First report of Neospora caninum infection in adult alpacas (Vicugna pacos) and llamas (Lama glama)

Evaluation of three immunological assays to mitigate the risk of transboundary spread of Coxiella burnetii by alpacas

Coxiella burnetii causes coxiellosis in animals and Q fever in humans, a potentially debilitating zoonotic disease commonly transmitted through domestic ruminants. To prevent transboundary spread of C. burnetii, animals may be tested prior to export. In alpacas, this process is complicated by the lack of scientific evidence for C. burnetii infection in the species, and the unique composition of camelid antibodies, which may cause false-positive results in assays developed for ruminants. We evaluated a complement fixation test (CFT; currently recommended for alpacas in New Zealand), an enzyme-linked immunosorbent assay (ELISA) and an immunofluorescence assay (IFA). Positive analytical control samples were generated through vaccination of alpacas with a human Q fever vaccine, whereas negative analytical control samples were sourced from New Zealand (deemed free of C. burnetii). Immunological assays were conducted on 131 alpaca sera submitted for export testing. Test characteristics (sensitivity, specificity, positive and negative predictive values) for CFT, ELISA and IFA were determined using Bayesian latent class analysis. Due to anticomplementary activity, 37 (28.2%) of the CFT results were inconclusive, making CFT unsuitable for routine use. Of the remaining 94 samples, 10.6%, 0% and 7.4% were positive for C. burnetii antibodies based on CFT, ELISA and IFA, respectively, yielding estimated sensitivities of 58%, 26% and 78%, and estimated specificities of 95%, 98% and 95%, with the estimates for sensitivity being imprecise, as evidenced by wide 95% credible intervals. Positive predictive values were similar across assays, albeit very low at the estimated seroprevalence of 5%. Our results indicate that, of the tests available, IFA appears to be the most appropriate for use in alpacas. Higher sensitivity of antibody detection, use of antigen detection assays and availability of samples from individuals with evidence of infection could provide additional insight into the risk of transboundary spread of C. burnetii by alpacas.

Toxoplasma gondii and Neospora caninum infections in South American camelids in Switzerland and assessment of serological tests for diagnosis

Background

Little is known about the epidemiology of Toxoplasma gondii and Neospora caninum infections in alpacas (Vicugna pacos) and llamas (Lama glama) outside South America. The study aimed to estimate the seroprevalence of T. gondii and N. caninum infections in South American camelids (SAC) in Switzerland, to optimize serological tests for SAC and to identify risk factors, which may favour infection.

Methods

A total of 571 sera from 132 Swiss farms (374 alpacas and 197 llamas, mean 4.3 animals/farm) were obtained. Four commercial enzyme-linked immunosorbent assays (ELISA) for detecting antibodies against T. gondii (ID Screen^® Toxoplasmosis Indirect (TOXO-MS)) or N. caninum (i.e. ID Screen^® Neospora caninum Indirect Multi-species (NCS-MS); ID Screen^® Neospora caninum Competition (NCC) and ID Screen^® Neospora caninum Indirect (NCS)) were first assessed for their use on SAC comparing their results with those in immunoblot, and optimizing cut-offs. Subsequently, two kits (TOXO-MS and NCS-MS) were selected for seroprevalence estimation. Additionally, a risk factor analysis for infection was performed on 41 farms, which agreed to participate in a web-based survey.

Results

Three kits (TOXO-MS, NCS-MS and NCC) showed almost perfect agreement (kappa > 0.901) with immunoblot results when the cut-offs were optimized, and one kit (NCS) proved not to be useful for detecting N. caninum seropositive SAC. By TOXO-MS ELISA, 82.3% (308/374) of the alpacas and 84.8% (167/197) of the llamas were seropositive for T. gondii, and 131/132 (99.2%) farms had seropositive animals. By NCS-MS ELISA, 3.5% (13/374) of the alpacas and 2.5% (5/197) of the llamas evidenced antibodies against N. caninum, and 9.1% (12/132) of the farms had seropositive animals. The variables “age” and “female sex” were identified as risk factors for T. gondii infection and “absence of cats in the farm during the last two years” as a protective factor. No risk or protective factors for N. caninum infection could be identified.

Conclusions

This nationwide cross-sectional study demonstrated for the first time the presence of antibodies against T. gondii and N. caninum in the Swiss SAC population, highlighting a high seroprevalence for T. gondii, the presence of cats as a risk factor and suggesting that SAC meat might represent an additional infection source for humans.

Evaluation of abortions spontaneously induced by Neospora caninum and risk factors in dairy cattle from Lima, Peru

Our objective was to identify the direct and indirect presence of Neospora caninum in dairy cattle and their aborted fetuses from Lima, Peru. A total 219 blood samples obtained from dairy cattle with records of spontaneous abortion were collected to detect antibodies against N. caninum in serum with indirect ELISA and search for risk-factor associations. 68 fetal aborted tissue samples of these cows were analyzed by PCR, indirect ELISA and histopathology assay to detect N. caninum presence. The prevalence ratio (PR) and 95% confidence intervals (CI) were estimated. Univariate analysis was performed using the chi-squared test. Among the 68 aborted fetuses collected, 10 (15%) were positive in at least two diagnostic tests. Among 219 serum samples, 46.6% (95% CI: 40.0%-53.3%) were positive. Cows with 4 years or older (PR: 7.10; 95% CI: 4.89-10.67) and multiparous (PR: 1.76; 95% CI: 1.11-2.80) were found to be more likely to possess N. caninum antibodies. This study detects presence of N. caninum in dairy cattle and their aborted fetus from Lima valley, suggesting biosecurity management improve to neosporosis control.

[Endo- and ectoparasites of South American camelids and their control]

In a literature review, common endo- and ectoparasites of South American camelids are described, presenting morphological details and clinical signs important for diagnosis. Based on the life cycle of the parasites, possibilities for prophylaxis and therapy are indicated. The review should aid the veterinarian to diagnose and control common parasitic infections in South American camelids.

Generation and characterization of the first immortalized alpaca cell line suitable for diagnostic and immunization studies

Raising of alpacas as exotic livestock for wool and meat production and as companion animals is growing in importance in the United States, Europe and Australia. Furthermore the alpaca, as well as the rest of the camelids, possesses the peculiarity of producing single-chain antibodies from which nanobodies can be generated. Nanobodies, due to their structural simplicity and reduced size, are very versatile in terms of manipulation and bio-therapeutic exploitation. In fact the biotech companies involved in nanobody production and application continue to grow in number and size. Hence, the development of reagents and tools to assist in the further growth of this new scientific and entrepreneurial reality is becoming a necessity. These are needed mainly to address alpaca disease diagnosis and prophylaxis, and to develop alpaca immunization strategies for nanobody generation. For instance an immortalized alpaca cell line would be extremely valuable. In the present work the first stabilized alpaca cell line from alpaca skin stromal cells (ASSCs) was generated and characterized. This cell line was shown to be suitable for replication of viruses bovine herpesvirus-1, bovine viral diarrhea virus and caprine herpesvirus-1 and the endocellular parasite Neospora caninum. Moreover ASSCs were easy to transfect and transduce by several methods. These two latter characteristics are extremely useful when recombinant antigens need to be produced in a host homologous system. This work could be considered as a starting point for the expansion of the biotechnologies linked to alpaca farming and industry.

Health impact evaluation of alternative management systems in vicuña (Vicugna vicugna mensalis) populations in Peru

To determine the impact of farming over vicuña population in Peru, serum samples were collected from 207 vicuñas (126 captive vicuñas and 81 free-ranging vicuñas) and 614 domestic South American camelids (571 alpacas and 43 llamas), in ten Andean communities at the Salinas y Aguada Blanca reserve, province of Arequipa, southern Peru. Samples were tested for the presence of leptospirosis, foot and mouth disease (FMD), bovine viral diarrhea (BVD), bovine herpesvirus type 1 (BHV-1), brucellosis, bluetongue disease (BT), paratuberculosis, and neosporosis. Serological results showed that 1.9% (4/207) of vicuñas, 18.6% (106/571) of alpacas, and 23.3% (10/43) of llamas were positive to one or more Leptospira serovars. One percent of vicuñas (2/207) and 2.4% of domestic camelids (15/614) had Neospora caninum antibodies tested by ELISA, but only two vicuñas and two alpacas were confirmed by Western blot. Epidemiological evaluation found an association of leptospirosis to sex and age (p < 0.001), with female subjects older than 2.5 years at higher risk of infection. Interestingly, antibodies against Leptospira serovars were only found in captive vicuñas. This is the first study where health status of free-ranging and captive vicuñas has been compared. Results indicate minimal to nil presence of FMD, BVD, BHV-1, brucellosis, BT, paratuberculosis, and neosporosis allied to health disorders in our sample. The detection of seropositive animals against Leptospira, however, unveils the likely significance of leptospirosis in wild and domestic South American camelids, the impact of mixed husbandry over vicuña population and the risk to human health.

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.

Molecular characterisation of BSR4, a novel bradyzoite-specific gene from Neospora caninum

Here we present the identification and cloning of the NcBSR4 gene, the putative Neospora caninum orthologue to the Toxoplasma gondii TgBSR4 gene. To isolate NcBSR4, genome walking PCR was performed on N. caninum genomic DNA using the expressed sequence tag NcEST3c28h02.y1 sequence, which shares a 44% identity with the TgBSR4 gene, as a framework. Nucleotide sequencing of amplified DNA fragments revealed a single uninterrupted 1227 bp open reading frame that encodes a protein of 408 amino acids with 66% similarity to the TgBSR4 antigen. A putative 39-residue signal peptide was found at the NH2-terminus, followed by a hydrophilic region. At the COOH-terminus, a potential site for a glycosylphosphatidylinositol anchor was identified at amino acid 379. A polyclonal serum against recombinant NcBSR4 protein was raised in rabbits, and immunolabelling demonstrated stage-specific expression of the NcBSR4 antigen in N. caninum bradyzoites produced in vitro and in vivo. Furthermore, RT-PCR analysis showed a slight increase of NcBSR4 transcripts in bradyzoites generated during in vitro tachyzoite-to-bradyzoite stage-conversion, suggesting that this gene is specifically expressed at the bradyzoite stage and that its transcription relies on the switch to this stage.

Epidemiology and control of neosporosis and Neospora caninum

Neospora caninum is a protozoan parasite of animals. Until 1988, it was misidentified as Toxoplasma gondii. Since its first recognition in dogs in 1984 and the description of the new genus and species Neospora caninum in 1988, neosporosis has emerged as a serious disease of cattle and dogs worldwide. Abortions and neonatal mortality are a major problem in livestock operations, and neosporosis is a major cause of abortion in cattle. Although antibodies to N. caninum have been reported, the parasite has not been detected in human tissues. Thus, the zoonotic potential is uncertain. This review is focused mainly on the epidemiology and control of neosporosis in cattle, but worldwide seroprevalences of N. caninum in animals and humans are tabulated. The role of wildlife in the life cycle of N. caninum and strategies for the control of neosporosis in cattle are discussed.

Seroprevalence of Neospora caninum in non-carnivorous wildlife from Spain

Serum samples from 1034 non-carnivorous wildlife from Spain were tested for antibodies to Neospora caninum by competitive screening enzyme linked immunosorbent assay (ELISA) and confirmed by an indirect fluorescent antibody test (IFAT). High agreement was observed between results in both techniques (kappa value higher than 0.9). Prevalences of N. caninum antibodies positive by both techniques were 11.8% of 237 red deer (Cervus elaphus), 7.7% of 13 barbary sheep (Ammotragus lervia), 6.1% of 33 roe deer (Capreolus capreolus) and 0.3% of 298 wild boar (Sus scrofa). In one of 53 hares (Lepus granatensis), antibodies were found in the ELISA but could not be confirmed by IFAT due to lack of sample. Antibodies to N. caninum were not found in any of 251 wild rabbits (Oryctolagus cuniculus), 79 fallow deer (Dama dama), 27 mouflon (Ovis ammon), 40 chamois (Rupicapra pyrenaica) and three Spanish ibex (Capra pyrenaica). Statistically significant differences were observed between N. caninum seroprevalence in red deer and management of hunting estates (open versus fenced) with higher prevalence in fenced estates, and among sampling sites. Seroprevalence was particularly high in some areas (MO estate in South-Central Spain or some estates of Catalonia, North-East Spain), while no contact with N. caninum was observed in others. Results indicate that in certain areas of Spain, N. caninum is present in wildlife, especially in red deer. These results have important implications in both sylvatic cycles and may influence the prevalence of infection in cattle farms in those areas. To our knowledge, this is the first report of antibodies to N. caninum in wildlife from Spain and the first report of N. caninum antibodies in barbary sheep and wild boar.

Multilocus microsatellite analysis reveals extensive genetic diversity in Neospora caninum

Neospora caninum is a world-wide parasite that causes neuromuscular disorders in dogs and bovine abortion. Biological diversity among isolates has been proved in both in vivo and in vitro studies. In contrast, little is known about the genetic diversity of this parasite. Microsatellite sequence analysis constitutes a suitable tool that has been used for the genetic analysis of other apicomplexan parasites. In this report, we describe the identification and analysis of 13 microsatellite loci from N. caninum DNA sequences deposited in public databases, which were evaluated with the use of 9 isolates grown in vitro. One microsatellite was monomorphic, and the remaining 12 loci exhibited 3 to 9 separate alleles. Multilocus analysis showed that each of the 9 isolates investigated here displayed a unique profile and revealed no association between the genetic similarity and host or geographic origin. The multilocus analysis approach described here might nevertheless provide the powerful tool needed to study the genetic complexity of N. caninum and the molecular epidemiology of neosporosis.

Diagnosis of bovine neosporosis: Recent advances and perspectives

Neospora caninum is considered a major cause of abortion in cattle. Appropriate techniques for diagnosis of bovine neosporosis, both in vivo and in aborted foetuses, have been developed in the last ten years and some of them are commercially available. For diagnosis in live animals, detection of antibodies in serum or milk has been shown to be the best option both at the herd and the individual level. These techniques are excellent tools to examine N. caninum-associated abortion problems and to adopt some basic herd-control measures. Concerning foetal diagnosis, detection of compatible lesions by histological examination and parasites by PCR in brain (as well as heart and liver) are the best choices. Diagnostic criteria to distinguish foetal infection and Neospora-associated abortion are based not only on the demonstration of the parasite in the foetus but also on the extent and severity of the lesions in the foetus, foetal age and the assessment of neosporosis at the herd level. In the near future, new tools to diagnose infection should help to detect animals with parasite reactivation by testing the immune response to stage-specific antigens and lead to the development of molecular typing methods to characterise different parasite isolates. Finally, uniform diagnostic procedures need to be established between laboratories and countries in order to standardise result interpretation. The role of National or Regional Reference Laboratories is essential in countries or regions where control programmes for the disease are being developed.

Detection of specific antibodies to Neospora caninum and Toxoplasma gondii in naturally infected alpacas (Lama pacos), llamas (Lama glama) and vicunas (Lama vicugna) from Peru and Germany

Sera of an experimentally Neospora caninum infected llama and a non-infected control llama were used to establish an immunoblot, an ELISA and an IFAT to detect antibodies against N. caninum tachyzoites. Subsequently, serum samples collected from a total of 871 South American Camelids (SAC: Lama glama, Lama pacos, Lama vicugna) of two farms in Peru and from 32 SAC of a farm in central Germany were examined for antibodies against N. caninum and Toxoplasma gondii. Based on the recognition of specific bands in the immunoblot, sera of SAC from Peru were differentiated into N. caninum-positive (n = 18) and T. gondii-positive (n = 30) samples and into samples negative or inconclusive for both parasites. Using the immunoblot results as the reference, a modified version of the p38-ELISA and the IFAT were evaluated for detecting N. caninum antibodies in SAC sera. Applying a cut-off as determined by two graph-receiver operating characteristic analysis both, the ELISA and the IFAT, exhibited a sensitivity and specificity of about 95% in the SAC sera from Peru. Serological testing confirmed that SAC may become infected with N. caninum under field conditions in Peru. In addition to alpacas and llamas also 114 wild living vicunas had been examined for antibodies against N. caninum. However, only the alpacas and llamas but no vicunas were found N. caninum-positive. In contrast, T. gondii-seropositive animals were detected in all three SAC species. The lack of N. caninum-seropositive vicunas indicates that in the study area in Peru wild canids might not serve as definitive hosts of N. caninum while for T. gondii a life cycle including wild felids is likely. On the German farm no N. caninum- but only T. gondii-seropositive SAC (n = 14) were detected. The seroprevalence of T. gondii infection was significantly higher in adult SAC (alpacas in Peru, llamas in Germany) than in crias (i.e. < 12 months old foals) indicating that the predominant route of infection is post natal. Since the present study was restricted to a few farms, the seroprevalences determined are not representative. However, our results confirm natural infections with N. caninum and T. gondii in SAC. Whether these infections are linked to any disease, e.g. reproductive losses, has to be clarified in further studies.

Toxoplasma gondii infection in adult llamas (Lama glama) and vicunas (Vicugnavicugna) in the Peruvian Andean region

The present study was designed to investigate Toxoplasma gondii infection in adult llamas (Lama glama) and vicunas (Vicugna vicugna) in the Peruvian Andean region, for which to date no information has been available. Serum samples from 43 llamas (L. glama) and 200 vicunas were tested by IFAT detecting titres of 1:50 or higher in 55.8% (33.9-70.9%) and 5.5% (2.8-9.6%), respectively. IFAT titres ranged from 1:50 to 1:6400. In order to avoid cross reactions with closely related coccidian parasites and to confirm the existence of T. gondii specific antibodies, IFAT positive sera from both ruminant species were also analysed by western blot. T. gondii specific antigens were recognised by IFAT positive sera, although different IFAT cut-off points could be selected for llamas (1:200) and vicunas (1:50) meaning seroprevalence of 44.2% (29.1-60.1%) and 5.5% (2.8-9.6%), respectively. Based on the frequency and intensity of tachyzoite antigen recognition, at least three immunodominant antigens with apparent molecular weights of 22-24, 30, and 38-40 kDa were detected, together with other minor protein fractions located in the 18-73 kDa range. This study documents for the first time the presence of T. gondii infection and reports the target T. gondii antigens in adult llamas and vicunas in Peru.

Neosporosis in South America

This work gathers reports about Neospora-infections in South America. Neospora-infections have been reported from Argentina, Brazil, Chile, Paraguay, Peru and Uruguay. Evidence of exposure to N. caninum was mentioned in cattle, goats, sheep, dogs, cats, water buffaloes, alpacas, llamas, South American opossums, wolves and other wild canids. No antibodies were found in horses. Interesting epidemiological and pathological data were described. Two isolations were performed from dogs, one from cattle, and recently five from water buffaloes. Since the cattle industry is important in South America and reproductive losses caused by Neospora-infection have been identified, more investigations are needed in order to understand its epidemiology and control the disease.