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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.
Evaluation and comparison of an indirect fluorescent antibody test for detection of antibodies to Sarcocystis neurona, using serum and cerebrospinal fluid of naturally and experimentally infected, and vaccinated horses. The objectives of this study were to evaluate the accuracy of the indirect fluorescent antibody test (IFAT) using serum and cerebrospinal fluid (CSF) of horses naturally and experimentally infected with Sarcocystis neurona, to assess the correlation between serum and CSF titers, and to determine the effect of S. neurona vaccination on the diagnosis of infection. Using receiver-operating characteristic analysis, the areas under the curve for the IFAT were 0.97 (serum) and 0.99 (CSF). Sensitivity and specificity were 83.3 and 96.9% (serum, cutoff 80) and 100 and 99% (CSF, cutoff 5), respectively...
Cell-mediated immune responses in horses with equine protozoal myeloencephalitis. Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome seen in horses from the Americas and is mainly caused by Sarcocystis neurona. Cell-mediated immune responses to mitogens have been shown to be reduced in horses with EPM, although it is not known whether the parasite causes this immunosuppression or if the immunosuppression is required for disease manifestation. Recently, a 29-kDa surface antigen from S. neurona merozoites was identified as being highly immunodominant on Western blot. This antigen has been sequenced and cloned, and the expressed protein has been named SnSAG1. Is...
Detection of EHV-1 and EHV-4 DNA in unweaned Thoroughbred foals from vaccinated mares on a large stud farm. A silent cycle of equine herpesvirus 1 infection has been described following epidemiological studies in unvaccinated mares and foals. In 1997, an inactivated whole virus EHV-1 and EHV-4 vaccine was released commercially in Australia and used on many stud farms. However, it was not known what effect vaccination might have on the cycle of infection of EHV-1. Objective: To investigate whether EHV-1 and EHV-4 could be detected in young foals from vaccinated mares. Methods: Nasal and blood samples were tested by PCR and ELISA after collection from 237 unvaccinated, unweaned foals and vaccinated an...
Detection of West Nile virus using formalin fixed paraffin embedded tissues in crows and horses: quantification of viral transcripts by real-time RT-PCR. West Nile virus (WNV) RNA was quantified in WNV infected crows and horses with the help of a real-time reverse transcriptase-PCR assay. A 5' nuclease assay, based on NS5 gene detection with a fluorescent probe was used for quantifying WNV RNA using formalin fixed paraffin embedded tissue specimens. Quantitative detection of WNV RNA showed the presence of a higher amount of the viral RNA in crow tissues compared to equine tissues and these results correlated well with the detection of WNV antigen by immunostaining. In crows, the highest amount of virus was seen in the intestine and in horses in...
Phage display of the Equine arteritis virus nsp1 ZF domain and examination of its metal interactions. A putative zinc finger (ZF) domain in the Equine arteritis virus (EAV) nsp1 protein was described recently to be required for viral transcription. The nsp1 ZF (50 aa) was expressed on the surface of M13KE gIII phage, fused to the N terminus of the phage pIII protein. To evaluate the functionality of the ZF domain, a binding assay was developed, based on the use of immobilized Ni(2+) ions (Ni-NTA). Phages displaying ZF bound significantly better to Ni-NTA than did phages displaying negative-control peptides, which also contained metal-coordinating residues. Also, binding of ZF-displaying phages...
Metabolism of MDCK cells during cell growth and influenza virus production in large-scale microcarrier culture. The production of equine influenza in Madin-Darby canine kidney (MDCK) cells in large-scale microcarrier culture is described with detailed on- and off-line analytical data during cell growth and virus replication. Metabolite concentration profiles for glucose, glutamine, lactate and ammonium are shown. Lactate and ammonium concentrations were always below inhibiting levels. Concentration profiles for essential and non-essential amino acids of the cell culture medium are discussed. During cell growth proline was released into the medium with a significant rate while two amino acids, serine and...
Evaluation of immune responses in horses immunized using a killed Sarcocystis neurona vaccine. Clinically normal horses developed cellular immunity to Sarcocystis neurona following IM vaccination with a commercial killed S. neurona vaccine, as indicated by the development of measurable anti-S. neurona IgG antibodies and additional intradermal skin testing. Large-scale independent assessments of the vaccine's performance and safety are in progress under field conditions. The next step in the evaluation of this vaccine would be to attempt experimental challenge after a reproducible reliable equine model of S. neurona encephalitis has been established that allows for reisolation of the pat...
Clinical West Nile virus infection in 2 horses in western Canada. Two horses had a history of ataxia and weakness or recumbency. One recovered and was diagnosed with West Nile virus (WNV) infection by serologic testing. The other was euthanized; it had meningoencephalomyelitis, WNV was detected by polymerase chain reaction. West Nile virus infection is an emerging disease. Year 2002 is the first year in which cases have been seen in Saskatchewan. Deux chevaux présentaient une histoire d’ataxie et de faiblesse ou de décubitus. Un cheval s’est rétabli et un diagnostic d’infection au virus du Nil occidental (VNO) a été posé par épreuve sérologiqu...
Serologic responses to eastern and western equine encephalomyelitis vaccination in previously vaccinated horses. A prospective study was performed to determine the serologic response of previously vaccinated horses to revaccination against eastern and western equine encephalomyelitis (EEE and WEE). Horses responded variably to each antigen, and some horses had low or undetectable antibodies 6 months after vaccination. Some horses did not develop increasing titers to EEE or WEE despite recent vaccination. Geometric mean titers peaked 2 weeks after revaccination and were significantly increased from before revaccination. Except for one horse, EEE:WEE titer ratios ranged from 0.25 to 2.0. Regular vaccinatio...
The mare reproductive loss syndrome and the eastern tent caterpillar: a toxicokinetic/statistical analysis with clinical, epidemiologic, and mechanistic implications. During 2001, central Kentucky experienced acute transient epidemics of early and late fetal losses, pericarditis, and unilateral endophthalmitis, collectively referred to as mare reproductive loss syndrome (MRLS). A toxicokinetic/statistical analysis of experimental and field MRLS data was conducted using accelerated failure time (AFT) analysis of abortions following administration of Eastern tent caterpillars (ETCs; 100 or 50 g/day or 100 g of irradiated caterpillars/day) to late-term pregnant mares. In addition, 2001 late-term fetal loss field data were used in the analysis. Experimental dat...
Identification and differentiation of avirulent and virulent Rhodococcus equi using selective media and colony blotting DNA hybridization to determine their concentrations in the environment. Selective agar media have been used for many years to facilitate the isolation of Rhodococcus equi from environmental and clinical samples. However, characterisation of R. equi still requires the use of immunochemical or polymerase chain reaction (PCR) analysis to differentiate between virulent and avirulent isolates. Here, we describe a novel method to detect and differentiate between R. equi isolates using colony blotting and DNA hybridization. Radiolabelled PCR product derived from the R. equi rrnA gene and specific hybridization conditions enabled differentiation of colonies of R. equi fro...
Helcococcus ovis isolated from a pulmonary abscess in a horse. Helcococcus ovis, a recently described organism cultured from sheep, was isolated in pure culture from a pulmonary abscess in a horse. This is the first report of this organism in horses and the first report in veterinary medicine to clearly demonstrate a pathogenic role for this organism.
Radiotherapy of a recurrent ossifying fibroma in the paranasal sinuses of a horse. A 7-year-old female Thoroughbred was admitted with a history of labored breathing, stridor, and exercise intolerance. Examination revealed a mass in the left paranasal sinuses that was determined to be an ossifying fibroma. Initial treatment consisted of surgical removal of the mass alone; however, the mass recurred 9 months after surgery. The mass was again removed, and adjunctive radiotherapy consisting of 3,000 cGy of cobalt radiation was administered. This time, the tumor did not recur for > 6 years. A third surgery was performed to remove the mass, and adjunctive radiotherapy consisting o...
Recombinant canarypoxvirus vaccine carrying the prM/E genes of West Nile virus protects horses against a West Nile virus-mosquito challenge. An ALVAC (canarypoxvirus)-based recombinant (vCP2017) expressing the prM and E genes derived from a 1999 New York isolate of West Nile virus (WNV) was constructed and assessed for its protective efficacy in horses in two different experiments. In the first trial, a dose titration study was conducted to evaluate both serum neutralising antibody responses to WNV and duration of immunity. In the second trial the onset of protection was determined. Twenty-eight adult horses received two doses of vCP2017 administered intramuscularly at 5-week intervals and sixteen horses comprised age-matched non-v...
Effect of growth medium on hydrophobicity of Staphylococcus epidermidis. The present study was undertaken to evaluate the effect of growth medium on expression of hydrophobicity of Staphylococcus epidermidis. A total of 24 hydrophobic isolates of S. epidermidis, determined by n-hexadecane adherence assay (HAA) earlier were included. Five different growth media: horse blood agar (HBA), brain heart infusion agar (BHIA), brain heart infusion broth (BHIB), tryptic soy broth (TSB) and proteose peptone broth (PPB) were used. All 24 isolates exhibited the reproducible hydrophobicity when grown on HBA; however, 20 (83.33%), 19 (79.16%), 15 (62.50%) and 13 (54.16%) isolates...
Equine beta-defensin-1: full-length cDNA sequence and tissue expression. beta-Defensins are cysteine-rich endogenously produced antimicrobial peptides that play an important role in innate immune defense. Although, previous investigations have identified beta-defensins in several mammalian species, no reports have identified equine beta-defensins. Using a strategy of database searching for expressed sequence tags (EST) we identified putative expression of equine beta-defensins in hepatic tissue. Based on this information, sequence specific primers were designed for the equine gene enabling the identification of the full-length cDNA sequence of equine beta-defensin-...
[Doubling of the number of cases of tick bites and lyme borreliosis seen by general practitioners in the Netherlands]. To obtain detailed information about the current geographical distribution and incidence of tick bites and Lyme borreliosis in the Netherlands and to identify regional differences in the ecological risk factors that might be involved. Methods: Retrospective questionnaire study. Methods: All Dutch general practitioner's (GP) practices. Methods: In April 2002, all GPs in the Netherlands were asked to complete a short questionnaire on the number of cases of tick bites and erythema migrans seen in 2001 and the size of their practice. Associations with possible risk factors were determined at the m...
Periapical curettage: an alternative surgical approach to infected mandibular cheek teeth in horses. To evaluate an alternative surgical method for treating periapical infection of the mandibular cheek teeth of horses. Methods: Retrospective study. Methods: Eleven horses (3-13 years) with periapical mandibular tooth infection. Methods: Hospital records (1992-2002) of horses that had periapical curettage for the treatment of mandibular cheek tooth root infection were retrieved. Clinical signs, radiographic, and surgical reports were reviewed. Outcome was obtained by telephone questionnaire for 7 horses and by physical examination in 2. Results: Eleven horses (14 infected mandibular molariform ...
Tritrichomonas foetus: a scanning electron microscopy study of erythrocyte adhesion associated with hemolytic activity. The in vitro hemolytic activity of Tritrichomonas foetus was investigated. The parasite was tested against human erythrocytes of groups A, B, AB, and O, and against erythrocytes of nine adult animals of different species (the rabbit, rat, chicken, cat, dog, swine, horse, bovine, and sheep). The results showed that T. foetus strains (ATCC KV1, K, PAL, 5022, RJ, 90) did not present any hemolytic activity against any human erythrocyte group nor against rabbit, rat, chicken, cat, dog and swine erythrocytes. T. foetus strains, however, lysed horse, bovine, and sheep erythrocytes. No hemolysin relea...
Occurrence of gastrointestinal parasites in horses in metropolitan Perth, Western Australia. To assess the occurrence of gastrointestinal parasites in horses in Perth. To apply polymerase chain reaction (PCR) for the identification of some species of encysted larval cyathostomes. Methods: Between February and September of 2000, the gastrointestinal tracts of 29 horses submitted to a local knackery and Murdoch University Veterinary hospital in Perth were examined post mortem for the presence of gastrointestinal parasites. Methods: The gastrointestinal tract was divided into six sections, which were screened for the presence of parasites such as Gasterophilus sp, Anoplocephala sp and Pa...
Polymerase chain reaction tests for the identification of Ross River, Kunjin and Murray Valley encephalitis virus infections in horses. To develop and validate specific, sensitive and rapid diagnostic tests using RT-PCR for the detection of Ross River virus (RRV), Kunjin virus (KV) and Murray Valley encephalitis virus (MVEV) infections in horses. Methods: Primer sets based on nucleotide sequence encoding the envelope glycoprotein E2 of RRV and on the nonstructural protein 5 (NS5) of KV and MVEV were designed and used in single round PCRs to test for the respective viruses in infected cell cultures and, in the case of RRV, in samples of horse blood and synovial fluid. Results: The primer pairs designed for each of the three vir...
Isolation of Ross River virus from mosquitoes and from horses with signs of musculo-skeletal disease. To report clinical and clinicopathological findings in horses naturally infected with Ross River virus (RRV) and identify likely mosquito arbovirus vector species. Methods: Veterinarians submitted serum samples from 750 horses because they suspected Ross River virus (RRV) infection. The samples were tested for the presence of IgM and IgG antibody to RRV and for the presence of virus. Mosquitoes were trapped, differentiated to species level and tested for the presence of RRV by virus isolation. Results: RRV was isolated from six species of mosquitoes (Ochlerotatus camptorhyncus, Culex globocoxi...
Coccidioidomycosis in Przewalski’s horses (Equus przewalskii). Coccidioidomycosis is a rare, often subclinical infection in domestic animals caused by the fungus Coccidioides immitis. Because of an apparent high incidence of coccidioidomycosis in Przewalski's horses (Equus przewalskii) housed at a single facility, necropsy records and biomaterials from animals that died between 1984 and 2000 were reviewed (n = 30, 15 males, 15 females). Coccidioidomycosis was the leading cause of death (33%) in this population with lesions in the lungs and tracheobronchial lymph nodes of all animals and variable involvement of the skeletal muscle, heart, kidney, liver, sk...
Treatment of suppurative facial cellulitis and panniculitis caused by Corynebacterium pseudotuberculosis in two horses. Two horses were examined for large head wounds suspected to be the result of trauma and characterized by extensive necrosis of the skin and subcutaneous tissue, with abundant purulent exudate. Corynebacterium pseudotuberculosis was isolated from the facial wounds in both horses. Histopathologic examination revealed severe suppurative cellulitis and panniculitis with fistulous tracts and granulation tissue in 1 horse. Both horses were treated with local wound care, nonsteroidal anti-inflammatory drugs, and administration of antimicrobials. The concept of moist wound care was used in the second ...
Uterine microbiology and antimicrobial susceptibility in isolated bacteria from mares with fertility problems. Uterine microbiology and antimicrobial susceptibility was investigated in 239 mares with fertility problems in a prospective study in Sweden. Uterine swab samples were collected with double guarded swabs and transported overnight before being cultured. The Minimum Inhibitory Concentrations (MIC) was determined for a panel of antimicrobials. From 152 of the 239 mares at least one bacterial species was isolated, most frequently E. coli (104 isolates), beta-haemolytic streptococci (31) and fungi (16). beta-haemolytic streptococci were more frequently (p < 0.01) associated with clinical endomet...
Pericarditis and pleuritis caused by Corynebacterium pseudotuberculosis in a horse. A 13-year-old Oldenburg mare was evaluated for lethargy and signs of mild colic. Pericardial tamponade caused by fibrinoeffusive pericarditis was diagnosed. Cytologic and biochemical evaluation of pericardial fluid was consistent with a septic effusion. Corynebacterium pseudotuberculosis, the cause of pigeon fever, was identified by bacteriologic culture of pericardial fluid. Drainage and lavage of the pericardial sac, local (intrapericardial) and systemic antimicrobial treatment, and subsequent corticosteroid treatment resulted in a successful outcome in this horse. To the authors' knowledge,...
