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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.
Detection of antibodies to Babesia equi in horses by a latex agglutination test using recombinant EMA-1. A latex agglutination test (LAT) using recombinant equi merozoite antigen 1 (EMA-1) for the detection of antibodies to Babesia equi was developed. The LAT was able to differentiate very clearly between sera from B. equi-infected horses and sera from Babesia caballi-infected horses or from normal horses. The LAT results were identical to those of a previously developed enzyme-linked immunosorbent assay. These results indicate that LAT using recombinant EMA-1 might be very useful as a routine screening method for the diagnosis of B. equi infection.
Large envelope glycoprotein and nucleocapsid protein of equine arteritis virus (EAV) induce an immune response in Balb/c mice by DNA vaccination; strategy for developing a DNA-vaccine against EAV-infection. Equine arteritis virus (EAV) is a member of the Arteriviridae family, that includes lactate dehydrogenase-elevating virus (LDV), porcine reproductive and respiratory syndrome virus (PRRSV), and simian haemorrhagic fever virus (SHFV). Equine arteritis is a contagious disease of horses and is spread via respiratory or reproductive tract. The objective of the present study is to evaluate the possibility for developing a model system for prevention horses against an EAV infection by DNAvaccination. A cDNA bank from the RNA of EAV was established. This gene library contains the translation unit of ...
Treatment of sepsis in the small tarsal joints of 11 horses with gentamicin-impregnated polymethylmethacrylate beads. Gentamicin-impregnated polymethylmethacrylate beads were used to treat infective arthritis in the small tarsal joints of 11 severely lame horses. Under general anaesthesia, between five and 10 beads were placed into a 7 to 8 mm tract drilled across the affected joint and, in all except one horse, they were left in place for 14 days. Two of the horses were euthanased for reasons other than persistent tarsal joint sepsis, but the other nine survived and seven of them returned to their previous level of athletic performance.
Characterization of the Oregon isolate of Neospora hughesi from a horse. Neospora hughesi was isolated in cell cultures inoculated with homogenate of spinal cord from a horse in Oregon. Tachyzoites of this Oregon isolate of N. hughesi were maintained continuously by cell culture passage and tachyzoites were infective to immunosuppressed mice. Gamma interferon gene knockout (KO) mice injected with tachyzoites developed fatal myocarditis and numerous tachyzoites were seen in lesions. Gerbils (Meriones unguiculatus) inoculated with tachyzoites developed antibodies (> or = 1:500) as indicated by the Neospora caninum agglutination test but did not develop clinical si...
Epidemiology of Rhodococcus equi strains on Thoroughbred horse farms. Pulsed-field gel electrophoresis of restriction endonuclease-digested genomic DNA from a large collection of clinical isolates of Rhodococcus equi, an important pathogen of foals, was used to compare strain distribution between farms and over time. Forty-four strains were found among 209 isolates, with 5 of these accounting for over half the isolates and the 22 strains isolated more than once accounting for 90% of the isolates. The average genotypic diversity on each farm and in each year was found to be less than the genotypic diversity of the isolates taken as a whole, with 5.2% of the total...
Identification of sources of Salmonella organisms in a veterinary teaching hospital and evaluation of the effects of disinfectants on detection of Salmonella organisms on surface materials. To determine sources of Salmonella organisms in a veterinary teaching hospital, compare bacterial culture with polymerase chain reaction (PCR) testing for detection of Salmonella organisms in environmental samples, and evaluate the effects of various disinfectants on detection of Salmonella organisms on surface materials. Methods: Prospective study. Methods: Fecal samples from 638 hospitalized horses and 783 environmental samples. Methods: Standard bacterial culture techniques were used; the PCR test amplified a segment of the Salmonella DNA. Five disinfectants were mixed with Salmonella suspe...
Estimating transmission potential in gastrointestinal nematodes (order: Strongylida). Microparasite virulence (the potential to cause harm in the host) is thought to be regulated by a direct trade-off with pathogen transmission potential, but it is unclear whether similar trade-offs occur in macroparasites (helminths). In this analysis, the transmission potentials of 5 nematode species (order Strongylida), known to differ in their virulence, were estimated using an index based on egg production and larval survivability. Virulence estimates were based on the minimum number of worms that cause host death. In nematode species where mature adults cause pathology (trichonematidic de...
Cross-sectional study of the seroprevalence to Borrelia burgdorferi sensu lato and granulocytic Ehrlichia spp. and demographic, clinical and tick-exposure factors in Swedish horses. A cross-sectional study of the seroprevalence to Borrelia burgdorferi sensu lato and granulocytic Ehrlichia spp. in Swedish horses was conducted to evaluate associations with demographic, clinical and tick-exposure factors. From September 1997-1998, blood samples from 2018 horses were collected from the animals presented to veterinary clinics affiliated with the Swedish Horserace Totalizator Board (regardless of the primary cause for consultation). Standardized questionnaires with information both from owners and attending veterinarians accompanied each blood sample. The apparent seroprevalenc...
Detection of Babesia caballi and Babesia equi in Dermacentor nuttalli adult ticks. Ticks play an important role in human and veterinary medicine particularly due to their ability to transmit protozoan pathogens. In this study we have demonstrated that polymerase chain reaction (PCR) and nested PCR methods enabled detection of Babesia caballi and Babesia equi in field isolates of Dermacentor nuttalli adult ticks from Mongolia. Primers specific for 218 bp fragment merozoite antigen 1 (EMA-1) gene of B. equi successfully amplified products from all samples of D. nuttalli adult ticks while primers for the 430 bp fragment product from BC48 gene of B. caballi amplified products fr...
The nine-banded armadillo (Dasypus novemcinctus) is an intermediate host for Sarcocystis neurona. The nine-banded armadillo (Dasypus novemcinctus) is an intermediate host of at least three species of Sarcocystis, Sarcocystis dasypi, Sarcocystis diminuta, and an unidentified species; however, life cycles of these species have not been determined. Following feeding of armadillo muscles containing sarcocysts to the Virginia opossum (Didelphis virginiana), the opossums shed sporulated Sarcocystis sporocysts in their faeces. Mean dimensions for sporocysts were 11.0x7.5 microm and each contained four sporozoites and a residual body. Sporocysts were identified as Sarcocystis neurona using PCR and...
Safety, efficacy, and immunogenicity of a modified-live equine influenza virus vaccine in ponies after induction of exercise-induced immunosuppression. To determine safety, efficacy, and immunogenicity of an intranasal cold-adapted modified-live equine influenza virus vaccine administered to ponies following induction of exercise-induced immunosuppression. Methods: Prospective study. Methods: Fifteen 9- to 15-month old ponies that had not had influenza. Methods: Five ponies were vaccinated after 5 days of strenuous exercise on a high-speed treadmill, 5 were vaccinated without undergoing exercise, and 5 were not vaccinated or exercised and served as controls. Three months later, all ponies were challenged by nebulization of homologous equine i...
Studies on the supply of immunoglobulin G to newborn camel calves (Camelus dromedarius). A major problem in camel productivity is the high mortality rate of camel calves in the first 3 months. The causes for mortality are mainly poor management practice and infectious diseases. The purpose of this research, carried out on a ranch in Kenya, was to determine the immunoglobulin G (IgG) concentration in camel colostrum as well as the extent of the calves' passive immunization by maternal antibodies. IgG concentration in colostrum and in the serum of the calf were measured during the first 3 d of life. Evaluation was carried out by comparing the respective values with those for horses ...
B-Cell epitope mapping of the VapA protein of Rhodococcus equi: implications for early detection of R. equi disease in foals. Linear B-cell epitopes of the Rhodococcus equi virulence-associated protein (VapA) were mapped using a synthetic peptide bank in this study. The peptides were screened in an enzyme-linked immunosorbent assay (ELISA) with a total of 70 sera from foals with current R. equi disease (51 sera), as well as from foals that had either recovered from R. equi infection 10 months previously (3 sera) or that had no known history of R. equi disease (16 sera). An epitope with the sequence NLQKDEPNGRA was identified and was universally recognized by all 51 sera from foals with R. equi disease and was not rec...
Comparison of nucleic acid amplification, serology, and microbiologic culture for diagnosis of Rhodococcus equi pneumonia in foals. Recently, a technique was described for amplification of Rhodococcus equi-specific chromosomal and vapA DNA from blood and tracheal wash fluids. It was hypothesized that this technique would be more sensitive than standard culture techniques or serology for diagnosis of R. equi pneumonia in foals. Tracheal wash fluid, nasal swabs, whole blood samples, and serum samples from 56 foals with pneumonia were analyzed. Final clinical diagnosis was determined by the attending clinician on the basis of final interpretation of all available information about each foal, including clinical presentation, d...
Factors associated with Salmonella shedding among equine colic patients at a veterinary teaching hospital. To evaluate factors potentially associated with fecal Salmonella shedding among equine patients hospitalized for colic at a veterinary teaching hospital and to determine the effects of probiotic treatment on fecal Salmonella shedding and clinical signs. Methods: Longitudinal study and controlled trial. Methods: 246 equine colic patients. Methods: History and medical information were obtained from patient records. Fecal and environmental samples were submitted for aerobic bacterial culture for Salmonella enterica. Fifty-one patients were treated with a commercially available probiotic; 46 were ...
Molecular epidemiology of Salmonella Heidelberg in an equine hospital. From 1992 to 1997, multi-drug resistant (MDR) Salmonella Heidelberg isolates were cultured from a number of horses hospitalised in a veterinary hospital in Victoria, Australia. To examine the relationships between the cases, 28 isolates from the hospital were compared by pulsed field gel electrophoresis (PFGE), IS200 element profiles, antimicrobial resistance patterns, plasmid profiles and phage typing. The PFGE patterns following digestion with XbaI and BlnI restriction endonucleases showed that the isolates from the veterinary hospital originated from a common source. These isolates also had...
Antigenic variation among equine H 3 N 8 influenza virus hemagglutinins. To provide information on the antigenic variation of the hemagglutinins (HA) among equine H 3 influenza viruses, 26 strains isolated from horses in different areas in the world during the 1963-1996 period were analyzed using a panel of monoclonal antibodies recognizing at least 7 distinct epitopes on the H 3 HA molecule of the prototype strain A/equine/Miami/1/63 (H 3 N 8). The reactivity patterns of the virus strains with the panel indicate that antigenic drift of the HA has occurred with the year of isolation, but less extensively than that of human H 3 N 2 influenza virus isolates, and diff...
Neurological disease associated with EHV-1-infection in a riding school: clinical and virological characteristics. An outbreak of neurological disease caused by EHV-1 infection is described with emphasis on diagnosis and prognosis for recumbent horses. In April 1995, an outbreak of the neurological form of Equine herpesvirus type 1 (EHV-1) occurred in a well-managed riding school with 41 horses: 34 horses showed a temperature spike and 20 some degree of neurological signs, of which 10 were nursed intensively in the indoor arena of the riding school for 3 to 20 days, 8 having to be maintained in slings for 2-18 days, while 9 needed bladder catheterisation b.i.d. for 2-16 days. Within the first 3 days, one h...
Equine herpesvirus myeloencephalopathy in a 14-year-old quarter horse stallion. A 14-year-old, quarter horse stallion was presented in lateral recumbency, unable to rise. Equine herpesvirus myeloencephalopathy was diagnosed, based on presentation, clinical signs, and the ruling out of other possibilities. After initial rapid improvements, ataxia remained, as did chronic cystitis secondary to bladder paralysis. He was euthanized after 2 months.
Infection of endothelial cells with equine herpesvirus-1 (EHV-1) occurs where there is activation of putative adhesion molecules: a mechanism for transfer of virus. Evidence is presented to show that activation of endothelial and leucoyte adhesion molecules is a key step in transferring virus from infected leucocytes; and determines the restricted tissue tropism. A range of tissues from 2 experimentally infected mares in late pregnancy at 4 and 8 days after infection with EHV-1 were compared with those from normal pregnant and nonpregnant mares. Rabbit antisera to equine activated endothelial cell molecules were used to identify which tissues expressed these molecules in normal nongravid and gravid mares, and to investigate whether the range of tissues wa...
ELISA and direct immunofluorescence test to detect equine arteritis virus (EAV) using a monoclonal antibody directed to the EAV-N protein. A monoclonal antibody (mAb) directed against the equine arteritis virus (EAV) nucleocapsid (N) protein was used for indirect enzyme-linked immunosorbent assays (ELISAs) using viral antigen from different sources. The same mAb was labelled with fluorescein isothiocyanate for direct immunofluorescence tests (DIFTs). The N-specific mAb appeared to be suitable for the detection in both ELISA and DIFT of different EAV strains and field isolates from semen and tissue samples after passage in lines of RK-13, Vero and fetal equine kidney cells. The ELISA described is an easy and fast method which can ...
Isolation of virulent Rhodococcus equi from native Japanese horses. R. equi was isolated from soil samples obtained from the environment of seven native Japanese horse breeds (Hokkaido, Kiso, Noma, Misaki, Tokara, Miyako and Yonaguni) and from fecal samples collected from three native horse breeds (Hokkaido, Kiso and Misaki). Virulent R. equi at various levels (ranging from 0.5 to 12.9%) was isolated from the feces or soil environment of Hokkaido, Kiso and Misaki horses. Isolates were investigated both for the presence of 15- to 17-kDa antigens (virulence-associated protein antigens; VapA) by colony blotting, using the monoclonal antibody 10G5, and the gene of...
An enzyme-linked immunosorbent assay for the convenient serodiagnosis of contagious equine metritis in mares. An enzyme-linked immunosorbent assay (ELISA) was developed for the serodiagnosis of contagious equine metritis (CEM), a sexually transmitted disease caused by Taylorella equigenitalis. Antigen preparation was simple, and antigens derived from both classical and atypical forms of T. equigenitalis enabled detection of antibody responses elicted in horses experimentally exposed to either form of the bacterium. Sera serially obtained from these horses from 0 to 63 days postexposure were tested by the traditional complement fixation test (CFT) for CEM and with the ELISA, using both antigens separat...
Evaluation of the specificity of five oligoprobes for identification of cyathostomin species from horses. Here, we report evaluation of five oligoprobes designed from intergenic spacer (IGS) region sequences for identification of cyathostomin species. Oligoprobes were designed for identification of Cylicocyclus ashworthi, Cylicocyclus nassatus, Cylicostephanus longibursatus, Cylicostephanus goldi and a fifth probe designed to identify all members of this tribe. PCR amplification of IGS DNA from 16 cyathostomin species allowed sequence comparison and identification of four putative species-specific probes. Southern blotting of amplified products from 16 species showed that all probes were species-s...
In vitro evidence for a bacterial pathogenesis of equine laminitis. Utilizing an in vitro laminitis explant model, we have investigated how bacterial broth cultures and purified bacterial proteases activate matrix metalloproteinases (MMPs) and alter structural integrity of cultured equine lamellar hoof explants. Four Gram-positive Streptococcus spp. and three Gram-negative bacteria all induced a dose-dependent activation of MMP-2 and MMP-9 and caused lamellar explants to separate. MMP activation was deemed to have occurred if a specific MMP inhibitor, batimastat, blocked MMP activity and prevented lamellar separation. Thermolysin and streptococcal pyrogenic ex...
Treatment of methicillin-resistant Staphylococcus epidermidis infection following repair of an ulnar fracture and humeroradial joint luxation in a horse. A 27-month-old Rocky Mountain Horse was examined because of a fracture of the proximal portion of the ulna and luxation of the humeroradial joint (Monteggia fracture). Open reduction was performed, using a mechanical distractor, and the ulnar fracture was stabilized by application of a bone plate and screws. After surgery, the horse developed an infection of the surgical site, and bacterial culture of fluid from the surgical site yielded a pure growth of methicillin-resistant Staphylococcus epidermidis susceptible to oxytetracycline, erythromycin, rifampin, and vancomycin. Treatment with oxyte...
