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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.
Extended x-ray absorption fine structure studies of a retrovirus: equine infectious anemia virus cysteine arrays are coordinated to zinc. Zinc finger arrays have been established as a critical structural feature of proteins involved in DNA recognition. Retroviral nucleocapsid proteins, which are involved in the binding of viral RNA, contain conserved cysteine-rich arrays that have been suggested to coordinate zinc. We provide metalloprotein structural data from an intact virus preparation that validate this hypothesis. Extended x-ray absorption fine structure (EXAFS) spectroscopy of well-characterized and active preparations of equine infectious anemia virus, compared with a peptide with known coordination and in combination wit...
Renal dysfunction associated with infection of Leptospira interrogans in a horse. Renal failure associated with infection of Leptospira interrogans was detected in a horse. Fever, leukocytosis, pyuria, isosthenuria, and azotemia were suggestive of an inflammatory urinary tract disease. Despite persistent pyuria, no bacteria were found during routine microscopic examinations or bacteriologic culturing of urine. A fluorescent antibody examination of the urine was positive for L interrogans. Serologic testing during a 6-month period, supported an acute infection with L interrogans serovar pomona. Treatment with intravenously administered fluids and antimicrobials resulted in c...
Immunoblot analysis of the humoral immune response to Pythium insidiosum in horses with pythiosis. Reactions to Pythium insidiosum by sera from horses with active pythiosis were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Five strains of P. insidiosum were grown in nutrient broth and then sonicated. After centrifugation, supernatant antigens were separated by SDS-PAGE. An exoantigen of Conidiobolus coronatus was also tested. Bands with molecular weights between 97,000 and 14,000 were identified by Coomassie blue and silver staining. After being transferred to nitrocellulose, the antigens were reacted against sera from six horses w...
Structural proteins of equine arteritis virus. We have recently shown that the genome of equine arteritis virus (EAV) contains seven open reading frames (ORFs). We now present data on the structural proteins of EAV and the assignment of their respective genes. Virions are composed of a 14-kDa nucleocapsid protein (N) and three membrane proteins designated M, GS, and GL. M is an unglycosylated protein of 16 kDa, and GS and GL are N-glycosylated proteins of 25 and 30 to 42 kDa, respectively. The broad size distribution of GL results from heterogeneous N-acetyllactosamine addition since it is susceptible to digestion by endo-beta-galactosidas...
Equine herpesvirus 5: comparisons with EHV2 (equine cytomegalovirus), cloning, and mapping of a new equine herpesvirus with a novel genome structure. A new equine herpesvirus, provisionally designated equine herpesvirus 5 (EHV5; Browning and Studdert (1987) J. Gen. Virol. 68, 1441-1447), was examined for the degree of genomic difference from equine herpesvirus 2 (EHV2) by Southern hybridizations. EHV5 and EHV2 whole genomic DNA probes were highly specific for homologous DNA only, indicating that significant genomic difference exists between the two viruses. Restriction endonuclease analysis of EHV5 strain 2-141 (EHV5.2-141) revealed that the genome is 179 kb and exists as a single isomer. Clones representing 82% of the genome were obtained ...
Phylogenetic analysis of alphaviruses in the Venezuelan equine encephalitis complex and identification of the source of epizootic viruses. We studied the evolution of alphaviruses in the Venezuelan equine encephalitis (VEE) complex using phylogenetic analysis of RNA nucleotide sequences from limited portions of the nsP4, E1, and 3' untranslated genome regions of representative strains. The VEE complex constituted a monophyletic group of viruses (descended from a common ancestor); some serologic VEE varieties such as subtype III formed monophyletic groups while subtype I did not. Subtype II Everglades and variety ID enzootic viruses formed a monophyletic group which also included all epizootic variety IAB and IC VEE isolates. Ever...
Animal immunodeficiency viruses. Feline immunodeficiency virus (FIV) has morphological, physical and biochemical characteristics similar to human immunodeficiency virus (HIV), the cause of AIDS in man. However, it is antigenically and genetically distinct from HIV; an antigenic relatedness with equine infectious anaemia virus has been demonstrated. FIV has been molecularly cloned and sequenced. Diagnostic tests are commercially available and attempts at preparing inactivated, subunit and molecularly engineered vaccines are being made in different laboratories. During FIV infection a transient primary illness can be recognized...
Cross-reactivity of existing equine influenza vaccines with a new strain of equine influenza virus from China. A novel strain of equine influenza virus, influenza A/equine/Jilin (China)/1/89, has emerged which is genetically distinct from all earlier strains of equine influenza. It is therefore possible that the vaccines against equine influenza may be unable to protect horses against disease caused by this virus strain. In vitro serological assays established that there were low levels of immunological cross-reactivity between the new virus, the current vaccine strains and the strains of equine-2 influenza virus now in circulation.
Equine protozoal myelitis in Panamanian horses and isolation of Sarcocystis neurona. Schizonts of Sarcocystis neurona were identified microscopically in hematoxylin-eosin-stained spinal cord sections from 2 native Panamanian horses that exhibited clinical signs of equine protozoal myelitis (EPM). Spinal cord homogenate from a third Panamanian horse with EPM was inoculated onto monolayers of cultured bovine monocytes (M617). Intracytoplasmic schizonts containing merozoites arranged in rosette forms surrounding a central residual body first were observed 13 wk postinoculation. Parasites divided by endopolygeny and lacked rhoptries. Schizonts from each horse reacted with Sarcocys...
Measurement of the cytotoxic effects of different strains of Mycoplasma equigenitalium on the equine uterine tube using a calmodulin assay. The cytopathic effects induced by five strains of Mycoplasma equigenitalium for cells of equine uterine tube explants were tested by measuring changes in cellular and extracellular concentrations of calmodulin (CaM). Calmodulin concentrations in samples of total homogenate (TH) and total homogenate supernates (THS) of the infected equine uterine tube explants were significantly lower than respective measurements on noninfected controls. In tissue culture medium fractions (TCM) of some infected explants, CaM concentrations were significantly higher than noninfected controls (p > 0.95). The r...
Seroprevalence of antibodies to Borrelia burgdorferi in a population of horses in central Texas. Four hundred sixty-nine serum samples were obtained from horses admitted to the internal medicine service of the Texas Veterinary Medical Center between Jan 1 and Dec 31, 1990. Serum samples were tested by ELISA for antibody to Borrelia burgdorferi. Of these 469 samples, 1 (0.2%) was repeatedly seropositive for the organism by ELISA. Confirmatory testing by protein immunoblot was negative. The observed seroprevalence was 0%; the upper bound of the 95% confidence interval was 0.6%. These findings indicate the evidence of infection with B burgdorferi is presently uncommon in horses in central Te...
C3 fixed in vivo to cornea from horses inoculated with Leptospira interrogans. C3 was detected bound in vivo to the opaque cornea of horses inoculated with killed Leptospira interrogans. Employing epithelial corneal cells isolated from a monolayer in tissue culture, we proved that C3 is fixed in vitro to the intact cell surface after incubation with a fresh equine anti-Leptospira serum. These findings, in addition to the infiltration of cornea with neutrophils and lymphocytes, may explain the mechanisms of tissue damage in recurrent uveitis of horses with leptospirosis.
Sarcocystis neurona-associated ataxia in horses in Brazil. Sarcocystis neurona-like schizonts were found in sections of brain and spinal cord of two ataxic horses from Brazil. The diagnosis was supported by staining with anti-Sarcocystis serum in an immunohistochemical test. One of the affected horses was born in Argentina and raised in Brazil, and the other horse was born and raised in Brazil.
Serological responses of specific pathogen-free foals to equine herpesvirus-1: primary and secondary infection, and reactivation. Serum antibody (virus neutralisation, complement fixation, IgM and IgG) responses to equine herpesvirus-1 (EHV-1) infection were measured in six foals which were initially free from EHV-1 and EHV-4 infection and maternally-derived antibodies. Following primary infection, high titres of virus neutralisation and complement fixation antibodies were detectable against EHV-1, however, corresponding antibody levels against EHV-4 were low or inapparent, although the two viruses share a number of cross-reactive epitopes. In addition, following the primary infection with EHV-1, IgM levels increased bef...
Retrospective evaluation of factors associated with the risk of seropositivity to Ehrlichia risticii in horses in New York State. A retrospective study was designed to determine the distribution of equine monocytic ehrlichiosis among the equine population in New York state, and to identify factors associated with risk of disease. Serum samples submitted to the diagnostic laboratory of the university during the period from January 1985 through December 1986 were examined for antibodies to Ehrlichia risticii, using the indirect fluorescent antibody technique. Factors evaluated included geographic origin and date of submission of the sample, and age, breed, and sex of the horse. Logistic regression analysis was used to iden...
Serological evidence of equine herpesvirus type 1 (EHV-1) activity in polo horses in Nigeria. Serological evidence of Equine Herpes virus type 1 (EHV-1) activity in Polo horses in Nigeria is reported for the first time. Eighty-two percent of horses tested with known antigen had precipitating antibodies to EHV-1 while 43% of sera tested against antigen prepared from nasal discharges were positive suggesting that the virus was being excreted in the nasal discharges and probably acting as a source of infection for incontact animals as occurs in on-going acute infections. The result of this study indicates a high prevalence of EHV-1 activity among Polo horses in Nigeria and demonstrates th...
[Legionella antibodies in domestic animals]. Serological examination of 420 domestic animals for the presence of antilegionella antibodies indicates their high exposure to legionellae. On examination by the microagglutination reaction with a serum dilution of 1:64 or more the highest positive values were recorded in horses which reacted with antigens of L. pneumophila 1-14 in 36.2% and with antigens of another 19 types of legionellae in 47.8%. In pigs positive values recorded in 16.2% and in 21.1%; in cattle in 3.8% and 29.5%, in sheep in 7.5% and 11.3% and laboratory rabbits were quite negative. The importance of these findings with reg...
Acholeplasma multilocale sp. nov., isolated from a horse and a rabbit. Acholeplasma strains were isolated from the nasopharynx of a horse (strain PN525T [T = type strain]) and the feces of a rabbit (strain B1). One clone of strain PN525T and one clone of strain B1 were examined in detail. These clones were indistinguishable from each other and were serologically distinct from the previously described Acholeplasma and Mycoplasma spp. The strains had the following properties: guanine-plus-cytosine content of 31 mol%; sterol was not required for growth, which occurred under both aerobic and anaerobic conditions; glucose was metabolized; and arginine was hydrolyzed. ...
Coccidioidomycosis in horses: 15 cases (1975-1984). Fifteen confirmed cases of equine coccidioidomycosis that originated in California and Arizona were studied retrospectively. Age, breed, and sex varied among affected horses. The most common historical problems were chronic weight loss (53% of cases) and persistent cough (33% of cases). The most frequent physical examination abnormalities were related to the respiratory tract (60% of cases). In 27% of cases, horses had signs of musculoskeletal pain. Horses consistently had hyperproteinemia, hyperfibrinogenemia, leukocytosis, and neutrophilia. An antemortem etiologic diagnosis was made for 11 (...
Immunokinetics of equine herpesvirus 1 in donkey mares: suppression of secondary cell-mediated response. To study the immunokinetics of equine herpesvirus 1 (EHV1), donkey mares were immunised with a laboratory strain of EHV1, or with recommended doses of Pneumabort-K vaccine (EHV1 Army 183 strain, formalin-inactivated, with an oil adjuvant) and a booster was given after three months. Humoral immune responses were studied by employing a virus neutralisation (VN) test. A leucocyte migration inhibition test (LMIT) was employed for the assay of cellular immune responses. The VN antibody titre reached 1:64 or 1:128 after primary immunisation and showed a marginal increase (1:256) after secondary immu...
Identification of equine herpesvirus 4 glycoprotein G: a type-specific, secreted glycoprotein. Equine herpesvirus 4 (EHV4) glycoproteins of M(r) 63K and 250K were identified in the supernatant of infected cell cultures. The 63K glycoprotein was type-specific; that is, it reacted with monospecific sera from horses that had been immunized or infected with EHV4, but not with monospecific sera from horses immunized or infected with EHV1, a closely related alphaherpesvirus. It was postulated that the secreted protein may be the homologue of similarly secreted glycoproteins of herpes simplex virus 2 glycoprotein G (HSV2 gG) and pseudorabies virus (PRV) gX, which is the homologue of HSV2 gG. T...
Rapid detection of equine herpesvirus type-1 antigens in nasal swab specimens using an antigen capture enzyme-linked immunosorbent assay. An antigen capture enzyme-linked immunosorbent assay (ELISA) was developed for the detection of equine herpesvirus type-1 (EHV-1) antigens in nasal swab specimens. The test was designed as a solid phase, amplified sandwich assay in which an EHV-1 specific monoclonal antibody was used to capture virus antigen and polyclonal antisera used to detect antigen bound to the test plates. Eight monoclonal antibodies were tested for their ability to capture virus antigen and one was selected for routine use. The sensitivity and specificity of the ELISA was compared with that of virus isolation using swa...
The activity of (S)-1-[(3-hydroxy-2-phosphonyl methoxy) propyl] cytosine (HPMPC) against equine herpesvirus-1 (EHV-1) in cell cultures, mice and horses. The activity of the nucleotide analogue, (S)-1-[(3-hydroxy-2-phosphonyl methoxy) propyl] cytosine (HPMPC), against equine herpesvirus-1 (EHV-1) was tested in cell culture, mice and foals. The ED50 for plaque reduction was found to be 0.07 and 0.03 microgram/ml in RK-13 and EEL cells respectively. In mice, a single administration of HPMPC (20 mg/kg, s.c.) was very effective at reducing clinical signs and virus replication if given on the day before intranasal inoculation with EHV-1. Treatment on the day of infection or day 1 p.i. was less effective, but still significantly reduced clinical sign...
Genomic variability among globally distributed isolates of equine arteritis virus. Equine arteritis virus (EAV), a non-arthropod borne togavirus, has been shown to have a global distribution. To date, no major antigenic variation has been demonstrated between EAV isolates from different geographic origins. In this study, the genomic RNA of EAV isolates obtained from horses of different breeds in various countries around the world was oligonucleotide fingerprinted. Comparisons of these fingerprints were used to determine the extent of genomic variation among such isolates. Comparisons among isolates from North American horses revealed, for the most part, oligonucleotide homol...
