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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.
Evolution of the herpes thymidine kinase: identification and comparison of the equine herpesvirus 1 thymidine kinase gene reveals similarity to a cell-encoded thymidylate kinase. We have identified the equine herpesvirus 1 (EHV-1) thymidine kinase gene (TK) by DNA-mediated transformation and by DNA sequencing. Alignment of the amino acid sequence of the EHV-1 TK with the TKs from 3 other herpesviruses revealed regions of homology, some of which correspond to the previously identified substrate binding sites, while others have as yet, no assigned function. In particular, the strict conservation of an aspartate within the proposed nucleoside binding site suggests a role in ATP binding for this residue. Comparison of 5 herpes TKs with the thymidylate kinase of yeast revea...
Impact of climate on western equine encephalitis in Manitoba, Minnesota and North Dakota, 1980-1983. Information was collected on confirmed outbreaks of western equine encephalitis (WEE) in North America east of the Rockies for 1981 and 1983 (epidemic years) and 1980 and 1982 (non-epidemic years). The initial pattern of outbreaks in Manitoba, Minnesota and North Dakota was determined for each year. Backward (and in some instances forward) wind trajectories were computed for each day 4-15 days (incubation period) before the initial outbreaks of WEE in a given area of province or state. During these years the timing and location of WEE outbreaks in horses and man, seroconversion in chickens, th...
Identification of Highlands J virus from a Florida horse. A virus, strain 64A-1519, isolated from the brain of a horse dying of encephalitis in Florida in 1964, was identified as western equine encephalomyelitis (WEE) virus. Recently, we used polyclonal and monoclonal immune reagents to identify this isolate by comparing it to 2 strains of WEE virus and to Highlands J (HJ) virus in hemagglutination-inhibition, immunofluorescent antibody, and plaque-reduction neutralization tests. These tests demonstrate that strain 64A-1519 is a strain of HJ virus distinct from WEE virus.
Clinical and clinicopathologic findings in two foals infected with Bacillus piliformis. Bacillus piliformis infection (Tyzzer's disease) in foals is rarely observed clinically because of the peracute course of the disease. Clinical and clinicopathologic findings as well as information on therapeutic attempts in two foals are described. Clinicopathologic abnormalities common to both cases included leukopenia, hyperfibrinogenemia, metabolic acidosis, and hypoglycemia. Treatment was unsuccessful in both cases.
Studies on the effect of short term, high dose praziquantel treatment against protoscoleces of ovine and equine Echinococcus granulosus within the cyst, and in vitro. Protoscoleces of Echinococcus granulosus were subjected to high concentrations of praziquantel (10-1000 micrograms/ml medium or cyst fluid) for a short, 10 min duration in vitro or in situ within cysts. Drug efficacy was then monitored either by in vitro culture in drug-free medium and/or by passage into rodents. The in vitro test of effectiveness suggested that ovine-derived protoscoleces were more sensitive than those of equine origin, and that the in vitro method of treatment was more successful than that performed in situ. However, the subsequent passage of treated protoscoleces, whether i...
Non-isotopic immunoassay drug tests in racing horses: a review of their application to pre- and post-race testing, drug quantitation, and human drug testing. We have introduced large scale non-isotopic immunoassay testing into pre- and post-race drug testing in racehorses. The technologies utilized are Particle Concentration Fluorescence Immuno Assay (PCFIA) and the one-step Enzyme Linked Immuno Sorbent Assay (ELISA). These technologies are rapid, inexpensive, and highly effective. On introduction into post-race testing in the Western United States, these ELISA tests exposed several previously undetected patterns of drug abuse. The drugs detected were buprenorphine, oxymorphone, mazindol, sufentanil and cocaine. This led to the suspension of a larg...
Susceptibility of cats to infection with Ehrlichia risticii, causative agent of equine monocytic ehrlichiosis. Eight adult cats were inoculated IV (n = 6) or SC (n = 2) with Ehrlichia risticii-infected P388D1 (continuous murine macrophage) cells or with E risticii released from P388D1 cells. Three additional cats were inoculated with organism-free P388D1 cultured monocytes, and 1 cat, which served as a medium control was inoculated with balanced salt solution. Clinical signs of illness were observed in the IV inoculated cats from which E risticii was isolated. One cat developed intermittent diarrhea between postinoculation days (PID) 8 and 18, and the other cat developed lymphadenopathy, acute depressi...
Molecular pathogenesis of equine coital exanthema: identification and expression of infected cell polypeptides at the restricted temperature during equine herpesvirus 3 infection. Equine herpesvirus 3 (EHV-3)-infected equine cells display a kinetics of infected cell polypeptide (ICP) synthesis at 34 degrees C that is typical of coordinate cascade gene regulation of herpesviruses. In contrast, when infected cell cultures are incubated at the restricted temperature of 39 degrees C, the shift from early (beta) gene expression to late (gamma) gene expression is perturbed, i.e., there is an accumulation of early (beta) gene products and a decrease in, or absence of, late (gamma) gene products. Some of the affected late (gamma) gene products may be glycoproteins since these I...
Some factors affecting isolation of Clostridium tetani from human and animal stools. Clostridium tetani was isolated from human and animal stools at the following rates [95% confidence interval (CI)]: Human, 0% (1.5-0); horse, 1% (5-0); cow in cowshed, 4% (10-1); cow in pasture, 8.3% (17-1), calf in pasture, 0% (7-0); dog, 2% (11-0) and sheep in pasture, 25% (44-14). Quantification of C. tetani in 16 animal stools positive for the bacillus was impossible in most cases, as the number of tetanus bacilli present was not large enough for this purpose. Contaminating anaerobic and facultative anaerobic bacteria in human and animal stools, i.e., C. perfringens and Streptococcus sp., ...
Omphalophlebitis and osteomyelitis associated with Klebsiella septicemia in a premature foal. Gram-negative neonatal septicemia was diagnosed in a premature Standardbred colt. Clinical signs included lethargy, weakness, loss of suckle reflex, tachypnea, and injected mucous membranes. Sequelae included pneumonia, omphalophlebitis, septic arthritis, and osteomyelitis. Prepartum maternal uterine infection, premature delivery, abnormal parturition with premature fetal membrane separation, and failure of passive transfer of colostral immunoglobulins increased the foal's risk for developing sepsis. Treatment included administration of moxalactam disodium and cefadroxil. The clinical efficacy...
Kairi virus identified from a febrile horse in Argentina. A virus isolated from the blood of a febrile horse in Argentina was identified as a strain of Kairi virus. This is the fifth Bunyamwera serogroup virus isolated from livestock and wild animals in the Americas. Bunyamwera serogroup viruses have been isolated from febrile humans in the Americas and Africa.
Production of monovalent anti-Bothrops asper antivenom: development of immune response in horses and neutralizing ability. A monovalent antivenom was produced by immunizing two horses with venom of the pit viper Bothrops asper (Ophidia: Viperidae). Although development of the immune response against four toxic and enzymatic activities of the venom was similar in both horses during the first two thirds of the immunization schedule, antibody response in one of the horses reached much higher levels in the last part of the immunization. Immunoelectrophoretic analysis indicates that there were precipitating antibodies in the sera of these horses during all the stages of immunization. However, immunoprecipitation did no...
Immune-mediated pathogenesis of Borna disease. Borna disease is an endemic progressive encephalomyelitis of horses and sheep prevalent in central Europe. A wide variety of animal species, ranging from chickens to primates can be infected experimentally with the causative virus, which is only poorly characterized. Furthermore, BD virus-specific antibodies have been detected in sera and cerebrospinal fluids of psychiatric patients. Our studies on the pathogenesis of BD have shown that-at least in rats-the disease is not caused by the infecting virus itself, but by a virus-induced immunopathological reaction. Thus, after intracerebral infecti...
Oxfendazole: activity of a two-dose treatment regimen on natural infections of internal parasites of equids, with emphasis on migrating large strongyles in controlled tests in 1986 and 1987. Oxfendazole paste formulation was administered intraorally at a dosage of 10 mg/kg of body weight, twice (48 hours between treatments) in 5 controlled tests (experiments A, B, C, D, and E) to 18 equids (14 horses and 4 ponies) that were 5 to 24 months old in 1986 and 1987. Activity was evaluated against naturally acquired infections of various internal parasites, with emphasis on migratory stages of Strongylus vulgaris and S edentatus. The number of treated and nontreated equids in each experiment (horses in experiments A to D and ponies in experiment E) was: A, 1 and 1; B, 3 and 3; C, 3 and 1...
A propagating epizootic of equine infectious anemia on a horse farm. An epizootic of equine infectious anemia (EIA) involved 35 horses on a farm in south Georgia. During a 126-day period, 21 of these horses became seropositive for EIA. After the initial diagnosis in July, the horses were tested every 7 to 10 days. At least one additional horse was found to be seropositive on each testing day. As soon as they were determined to be seropositive, the horses were removed from the herd and sent to slaughter. The removal of the seropositive horses, however, did not stop the epizootic. We believe the initial infection was from a 7-year-old stallion that recently had b...
Use of a monoclonal antibody in the diagnosis of infection by Dermatophilus congolensis. A monoclonal antibody (McAb) to Dermatophilus congolensis was produced from murine hybridoma cultures and purified by affinity chromatography. Species specificity was demonstrated using indirect immunofluorescent staining; the McAb was shown to react with 10 D congolensis isolates but not with 10 Nocardia species isolates, a Rhodococcus and a Streptomyces species isolate. The McAb was used to demonstrate D congolensis in clinical material from confirmed bovine and ovine cases and presumptive equine cases of dermatophilosis by indirect immunofluorescent staining.
Serum and synovial fluid steady-state concentrations of trimethoprim and sulfadiazine in horses with experimentally induced infectious arthritis. The tarsocrural joints of 11 horses were inoculated with 1.2 to 2.16 x 10(6) viable Staphylococcus aureus organisms susceptible to a trimethoprim-sulfadiazine (TMP-SDZ) combination with minimal inhibitory concentration (MIC) of 0.25 micrograms of TMP/ml and 4.75 micrograms of SDZ/ml. Antimicrobial treatment consisted of oral administration of a TMP-SDZ combination--30 mg/kg of body weight given once daily (group-1 horses) or 60 mg/kg given as 30 mg/kg every 12 hours (group-2 horses). Paired serum and synovial fluid samples were obtained before intra-articular inoculation with the S aureus, aft...
Detection of eastern equine encephalomyelitis virus antigen in equine brain tissue by enzyme-linked immunosorbent assay. Sensitivity and specificity of an antigen-capture ELISA vs virus isolation in cell culture were evaluated for the detection of eastern equine encephalomyelitis (EEE) virus in the brain tissue of naturally infected equids. Brain specimens from 16 equids with neurologic disease were examined by ELISA and by inoculation onto baby hamster kidney cell cultures. Of 10 brain samples from which virus was isolated in the cell culture bioassay, all were correctly identified as containing EEE virus antigen by ELISA. None of the remaining 6 specimens, without detectable infectious EEE virus, contained det...
Passive hemagglutination test for detection of antibodies against Taylorella (Haemophilus) equigenitalis in sera of mares. The passive hemagglutination (PHA) test was improved to enable the detection of antibodies to Taylorella (Haemophilus) equigenitalis in the sera of mares. Horse red blood cells (RBC) fixed with glutaraldehyde were compared with similarly treated RBC of a cow, pig and sheep for the PHA test. The horse RBC were superior to those of the other animals tested in detecting mares affected with contagious equine metritis (CEM). A PHA test using these cells as indicator and an antigen prepared from T. equigenitalis by sonication following treatment with hyaluronidase was the most satisfactory in terms ...
California serogroup virus infections in Wisconsin domestic animals. A serologic survey and experimental virus transmission studies were done to assess the role of domestic animals as amplifier hosts of La Crosse (LACV) and Jamestown Canyon (JCV) viruses. Serum from 319 cows, 88 dogs, 122 equines, 47 swine, 10 goats, and 4 cats were tested for neutralizing antibody to LACV, JCV, trivittatus (TVTV), and snowshoe hare (SSHV) viruses. Antibody prevalences of LACV, TVTV, and SSHV were less than 10% in all species. Antibody to JCV was detected in all species except cats. Prevalence ranged from 10% in goats and swine to 29% in dogs. No age-associated trends in JCV pr...
Micronema deletrix-induced granulomatous osteoarthritis in a lame horse. Necropsy of a chronically lame 16-year-old thoroughbred gelding revealed granulomatous osteomyelitis and polyarthritis due to a widely disseminated infection by Micronema deletrix. Diagnosis was based upon the nematode's morphology with its characteristic rhabditiform oesophagus. Granulomata, often containing one or more centrally located M. deletrix, were observed histologically in sections prepared from femur, kidney, stomach, lung, adrenal gland and sublumbar lymph nodes. Neither verminous meningo-encephalitis nor cephalic granulomata, which are the more commonly described lesions, was foun...
Disease features in horses with induced equine monocytic ehrlichiosis (Potomac horse fever). Fifty-five horses were inoculated IV and/or SC with materials containing Ehrlichia risticii, ie, infected whole blood, buffy coat cells, or cell culture, to study clinical and hematologic features of equine monocytic ehrlichiosis (Potomac horse fever). Major clinical and hematologic features of induced E risticii infection were biphasic increase in rectal temperature with peak increases of 38.9 C and 39.3 C on postinoculation days (PID) 5 and 12, respectively; depression; anorexia; decreased WBC count (maximal decrease of 47% on PID 12); and diarrhea from PID 14 to PID 18. Increased WBC count ...
Analysis of the in vitro translation products of the equine herpesvirus type 1 immediate early mRNA. Equine herpesvirus type 1 (EHV-1) gene expression is coordinately regulated in an alpha, beta, gamma fashion. Viral alpha gene products include a 6.0-kb immediate early (IE) mRNA species (W. L. Gray et al., 1987, Virology 158, 79-87) and at least four closely related IE polypeptides (IEPs) (G.B. Caughman et al., 1985, Virology 145, 49-61). In this report, we describe results obtained from a series of in vitro translation experiments which were performed in an effort to characterize the IEPs and identify the mechanism by which individual IE protein species are generated. Our data indicate that ...
