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Topic:Infectious Disease
Infectious diseases in horses encompass a range of illnesses caused by bacteria, viruses, fungi, or parasites. These diseases can affect various systems within the equine body, leading to symptoms that range from mild discomfort to severe systemic illness. Common infectious diseases in horses include equine influenza, strangles, equine herpesvirus, and West Nile virus. These diseases can be transmitted through direct contact with infected animals, contaminated surfaces, or vectors such as insects. Understanding the mechanisms of transmission, pathogenesis, and immune response is essential for effective prevention and control. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, diagnosis, treatment, and management of infectious diseases in horses.
Isolation of equine herpesvirus type 5 in New Zealand. To report the first isolation of equine herpesvirus 5 (EHV-5) in New Zealand as part of a study of equine respiratory viruses in New Zealand. Methods: Nasal swabs and peripheral blood leukocytes were collected from 114 foals and adult horses, inoculated on to equine fetal kidney, rabbit kidney and Vero cell lines and observed for cytopathic effect. EHV-5 isolates were identified using an EHV-5 specific polymerase chain reaction. All samples positive for EHV-5 were also checked for the presence of EHV-2, EHV-1 or EHV-4 DNA using published type-specific primers. The polymerase chain reaction res...
Viruses associated with outbreaks of equine respiratory disease in New Zealand. To identify viruses associated with respiratory disease in young horses in New Zealand. Methods: Nasal swabs and blood samples were collected from 45 foals or horses from five separate outbreaks of respiratory disease that occurred in New Zealand in 1996, and from 37 yearlings at the time of the annual yearling sales in January that same year. Virus isolation from nasal swabs and peripheral blood leukocytes (PBL) was undertaken and serum samples were tested for antibodies against equine herpesviruses (EHV-1, EHV-2, EHV-4 and EHV-5), equine rhinitis-A virus (ERAV), equine rhinitis-B virus (ERBV...
Meningoencephalomyelitis in a foal due to Salmonella agona infection. A neonatal Thoroughbred foal was presented with rib fractures and left forelimb lameness secondary to dystocia. Results: The foal developed a head tilt, seizures and watery diarrhoea during hospitalisation and died at 7 days of age. Histological examination of the brain and spinal cord revealed a suppurative meningoencephalomyelitis with vasculitis, and numerous intralesional, gram-negative bacilli. Similar microscopic lesions were noted in the lungs, renal medullary interstitium, and umbilicus. Bacilli in the brain, spinal cord and umbilicus were identified immunohistochemically as Salmonella...
Methicillin-resistant Staphylococcus aureus (MRSA) isolated from animals and veterinary personnel in Ireland. Reports of methicillin-resistant Staphylococcus aureus (MRSA) in animals have become more frequent in recent years. This paper documents the recovery of MRSA from animals with respiratory, urinary tract or wound infection and from animals subjected to surgical procedures following treatment in one veterinary hospital and 16 private veterinary clinics in different geographical locations throughout Ireland. MRSA was recovered from 25 animals comprising 14 dogs, eight horses, one cat, one rabbit and a seal, and also from 10 attendant veterinary personnel. Clinical susceptibility testing suggested...
West Nile virus surveillance, Guadeloupe, 2003-2004. We conducted extensive surveillance for West Nile virus infection in equines and chickens in Guadeloupe in 2003-2004. We showed a high seroprevalence in equines in 2003 related to biome, followed by a major decrease in virus circulation in 2004. No human or equine cases were reported during the study.
Isolation of equine herpesvirus-1 lacking glycoprotein C from a dead neonatal foal in Japan. We isolated a variant equine herpesvirus-1 (EHV-1), strain 5089, from the lung of a dead neonatal foal in Japan and characterized the biological nature of the virus. The virus spread in cultured cells mainly by cell-to-cell infection, unlike wild-type EHV-1, which spreads efficiently as a cell-free virus. The virus titer in cultured supernatant and the intracellular virus titer were low compared to those of wild-type EHV-1. Heparin treatment of the virus had no effect on viral infectivity in cell culture. Glycoprotein C (gC) was not detected by Western blotting and fluorescent antibody tests i...
Quantitative assessment of the risks of reducing the routine swabbing requirements for the detection of Taylorella equigenitalis. The transmission of contagious equine metritis (CEM) on stud farms in Britain, Ireland and other European countries is prevented by following the recommendations in the Horserace Betting Levy Board's Code of Practice on CEM. A quantitative risk assessment was undertaken to estimate the likely impact of removing the recommendation, from the 2002 code, to culture endometrial or cervical swabs microaerophilically for the presence of Taylorella equigenitalis, the causative organism. The scientific literature was reviewed for evidence about the anatomical distribution of T. equigenitalis at differe...
Molecular characterisation of equine group A rotavirus, Nasuno, isolated in Tochigi Prefecture, Japan. In this study, equine group A rotavirus (RV-A), Nasuno, isolated from foal diarrhoea in Tochigi Prefecture, Japan was characterised genetically by sequence analysis of the genome segments encoding VP4 and VP7. The nucleotide and deduced amino acid sequences revealed high homology with P[12] RV-As (94.0-99.3% and 94.9-99.4%) and G3 RV-As (86.9-99.5% and 91.1-99.4%). Nasuno was also classified into P[12] and G3 in the phylogenetic analysis of the nucleotide sequences of the genome segments encoding VP4 and VP7.
The absence of Rhodococcus equi in Mongolian horses. In native Mongolian horses, the incidence and distribution of Rhodococcus equi are poorly understood. One hundred and fourteen equine fecal samples and 71 soil samples were collected from the camp sites of 26 nomadic families located in three areas less than 100 km from Ulaanbaatar, Mongolia. Five fecal samples were also collected from foals of Przewalski's Horses introduced into the Hustai National Park, Mongolia. No R. equi was isolated from the Mongolian horses or the soil samples. However, three colonies of R. equi were isolated from two fecal samples collected from foals of Przewalski's H...
Genomic diversity among equine herpesvirus-4 field isolates. Infection with equine herpesvirus-4 (EHV-4) is a major cause of respiratory tract disease, equine rhinopneumonitis, in horses. Although the full sequence of EHV-4 has been reported, genomic differences among EHV-4 field isolates have not yet been characterized. In this study, the genomic diversity between 23 Japanese EHV-4 isolates was analyzed by digestion with restriction endonucleases (BamHI, BgIII, EcoRI, SacI, and SalI) and polymerase chain reaction (PCR). The restriction endonuclease digestion patterns of the EHV-4 field isolates showed distinct differences which included mobility shifts...
Equine infection with Leishmania in Portugal. The present report describes the first case of equine leishmaniasis in Portugal. Leishmania infection was detected in one animal, which presented an ulcerated skin lesion. Diagnosis was based on serology by CIE, and parasite DNA detection by real-time PCR using a probe specific for L. infantum. This finding requests further leishmaniasis equine surveys in order to clarify the role of the horse as reservoir host in european endemic areas.
Importation of canid rabies in a horse relocated from Zimbabwe to South Africa. In July 2003 a 2-year-old Thoroughbred colt was imported from Harare, Zimbabwe to the Ashburton Training Centre, Pietermaritzburg, South Africa. Five months after importation, the colt presented with clinical signs suggestive of rabies: it was uncoordinated, showed muscle tremors and was biting at itself. Brain tissue was submitted for analysis and the clinical diagnosis was confirmed by the fluorescent antibody test and reverse-transcription polymerase chain reaction (RT-PCR). Phylogenetic analysis of the nucleotide sequence of the cytoplasmic domain of the glycoprotein and the G-L intergenic...
Anti-Trichinella antibodies detected in chronically infected horses by IFA and Western blot, but not by ELISA. In the Balkan countries, where trichinellosis is a re-emerging zoonosis, it is of great importance to determine Trichinella infection prevalence among the major hosts, including horses. One method for monitoring prevalence is serological surveillance; however, the validity of serological methods in horses is not well understood. The dynamics of anti-Trichinella IgG production and circulating excretory/secretory (ES) antigens were investigated in three horses experimentally-infected with Trichinella spiralis. Horses were slaughtered at 32 week post infection (p.i.). Low worm burdens were found ...
Equine infectious anemia virus Gag p9 function in early steps of virus infection and provirus production. We have previously reported that serial truncation of the Gag p9 protein of equine infectious anemia virus (EIAV) revealed a progressive loss in replication phenotypes in transfected cells, such that a proviral mutant (E32) expressing the N-terminal 31 amino acids of p9 produced infectious virus particles similarly to parental provirus, while a proviral mutant (K30) with two fewer amino acids produced replication-defective virus particles, despite containing apparently normal levels of processed Gag and Pol proteins (C. Chen, F. Li, and R. C. Montelaro, J. Virol. 75:9762-9760, 2001). Based on ...
Envelope glycoprotein mutations mediate equine amplification and virulence of epizootic venezuelan equine encephalitis virus. Epidemics of Venezuelan equine encephalitis (VEE) result from high-titer equine viremia of IAB and IC subtype viruses that mediate increased mosquito transmission and spillover to humans. Previous genetic studies suggest that mutations in the E2 envelope glycoprotein allow relatively viremia-incompetent, enzootic subtype ID strains to adapt for equine replication, leading to VEE emergence. To test this hypothesis directly, chimeric VEEV strains containing the genetic backbone of enzootic subtype ID strains and the partial envelope glycoprotein genes of epizootic subtype IC and IAB strains, as ...
Recombinant NhSAG1 ELISA: a sensitive and specific assay for detecting antibodies against Neospora hughesi in equine serum. Neospora hughesi is a recently identified cause of equine protozoal myeloencephalitis. However, the significance of this parasite is poorly understood. An enzyme-linked immunosorbent assay (ELISA) with a recombinant form of the N. hughesi 29-kDa surface antigen (rNhSAG1) was developed for serodiagnosis of equine N. hughesi infections. Parallel ELISA analysis showed that animals immunized or infected with N. hughesi exhibited greater antibody reactivity with rNhSAG1 than with the Neospora caninum homolog, rNcSAG1. The rNhSAG1 ELISA showed 94.4% sensitivity and 95.0% specificity when compared wi...
Cytotoxic T lymphocytes in protection against equine infectious anemia virus. Cytotoxic T lymphocytes (CTL) are associated with virus control in horses infected with equine infectious anemia virus (EIAV). Early in infection, control of the initial viremia coincides with the appearance of CTL and occurs before the appearance of neutralizing antibody. In carrier horses, treatment with immunosuppressive drugs results in viremia before a change in serum neutralizing antibody occurs. Clearance of initial viremia caused by other lentiviruses, including human immunodeficiency virus-1 and simian immunodeficiency virus, is also associated with CTL and not neutralizing antibody. ...
A tumor necrosis factor receptor family protein serves as a cellular receptor for the macrophage-tropic equine lentivirus. Characterization of cellular receptors for human, simian, and feline immunodeficiency viruses that are tropic for lymphocytes and macrophages have revealed a common theme of a sequential binding of viral envelope proteins with two coreceptors to mediate virus infection of target cells. In contrast to these dual tropic immunodeficiency viruses, the ungulate lentiviruses, including equine infectious anemia virus (EIAV), exclusively infect cells of the monocyte-macrophage lineage to cause progressive degenerative diseases without clinical immunodeficiency. EIAV causes a uniquely dynamic disease t...
Early detection of dominant Env-specific and subdominant Gag-specific CD8+ lymphocytes in equine infectious anemia virus-infected horses using major histocompatibility complex class I/peptide tetrameric complexes. Cytotoxic T lymphocytes (CTL) are critical for control of lentiviruses, including equine infectious anemia virus (EIAV). Measurement of equine CTL responses has relied on chromium-release assays, which do not allow accurate quantitation. Recently, the equine MHC class I molecule 7-6, associated with the ELA-A1 haplotype, was shown to present both the Gag-GW12 and Env-RW12 EIAV CTL epitopes. In this study, 7-6/Gag-GW12 and 7-6/Env-RW12 MHC class I/peptide tetrameric complexes were constructed and used to analyze Gag-GW12- and Env-RW12-specific CTL responses in two EIAV-infected horses (A2164 an...
Species composition of Gasterophilus spp. (Diptera, Oestridae) causing equine gastric myiasis in southern Italy: parasite biodiversity and risks for extinction. Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on...
Evidence to support horses as natural intermediate hosts for Sarcocystis neurona. Opossums (Didelphis spp.) are the definitive host for the protozoan parasite Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis (EPM). Opossums shed sporocysts in feces that can be ingested by true intermediate hosts (cats, raccoons, skunks, armadillos and sea otters). Horses acquire the parasite by ingestion of feed or water contaminated by opossum feces. However, horses have been classified as aberrant intermediate hosts because the terminal asexual sarcocyst stage that is required for transmission to the definitive host has not been found in their tissues despite...
Transmission of a Venezuelan equine encephalitis complex Alphavirus by Culex (Melanoconion) gnomatos (Diptera: Culicidae) in northeastern Peru. Venezuelan equine encephalitis (VEE) complex alphaviruses are serious health threats in the Americas and regularly infect humans living in or near Amazonian rain forests. As part of a larger surveillance program, we placed six hamster-baited mosquito traps in a disturbed white sand forest of northeastern Peru for 3 d. Virus isolations from hamster serum and trapped mosquito pools demonstrated that a VEE subtype IIIC alphavirus was transmitted to a hamster by the mosquito Culex (Melanoconion) gnomatos Sallum, Hutchings & Ferreira. This species, like the other seven proven VEE complex alphav...
Surveillance of Staphylococcus aureus in veterinary teaching hospitals. Staphylococcus aureus isolates (n = 70) from 65 patients (36 canine, 18 equine, 7 bovine, 2 avian, and 2 feline) at seven veterinary teaching hospitals in the United States were studied. The majority of patients (83%) with an S. aureus infection were canine and equine, but this may have reflected a sample bias based on clinic case loads and diagnostic lab submissions at the participating institutions. Fourteen percent of patients with an S. aureus infection were infected with a methicillin-resistant S. aureus (MRSA) isolate. Six of seven institutions had at least one MRSA infection during the ...
Attenuation of equine influenza viruses through truncations of the NS1 protein. Equine influenza is a common disease of the horse, causing significant morbidity worldwide. Here we describe the establishment of a plasmid-based reverse genetics system for equine influenza virus. Utilizing this system, we generated three mutant viruses encoding carboxy-terminally truncated NS1 proteins. We have previously shown that a recombinant human influenza virus lacking the NS1 gene (delNS1) could only replicate in interferon (IFN)-incompetent systems, suggesting that the NS1 protein is responsible for IFN antagonist activity. Contrary to previous findings with human influenza virus, w...
Comparison of serological tests for equine trypanosomosis in naturally infected horses from Kazakhstan. In this study, we compared the complement fixation test (CFT), the horse complement fixation test (HCFT) and a card agglutination test for trypanosomosis (CATT/T. evansi) for the diagnosis of equine trypanosomosis in the Republic of Kazakhstan. Cohen's kappa test was used to evaluate the concordance between the three tests. Kappa scores for CFT versus HCFT and CATT are both 0.6165 (95% Confidence Interval CI 0.414--0.819) indicating a "substantial" agreement between CFT and HCFT or CATT, respectively. Kappa for HCFT versus CATT is 0.395 (CI 0.142--0.648) indicating a "fair" agreement between t...
