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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.
Transient suppression of equine immune responses by equine infectious anemia virus (EIAV). Suppression of the immune system is a common aspect of the disease pathogenesis associated with retroviral infections in both man and animals. We have measured transient suppression of the equine immune system as a loss or decrease in antigen-specific and polyclonal lymphocyte proliferation following experimental infection of ponies with three variants of equine infectious anemia virus (EIAV) with difference virulence characteristics. The transient suppression of proliferative responses was temporally associated with recurrent febrile episodes, which are the hallmark symptom of EIAV-induced di...
Streptokinases produced by pathogenic group C streptococci demonstrate species-specific plasminogen activation. The species specificities of plasminogen activation and binding of plasmin by pathogenic group C streptococci isolated from humans, horses, and pigs were examined. Of 56 streptococcal isolates, 52 elaborated plasminogen activator activity and 49 of these had specificity for plasminogen of the homologous host. Analysis of supernatants from 13 isolates indicated that the plasminogen activator activity resulted from secreted streptokinases. These 13 streptokinases were antigenically related and bound all three plasminogens, indicating that the binding recognition sites were conserved despite the ...
Botulism associated with feeding alfalfa hay to horses. Botulism was believed to be the cause of progressive symmetric myasthenia in 8 horses on a farm in North Carolina. One horse was found dead, 6 were euthanatized after becoming recumbent, and 1 affected horse recovered. Cecal and colonic contents of 2 horses were determined to contain Clostridium botulinum spores. Alfalfa hay that was fed to the horses contained spores and toxin.
Actinobacillus suis-like organisms and evidence of hemolytic strains of Actinobacillus lignieresii in horses. Thirty-seven local isolates of Actinobacillus suis-like organisms from diseased and clinically normal horses and 1 llama were compared with reference strains of A suis, A lignieresii, A equuli, A capsulatus, A hominis, A (Pasteurella) ureae, and equine A suis-like organisms (ASLO) previously described in literature. Comparison was by cultural characteristics, carbohydrate fermentation, enzyme profiles, and whole-cell protein polyacrylamide gel electrophoresis. Carbohydrate fermentation, determined by API-CH gallery, divided 36 equine ASLO isolates into 6 API-CH biotypes. The llama isolate was ...
Attempts to immunoprotect adult horses, specifically pregnant mares, with commercial vaccines against clinical disease induced by equine herpesvirus-1. In a project lasting 4 years more than 300 Lipizzans, around 180 of them adults, were vaccinated systematically against Equine Herpesvirus-1 (EHV-1) and representative groups thereof were serologically controlled for their antibody responses. In part, vaccination intervals recommended on packing slips were followed, in part other intervals, implicated by intermediary results, were used. A live virus vaccine proved ineffective if humoral antibodies were present. An oil-adjuvanted vaccine proved of highest antiviral immunogenicity, but after repeated revaccinations caused severe local reactions ...
Increased sensitivity of a rotavirus serotyping enzyme-linked immunosorbent assay by the incorporation of CaCl2. The sensitivity of a rotavirus serotyping enzyme-linked immunosorbent assay (ELISA) was improved by the addition of 0.5 mM CaCl2 to the washing buffer and reagent diluent. Twenty-nine of 63 (46%) previously untyped bovine and equine faecal rotavirus samples were serotyped in the modified assay. A differential response to Ca2+ ions was noted for different G-serotypes suggesting that serotyping assays performed without the inclusion of CaCl2 in the assay buffers may produce biased results.
Comparative evaluation of enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of dourine. The detection of antibodies against Trypanosoma equiperdum in 689 equid sera was compared by enzyme-linked immunosorbent assay (ELISA), the complement fixation test (CFT) and an indirect immunofluorescent test (IIF). CFT was the least sensitive technique, susceptible to anti-complementary factors and the most technically demanding. IIF was more sensitive, but was only suitable for testing limited numbers of samples. In this study, ELISA was the most sensitive test, the least labour intensive and lends itself to a considerable degree of automation. It is suggested that ELISA would be relatively...
Characterization of variable regions in the envelope and S3 open reading frame of equine infectious anemia virus. The polymerase chain reaction was used to amplify and clone parts of the envelope gene and overlapping S3 open reading frame, thought to encode rev, of the virulent in vivo-derived Th-1 isolate of equine infectious anemia virus (EIAV). The results indicated that EIAV consists of a heterogeneous mixture of genotypes present at the first febrile cycle after initial infection. We showed that the Th-1 isolate apparently contains nondefective genotypes as well as types which have transmembrane protein truncations or are rev deficient. Furthermore, we could confirm the presence of a hypervariable re...
[Equine monocytic ehrlichiosis (EME), a review]. Serological surveys showed that equine monocytic ehrlichiosis (EME) occurs in the USA, Canada and Europe. The causative agent is Rickettsia Ehrlichia risticii, isolated for the first time in 1984. The clinical features of the disease are sluggishness, anorexia, colic and fever, possibly followed by watery diarrhoea. Complications of an infection with E. risticii are laminitis and abortion. Colitis of the ascending colon may be observed at autopsy. Following a positive serological diagnosis (IgM ELISA) of EME, treatment with oxytetracycline can be initiated. It is also important to restore the ...
A monoclonal antibody defines a geographically conserved surface protein epitope of Babesia equi merozoites. Babesiosis is a tick-borne hemoparasitic disease affecting horses worldwide. To investigate mechanisms of immunity to this parasite, the antibody response of infected horses to Babesia equi merozoite proteins was evaluated. Immunoprecipitation of B. equi merozoite antigens with sera from infected horses revealed 11 major proteins of 210, 144, 108, 88, 70, 56, 44, 36, 34, 28, and 25 kDa. Monoclonal antibody (MAb) 36/133.97, which binds to live merozoites, immunoprecipitated proteins of 44, 36, 34, and 28 kDa. When immunoprecipitations were performed with in vitro translation products of merozoi...
Fumonisin B1 concentrations in feeds from 45 confirmed equine leukoencephalomalacia cases. During the fall of 1989 and winter of 1990, numerous reports of equine leukoencephalomalacia (ELEM) occurred from many regions of the United States. Typically, horses were consuming feed partially or entirely composed of corn and/or corn screenings. From October 1989 through May 1990, samples from 55 confirmed or suspected ELEM cases were received at the National Veterinary Services Laboratories, Ames, Iowa, for fumonisin B1 analysis. Samples from 9 cases in 1984-1985 were also obtained. Fumonisin B1, a mycotoxin produced by Fusarium moniliforme, causes ELEM, but little is known of naturally o...
Detection of Babesia equi in infected horses and carrier animals using a DNA probe. The ability of the Babesia equi repetitive probes, pSE2 and pSB20, to detect parasites in blood from experimentally infected, naturally infected and carrier animals was tested using a spot hybridization assay. The clinical course of the experimentally infected horses was monitored using microscopy, indirect fluorescent antibody tests, packed cell volume, temperature and the probe assay. The probes sensitively monitored the parasite level during the development of the disease and correlated well with the other parameters tested. The sensitivity of the probe assay was superior to that of light m...
Evidence for non-siderophore-mediated acquisition of transferrin-bound iron by Pasteurella multocida. Two clinical isolates of Pasteurella multocida associated with bovine pneumonia were examined for iron acquisition. Both isolates were capable of obtaining iron for growth from bovine but not from human, avian, equine or porcine transferrin. This correlated with specific binding of bovine transferrin by iron-limited cells or isolated membranes. No siderophore was detected in the strains by a general screening assay. In response to iron-limited conditions, a number of high molecular mass iron-regulated outer membrane proteins were produced including an 82 kDa receptor protein which was affinity...
An outbreak of equine neonatal salmonellosis. An outbreak of salmonellosis in foals occurred on a large Thoroughbred farm in California. Only foals less than 8 days of age exhibited clinical signs, which included depression, anorexia, and diarrhea. Three foals died from septicemia. The agent responsible was Salmonella ohio, which is rarely involved in salmonellosis in horses. During the course of the outbreak, S. ohio was isolated from 27 of 97 mares (27.8%) and 34 of 97 foals (35.1%). Mares were the presumed source of infection for foals. The absence of clinical signs in mares allowed for increased exposure of foals through environmental...
Neutralization of HIV-1: a paradox of humoral proportions. The production of immunoglobulin capable of neutralizing the infectivity of a virus represents one of the most remarkable molecular accomplishments of the host's available immune defenses. It should be no surprise that a virus that has existed in the parenchyma of the immune system has evolved as an equally dynamic molecule (i.e., viral envelope) for survival. Neutralizing immunoglobulin (Ig) can best serve the host under conditions where the invading pathogen requires a well-defined cell-free state for establishing an infection or transmission. Evidence for a controlling and therefore protect...
[Detection of bovine papillomavirus DNA in equine sarcoids using the polymerase chain reaction (PCR)]. Unfixed and formalin-fixed frozen sections and paraffin-sections of histopathologically confirmed sarcoids of 20 horses were studied in the PCR. The used set of primers was located in the E5 open reading frame fitting both to bovine papillomavirus 1 (BPV-1) and BPV-2. Independent of the quality of the used tissues BPV-DNA was detected in all 20 sarcoids. By cleaving with restriction endonuclease Bst XI it was shown that the DNA-sequences amplified by PCR were identical with that of BPV-1. The results support the general view that BPV play an important role in equine sarcoids.
[Immunopathogenesis of Borna disease]. An overview of the pathogenesis of Borna disease (BD) in rats as a model for the naturally occurring infection in horses and sheep is presented. Our findings revealed a virus infection in which a virus-specific T cell-mediated immune response leads to disease. The immune cells capable of mediating this immunopathological reaction were defined as helper/inducer T cells. In all, the described observations indicate that CD4+ T cells and macrophages trigger a delayed-type hypersensitivity reaction and cause BD together with other cells of the immune system.
Molluscum contagiosum in a horse. An adult stallion presented with a severe papular dermatitis of especially the neck, chest and genitalia. A marked scrotal oedema was present. Histopathological examination of skin biopsies, revealed the presence of numerous intracytoplasmic molluscum bodies in areas of focal epidermal hyperplasia. Electron microscopical examination showed the presence of typical pox virions in affected epidermal cells. Attempts at viral isolation were unsuccessful. This is believed to be the first reported case of molluscum contagiosum in a horse in the Republic of South Africa.
Molluscum contagiosum in three horses. Suspected molluscum contagiosum was diagnosed in 3 horses in the Chingola district of Zambia. The horses were found to be suffering from a slow progressive skin disease with lesions on the chest, shoulders, inner and lateral aspects of the fore- and hindlimbs, the face, fetlocks, pasterns and on the lateral surfaces of the body. The lesions varied from 4 to 20mm in diameter, were hairless but covered by soft keratin projections which, when removed, left a raw elevated base tightly adherent to the epidermis. These lesions bled profusely when the animals were groomed. Older lesions were well cir...
Equine arteritis virus is not a togavirus but belongs to the coronaviruslike superfamily. The nucleotide sequence of the genome of equine arteritis virus (EAV) was determined from a set of overlapping cDNA clones and was found to contain eight open reading frames (ORFs). ORFs 2 through 7 are expressed from six 3'-coterminal subgenomic mRNAs, which are transcribed from the 3'-terminal quarter of the viral genome. A number of these ORFs are predicted to encode structural EAV proteins. The organization and expression of the 3' part of the EAV genome are remarkably similar to those of coronaviruses and toroviruses. The 5'-terminal three-quarters of the genome contain the putative EAV p...
Equine helminth infections: control by selective chemotherapy. A programme of selective anthelmintic therapy was used in a herd of 31 horses. Faecal egg counts were done during the months of September, November, January, March, May and the following September. Horses with greater than or equal to 100 eggs per gram (epg) were treated with ivermectin, and those with less than 100 epg were not treated. The criteria for adequate internal parasite control in the herd was a median herd faecal egg count of less than or equal to 100 epg. Effectiveness of selective therapy was assessed by faecal egg count after nine months of treatment and was determined to be ade...
[Possibilities of clinico-cytological diagnosis in contagious equine metritis (CEM)]. Clinical, bacteriological and serological examinations on a 6 years old pony mare were performed. Cytological alterations in the genital tract were also recorded. A cellular reaction was seen after infection with T. equigenitalis. This reaction is an evidence for infection but it is not specific for this organism. Cytological studies should be performed on mares especially in cases of latent infections to complete bacteriological examination and to prevent false positive or negative results.
