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Topic:Pathogens
Pathogens are microorganisms, such as bacteria, viruses, fungi, and parasites, that can cause disease in horses. These microorganisms interact with the equine immune system, often leading to a range of health issues that can affect individual horses or entire populations. Pathogens can be transmitted through various routes, including direct contact, vectors, or environmental exposure. Common equine pathogens include Streptococcus equi, Equine Herpesvirus, and Strongylus vulgaris. Understanding the interactions between equine hosts and pathogens is essential for disease prevention, management, and treatment. This page compiles peer-reviewed research studies and scholarly articles that explore the identification, transmission, and impact of pathogens on equine health.
Characterization of immunogenic proteins of Trypanosoma evansi isolated from three different Indian hosts using hyperimmune sera and immune sera. The western blot analysis for identification of immunogenic proteins in whole cell lysate (WCL) antigens (Ags) prepared from the Trypanosoma evansi of buffalo, horse and cattle origins using hyperimmune sera (HIS) showed 11 immunogenic proteins and naturally T. evansi infected immune sera (IS) of horse detected 19 immunogenic proteins. HIS and IS of horse recognized five common immunogenic proteins of relative molecular weight (M(r)) ranges 61-64, 44-47, 33-34, 25-26 and 14-16 kilo Dalton (kDa). HIS rose against WCL Ags of T. evansi of buffalo origin and immune sera of horse cross reacted with...
Detection of Bartonella henselae in the blood of 2 adult horses. Bartonella spp. are emerging zoonotic agents that have been found in a wide variety of domestic animals and wildlife and cause a number of clinical syndromes. Bartonella sp. infection has been identified in a growing number of animal species, including cats, rodents, porpoises, and canids, but has not been reported in horses. Objective: To document the presence of Bartonella sp. in the blood of horses. Methods: One horse with chronic arthropathy and 1 horse with presumptive vasculitis. Methods: Blood samples were tested for the presence of Bartonella sp. by a combination of multiplex real-time...
Identification of a LIM domain-containing gene in the Cyathostominae. The Cyathostominae are a complex group of nematodes and are the primary parasitic pathogens of horses. Little is known of their basic biology. As part of an investigation into mechanisms involved in reactivation of mucosal larval stages, we identified a gene encoding a predicted LIM domain-containing protein (Cy-LIM-1). LIM domains are cysteine- and histidine-rich motifs that are thought to direct protein-protein interactions. Proteins that contain these domains have a wide range of functions including gene regulation, cell fate determination and cytoskeleton organization. The Cy-lim-1 mRNA wa...
A case of equine abortion caused by Encephalitozoon sp. A Lippizan mare aborted a male fetus a few days before the expected foaling date without showing any clinical sings. Focal lympho-histiocytic hepatitis in the foal and multiplex focal lympho-histiocytic villitis accompanied by villus necroses and marked hypertrophy of chorionic epithelial cells in the arcades were observed. Elongated nucleated organisms were seen in groups in vacuoles or solitarily located in the cytoplasm of the chorionic epithelial cells. The organisms were in large numbers and often extracellularly in areas of villitis and villus necroses. They were Gram-positive, stained w...
Venezuelan equine encephalitis virus capsid protein inhibits nuclear import in Mammalian but not in mosquito cells. Venezuelan equine encephalitis virus (VEEV) represents a continuous public health threat in the United States. It has the ability to cause fatal disease in humans and in horses and other domestic animals. We recently demonstrated that replicating VEEV interferes with cellular transcription and uses this phenomenon as a means of downregulating a cellular antiviral response. VEEV capsid protein was found to play a critical role in this process, and its approximately 35-amino-acid-long peptide, fused with green fluorescent protein, functioned as efficiently as did the entire capsid. We detected a...
High subclinical West Nile virus incidence among nonvaccinated horses in northern California associated with low vector abundance and infection. Although horse cases frequently are reported during West Nile virus (WNV) outbreaks, few investigations have focused on the epidemiology of this transmission. From April to October 2003 to 2005, mosquito abundance and infection were monitored 3 days per week at an equine research facility at the University of California, Davis. Thirty-two nonvaccinated horses enrolled as controls in a vaccine study were bled monthly, and their serum was tested for evidence of WNV infection by plaque reduction neutralization test (PRNT). In 2004, one positive Culex pipiens pool was associated with a single hors...
Actinobacillus equuli subsp. equuli associated with equine valvular endocarditis. Microbiological and pathological data from a case of equine valvular endocarditis are reported. Limited information is available on the pathogenic potential of equine Actinobacillus species as several strains originate from apparently healthy horses. After the establishment of two subspecies within this species, this seems to be the first report of an etiological association between A. equuli subsp. equuli and equine endocarditis. Furthermore, new information on some phenotypical characteristics of this subspecies is reported, compared to previous findings.
In vitro efficacy of an ophthalmic drug combination against corneal pathogens of horses. To evaluate the in vitro efficacy of an ophthalmic drug combination against common corneal pathogens of horses. Methods: Representative isolates of 3 bacterial and 2 fungal corneal pathogens of horses. Methods: Pathogens were subjected to minimum inhibitory concentration (MIC) testing of a drug combination that consisted of equal volumes of natamycin 3.33%, tobramycin 0.3%, cefazolin 5.5%, and equine serum. Proteinase inhibitory activity of the drug combination was assessed by use of a fluorescence microplate assay with gelatin and collagen I as substrates. The MICs of the drug combination wer...
Brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona and act as intermediate hosts. We tested the hypothesis that brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona, the agent of equine protozoal myeloencephalitis (EPM), and act as intermediate hosts for this parasite. In summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with Sarcocystis spp. by macroscopic inspection. Seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. Histopathology revealed two classes of sarcocysts in leg muscles, thin-walled and thick-walled suggesting two species. Electron microscopy sh...
Resistance studies of erythromycin and rifampin for Rhodococcus equi over a 10-year period. This study sought to determine whether an increase in resistance of Rhodococcus equi to the antibiotics rifampin and erythromycin occurred over a 10-year period. This was carried out by the use of E test strips for rifampin and erythromycin to determine the MIC (minimum inhibitory concentration) values of Rhodococcus equi to this combination of antibiotics.The findings of this study indicated that there was an increase in resistance of Rhodococcus equi to rifampin and erythromycin over the 10-year period. The MIC for rifampin increased from 0.081 μg/ml in 1996 to 0.187 μg/ml in 2006 and from...
Comparison of five real-time PCR assays for detecting virulence genes in isolates of Escherichia coli from septicaemic neonatal foals. Fifty-five isolates of Escherichia coli from septicaemic neonatal foals were used to validate five real-time pcr assays targeting different known virulence factor genes: curli fibre (csgD), ferric hydroxamate uptake (fhuA), type 1A pilin (fimA), aerobactin (lutA) and yersiniabactin (fyuA). A pcr assay targeting a universal sequence of the bacterial 16S rrna gene served as quality control. The pcr assays showed good analytical specificity and sensitivity on the basis of sequencing the pcr products, their lack of cross-reactivity with non-E coli organisms, high amplification efficiency and a lim...
Safety and immunogenicity of a live-attenuated auxotrophic candidate vaccine against the intracellular pathogen Rhodococcus equi. Rhodococcus equi causes serious pneumonia in neonatal foals and is an opportunistic pathogen of people with compromised cellular immunity. No effective vaccine against R. equi disease in foals is available. We tested the safety and immunogenicity of a live, fully attenuated riboflavin auxotrophic candidate vaccine strain of R. equi (R. equi rib-). We demonstrated that R. equi rib- is immunogenic and capable of inducing IFN-gamma responses in immunocompetent BALB/c mice, yet it is safe even in an immunocompromised SCID mouse infection model. Moreover, it protects immunocompetent mice against vi...
A mycolyl transferase mutant of Rhodococcus equi lacking capsule integrity is fully virulent. Rhodococcus equi is a mucoid Gram-positive facultative intracellular pathogen which can cause severe bronchopneumonia in foals and AIDS patients. A polysaccharide capsule which gives R. equi a mucoid appearance has long been suspected to be a virulence factor. Here, we describe a transposome mutant in the gene fbpA of strain R. equi 103 causing absence of a capsular structure. FbpA is a chromosomal gene homologous to antigen 85 (Ag85) mycolyl chain transferase gene of Mycobacterium tuberculosis. The mutant multiplied normally in isolated macrophages, was able to establish the unusual R. equi-c...
Comparison of polymerase chain reaction methods for the detection of Theileria equi infection using whole blood compared with pre-extracted DNA samples as PCR templates. Rapid, efficient, and reproducible procedures for isolating DNA before PCR gene amplification are essential for the diagnosis of piroplasms. In this study, we evaluated the ease and reliability of detecting Theileria equi by PCR using pre-extracted DNA samples (by QIAamp DNA Mini Kit and phenol-chloroform methods) compared with blood spotted on FTA cards as PCR templates. Although minimal variations in limit of detection were observed among the methods compared, overall, the use of pre-extracted DNA samples and blood spotted on FTA cards had comparable detection limits. These results indicate ...
Acute in vivo interactions of Helicobacter equorum with its equine host. A novel urease-negative Helicobacter species has been isolated from faecal samples of clinically healthy horses, but no information is available about the main sites of colonisation in the equine gastrointestinal tract nor is the pathogenic potential of this microorganism known. An experimental infection in horses was therefore carried out. Methods: Four horses were infected with H. equorum strain CCUG 52199T and subjected to euthanasia at 10 (n = 2) and 30 days (n = 2) post inoculation. A fifth animal was inoculated with phosphate buffered saline and used as control. Gastrointestinal samples ...
Culicoides species attracted to horses with and without insect hypersensitivity. The aims of this study were to determine (1) which species of Culicoides is most commonly attracted to horses, (2) whether horses suffering insect hypersensitivity attract more Culicoides spp. than unaffected horses, and (3) the times when Culicoides spp. are most active. Horses affected by insect hypersensitivity and unaffected horses were placed inside mosquito netting tents for 30 min at different times of the day. All Culicoides spp. trapped inside the tents were collected and identified. C. obsoletus was the most common species found, followed by C. pulicaris. Healthy horses attracted sli...
The diversity of coliphages and coliforms in horse feces reveals a complex pattern of ecological interactions. The diversity of coliphages and indigenous coliform strains (ICSs) simultaneously present in horse feces was investigated by culture-based and molecular methods. The richness of coliforms (as estimated by the Chao1 method) is about 1,000 individual ICSs distinguishable by genomic fingerprinting present in a single sample of feces. This unexpectedly high value indicates that some factor limits the competition of coliform bacteria in the horse gut microbial system. In contrast, the diversity of phages active against any selected ICS is generally limited to one to three viral genotypes present in...
Characterization and structure analysis of a novel bacteriocin, lacticin Z, produced by Lactococcus lactis QU 14. A novel bacteriocin, lacticin Z, produced by Lactococcus lactis QU 14 isolated from a horse's intestinal tract was identified. Lacticin Z was purified through a three step procedure comprised of hydrophobic-interaction, cation-exchange chromatography, and reverse-phase HPLC. ESI-TOF MS determined the molecular mass of lacticin Z to be 5,968.9 Da. The primary structure of lacticin Z was found to consist of 53 amino acid residues without any leader sequence or signal peptide. Lacticin Z showed homology to lacticin Q from L. lactis QU 5, aureocin A53 from Staphylococcus aureus A53, and mutacin BH...
Pharmacokinetics of a single intravenous dose of marbofloxacin in adult donkeys. Six donkeys each received 2 mg/kg marbofloxacin as a 10 per cent aqueous solution administered intravenously. Principal pharmacokinetic parameters were determined and two efficacy indices were computed by using pharmacokinetic parameters and selected mic90 values of marbofloxacin against pathogenic equine strains to predict the efficacy of the drug at this dose. The pharmacokinetics of marbofloxacin in donkeys was characterised by a large mean volume of distribution at a steady state (1.15 [0.09] l/kg) and a long mean (sd) elimination half-life of 9.24 (1.96) hours. It was also characterised b...
Fluorescence in situ hybridization analysis of hindgut bacteria associated with the development of equine laminitis. Carbohydrate-induced laminitis in horses is characterized by marked changes in the composition of the hindgut microbiota, from a predominantly Gram-negative population to one dominated by Gram-positive bacteria. The objective of this study was to monitor changes in the relative abundance of selected hindgut bacteria that have previously been implicated in the pathophysiology of equine laminitis using fluorescence in situ hybridization (FISH). Caecal cannulae were surgically implanted in five Standardbred horses and laminitis induced by oral administration of a bolus dose of oligofructose. Caec...
Use of a low-volume uterine flush for diagnosing endometritis in chronically infertile mares. Low-volume uterine flush (n=401) was performed in 308 infertile mares to diagnose endometritis. Mares evaluated were either barren after three or more breedings or had two or more unsuccessful embryo recovery attempts during consecutive cycles. Culture results were compared with cytological and histological findings, efflux clarity and pH to substantiate that the micro-organisms recovered were truly pathogens. Cytological specimens were evaluated for presence of epithelial and inflammatory cells, bacteria, yeast and debris. Endometrial biopsies (n=110) were examined for the presence of neutrop...
Immunization by intrabronchial administration to 1-week-old foals of an unmarked double gene disruption strain of Rhodococcus equi strain 103+. Rhodococcus equi causes fatal granulomatous pneumonia in foals and immunocompromised animals and humans. However, there is no effective vaccine against this infection. In this study, the chromosomal genes isocitrate lyase (icl) and cholesterol oxidase (choE) were chosen as targets for mutation and assessment of the double mutant as an intrabronchial vaccine in 1-week-old foals. Using a modification of a suicide plasmid previously developed in this laboratory, we developed a choE-icl unmarked deletion mutant of R. equi strain 103+. Five 1-week-old foals were infected intrabronchially with the m...
Methicillin-resistant Staphylococcus aureus ST398 in humans and animals, Central Europe. Methicillin-resistant Staphylococcus aureus of clonal lineage ST398 that exhibits related spa types and contains SCCmec elements of types IVa or V has been isolated from colonized and infected humans and companion animals (e.g., dog, pig, horse) in Germany and Austria. Of particular concern is the association of these cases with cases of nosocomial ventilator-associated pneumonia.
Phenotypical assays and partial sequencing of the hsp60 gene for identification of Streptococcus equi. Strangles is an acute and contagious disease characterized by inflammation of the upper respiratory tract of horses. The etiological agent of strangles is the bacteria S. equi subsp. equi, which belongs to the Lancefield group C. Opportunistic agents from the same group are frequently isolated from horses with strangles and may induce mistaken diagnoses. Among the subspecies of S. equi, the phenotypic features are almost undistinguishable; however, the pathogenic potential is widely differentiated. The aim of this study was to characterize S. equi isolates obtained from clinical samples of str...
Pharmacokinetics of oral doxycycline and concentrations in body fluids and bronchoalveolar cells of foals. The objective of this study was to determine the disposition of orally administered doxycycline in foals. Six healthy 4- to 8-week-old foals were used. Doxycycline was administered to each foal via the intragastric (IG) route at dosages of 10 and 20 mg/kg, in a cross-over design. After the first 10 mg/kg dose, five additional doses were administered at 12-h intervals. A microbiological assay was used to measure doxycycline activity in serum, urine, peritoneal fluid, synovial fluid, cerebrospinal (CSF), pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. Following adminis...
