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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.
Evaluation of travel and use as a risk factor for seropositivity to Ehrlichia risticii in horses of New York state. To determine whether mean annual frequency and destination of equine travel was associated with exposure to Ehrlichia risticii and whether these associations were modified by horses' place of residence. Methods: Cross-sectional study. Methods: 511 equine operations containing 2,587 horses were visited in New York state from a target population of 39,000 operations. Methods: Each horse was tested for serum antibodies against E risticii, using indirect fluorescent antibody. Information on the horse's travel history, farm's management practices, and surrounding ecology was obtained by personal in...
Cross-sectional evaluation of environmental, host, and management factors associated with risk of seropositivity to Ehrlichia risticii in horses of New York state. To locate counties within New York state with a high seroprevalence among the equine population, to determine host, management, and environmental factors that were associated with seropositivity to Ehrlichia risticii, and to determine evidence for arthropod- or helminth-mediated transmission of E risticii to horses. Methods: Cross-sectional study. Methods: A random sample of 3,000 of the 39,000 equine operations in New York state was selected, and 2,587 horses from 511 operations were tested. Methods: Blood samples were collected from horses and tested for seropositivity, using the indirect fl...
Alterations in the equine herpesvirus type-1 (EHV-1) strain RacH during attenuation. The equine herpesvirus type-1 modified live-vaccine strain RacH (256th passage on porcine embryonic kidney cells) was investigated by restriction-enzyme analysis and compared to representative plaque isolates of the 12th passage (RacL11, RacL22) and 185th passage (RacM24, RacM36). The restriction patterns of all Rac plaque isolates differed compared with reference strain Ab4. The left UL terminus was shortened by 0.1 kbp and a missing BamHI site led to the fusion of the f and t fragments. In some Rac derivatives, losses of restriction sites without deletions were observed: 1. One BamHI site lo...
The role of the gene 71 product in the life cycle of equine herpesvirus 1. Equine herpesvirus type 1 (EHV-1) gene 71 encodes a heavily O-glycosylated 192 kDa protein with no identified herpesvirus homologue. Isolation of a deletion mutant in gene 71 (ED71) demonstrated that its protein product is not essential in vitro. To investigate the role of the gene 71 protein in the virus life cycle, ED71 has been characterized in vitro in terms of cellular adsorption, penetration, egress and transmission compared to wild-type and revertant virus. ED71 virions adsorbed to cells less efficiently than wild-type and revertant virus with a consequential effect on virus penetration...
Subcellular localization of the nonstructural protein NS3 of African horsesickness virus. The subcellular localization of the minor nonstructural protein NS3 of African horsesickness virus (AHSV) has been investigated by means of immunogold electron-microscopical analysis. NS3 was observed in perturbed regions of the plasma membrane of AHSV-infected VERO cells, and its presence appears to be associated with events of viral release. These events are budding, whereby released viruses acquire fragments from the host-cell membrane, as well as by the extrusion of nonenveloped particles through the cell membrane. The membrane association of NS3 was confirmed by its detection in the disru...
Eosinophilic colitis and hepatitis in a horse with colonic intramucosal ciliated protozoa. Tissues from a 9-year-old American Standardbred gelding with a history of anorexia, mild colic, and unexpected death were submitted to the Laboratories of Veterinary Diagnostic Medicine at the University of Illinois for histopathologic examination. Microscopic diagnoses were severe subacute, diffuse eosinophilic colitis with intralesional protozoa and a subacute to chronic eosinophilic portal hepatitis with granuloma formation. Two tissue-invading, ciliated protozoa were identified in large numbers within the colonic mucosa. The ciliates were Polymorphella ampulla and Cycloposthium sp., Phylum...
Isolation of the equine granulocytic ehrlichiosis agent, Ehrlichia equi, in tick cell culture. The equine granulocytic ehrlichiosis agent, Ehrlichia equi, is closely related or identical to the human granulocytic ehrlichiosis (HGE) agent. Both are suspected of being transmitted by ticks. We have successfully isolated E. equi in a cell line, IDE8, derived from a putative vector, the tick Ixodes scapularis. Peripheral blood leukocytes from an experimentally infected horse were inoculated onto IDE8 monolayers. Cultures were incubated in a candle jar at 34 degrees C in tick cell culture medium with NaHCO3 and an organic buffer [3-(N-morpholino)-propanesulfonic acid] (MOPS). Within 2 weeks, ...
Correlation between DNA restriction fragment length polymorphisms in Leptospira interrogans serovar pomona type kennewicki and host animal source. Isolates (n = 147) of Leptospira interrogans serovar pomona type kennewicki from cattle, swine, horses, and wildlife were analyzed by DNA restriction endonuclease analysis. Restriction fragment length polymorphisms were identified in DNA digested with HpaII, and the restriction fragment length polymorphisms were correlated with the host animal source of the isolates. These results will be useful in understanding the epidemiology of serovar pomona infections in livestock.
Use of excretory/secretory antigens for the serodiagnosis of Anoplocephala perfoliata cestodosis. Whole worm extract (WWE) and excretory/secretory (E/S) antigens of Anoplocephala perfoliata were characterised by SDS-PAGE and their use in the serodiagnosis of equine cestodosis was evaluated. An enzyme-linked immunosorbent assay (ELISA) was used to compare WWE and E/S antigen as the capture layer in an antibody capture ELISA. E/S antigen gave the best differentiation between sera from tapeworm-positive and tapeworm-negative horses. The E/S-ELISA was optimised and validated against sera from horses of known tapeworm status. This assay gave a diagnostic sensitivity of 68% (n = 38) and a specif...
Visceral neosporosis in a 10-year-old horse. No abstract available
Rapid diagnosis of African horse sickness. The rapid diagnosis of African horse sickness (AHS) during the incubation period using virus antigens in peripheral blood mononuclear cells (PBMC) and red blood cells (RBC) in a sandwich indirect enzyme-linked immunosorbent assay (ELISA) is reported. PMBC consistently gave higher positive ELISA results than RBC from blood collected during viraemia from clinically affected horses. The potential of the method described for wider application in rapid diagnosis and virus surveillance in susceptible equine populations, particularly in AHS-free and in enzootic areas, for effective control strategies...
Control of Karoo paralysis ticks through vegetation management. Karoo paralysis, caused by feeding Ixodes rubicundus females, is a major disease of small stock in South Africa. Control methods currently practised are almost exclusively chemical based. To limit overdependance on chemicals, vegetation management was investigated as a possible method for control, to be incorporated in an integrated tick management system. Laboratory and field experiments were conducted to determine, firstly, the extent of vertical migration and survival of ticks on long and short copper rods which simulated grasses as questing substrates; secondly, the infestation burdens of ...
Differences between Taylorella equigenitalis strains in their invasion of and replication in cultured cells. The ability of Taylorella equigenitalis, the causative agent of contagious equine metritis, to invade and replicate in equine derm cells was studied. The kinetics of invasion and replication were determined for four T. equigenitalis strains. On the basis of these experiments, a simpler assay in which the invasive as well as the replicative properties of a particular strain could be determined was developed. This assay was used to characterize 32 strains, which had previously been typed by field inversion gel electrophoresis of genomic restriction fragments. The invasiveness of T. equigenitalis...
[Identification and diagnosis of Taylorella equigenitalis by a DNA amplification method (PCR)]. A polymerase chain reaction (PCR) for identification of Taylorella equigenitalis was developed. The oligonucleotide primers are based on the DNA sequence of the rrs gene of T. equigenitalis, encoding for the 16S ribosomal RNA. Analysis of 21 strains of T. equigenitalis from England, USA and Switzerland showed an amplification product of 410 bp with identical Sau3A restriction profile. The sensitivity of the PCR-Assay was estimated to detect 50 to 500 bacteria of T. equigenitalis in a mixture with frequently found contaminants. Further analysis of culture from 60 genital swabs, taken in the cou...
Ixodes pacificus (Acari: Ixodidae) as a vector of Ehrlichia equi (Rickettsiales: Ehrlichieae). Ehrlichia equi, a rickettsia described from horses in California 30 yr ago, causes equine granulocytic ehrlichiosis throughout the Americas and possibly Europe. Here, we report experimental transmission of E. equi from infected to susceptible horses through bites of western blacklegged ticks, Ixodes pacificus (Cooley & Kohls). In preliminary field studies, only I. pacificus consistently infested horses and vegetation at 3 locations with contemporary cases of equine ehrlichosis, and in particular, I. pacificus was the only species found attached to all of the infected horses. Exposure to bi...
Equine infectious anemia virus replication is upregulated during differentiation of blood monocytes from acutely infected horses. Equine infectious anemia virus is a lentivirus that replicates in mature tissue macrophages of horses. Ponies were infected with equine infectious anemia virus. During febrile episodes, proviral DNA was detectable, but viral mRNA was not detectable. As cultured blood monocytes from these ponies differentiated into macrophages, viral expression was upregulated. In situ hybridization confirmed that viral transcription occurred in mature macrophages.
Nationwide serological survey of equine influenza in Nigeria. The objective of this work was to examine the incidence of equine influenza viruses in the equine population of an area of tropical Africa where equine influenza virus activity has recently been reported for the first time. A serological survey of sera from horses and donkeys from regions of Nigeria taken from 1990 to 1993 was carried out and the results obtained were com-pared with equine sera from Western Europe (Ireland). The sera were assayed for presence of antibodies by both haemagglutination inhibition (HI) and ELISA using a monoclonal antibody to the prototype H3 equine influenza virus...
Transmission patterns of St. Louis encephalitis and eastern equine encephalitis viruses in Florida: 1978-1993. Sentinel chickens were maintained at field sites in 40 Florida counties for varying periods between 1978 and 1993. For each county, the total number of St. Louis encephalitis virus (SLE) or eastern equine encephalitis (EEE) virus seroconversions were divided by the number of chickens exposed to calculate a mean annual seroconversion rate. These rates were used to evaluate the annual and geographical distributions of these viruses within Florida. For SLE, the rates in counties that reported human SLE cases during a widespread epidemic in 1990 were compared with adjusted mean annual seroconversi...
Survey of equine rotaviruses shows conservation of one P genotype in background of two G genotypes. DIG-labelled ssRNA probes were prepared from variable regions of VP4 and VP7 cognate genes, and used in hybridization assays for P and G genotyping of group A cell culture-adapted equine rotaviruses and fecal samples collected from foals with and without diarrhea. The probes confirmed known P and G serotypes of sixteen cell culture-adapted strains. From one-hundred and twenty-one rotavirus-positive samples, 83 reacted when tested for their P and G genotype specific probes. From these, 71 were found to contain G3 P12 genotypes, and 11 G14 P12 genotypes. No sample reacted with H1 or L338 P and G...
Species-specific and interspecies relatedness of NSP1 sequences in human, porcine, bovine, feline, and equine rotavirus strains. We have sequenced gene 5 encoding NSP1 for three human, two porcine, two bovine, one feline, and five equine rotavirus strains, and compared the nucleotide and deduced amino acid sequences with the published sequences for other various strains. Subgroup I human strains L26, 69M, and DS-1 were found to have a similar NSP1 sequence despite their different G serotypes, VP4 genotypes, and RNA patterns. The NSP1 sequence of the human strain K8 showed a high degree of homology to those of porcine strains OSU and YM. A high degree of homology was found among three equine strains (H2, FI-14, and FI23)...
Comparison of nucleic and amino acid sequences and phylogenetic analysis of the Gs protein of various equine arteritis virus isolates. The genetic variation in equine arteritis virus (EAV) Gs protein encoding gene was investigated. Nucleic and deduced amino acid sequences from eight different EAV isolates (one European, two American and five Canadian isolates) were compared with those of the Bucyrus reference strain. Nucleotide and amino acid identities between these isolates and the Bucyrus reference strain ranged from 92.3 to 96.4%, and 93.2 to 95.5%, respectively. However, phylogenetic tree analysis and estimation of genetic distances based on the Gs protein encoding gene sequences showed that the European prototype Vienna...
Sequence variability of Borna disease virus open reading frame II found in human peripheral blood mononuclear cells. A cDNA fragment of the Borna disease virus (BDV) open reading frame II (ORF-II), which encodes a 24-kDa phosphoprotein (p24 [P protein]), was amplified from total RNA of peripheral blood mononuclear cells (PBMC) from three psychiatric inpatients. The amplified cDNA fragments were cloned, sequenced, and analyzed. A total of 15 clones, 5 from each patient, were studied. Intrapatient divergencies of the BDV ORF-II nucleotide sequence were 4.2 to 7.3%, 4.8 to 7.3%, and 2.8 to 7.1% for the three patients, leading to differences of 7.7 to 14.5%, 10.3 to 17.1%, and 6.0 to 16.2%, respectively, in the ...
Lymphoid leukosis viruses, their recognition as ‘persistent’ viruses and comparisons with certain other retroviruses of veterinary importance. Diseases caused by lymphoid leukosis virus (LLV), a retrovirus, take a long time after infection to develop and have a wide variety of pathological manifestations. This long latent period is characteristic of 'persistent virus infections'. Disease produced by LLV infection and its underlying mechanisms is compared with 'persistent' infections caused by other retroviruses in birds and mammals of veterinary importance. The diseases considered for comparison are those caused by reticuloendotheliosis, feline leukaemia, bovine leukosis and equine infectious anaemia viruses. There are significant ch...
Equine gammaherpesvirus 2 (EHV2) is latent in B lymphocytes. Peripheral blood leukocytes were collected from 5 Thoroughbred horses and examined for the presence of EHV2 in sub-populations of mononuclear cells. Peripheral blood mononuclear cells were separated on Percoll gradients and then enriched for plastic adherent cells (predominantly monocytes), surface immunoglobulin positive (sIg+) B lymphocytes and T lymphocytes, using panning techniques. The purity of each cell population was assessed by fluorescence activated cell scanning. In an infectious centre assay, each cell population was inoculated onto equine foetal kidney monolayer cell cultures whic...
Phylogenetic analysis of open reading frame 5 of field isolates of equine arteritis virus and identification of conserved and nonconserved regions in the GL envelope glycoprotein. The variation and phylogenetic relationship of open reading frame 5 (ORF5) of 3 different laboratory strains of the original prototype Bucyrus strain of equine arteritis virus (EAV), the modified live virus vaccine (ARVAC, Fort Dodge Laboratories), and 18 field isolates of EAV from North America and Europe were determined by comparison of their gene sequences. The viruses differed from the published sequence by between 3 (99.6% homology) and 94 (87.8%) nucleotides and by between 3 (98.8%) and 24 (90.6%) amino acids. The field isolates differed from each other by between 2 (99.7%) and 110 (85.7...
