. antibodies was evaluated in 31 aborting mares by indirect fluorescent antibody test (IFAT) and the presence of parasite DNA in their aborted fetuses was evaluated by polymerase chain reaction (PCR), using two target loci (ITS1 and Nc5). The seroprevalence found in aborting mares was 70.9% and the prevalence by DNA detection in the aborted fetuses was 41.9%. Transplacental transmission from positive mares to their fetuses was 45.4% (10/22), while 33.3% (3/9) of fetuses of seronegative mares also tested positive for Neospora. The use of two PCR targets improved the sensitivity of parasite detection, and positive samples were identified by sequence analyses as N. caninum. These finding suggest that N. caninum could be a significant cause of abortion in horses, and that transplacental transmission in horses is an important way of transmission of N.caninum. The results presented here demonstrated the necessity to use several tests concurrently, including serological and molecular assays in order to confirm the involvement of Neospora in mare abortions.

High Exposure to Toxoplasma gondii and Neospora Spp. in Donkeys in Israel: Serological Survey and Case Reports

Simple Summary

Toxoplasma gondii and Neospora spp. are major pathogenic parasites of animals worldwide, with the first also affecting humans. These parasites have two-host life cycles, with the cat and the dog being the definitive hosts of T. gondii and N. caninum, respectively. Both parasites can infect various animal species, as intermediate hosts, in which they form tissue cysts and may cause abortions and neurological disease. Both parasites have been reported in wild and domestic animals in Israel. This study aimed to evaluate the serologic exposure of donkeys to these parasites. A total of 98 donkeys were examined. Half of them (n = 49) were from animal shelters in Israel, and the rest (n = 49) were working donkeys from the Palestinian Authority. Anti-T. gondii antibodies and anti-Neospora spp. antibodies were found in 94% and in 70% of the donkeys, respectively. In addition, two cases of donkeys presenting N. caninum tissue cysts, which were detected during post-mortem examination, were described. This is the first report of the exposure of donkeys to Toxoplasma gondii and Neospora spp. in the area. The exposure of donkeys to both parasites was considerably higher than the exposure of other species in the area and may be the result of poor husbandry conditions and higher exposure to infection. These results indicate that donkeys may have an important role in the maintenance and transmission of these parasites.

Abstract

Toxoplasma gondii and Neospora spp. are closely related cyst-forming coccidian parasites, which infect various animal species and have considerable zoonotic and economic implications, respectively. Both parasites are endemic in Israel and have been reported to infect wild and domestic animals. This study was conceived to evaluate the serologic exposure of donkeys to these parasites. Serum samples were collected from 98 donkeys. Half of them (n = 49) were from animal shelters in Israel, and the rest (n = 49) were working donkeys from the Palestinian Authority. The donkeys were screened for the presence of anti-Toxoplasma and anti-Neospora antibodies by immunofluorescence antibody tests (IFATs). The seroprevalence of T. gondii and Neospora spp. was 94% and 70%, respectively, and 69% of the donkeys were exposed to both parasites. In addition, N. caninum tissue cysts were documented in two donkeys during post-mortem examination. This is the first report of the exposure of donkeys to T. gondii and Neospora spp. in the area. The high prevalence found in this study suggests that donkeys may have a role in the maintenance of these parasites in the area, thus serving as a source of infection for the definitive hosts.

Evidence of infection with Toxoplasma gondii and Neospora caninum in South Australia: using wild rabbits as a sentinel species

OBJECTIVE

The aim of this study was to utilise wild rabbits (Oryctolagus cuniculus) as a sentinel species to study levels of environmental contamination with N. caninum and T. gondii in South Australia, and to examine associations with rainfall, climate and land use.

DESIGN

Toxoplasma gondii (T. gondii), an apicomplexan parasite, causes the clinical disease toxoplasmosis, which can affect sheep as well as humans and many other animals. Neosporosis, the clinical disease caused by closely related Neospora caninum (N. caninum), causes abortions in cattle, with large economic impacts to cattle industries.

METHODS

Aliquots of wild rabbit (Oryctolagus cuniculus) serum were obtained from twelve sites across South Australia over a period of eighteen years, with a total of 2114 samples. An in-house Modified Agglutination Test (MAT) was developed, and samples were screened for the specific antibodies against both T.gondii and N. caninum.

RESULTS

Overall, 9.9% of samples screened for T. gondii tested positive and 6.1% of samples screened for N. caninum tested positive. There was no difference observed in seroprevalence of T.gondii specific antibodies between samples collected throughout summer, autumn, winter or spring. By contrast, a significantly higher (p=0.030) seroprevalence of N. caninum specific antibodies was observed in spring than any other season. T. gondii and N. caninum antibodies were discovered at sites across a broad area of South Australia, indicating these environments maybe infected with both parasites.

CONCLUSION

Results provide evidence that suggests N. caninum oocysts may have different survival characteristics, such as varying tolerances to low relative humidity, than T. gondii oocysts.

Evidence of Neospora caninum infection in buffaloes (Bubalus bubalis) from Northwestern Romania

Neospora caninum is a heteroxenous parasitic Apicomplexan protozoan, able to infect a variety of domestic and wild animals, mainly associated with reproductive disorders and abortions in susceptible species. Considering the importance of Romania in the European buffalo industry and the severe economic losses caused by N. caninum infection in livestock, the aim of the present study was to assess the occurrence of neosporosis in buffaloes raised in household and farming systems in northwestern Romania. Overall, 197 serum samples were tested for the presence of N. caninum-specific antibodies by ELISA. Additionally, from 74 slaughtered buffaloes, diaphragm digest, heart, and lymph node samples were tested for the presence of N. caninum DNA. The overall seroprevalence was 68.5%. The seroprevalence was significantly higher in adult animals compared to calves and young ones and in the household system compared to farm. By nPCR, six samples were found to be positive for N. caninum DNA, of which three were serologically negative. The present study reveals a high prevalence of N. caninum-specific antibodies in buffaloes in northwestern Romania and to our best knowledge, it is the first one performed in Romania.

Zoonotic and economically significant pathogens of peri-urban wild dogs across north-eastern New South Wales and south-eastern Queensland, Australia

Context Peri-urban wild dogs are known to reside within high-risk and densely populated regions and are capable of harbouring a variety of zoonotic pathogens. Despite recognising the potential of peri-urban wild dogs to carry zoonotic pathogens, limited prevalence data are currently available to assist in understanding the potential risks that peri-urban wild dogs pose within developed communities. Aims The aim of the present research was to establish the current status of key zoonotic and economically significant pathogens in peri-urban wild dogs. Methods Two hundred and one peri-urban wild dog cadavers were collected from south-eastern Queensland and northern New South Wales. In addition, whole blood, serum and faecal samples were also collected. Pathogens were identified through several morphological, microbiological and molecular methods. Key results Helminth parasites were detected within 79.6% of peri-urban wild dogs; Echinococcus granulosus was the most common pathogen, with adult worms being detected within 50.7 ± 6.9% of intestines, followed by Spirometra erinacei (36.6 ± 6.4%); hookworms, including Ancylostoma caninum and Uncinaria stenocephala (28.8 ± 7.1%); Toxocara canis (5.4 ± 3.1%) and Taenia spp., including T. serialis and T. pisiformis (4.5 ± 2.8%). Bacterial pathogens detected included methicillin-resistant Escherichia coli (20.0 ± 10.1%), Salmonella spp. (3.7 ± 4.0%) and methicillin-sensitive Staphylococcus aureus (3.3 ± 2.7%). Conclusions The present study is the most comprehensive investigation of zoonotic pathogen carriage in peri-urban wild dogs in Australia. Parasitic infections in peri-urban wild dogs are common, with tapeworms representing the majority of intestinal pathogens. Important zoonotic bacterial pathogens are carried by peri-urban wild dogs, although at a much lower prevalence than are parasites. Implications The presence of these pathogens in free-ranging peri-urban dog populations suggests a strong potential for public health risk, most notably from E. granulosus. These data are inherently important as baseline information, which is essential to guide risk-based management of peri-urban wild dog impacts.

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 and Ehrlichia canis co-infection in a dog with meningoencephalitis

An 8-year-old mixed-breed dog was presented for acute, progressive weakness and ataxia, inappetence, and weight loss. The patient was mentally normal, but nonambulatory, with a right head tilt, right positional ventral strabismus, and slight head tremors. A neurologic lesion was localized to the cerebellum and right brainstem. Cerebrospinal fluid (CSF) analysis showed a markedly increased protein concentration and mixed pleocytosis, with eosinophil predominance (44%), intracytoplasmic inclusions within eosinophils, consistent with Ehrlichia canis (E canis) morulae, and Toxoplasma gondii (T gondii) or Neospora caninum (N caninum) tachyzoites within eosinophils and monocytes. A serum indirect immunofluorescent antibody test was positive for N caninum (titer 1:12 800) and negative for T gondii. Both blood and CSF PCR results were N caninum- and E canis-positive and T gondii- and Anaplasma phagocytophilum-negative, and blood PCR, but not CSF PCR, was Hepatozoon canis-positive. The dog was treated for 30 days with clindamycin, sulfamethoxazole-trimethoprim, doxycycline, prednisone, and cephalosporin, but did not improve neurologically, and was euthanized. Brain histopathology showed moderate multifocal, subacute meningoencephalitis with necrosis and gliosis. The neurologic disease was mostly attributed to central nervous system (CNS) neosporosis, with the possible contribution of ehrlichiosis, which was likely a manifestation of blood-brain barrier disruption. Hepatozoonosis was probably a result or cause of underlying immunosuppression. To our knowledge, this is the first report of CNSN caninum and E canis co-infection detected by both CSF PCR and cytology and E canis morulae identified within CSF eosinophils.

Repurposing of antiparasitic drugs: the hydroxy-naphthoquinone buparvaquone inhibits vertical transmission in the pregnant neosporosis mouse model

The three anti-malarial drugs artemiside, artemisone, and mefloquine, and the naphthoquinone buparvaquone known to be active against theileriosis in cattle and Leishmania infections in rodents, were assessed for activity against Neospora caninum infection. All four compounds inhibited the proliferation of N. caninum tachyzoites in vitro with IC₅₀ in the sub-micromolar range, but artemisone and buparvaquone were most effective (IC₅₀ = 3 and 4.9 nM, respectively). However, in a neosporosis mouse model for cerebral infection comprising Balb/c mice experimentally infected with the virulent isolate Nc-Spain7, the three anti-malarial compounds failed to exhibit any activity, since treatment did not reduce the parasite burden in brains and lungs compared to untreated controls. Thus, these compounds were not further evaluated in pregnant mice. On the other hand, buparvaquone, shown earlier to be effective in reducing the parasite load in the lungs in an acute neosporosis disease model, was further assessed in the pregnant mouse model. Buparvaquone efficiently inhibited vertical transmission in Balb/c mice experimentally infected at day 7 of pregnancy, reduced clinical signs in the pups, but had no effect on cerebral infection in the dams. This demonstrates proof-of-concept that drug repurposing may lead to the discovery of an effective compound against neosporosis that can protect offspring from vertical transmission and disease.

Neospora caninum: Chronic and congenital infection in consecutive pregnancies of mice

Neospora caninum, the causative agent of bovine neosporosis is the major cause of abortion in cattle worldwide. The principal route of transmission is via in utero infection of the offspring. Congenitally-infected dams remain persistently infected for life and might undergo abortions in consecutive pregnancies. In the present study, the effect of N. caninum in chronic and congenital infection was examined. CD1 mice were infected intra-peritoneally with live tachyzoites of the NcIs491 isolate, while non-infected mice served as a control. There were no clinical signs of infection observed following inoculation, but high titers of specific anti- N. caninum antibodies were detected. A month after infection, when chronic-infection was established, mice were mated. Fertility, litter size and mortality rate were monitored within two generations of four consecutive pregnancies. During a nine months period of the study all females maintained high level of antibodies, while the non- infected control mice remained seronegative. There was no difference in the fertility rate of the dams, or in the litter size of infected and control mice. Mortality of offspring of the first and second generations of the infected dams was observed within the two first weeks of life. The vertical transmission was analyzed by PCR assay of offspring brains. PCR positive results were found in all 13 litters of the first generation tested during four consecutive pregnancies. The rate of vertical transmission slightly decreased in successive pregnancies being 74.2%, 59.5%, 48.1% and 40% for the first to fourth pregnancies respectively. In the second generation 21 out of 28 litters were found positive and the overall rate of vertical transmission was 28.5%. In chronically and congenitally infected dams N. caninum infection was maintained during all successive pregnancies for about 9 months. The results show that CD-1 outbred mice are a suitable model for studying chronic and congenital neosporosis.

The effect of a live Neospora caninum tachyzoite vaccine in naturally infected pregnant dairy cows

Neosporosis, caused by the intracellular protozoan Neospora caninum, is a major cause of abortion and reproductive failure in cattle worldwide. The principal route of transmission of neosporosis is via in utero infection of the offspring. There is no effective prophylactic treatment or vaccine available against bovine neosporosis. A N. caninum NcIs491 isolate was examined for its ability to immunize and reduce abortions in naturally infected dairy cows under field conditions. N. caninum-seropositive pregnant dams were inoculated with 10(8) live tachyzoites during mid-term pregnancy. A total of 520 N. caninum seropositive dams were included in this study, of these, 146 were immunized and 374 cows served as a non-vaccinated control group. A significantly lower incidence of abortion was observed in vaccinated compared to non-vaccinated cows, 16 and 26% respectively (P=0.01), with a vaccine efficacy of 39%. However, the number of seropositive offspring remained similar in both groups. Overall, this field trial suggests that vaccination with live N. caninum tachyzoites should be considered as an effective measure to reduce abortions caused by neosporosis in naturally infected cows.

Molecular identification of Neospora caninum from calf/foetal brain tissue and among oocysts recovered from faeces of naturally infected dogs in southern Ethiopia

This study sought to confirm and investigate further recently published information regarding the occurrence of Neospora caninum in cattle in Ethiopia and investigate infection in dogs, the canine definitive host, in this region. Faecal samples from 383 dogs in Hawassa, Ethiopia were examined by microscopy for Neospora-like oocysts, and positive samples then analysed by a molecular approach (DNA isolation, PCR and sequencing at the ITS1 gene). Brain tissue samples from four late term aborted foetuses, one congenitally defective calf (hind leg arthrogryposis) and placental tissue from cattle in the same area were also examined by the same molecular approach. All foetal, calf and placental tissue were associated with Neospora seropositive dams. A high prevalence of Neospora-like oocysts (11.5 μm±1.5 μm diameter) was observed in faecal samples from dogs (37 positive samples; 9.7% prevalence), and in 17 of these the identification was confirmed by PCR, giving a prevalence of confirmed infection of 4.4%. N. caninum DNA was also detected in all foetal and calf brain tissue samples. Sequencing revealed only minor differences among all PCR products, whether from oocysts or from brain tissue samples. These data provide molecular evidence of the presence of N. caninum infection in both dog and cattle in this region of Ethiopia. Moreover these findings highlight the role of dogs in maintaining and spreading the infection horizontally in the study area. The high frequency of N. caninum infection in household dogs as well as farm dogs is worthy of further investigation.

Neospora caninum: in vivo and in vitro treatment with artemisone

Neosporosis caused by Neospora caninum has global economic, clinical, and epidemiological impacts, mainly in the cattle industry. Currently, there is no useful drug for treatment of neosporosis. This publication is the first to describe the significant benefits that artemisone has on Neospora infections both in vitro and in vivo. Artemisone is a new semi-synthetic 10-alkylamino artemisinin that is superior to other artemisinin derivatives in terms of its significantly higher antimalarial activity, its tolerance in vivo, lack of detectable neurotoxic potential, improved in vivo pharmacokinetics and metabolic stability. Low micromolar concentrations of artemisone inhibited in vitro Neospora development. Prophylactic and post-infection treatment profoundly reduced the number of infected cells and parasites per cell. In the in vivo gerbil model, a non-toxic dose prevented typical cerebral symptoms, in most animals. There were no signs of clinical symptoms and brain PCR was negative. Most treated gerbils produced high specific antibody titer and were protected against a challenge. Overall, artemisone could be considered as a future drug for neosporosis.

Genetic diversity amongst isolates of Neospora caninum, and the development of a multiplex assay for the detection of distinct strains

Infection with Neospora caninum is regarded as a significant cause of abortion in cattle. Despite the economic impact of this infection, relatively little is known about the biology of this parasite. In this study, mini and microsatellite DNAs were detected in the genome of N. caninum and eight loci were identified that each contained repetitive DNA which was polymorphic among different isolates of this parasite. A multiplex PCR assay was developed for the detection of genetic variation within N. caninum based on length polymorphism associated with three different repetitive markers. The utility of the multiplex PCR was demonstrated in that it was able to distinguish amongst strains of N. caninum used as either vaccine or challenge strains in animal vaccination experiments and that it could genotype N. caninum associated with naturally acquired infections of animals. The multiplex PCR is simple, rapid, informative and sensitive and should provide a valuable tool for further studies on the epidemiology of N. caninum in different host species.