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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.
Spreading of West Nile virus infection in Croatia. West Nile virus (WNV) is an emerging zoonotic pathogen with rapid global expansion. The virus circulation is confirmed in many countries of Mediterranean Basin and Southern and Central Europe. In our study detection of specific WNV antibodies was performed in horses and cattle sera samples collected from October 2010 to April 2011. Serum samples were randomly taken from different parts of Croatia and tested by IgG and IgM ELISA. Positive serological results were confirmed by virus neutralization assay (VN-assay) and plaque reduction neutralization test (PRNT). Results showed that WNV antibodie...
New equine antitoxins to botulinum neurotoxins serotypes A and B. Hyperimmune monovalent antitoxins to botulinum neurotoxin serotypes A and B have been produced by immunizing horses with newly developed formalin toxoids. After primary immunization, horses developed acceptable prophylactic antibody titers (1-5 IU/mL). Three horses received additional toxoid booster injections to induce hyperimmune antibody titers with antitoxin-A and antitoxin-B titers reaching peaks of approximately 2000 IU/mL and 150-625 IU/mL, respectively. Titers were quantified throughout the process by antigen-capture ELISA and by in-vivo neutralization. ELISA titers and neutralization ...
Seroprevalence of Toxoplasma gondii infection in domestic horses in Durango State, Mexico. The seroprevalence of Toxoplasma gondii infection in horses in Mexico is unknown. Therefore, antibodies to T. gondii were assessed in 495 horses in Durango State, Mexico, using the modified agglutination test (MAT). Horses were from 18 farms in 3 municipalities in the valley region of Durango State. Antibodies to T. gondii were found in 30 (6.1%) of 495 horses, with MAT titers of 1:25 in 19, 1:50 in 6, and 1:100 in 5. Seropositive horses were found in 8 (44.4%) of 18 farms sampled in all 3 municipalities. Age, gender, and breed of horses did not influence significantly the seroprevalence of T....
Subclinical leptospirosis may impair athletic performance in racing horses. The infection by Leptospira in horses, in both its acute disease and subclinical forms, is very common, particularly in endemic regions. Therefore, the objective of this study was to evaluate the effects of subclinical leptospirosis in the athletic performance of racing thoroughbred horses. Athletic performance of 119 racing Thoroughbred horses from Rio de Janeiro, Brazil, was calculated by assigning a point value for the results in racing (performance index (PI)), and serology for leptospirosis was conducted. A total of 85 (71.4 %) horses showed reactive titers (≥ 100), and of which 52 had ...
Efficacy of an avirulent live vaccine against Lawsonia intracellularis in the prevention of proliferative enteropathy in experimentally infected weanling foals. To determine the efficacy of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy in weanling foals. Methods: 12 healthy weanling foals. Methods: Foals were randomly assigned to a vaccinated, nonvaccinated, or control group. Vaccinated foals received an avirulent porcine L intracellularis frozen-thawed vaccine intrarectally 60 and 30 days prior to experimental challenge. On day 1, vaccinated and nonvaccinated foals were challenged via nasogastric intubation with a virulent heterologous isolate of L intracellularis. Control foals were not challenged. Clinical ob...
Detection of Neospora sp. antibodies in cart horses from urban areas of Curitiba, Southern Brazil. Neospora caninum is a protozoan parasite which affects dogs as definitive hosts and several mammalian species as intermediate hosts mainly causing abortions and central nervous system disorders. The reemerging population of cart horses for carrying recycling material in urban areas of major cities in Brazil may have an impact on disease spreading, and these animals may be used as sentinels for environmental surveillance. Thus, the present study investigated the frequency of Neospora sp. antibodies in cart horses from Curitiba and surrounding areas, Paraná State, Southern Brazil. IgG antibodie...
Clinical, pathological, and genetic characterization of Listeria monocytogenes causing sepsis and necrotizing typhlocolitis and hepatitis in a foal. Listeria monocytogenes was isolated from the blood, lungs, and liver of a 5-week-old American Quarter Horse filly that presented with a 2-day history of fever, lethargy, ataxia, and seizure activity. The foal was born on a well-managed breeding facility to a multiparous mare with no periparturient complications. At 8 hr of age, the foal had an adequate passive transfer of immunity (immunoglobulin G > 2,000 mg/dl). Since the time of birth, the foal reportedly had mild, intermittent diarrhea that responded to gastrointestinal protectants and probiotics. Despite prompt and aggressive treatment af...
Quantitative real-time PCR for detection of the neurotoxin gene of Clostridium botulinum type B in equine and bovine samples. Clostridium botulinum type B is estimated to cause more than 85% of cases of equine botulism in the United States, as well as many outbreaks in cattle. In this study, a quantitative real-time polymerase chain reaction for detection of the neurotoxin gene of C. botulinum type B was compared to the mouse bioassay using 45 positive and 43 negative samples of equine, bovine or associated environmental origin. The sensitivity of the qPCR assay was 96%, whereas the sensitivity of the mouse bioassay was 84%. The specificity of the qPCR assay was 95% and the specificity of the mouse bioassay was 100%....
ELA-DRA polymorphisms are not associated with Equine Arteritis Virus infection in horses from Argentina. Polymorphisms at Major Histocompatibility Complex (MHC) genes have been associated with resistance/susceptibility to infectious diseases in domestic animals. The aim of this investigation was to evaluate whether polymorphisms of the DRA gene the Equine Lymphocyte Antigen is associated with susceptibility to Equine Arteritis Virus (EAV) infection in horses in Argentina. The equine DRA gene was screened for polymorphisms using Pyrosequencing® Technology which allowed the detection of three ELA-DRA exon 2 alleles. Neither allele frequencies nor genotypic differentiation exhibited any statistical...
Characterization of virulent West Nile virus Kunjin strain, Australia, 2011. To determine the cause of an unprecedented outbreak of encephalitis among horses in New South Wales, Australia, in 2011, we performed genomic sequencing of viruses isolated from affected horses and mosquitoes. Results showed that most of the cases were caused by a variant West Nile virus (WNV) strain, WNV(NSW2011), that is most closely related to WNV Kunjin (WNV(KUN)), the indigenous WNV strain in Australia. Studies in mouse models for WNV pathogenesis showed that WNV(NSW2011) is substantially more neuroinvasive than the prototype WNV(KUN) strain. In WNV(NSW2011), this apparent increase in vir...
Infected dendritic cells are sufficient to mediate the adjuvant activity generated by Venezuelan equine encephalitis virus replicon particles. Replicon particles derived from Venezuelan equine encephalitis virus (VEE) are infectious non-propagating particles which act as a safe and potent systemic, mucosal, and cellular adjuvant when delivered with antigen. VEE and VEE replicon particles (VRP) can target multiple cell types including dendritic cells (DCs). The role of these cell types in VRP adjuvant activity has not been previously evaluated, and for these studies we focused on the contribution of DCs to the response to VRP. By analysis of VRP targeting in the draining lymph node, we found that VRP induced rapid recruitment of TNF-s...
The influence of meteorology on the spread of influenza: survival analysis of an equine influenza (A/H3N8) outbreak. The influences of relative humidity and ambient temperature on the transmission of influenza A viruses have recently been established under controlled laboratory conditions. The interplay of meteorological factors during an actual influenza epidemic is less clear, and research into the contribution of wind to epidemic spread is scarce. By applying geostatistics and survival analysis to data from a large outbreak of equine influenza (A/H3N8), we quantified the association between hazard of infection and air temperature, relative humidity, rainfall, and wind velocity, whilst controlling for prem...
Retrospective study of 103 presumed cases of tick (Ixodes holocyclus) envenomation in the horse. Review 103 cases of presumed tick envenomation in horses. Methods: Retrospective study. Methods: Variables, including date of presentation, age, breed, weight, presence of ticks, gait and respiration scores, duration of recumbency, treatment, outcome and complications were recorded. A series of univariable screening tests were performed and used in a multivariable logistic regression model. Results: There were a total of 103 cases affecting 10 breeds, aged between 1 week and 18 years of age. Horses >6 months old and weighing >100 kg had a higher odds of death than those...
Optimization of an in vitro assay to detect Streptococcus equi subsp. equi. Streptococcus equi is the etiologic agent of a highly infectious upper respiratory disease of horses known as strangles. Bacterial culture methods and polymerase chain reaction (PCR) of nasopharyngeal washes and guttural pouch lavages are used routinely to test clinical and carrier animals for the presence of S. equi but no definitive or gold standard test method has been shown to be optimal. We hypothesized that (i) a flocked swab submerged in ten-fold serial dilution suspensions of S. equi prepared in 0.9% NaCl would detect more colony forming units (CFU) than a rayon swab when used to inocu...
No evidence of horizontal infection in horses kept in close contact with dogs experimentally infected with canine influenza A virus (H3N8). Since equine influenza A virus (H3N8) was transmitted to dogs in the United States in 2004, the causative virus, which is called canine influenza A virus (CIV), has become widespread in dogs. To date, it has remained unclear whether or not CIV-infected dogs could transmit CIV to horses. To address this, we tested whether or not close contact between horses and dogs experimentally infected with CIV would result in its interspecies transmission. Methods: Three pairs of animals consisting of a dog inoculated with CIV (10(8.3) egg infectious dose 50/dog) and a healthy horse were kept together in i...
New insights into sequence variation in the IGS region of 21 cyathostomin species and the implication for molecular identification. Cyathostomins comprise a group of 50 species of parasitic nematodes that infect equids. Ribosomal DNA sequences, in particular the intergenic spacer (IGS) region, have been utilized via several methodologies to identify pre-parasitic stages of the commonest species that affect horses. These methods rely on the availability of accurate sequence information for each species, as well as detailed knowledge of the levels of intra- and inter-specific variation. Here, the IGS DNA region was amplified and sequenced from 10 cyathostomin species for which sequence was not previously available. Also, add...
Complete genomic sequence of an equine herpesvirus type 8 Wh strain isolated from China. A new strain of equine herpesvirus type 8 (EHV-8), Wh, has been isolated from horses in China, and its complete genome has been sequenced and analyzed. The result indicates that the new strain has the same constitution and arrangement of open read frames as EHV-1 and EHV-9. This work is the first announced complete genome sequence of EHV-8.
Seroprevalence study on Theileria equi and Babesia caballi antibodies in horses from central province of Saudi Arabia. In total, 241 sera from clinically healthy adult horses were collected from 6 locations in Saudi Arabia and examined for Theileria equi and Babesia caballi antibodies by an indirect fluorescent antibody test. Antibodies to Theileria equi were detected in 25 horses (10.4%) while the antibodies to Babesia caballi were observed in 18 horses (7.5%). In addition, 7 serum samples were positive for antibodies to both parasites (3%). The horses sampled in Al-Janadriah had the highest prevalence of infection with T. equi at 16.5% and with B. caballi at 8.8%, while the lowest prevalence of infection wit...
Immunogenicity of two adjuvant formulations of an inactivated African horse sickness vaccine in guinea-pigs and target animals. Monovalent, inactivated and adjuvanted vaccines against African horse sickness, prepared with serotypes 5 and 9, were tested on guinea-pigs to select the formulation that offered the greatest immunity. The final formulation of the vaccines took into account the immune response in the guinea-pig and the inflammatory properties of two types of adjuvant previously tested on target animals. A pilot study was subsequently conducted on horses using a vaccine prepared with serotype 9. The vaccine stimulated neutralising antibodies from the first administration and, after the booster dose, 28 days lat...
Pulmonary Disease due to Mycobacterium tuberculosis in a Horse: Zoonotic Concerns and Limitations of Antemortem Testing. A case of pulmonary tuberculosis caused by Mycobacterium tuberculosis was diagnosed in a horse. Clinical evaluation performed prior to euthanasia did not suggest tuberculosis, but postmortem examination provided pathological and bacteriological evidence of mycobacteriosis. In the lungs, multiple tuberculoid granulomas communicating with the bronchiolar lumen, pleural effusion, and a granulomatous lymphadenitis involving mediastinal and tracheobronchial lymph nodes were found. Serologic response to M. tuberculosis antigens was detected in the infected horse, but not in the group of 42 potential...
Bilateral ovarian adenocarcinoma in a mare causing haemoperitoneum and colic. A 13-year-old Thoroughbred mare was presented with a history of mild colic over 3 days. This colic had acutely exacerbated and was unresponsive to analgesic treatment, and was referred to Massey University Veterinary Teaching Hospital. Results: On examination the heart rate was 100 beats per minute, and mucous membranes were pale and tacky. A large mass was detected on transrectal palpation in the caudal abdomen to the left of midline. Explorative laparotomy revealed severe haemoperitoneum and several masses that were associated with the reproductive tract. The mare was then subject to euthana...
Guttural pouch mycosis in six horses in New Zealand. Six horses from several geographical locations in New Zealand presented with signs of guttural pouch mycosis. All horses had experienced epistaxis within 14 days of presentation. Results: In five horses with epistaxis, a diagnosis of guttural pouch mycosis was made on endoscopic observation of fungal plaques in the affected guttural pouches. One of these cases died before surgery was attempted. The remaining four cases underwent ligation and balloon catheter occlusion of the internal carotid artery of the affected pouch. Three of these horses survived and were reported to be healthy 1 year aft...
Ecological aspects of hendra virus. Hendra virus, a novel and fatally zoonotic member of the family Paramyxoviridae, was first described in Australia in 1994. Periodic spillover from its natural host (fruit bats) results in catastrophic disease in horses and occasionally the subsequent infection of humans. Prior to 2011, 14 equine incidents involving seven human cases (four fatal) were recorded. The year 2011 saw a dramatic departure from the sporadic incidents of the previous 16 years, with a cluster of 18 incidents in a single 3-month period. The fundamental difference in 2011 was the total number of incidents, the geographic ...
Comparative genomic analyses of the Taylorellae. Contagious equine metritis (CEM) is an important venereal disease of horses that is of concern to the thoroughbred industry. Taylorella equigenitalis is a causative agent of CEM but very little is known about it or its close relative Taylorella asinigenitalis. To reveal novel information about Taylorella biology, comparative genomic analyses were undertaken. Whole genome sequencing was performed for the T. equigenitalis type strain, NCTC11184. Draft genome sequences were produced for a second T. equigenitalis strain and for a strain of T. asinigenitalis. These genome sequences were analysed an...
Henipaviruses in their natural animal hosts. Hendra virus (HeV) and Nipah virus (NiV) form a separate genus Henipavirus within the family Paramyxoviridae, and are classified as biosafety level 4 pathogens due to their high case fatality rate following human infection and because of the lack of effective vaccines or therapy. Both viruses emerged from their natural reservoir during the last decade of the twentieth century, causing severe disease in humans, horses and swine, and infecting a number of other mammalian species. The current review summarizes our up to date understanding of pathology and pathogenesis in the natural reservoir spe...
Hendra and Nipah viruses: why are they so deadly? Henipavirus, including Hendra and Nipah viruses, is a group of emerging bat-borne paramyxoviruses which were responsible for severe disease outbreaks in humans, horses and pigs. The mortality rate of human infection varies between 50 and 100%, making them one of the most deadly viruses known to infect humans. Its use of highly conserved cell surface molecules (ephrin) as entry receptors and its highly effective replication and fusion strategies are believed to be important characteristics responsible for its high pathogenicity. Henipavirus also encodes multiple accessory proteins which play a ...
Summary of current knowledge of the size and spatial distribution of the horse population within Great Britain. Robust demographic information is important to understanding the risk of introduction and spread of exotic diseases as well as the development of effective disease control strategies, but is often based on datasets collected for other purposes. Thus, it is important to validate, or at least cross-reference these datasets to other sources to assess whether they are being used appropriately. The aim of this study was to use horse location data collected from different contributing industry sectors ("Stakeholder horse data") to calibrate the spatial distribution of horses as indicated by owner lo...
Serology-enabled discovery of genetically diverse hepaciviruses in a new host. Genetic and biological characterization of new hepaciviruses infecting animals contributes to our understanding of the ultimate origins of hepatitis C virus (HCV) infection in humans and dramatically enhances our ability to study its pathogenesis using tractable animal models. Animal homologs of HCV include a recently discovered canine hepacivirus (CHV) and GB virus B (GBV-B), both viruses with largely undetermined natural host ranges. Here we used a versatile serology-based approach to determine the natural host of the only known nonprimate hepacivirus (NPHV), CHV, which is also the closest p...
