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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.
Eosinophilic keratoconjunctivitis in a horse. An 11-year-old Quarter Horse gelding was evaluated because of a persistent, raised band of 1- to 2-mm subepithelial plaques of the left cornea. Cytologic examination of corneal scrapings revealed numerous eosinophils and segmented neutrophils, with few mast cells, plasma cells, and lymphocytes. Bacteriologic culture yielded sparse growth of alpha-hemolytic Streptococcus and Staphylococcus spp. Histologically, the plaques consisted of subepithelial foci of fragmented and degenerated collagen fibers infiltrated by eosinophils and neutrophils, with few lymphocytes, plasma cells, and macrophages. ...
Presence of African horse sickness virus in equine tissues, as determined by in situ hybridization. In a retrospective study, a negative-sense digoxigenin-labeled RNA probe, corresponding to the gene encoding nonstructural protein-1 of African horse sickness virus (AHSV) serotype 4, was applied to formalin-fixed, paraffin-embedded tissue taken from horses in the terminal stages of infection with AHSV. Fifteen infected ponies and one noninfected control were studied. Ponies exhibited a range of clinical signs and lesions. Thirteen ponies were infected with serotype 4, one with serotype 1, and one with serotype 2. Ponies were monitored clinically and euthanatized when severely clinically ill. ...
Distribution of equid herpesvirus-1 (EHV-1) in respiratory tract associated lymphoid tissue: implications for cellular immunity. Twelve adult ponies and 2 conventional foals were exposed intranasally to EHV-1, strain Ab4 (TCID50 10(-6.6) and samples of respiratory tract associated lymphoid tissues were recovered between 12 h and 13 days after infection. Infectious virus was detected in tissue homogenates using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry on paraffin sections. The results showed both infectious EHV-1 and viral antigens in respiratory tract associated lymph nodes 12 h after exposure. Infected leucocytes were identified morphologi...
Structural protein relationships among eastern equine encephalitis viruses. We have re-evaluated the relationships among the polypeptides of eastern equine encephalitis (EEE) viruses using SDS-PAGE and peptide mapping of individual virion proteins. Four to five distinct polypeptide bands were detected upon SDS-PAGE analysis of viruses: the E1, E2 and C proteins normally associated with alphavirus virions, as well as an additional more rapidly-migrating E2-associated protein and a high M(r) (HMW) protein. In contrast with previous findings by others, the electrophoretic profiles of the virion proteins of EEE viruses displayed a marked correlation with serotype. The pro...
Disseminated equine herpesvirus-1 infection in a two-year-old filly. No abstract available
Hosts of Lutzomyia shannoni (Diptera: Psychodidae) in relation to vesicular stomatitis virus on Ossabaw Island, Georgia, U.S.A. Hosts of Lutzomyia shannoni Dyar, a suspected biological vector of the New Jersey serotype of vesicular stomatitis (VSNJ) virus, were determined using an indirect enzyme-linked immunosorbent assay (ELISA) of 333 blood-fed female sandflies collected from their diurnal resting shelters on Ossabaw Island, Georgia, U.S.A. Sandflies had fed primarily on white-tailed deer (Odocoileus virginianus) (81%) and to a lesser extent on feral swine (Sus scrofa) (16%), two species of host infected annually with VSNJ. Other hosts were raccoons (Procyon lotor) and horses (Equus caballus) or donkeys (E. asinus),...
Endocarditis and pulmonary aspergillosis in a horse. No abstract available
[Eumycotic mycetomas in horses caused by Curvularia verruculosa]. The fungus Curvularia verruculosa, which produces eumycotic mycetomas, was isolated from skin of horses with granulomatous lesions on the legs. The isolation was made in Sabouraud dextrose agar medium. The horses came from Comandante Fontana suburb, Formosa-Argentina. This finding would be the first report of Curvularia in horses in Argentina.
Characterization and identification of Vagococcus fluvialis strains isolated from domestic animals. Strains of Vagococcus fluvialis, a species of Gram-positive catalase-negative cocci, related to the genera Enterococcus and Carnobacterium, were isolated from various lesions of pigs, from lesions and tonsils of cattle and cats and from tonsils of a horse. Most lesion strains were isolated in mixed culture from animals with disease conditions unrelated to coccal infection. Certain differences with the species description of Vagococcus fluvialis were found: only a proportion of the strains was motile; many strains gave positive reactions to Voges-Proskauer, alkaline phosphatase and leucine aryl...
Monocyte maturation controls expression of equine infectious anemia virus. In vivo, equine infectious anemia virus (EIAV) replicates in tissues rich in macrophages, and it is widely believed that the tissue macrophage is the principal, if not sole, cell within the host that replicates virus. No viral replication has been detected in circulating peripheral blood monocytes. However, proviral DNA can be detected in these cells, and monocytes may serve as a reservoir for the virus. In this study, an in vitro model was developed to clarify the role of monocyte maturation in regulating EIAV expression. Freshly isolated, nonadherent equine peripheral blood monocytes were in...
Characterization of a novel streptokinase produced by Streptococcus equisimilis of non-human origin. Streptokinases are proteins with plasminogen activator activity produced by certain hemolytic streptococci. We previously identified equine streptococcal isolates which produced streptokinases (ESKs) that bound both human and equine plasminogen but only readily activated equine plasminogen (14). This property was exploited to purify a representative ESK produced by Streptococcus equisimilis strain 87-542-W. Affinity chromatography with human plasminogen resulted in the isolation of a M(r) approximately 49,000 molecule with two isoforms. This ESK was subsequently compared to well characterized ...
[Tapeworms, a problem in equine practice?]. This paper gives a survey on biology and ecology of equine tapeworms as well as on pathogenesis, clinics, diagnosis, therapy, and prophylaxis of tapeworm infections.
[Epidemiology of melioidosis in China]. From 1975 to 1989, a total of 73 strains of P. pseudomallei was isolated from the water samples and the pathological samples of human and domestic animals in 13 counties and cities located different latitude from four provinces Qiong, Yue, Gui and Xiang in China. Serological investigation demonstrated that the geographical distribution of the organism had a significant correlation with the positive rate of antibodies against P. pseudomallei and the native foci of the organisms distributed over the southern subtropical zone and the edge of tropical zone in Qiong, Yue and Gui. In endemic areas, ...
Equine rotaviruses with G14 serotype specificity circulate among venezuelan horses. Two group A rotavirus strains isolated from diarrheic foals in Venezuela were classified as belonging to G14 serotype by cross-neutralization tests and on the basis of the homology of the sequenced VP7 gene. This report confirms that rotavirus strains of G14 serotype specificity circulate among equine populations.
Titers to Leptospira species in horses in Alberta. Sera from horses in Alberta, submitted to Agriculture and Agri-Food Canada for routine testing for equine infectious anemia from January 1987 to June 1989, were tested for antibody against 13 serovars of pathogenic Leptospira spp., using the microscopic agglutination test. The purpose of the study was to investigate the prevalence of serum titers to those serovars in horses in Alberta, and to analyze the associated risk factors. Descriptive statistics were compiled and logistic regressions were computed. Titers to L. interrogans serovars icterohaemorrhagiae, bratislava, copenhageni, and autumn...
Histopathology of the brain-stem nuclei of horses with “Mal seco”, an equine dysautonomia. "Mal seco" is a disease of unknown aetiology affecting horses in Argentina. It is similar to grass sickness, a primary dysautonomia of horses in Europe. A histopathological study of the brain stem nuclei of three horses with "mal seco" was performed. Changes were found that consisted of chromatolysis, cytoplasmic vacuoles, eosinophilic sphaeroids, and pyknotic and eccentric nuclei. These changes were most severe at the oculomotor, vestibular and abducent nuclei. The results provide further evidence to suggest that "mal seco" and grass sickness may be the same disease.
Survival and replication of Rhodococcus equi in macrophages. Rhodococcus equi is a facultative intracellular bacterium of macrophages that can cause serious pneumonia in both young horses and immunocompromised people. Essential to understanding rhodococcus pathogenesis is a quantitative documentation of the intracellular events that follow macrophage phagocytosis of the organism. By using a bacterial immunofluorescence staining assay, we verified the intracellular survival and replicative potential of R. equi in both murine peritoneal macrophages and equine alveolar macrophages in vitro. Following an initial lag period of 6 to 12 h, the intracellular nu...
Rapid diagnosis of equine influenza by the Directigen FLU-A enzyme immunoassay. The Directigen FLU-A enzyme immunoassay was tested for its ability to detect equine-2 influenza viruses in nasopharyngeal fluids from horses and ponies. A total of 125 swabs from experimental infections and from different sources of natural infection in the USA and Hong Kong were examined. The assay results were compared with the results of standard virus culture in embryonated chicken eggs or Madin-Darby canine kidney cells, and with the serology of the horses sampled. In comparison with virus culture the enzyme immunoassay exhibited 83 per cent sensitivity, 78 per cent specificity, 70 per ce...
Pituitary abscess and basilar empyema in 4 horses. Abscess of the pituitary gland is a rare condition which has been
described in man (Domingue and Wilson 1977; Ahmed et al. 1989),
ruminants (Taylor and Meads 1963; Moriwaki er al. 1973; Lomas and
Hazell 1983; Perdrizet and Dinsmore 1986) and one horse
(Rumbaugh 1977). The some of infection may be either direct
extension from an adjacent focus or haematogenous spread from a site
elsewhere in the body. In man, pituitary abscess may result from
meningitis, sphenoid sinusitis (Selose et al. 1980), and osteomyelitis
(Rongetti and Daniels 1950). A review of 20 cases of pituitary abscess
in ...
Detection of Ehrlichia risticii from feces of infected horses by immunomagnetic separation and PCR. Potomac horse fever, caused by Ehrlichia risticii, is an important disease of equines. The major features of the disease are fever, leukopenia, and diarrhea. The organism has been detected from the blood mononuclear cells of infected horses, but its presence in the feces has not been known. A method for immunomagnetic separation of E. risticii from the feces of infected horses was developed, and the separated organisms were detected by PCR. Coating immunomagnetic beads (Dynabeads) with a 1:5 dilution of rabbit anti-E. risticii serum and incubating the Dynabeads with fecal samples for 25 min at...
[Equine infectious arteritis: molecular biology, epidemiology and preventative measures]. After a brief historical account of the outbreak of infectious arteritis of horses which occurred in 1984 in Kentucky (United States of America), the author reports on the present state of knowledge concerning the organisation of the genome of the virus. Clinical signs of the disease are described, as well as modes and routes of transmission. Finally, currently-available vaccination procedures are discussed and their value is assessed.
[Sporotrichosis in a horse]. A 9-year old male Arabian horse was referred to the Department of Large Animal Surgery of the University of Utrecht because of multiple nodules on the inner side of the right hind leg. The nodules seemed to follow a cutaneolymphatic pattern. Histopathology of a nodule showed a granulomatous inflammation with the presence of multinucleated giant cells. In PAS- and Grocott-stained sections, spheroid yeast-like organisms with some budding were found throughout the tissue. A preliminary diagnosis of sporotrichosis was made. A fresh nodule was cultured and the presence of Sporothrix c.f. schenckii ...
African horse sickness and the overwintering of Culicoides spp. in the Iberian peninsula. The presence at different latitudes and the seasonal distribution of two known or potential vectors of African horse sickness (AHS) virus--Culicoides imicola and C. obsoletus--were investigated in the Iberian peninsula using light trap collections. Culicoides imicola was present as far north as 41 degrees N but not at 43 degrees N (Asturias, Spain), whereas C. obsoletus was found at all latitudes. In the northern part of the distribution of C. imicola, adults of this species were present for only a few months of the year, but adults were continually present further south. Culicoides obsoletus ...
Mycoflora of the toxic feeds associated with equine leukoencephalomalacia (ELEM) outbreaks in Brazil. The mycoflora of 39 feed samples associated with 29 Equine Leukoencephalomalacia (ELEM) outbreaks was studied from 1988 to 1990, in Brazil. Microbiological examination indicated Fusarium spp. as the most frequent mold which occurred in 97.4% of samples followed by Penicillium spp. in 61.5% and Aspergillus spp. in 35.9%. The moisture content of feed implicated in death of horses was above 15% which can favor the development of Fusarium spp. From the genus, F. moniliforme was the predominant species with an occurrence of 82.0%. Two additional species, not commonly associated with animal toxicosi...
Eastern equine encephalomyelitis virus in relation to the avian community of a coastal cedar swamp. Eastern equine encephalomyelitis virus (EEEV) is perpetuated in eastern North America in a mosquito-wild bird maintenance cycle that involves Culiseta melanura (Coquillett) as the principal enzootic vector and passerine birds as the primary amplifying hosts. We examined the role of birds in the EEEV cycle at a site in southern New Jersey where EEEV cycles annually at high levels. Birds and mosquitoes were sampled during three epiornitics and one season of limited virus activity. We examined antibody prevalence in birds in relation to eight physical and natural history characteristics. Our goal...
Monoclonal antibodies to equine arteritis virus proteins identify the GL protein as a target for virus neutralization. Monoclonal antibodies (MAbs) to equine arteritis virus (EAV) proteins were produced and characterized. The protein specificities of eight MAbs were determined definitively by immunoprecipitation of EAV proteins expressed from vaccinia virus recombinants (VVRs). Included were two new VVRs produced for this study, expressing the M and the GL proteins, respectively. Three MAbs were determined to be N-specific and five MAbs recognized the GL protein. One GL-specific MAb, 17F5, of the IgA class, efficiently neutralized EAV infectivity. In competitive binding assays (CBAs), the N-specific MAbs defin...
