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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 two serotypes of equine adenovirus from horses in New Zealand. Two serologically unrelated adenoviruses were isolated from ill-thrifty young horses on a thoroughbred stud. The viruses differed in their cytopathic effects in cell culture and in their haemagglutination properties. A serological survey of horses in the northern half of the North Island showed the prevalence of precipitating antibodies against equine adenoviruses to be 39%.
Observation on the morphology of contagious equine metritis bacterial colonies isolated from infected pony mares. In uterine or cervical specimens obtained from pony mares infected with streptomycin-resistant contagious equine metritis bacteria, several colonies of the bacteria which differed in morphologic characteristics were recognized during their primary isolation on Eugon chocolate agar and tryptose chocolate agar plates. The differences were usually not observed until plates were incubated 10 to 15 days. On Eugon chocolate agar plates, smooth colony, sandy colony with rings, and colony with blebs were recognized. On tryptose chocolate agar plates, only a round smooth convex colony was observed. By ...
Isolation of a retrovirus from cultured equine sarcoid tumor cells. A virus with the morphologic and biochemical properties of the family Retroviridae has been isolated from cultured cells explanted from a malignant tumor induced by intradermal inoculation of equine sarcoid cells into a combined immunodeficient Arabian foal. By electron microscopy, intracytoplasmic, extracellular, and budding particles measuring 89 to 120 nm with electron-lucent cores were seen. Virus purified from the medium of cultured cells had a buoyant density of 1.15 g/cm3 in isopycnic sucrose-gradient centrifugation, incorporated radiolabeled uridine but not thymidine, and had constitut...
Serological investigation of horse sera for antibodies against mycoplasmas and acholeplasmas. Sera from horses with respiratory disease (RD) have been investigated using the complement fixation test, indirect hemagglutination test, enzyme immune assay, and the metabolic inhibition test, and sera from mares after abortion, using the complement fixation test, indirect hemagglutination test and enzyme immune assay, for antibodies against Mycoplasma equirhinis, M subdolum, M. equigenitalium, M. pulmonis, M. felis, Acholeplasma laidlawii, A. hippikon and A. equifetale. Antibodies were found against all mycoplasma and acholeplasma species tested, more often against acholeplasmas. The antibod...
Epidemiological significance of Venezuelan equine encephalomyelitis virus in vitro markers. One hundred and fifty-eight strains of Venezuelan equine encephalomyelitis virus were typed antigenically and classified epidemiologically as either epizootic or enzootic. Plaque sizes for 148 of these strains were determined, and the pH requirements for hemagglutination (HA) of goose erythrocytes of 131 were studied. Only antigenic variant group IABC strains could be classified epidemiologically as epizootic. In vitro these strains were characterized by the formation of small plaques in Vero cells and a relatively narrow pH range for optimum HA reactivity. Experimental studies in horses confi...
Live temperature-sensitive equine influenza virus vaccine: generation of the virus and efficacy in hamsters. Temperature-sensitive (ts) reassortants of an equine influenza virus, subtype A-1, were produced by mating a human influenza ts donor virus with an equine influenza A/Cornell/16/74 wild-type virus and by isolating a ts reassortant virus possessing the equine hemagglutinin and neuraminidase surface antigens. Two equine its reassortant clones, 8B1 and 71A1, were produced which had an in vitro shutoff temperature for plaque formation of 38 and 37 C, respectively. The human ts donor virus had ts mutation(s) on the polymerase 3 (P3) and nucleoprotein genes so that a ts equine reassortant virus coul...
Haematological changes in 2 ponies before and during an infection with equine influenza. MOST viral infections in animals, including man, have been
shown to alter the absolute and relative numbers of circulating
leucocytes. This usually causes a lymphopenia or neutropenia
but, occasionally, a lymphocytosis occurs (Gresser and Lang
1966). Several studies and reviews of respiratory viral
infections in horses have noted changes in the blood pictures
of infected animals, particularly during the early stages of the
disease (Steck and Gerber 1965; Gerber 1966, 1969; Bryans
and Gerber 1972; Hofer, Steck and Gerber 1978). The
transient nature of the leucocyte response is, probabl...
Equine abortion associated with Enterobacter agglomerans. During a 20 month period Enterobacter agglomerans was
isolated from 17 cases of equine abortion. In 8 cases E
agglomerans was isolated in pure culture and in 9 cases it was
isolated in mixed culture from the foetus and/or foetal
membranes. Fifteen cases had histological evidence of foetal
infection and/or placentitis.
The occurrence of E agglomerans in pure culture, associated
with inflammatory lesions in the foetus and foetal membranes,
suggests it to be a cause of abortion in mares.
Survey of equine hydatidosis in Great Britain. A survey of 1141 horses and ponies, for the presence of hydatid infection, was carried out at an export meat plant near Bristol. Lesions were attributed carefully by morphological, histological and immunological examinations and assessed by flame cell activity. All available detail concerning the animals was recorded. The surveys in the literature were assessed for the criteria on which their figures were based and were compared with the findings of this present survey. Attention was drawn to the apparent discord between the results of some surveys and others.
Intussusception associated with Anoplocephala perfoliata infection in five horses. Intussusception associated with Anoplocephala perfoliata infection was found in 5 horses. The unusual types of intussusception and the presence of tapeworms at the leading edge of the intussuscipiens suggested tapeworms as the cause of the problem. Lesions attributable to tapeworm attachment on the mucosa were found to fit a mechanical model of intussusception. Treatment of two of the horses and some of their pasturemates with pyrantel pamoate caused elimination of intact tapeworms.
Antigenic stimulation of T lymphocytes in chronic nononcogenic retrovirus infection: equine infectious anemia. Equine infectious anemia is a chronic disease of horses caused by a nononcogenic retrovirus. Studies were undertaken to determine the types of cells involved in the in vitro lymphoproliferative response to viral antigens and the dynamics of this reaction. It was observed that reactive lymphocytes were present at unpredictable times in the peripheral blood of infected horses. This reaction was shown to be specific for the interaction of equine infectious anemia virus and T lymphocytes. Enriched B-lymphocyte populations did not divide when exposed to equine infectious anemia virus. Macrophages w...
Comparative measurement of equine influenza virus antibodies in horse sera by single radial hemolysis, neutralization, and hemagglutination inhibition tests. Single radial hemolysis (SRH), neutralization (NT), and hemagglutination inhibition (HI) tests were carried out on sera from horses immunized against the Prague and Miami strains of equine influenza virus. The HI and NT tests demonstrated good sensitivity; the sensitivity of the SRH test was somewhat lower. The NT titers of individual sera were correlated very closely with the HI titers, although the NT titers were higher. SRH zone diameters of individual sera also showed significant correlation with the NT and NI titers. The SRH test appears to be suitable for large-scale serological surveys ...
Isolation of an adenovirus antigenically distinct from equine adenovirus type 1 from diarrheic foal feces. Adenovirus was isolated in equine fetal kidney cell cultures from the feces of 2 foals with diarrhea that also had large numbers (greater than 10(6)/g) of rotavirus particles in their feces. Unlike equine adenovirus type 1 (EAdV1), the fecal EAdV did not hemagglutinate human O, rhesus macaque, or equine RBC. By serum neutralization, the fecal viruses were identical with each other, but showed no relationship to EAdV1. Antiserum prepared against the fecal viruses did not contain hemagglutination-inhibiting antibody to EAdV1. It is proposed that the fecal viruses be considered prototypic of EAdV...
Detection of equine infectious anemia virus in a horse with an equivocal agar gel immunodiffusion test reaction. A horse whose serum reacted equivocally in the agar gel immunodiffusion (AGID) test for equine infectious anemia was studied over a 3-year period. The horse remained afebrile and virus was detected in only 1 of 6 horse inoculation tests. The intensity of AGID test reactions increased temporarily following this evidence for virus. Although the AGID test reaction was equivocal and 5 of the 6 transmission attempts failed, the 1 successful transmission proved the horse was infected.
Identification of immunoglobulin heavy-chain isotypes of specific antibodies of horse 46 group B meningococcal antiserum. Hyperimmune horse serum from a single animal (horse 46) immunized with group B (strain B-11) meningococcal vaccine provides a standardized, readily available diagnostic reagent used in primary isolation medium and for serogrouping of meningococci. Identification of the heavy-chain isotypes of specific anticapsular polysaccharide and anti-lipopolysaccharide isolated from horse 46 serum revealed a differential distribution in the occurrence of immunoglobulin classes. Meningococcal anticapsular antibodies of horse 46 serum were restricted predominately to the immunoglobulin M (IgM) class, with on...
Capsular serotypes of Rhodococcus equi. One hundred strains of Rhodococcus equi from various animal species and sources in Australia were examined for capsular serotype. Eighty-four of the strains fell into the existing 7 serotypes, and just under half of the strains belonged to serotype 1. Isolates from the intestines and faeces of horses, cattle, pigs and other species, and from soil, were found to belong to the same serotypes as those recovered from the lungs of foals with R. equi pneumonia. There was no clear relationships between capsular serotype and source of origin of the isolates.
Teratological effects of western equine encephalitis virus on the fetal nervous system of Macaca mulatta. Fetal rhesus monkeys were inoculated intracerebrally with an attenuated strain of western equine encephalitis virus. All animals developed microcephaly. Twelve of sixteen monkeys developed ex vacuo hydrocephalus. All virus inoculated fetuses developed WEE virus antibody. Virus could not be recovered at the time of delivery. Monkeys with the highest WEE antibody titers showed the greatest degree of hydrocephalus.
Transmission of equine infectious anemia virus from horses without clinical signs of disease. Twenty seven adult horses positive to the agar gel immunodiffusion (AGID) test for equine infectious anemia (EIA), but with no history of clinical EIA, were used in transfusion studies to determine whether infectious EIA virus was present in 1 to 5 ml of their blood. Of 27 recipients, 21 (78%) became AGID test-positive at an average of 24 days after inoculation. Two horses that were initially negative when screened were retested and found to carry infectious virus in 5-300 ml of whole blood; the other 4 horses were not retested. Horse flies (Tabanus fuscicostatus Hine) were unable to transmit ...
Radioimmunoassay for the detection of antigen-specific IgM, IgG, and IgA in equine sera. A radioimmunoassay was developed to discriminate immunoglobulin (Ig) classes specific for the J-5 mutant of Escherichia coli (serotype O:111-B4). Adult horses were periodically inoculated IM with a nonviable suspension of the J-5 mutant emulsified in Freund's incomplete adjuvant. Before and after the horses were inoculated, sera were collected sequentially and examined by radioimmunoassay. Rabbit anti-(horse) Ig and [125I]protein A served as the indicator system. Antigen-specific IgM, IgG, and IgA were observed to follow a classic immune response. The radioimmunoassay offers a valuable tool fo...
