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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.
Evaluation of the affinity of various species and strains of Staphylococcus to adhere to equine corneocytes. Meticillin-resistant Staphylococcus aureus (MRSA) strain USA 500 predominately colonizes horses and people working with them. Previous studies demonstrate that some Staphylococcus species exhibit higher affinity for corneocytes of specific mammalian species. Objective: The objective was to determine the relative affinities of various MRSA strains, meticillin-susceptible S. aureus (MSSA) strains and a meticillin-susceptible Staphylococcus pseudintermedius (MSSP) for equine corneocytes. We hypothesized that MRSA strain USA 500 would exhibit greater adhesion than other staphylococcal strains te...
Infectious agents associated with diarrhoea in neonatal foals in central Kentucky: a comprehensive molecular study. Diarrhoea caused by infectious agents is common in foals but there is no comprehensive molecular work-up of the relative prevalence of common agents and appearance of coinfections. Objective: To determine the prevalence of 9 infectious agents in gastrointestinal (GI)-diseased and healthy foals with ages ranging from 1 to 20 weeks of age and to what degree coinfections are associated with clinical signs of GI disease. Methods: Retrospective controlled observational study. Methods: The population consisted of 88 Thoroughbred foals aged 2 days to 17 weeks born on 32 different studfarms in Kentuck...
Plasma and pulmonary pharmacokinetics of desfuroylceftiofur acetamide after weekly administration of ceftiofur crystalline free acid to adult horses. Current labelling for the use of ceftiofur crystalline free acid (CCFA) in horses states that 2 i.m. doses must be administered 4 days apart to provide 10 days of therapeutic coverage. A 10 day treatment regimen is not sufficient for the long-term treatment of horses with severe lung consolidation or pleuropneumonia. There are currently no data to guide an appropriate dosing interval when a longer treatment regimen is warranted. Objective: To determine steady-state plasma and pulmonary epithelial lining fluid (PELF) concentrations of desfuroylceftiofur acetamide (DCA) after weekly i.m. adminis...
Infectious risk factors and clinical indicators for tracheal mucus in British National Hunt racehorses. Many studies of respiratory disease in racehorses have focused on a combination of increased tracheal mucus and airway neutrophilia. Examination of each component separately should provide further insight into this condition. Objective: To identify infectious risk factors for endoscopically visible tracheal mucus in National Hunt racehorses. Methods: A 2 year prospective longitudinal study. Methods: Monthly quantitative bacteriological examinations of tracheal wash samples and viral serological examinations were conducted. Risk factors for 'small amounts of mucus' (mucus score = 1/3) and 'incr...
PCR-based Methodologies Used to Detect and Differentiate the Burkholderia pseudomallei complex: B. pseudomallei, B. mallei, and B. thailandensis. Methods for the rapid detection and differentiation of the Burkholderia pseudomallei complex comprising B. pseudomallei, B. mallei, and B. thailandensis, have been the topic of recent research due to the high degree of phenotypic and genotypic similarities of these species. B. pseudomallei and B. mallei are recognized by the CDC as tier 1 select agents. The high mortality rates of glanders and melioidosis, their potential use as bioweapons, and their low infectious dose, necessitate the need for rapid and accurate detection methods. Although B. thailandensis is generally avirulent in mammals, ...
Trypanosoma evansi and surra: a review and perspectives on origin, history, distribution, taxonomy, morphology, hosts, and pathogenic effects. Trypanosoma evansi, the agent of "surra," is a salivarian trypanosome, originating from Africa. It is thought to derive from Trypanosoma brucei by deletion of the maxicircle kinetoplastic DNA (genetic material required for cyclical development in tsetse flies). It is mostly mechanically transmitted by tabanids and stomoxes, initially to camels, in sub-Saharan area. The disease spread from North Africa towards the Middle East, Turkey, India, up to 53° North in Russia, across all South-East Asia, down to Indonesia and the Philippines, and it was also introduced by the conquistadores into Latin ...
The antimicrobial activity of honey against common equine wound bacterial isolates. Delayed healing associated with distal limb wounds is a particular problem in equine clinical practice. Recent studies in human beings and other species have demonstrated the beneficial wound healing properties of honey, and medical grade honey dressings are available commercially in equine practice. Equine clinicians are reported to source other non-medical grade honeys for the same purpose. This study aimed to assess the antimicrobial activity of a number of honey types against common equine wound bacterial pathogens. Twenty-nine honey products were sourced, including gamma-irradiated and no...
The changing face of the henipaviruses. The Henipavirus genus represents a group of paramyxoviruses that are some of the deadliest of known human and veterinary pathogens. Hendra and Nipah viruses are zoonotic pathogens that can cause respiratory and encephalitic illness in humans with mortality rates that exceed 70%. Over the past several years, we have seen an increase in the number of cases and an altered clinical presentation of Hendra virus in naturally infected horses. Recent increase in the number of cases has also been reported with human Nipah virus infections in Bangladesh. These factors, along with the recent discovery of...
Identification of a human monoclonal antibody to replace equine diphtheria antitoxin for treatment of diphtheria intoxication. Diphtheria antitoxin (DAT) has been the cornerstone of the treatment of Corynebacterium diphtheriae infection for more than 100 years. Although the global incidence of diphtheria has declined steadily over the last quarter of the 20th century, the disease remains endemic in many parts of the world, and significant outbreaks still occur. DAT is an equine polyclonal antibody that is not commercially available in the United States and is in short supply globally. A safer, more readily available alternative to DAT would be desirable. In the current study, we obtained human monoclonal antibodies (h...
Development, evaluation, and laboratory validation of immunoassays for the diagnosis of equine infectious anemia (EIA) using recombinant protein produced from a synthetic p26 gene of EIA virus. Equine infectious anemia (EIA)-a retroviral disease caused by equine infectious anemia virus (EIAV)-is a chronic, debilitating disease of horses, mules, and donkeys. EIAV infection has been reported worldwide and is recognized as pathogen of significant economic importance to the horse industry. This disease falls under regulatory control program in many countries including India. Control of EIA is based on identification of inapparent carriers by detection of antibodies to EIAV in serologic tests and "Stamping Out" policy. The current internationally accepted test for diagnosis of EIA is the ...
What can mathematical models bring to the control of equine influenza? Mathematical modelling of infectious disease is increasingly regarded as an important tool in the development of disease prevention and control measures. This article brings together key findings from various modelling studies conducted over the past 10 years that are of relevance to those on the front line of the battle against equine influenza.
Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland. To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. Methods: Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detect...
The equine alveolar macrophage: functional and phenotypic comparisons with peritoneal macrophages. Alveolar macrophages (AMs) constitute the first line of defence in the lung of all species, playing a crucial role in the regulation of immune responses to inhaled pathogens. A detailed understanding of the function and phenotype of AMs is a necessary pre-requisite to both elucidating their role in preventing opportunistic bacterial colonisation of the lower respiratory tract and developing appropriate preventative strategies. The purpose of the study was to characterise this important innate immune cell at the tissue level by making functional and phenotypic comparisons with peritoneal macrop...
Recovery of African horse sickness virus from synthetic RNA. African horse sickness virus (AHSV) is an insect-vectored emerging pathogen of equine species. AHSV (nine serotypes) is a member of the genus Orbivirus, with a morphology and coding strategy similar to that of the type member, bluetongue virus. However, these viruses are distinct at the genetic level, in the proteins they encode and in their pathobiology. AHSV infection of horses is highly virulent with a mortality rate of up to 90 %. AHSV is transmitted by Culicoides, a common European insect, and has the potential to emerge in Europe from endemic countries of Africa. As a result, a safe an...
Identification of novel immunoreactive proteins of Streptococcus zooepidemicus with potential as vaccine components. Streptococcus zooepidemicus is an important opportunistic pathogen of the equine respiratory and reproductive tracts. A normal tonsillar and mucosal commensal, it becomes invasive under conditions of stress such as virus infection, weaning, high temperature, prolonged transportation and failure of uterine involution. The aim of this study was to evaluate the vaccine potential of several surface exposed and secreted proteins of a novel mucoid clone of SzNC78 (ST-307) from an epizootic of equine respiratory disease. Methods: An expression gene library of SzNC78 was probed with a pool of convales...
Equine herpesviruses type 1 (EHV-1) and 4 (EHV-4)–masters of co-evolution and a constant threat to equids and beyond. The equine herpesviruses type 1 (EHV-1) and 4 (EHV-4) are ubiquitous pathogens that affect horse populations on all continents. Despite widespread vaccination, EHV-1 and EHV-4 infections remain a permanent risk. While the two viruses share a high degree of genetic and antigenic similarity, they differ significantly in host range and pathogenicity. Compared to EHV-4, which mainly infects horses and causes respiratory disease, EHV-1 has a broader host range and can result in respiratory disease, abortions, neonatal death, and equine herpesvirusmyeloencephalopathy (EHM). Recent studies have eluci...
Rhodococcus equi: the many facets of a pathogenic actinomycete. Rhodococcus equi is a soil-dwelling pathogenic actinomycete that causes pulmonary and extrapulmonary pyogranulomatous infections in a variety of animal species and people. Young foals are particularly susceptible and develop a life-threatening pneumonic disease that is endemic at many horse-breeding farms worldwide. R. equi is a facultative intracellular parasite of macrophages that replicates within a modified phagocytic vacuole. Its pathogenicity depends on a virulence plasmid that promotes intracellular survival by preventing phagosome-lysosome fusion. Species-specific tropism of R. equi fo...
The equine antimicrobial peptide eCATH1 is effective against the facultative intracellular pathogen Rhodococcus equi in mice. Rhodococcus equi, the causal agent of rhodococcosis, is a major pathogen of foals and is also responsible for severe infections in immunocompromised humans. Of great concern, strains resistant to currently used antibiotics have emerged. As the number of drugs that are efficient in vivo is limited because of the intracellular localization of the bacterium inside macrophages, new active but cell-permeant drugs will be needed in the near future. In the present study, we evaluated, by in vitro and ex vivo experiments, the ability of the alpha-helical equine antimicrobial peptide eCATH1 to kill int...
Transmission of Streptococcus equi subspecies zooepidemicus infection from horses to humans. Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) is a zoonotic pathogen for persons in contact with horses. In horses, S. zooepidemicus is an opportunistic pathogen, but human infections associated with S. zooepidemicus are often severe. Within 6 months in 2011, 3 unrelated cases of severe, disseminated S. zooepidemicus infection occurred in men working with horses in eastern Finland. To clarify the pathogen's epidemiology, we describe the clinical features of the infection in 3 patients and compare the S. zooepidemicus isolates from the human cases with S. zooepidemicus isolates...
Comparative analysis of 16S RNA nucleotide sequences of Anaplasma phagocytophilum detected in the blood of horses from various parts of Europe. The aim of this study was to conduct a comparative analysis of the 16S rRNA gene fragment nucleotide sequences for Anaplasma phagocytophilum strains detected in the blood of horses from various parts of Europe. The study comprised 234 horses that had had contact with ticks. Using PCR, the genetic material of A. phagocytophilum was identified in the blood of 42 animals. The sequences of the 16S RNA gene amplicons that were obtained from our A. phagocytophilum isolates had 100 % similarity with each other and 96.4-100 % similarity with Anaplasma spp. sequences selected from those available i...
First detection of methicillin-resistant Staphylococcus aureus ST398 and Staphylococcus pseudintermedius ST68 from hospitalized equines in Spain. Eight coagulase-positive staphylococci from equines with different pathologies obtained between 2005 and 2011 were investigated. Isolates were characterized by different molecular techniques (spa-, agr-, MLST), and clonal relatedness of strains was investigated by ApaI and SmaI PFGE. Anti-microbial resistance and virulence profiles were determined. Six isolates were identified as Staphylococcus aureus, and two as Staphylococcus pseudintermedius. Of these, four isolates were methicillin-resistant S. aureus (MRSA) ST398 and one S. pseudintermedius was mecA positive and typed as ST68. One MRSA ...
Effects of administration of live or inactivated virulent Rhodococccus equi and age on the fecal microbiome of neonatal foals. Rhodococcus equi is an important pathogen of foals. Enteral administration of live, virulent R. equi during early life has been documented to protect against subsequent intrabronchial challenge with R. equi, indicating that enteral mucosal immunization may be protective. Evidence exists that mucosal immune responses develop against both live and inactivated micro-organisms. The extent to which live or inactivated R. equi might alter the intestinal microbiome of foals is unknown. This is an important question because the intestinal microbiome of neonates of other species is known to change over...
Biocide and antimicrobial susceptibility of methicillin-resistant staphylococcal isolates from horses. The aim of this study was to evaluate the biocide and antimicrobial susceptibility of methicillin-resistant staphylococcal isolates from horses. Fourteen methicillin-resistant staphylococci (MRS) were subjected to an extensive genotype characterization, including SCCmec, dru, spa, PFGE and MLST typing. Antimicrobial susceptibility testing was performed and resistance genes were detected by PCR. Minimum bactericidal concentrations (MBCs) of four biocides [chlorhexidine acetate (CHA), benzalkonium chloride (BAC), triclosan (TCL) and glutaraldehyde (GLA)] were determined following the recommendat...
Lineages of Streptococcus equi ssp. equi in the Irish equine industry. Streptococcus equi ssp. equi is the causative agent of 'Strangles' in horses. This is a debilitating condition leading to economic loss, yard closures and cancellation of equestrian events. There are multiple genotypes of S. equi ssp. equi which can cause disease, but to date there has been no systematic study of strains which are prevalent in Ireland. This study identified and classified Streptococcus equi ssp. equi strains isolated from within the Irish equine industry. Results: Two hundred veterinary isolates were subjected to SLST (single locus sequence typing) based on an internal sequenc...
Outbreak of upper respiratory disease in horses caused by Streptococcus equi subsp. zooepidemicus ST-24. Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is generally considered a commensal and an opportunistic pathogen of the upper airways in horses. Establishing whether certain strains of S. zooepidemicus can cause upper respiratory disease as a host-specific pathogen of horses, and if there are certain genogroups of S. zooepidemicus that are more virulent than others is of major clinical importance. In this study, we describe an outbreak of upper respiratory disease in horses that was associated with S. zooepidemicus. Upper respiratory samples were cultured, analyzed by real-time PCR...
Yeast-like fungi and yeasts isolated from healthy breeding horses. Horses are characterized by a very high incidence of mycoses in comparison with most livestock and companion animals. They are highly susceptible to asymptomatic infections caused by yeast-like fungi, but the carrier state may be disrupted under the influence of autogenic and allogenic factors. The above leads to severe organ mycoses, often with an acute form of infection. "Carrier horses" may also act as vectors which transmit potential pathogens between individuals and species. The aim of this study was to identify yeast-like fungi and yeast colonizing the ontocenoses of healthy horses and t...
Diarrhea-associated pathogens, lactobacilli and cellulolytic bacteria in equine feces: responses to antibiotic challenge. Antibiotics are important to equine medicine, but antibiotic-associated diarrhea (AAD) can lead to poor performance and even mortality. AAD is attributed to disruption of the hindgut microbiota, which permits proliferation of pathogenic microbes. The goal of this study was to evaluate the effects of common antibiotics on cellulolytic bacteria, lactobacilli, and AAD-associated pathogens in the feces of healthy horses. Fifteen horses were assigned to three treatment groups (blocked by age and sex): control (no antibiotics), trimethoprim-sulfadiazine (PO), or ceftiofur (IM). Fecal samples (n=8 pe...
Age-related changes following in vitro stimulation with Rhodococcus equi of peripheral blood leukocytes from neonatal foals. Rhodococcus equi is an intracellular bacterium primarily known as an equine pathogen that infects young foals causing a pyogranulomatuous pneumonia. The molecular mechanisms mediating the immune response of foals to R. equi are not fully elucidated. Hence, global genomic high-throughput tools like gene expression microarrays might identify age-related gene expression signatures and molecular pathways that contribute to the immune mechanisms underlying the inherent susceptibility of foals to disease caused by R. equi. The objectives of this study were 2-fold: 1) to compare the expression profil...
