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Topic:Epidemiology
Epidemiology in horses involves the study of the distribution and determinants of health-related states and events in equine populations. It encompasses the investigation of patterns, causes, and effects of diseases and health conditions within horse populations. This field of study aims to identify risk factors for disease and targets for preventive healthcare. Key components of equine epidemiology include disease surveillance, outbreak investigation, and the study of disease dynamics within herds or regions. Research in this area often focuses on infectious diseases, zoonotic diseases, and the impact of environmental factors on equine health. This page compiles peer-reviewed research studies and scholarly articles that explore various aspects of epidemiology in horses, including disease prevalence, transmission pathways, and strategies for disease prevention and control.
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...
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...
Protection against Ehrlichia equi is conferred by prior infection with the human granulocytotropic Ehrlichia (HGE agent). A Thoroughbred filly that developed clinical signs of equine granulocytic ehrlichiosis following inoculation with the human granulocytotropic ehrlichia was shown to be resistant to challenge with Ehrlichia equi, a closely related agent. This result further substantiates the close and potentially conspecific relationship between these two granulocytotropic ehrlichiae.
Sero-positivity of domestic animals against Japanese encephalitis in Bareilly area, U.P. A study on seroprevalence of Japanese Encephalitis (JE), West Nile (WN) and Dengue-2 (DN-2) was undertaken in and around Bareilly, Uttar Pradesh to explore the role of non-human hosts in the natural cycle of these infections. A total of 1449 animal sera samples collected from 104 dogs, 170 pigs, 170 horses, 333 buffaloes, 252 cattle, 168 sheep and 252 goats were screened for antibodies against JE, WN and DN-2 by Micro-haemagglutination inhibition (HI) test employing 4 to 16 HA units of JE, WN and DN-2 antigens. The HI positivity against JE was found in dogs (55.77%) followed by pigs (40%), hor...
Evidence for a high rate of false-positive results with the indirect fluorescent antibody test for Ehrlichia risticii antibody in horses. The original objective was to determine seroprevalence of Ehrlichia risticii antibody among horses in California. On the basis of the unexpected results of the survey, an investigation into the accuracy and reproducibility of results of the indirect fluorescent antibody (IFA) test for E risticii was carried out. Methods: Prospective, seroprevalence study. Methods: Healthy horses (n = 655) and horses with clinical signs of equine monocytic ehrlichiosis (EME; n = 514) from various regions of California. Methods: The IFA test was performed. Results were compared with results of an ELISA and with ...
Identification of opossums (Didelphis virginiana) as the putative definitive host of Sarcocystis neurona. Sarcocystis neurona is an apicomplexan that causes equine protozoal myeloencephalitis (EPM) in North and South America. Horses appear to be an aberrant host, because the merozoites continually divide in the central nervous system, without encysting. The natural host species has not previously been identified. The small subunit ribosomal RNA (SSURNA) gene of S. neurona was compared to those of Sarcocystis muris, Sarcocystis cruzi, Toxoplasma gondii, and Cryptosporidium parvum to identify a unique region suitable for a species-specific amplification primer. The S. neurona SSURNA primer was used ...
Sarcocystis falcatula from passerine and psittacine birds: synonymy with Sarcocystis neurona, agent of equine protozoal myeloencephalitis. Equine protozoal myeloencephalitis (EPM) is a neurologic disease of horses caused by Sarcocystis neurona. The horse is a dead-end host for S. neurona and the definitive and intermediate hosts have not previously been identified. We hypothesized that S. neurona is actually Sarcocystis falcatula, a parasite that cycles in nature between Virginia opossums (Didelphis virginiana) and any of a variety of avian intermediate hosts. We extracted DNA from S. falcatula sarcocysts in the muscle of a brown-headed cowbird (Molothrus ater) and from schizonts in a fixed specimen of lung from a Moluccan cockat...
Association of leptospiral seroreactivity and breed with uveitis and blindness in horses: 372 cases (1986-1993). Recurrent uveitis, a leading cause of blindness in horses, often develops as a sequela to systemic leptospirosis. Over a 7-year period, 63 of 112 (56%) horses with uveitis were seropositive for Leptospira interrogans serovar pomona, but only 23 of 260 (9%) horses without uveitis were seropositive. Odds-ratio analysis revealed that seropositive horses were 13.2 times more likely to have uveitis than were seronegative horses. Of the 63 seropositive horses with uveitis, 59% developed blindness, compared with only 24% in the 49 seronegative horses with uveitis that lost vision in 1 or both eyes du...
Equine arteritis virus subgenomic RNA transcription: UV inactivation and translation inhibition studies. The expression of the genetic information of equine arteritis virus (EAV), an arterivirus, involves the synthesis of six subgenomic (sg) mRNAs. These are 5' and 3' coterminal since they are composed of a leader and a body sequence, which are identical to the 5' and 3' ends of the genome, respectively. Previously, it has been suggested that cis-splicing of a genome-length precursor RNA is involved in their synthesis. This was reevaluated in a comparative analysis of the sg RNA synthesis of EAV, the coronavirus mouse hepatitis virus (MHV), and the alphavirus Sindbis virus. UV transcription mappi...
Failure of hyperimmune plasma to prevent pneumonia caused by Rhodococcus equi in foals. A trial was conducted on a Thoroughbred stud to determine whether or not the administration of anti-Rhodococcus equi hyperimmune plasma would reduce the prevalence of R equi pneumonia (rattles) in foals born in the 1992 horse breeding season. Hyperimmune plasma was administered to 34 foals; another 57 foals were untreated. There was no significant difference in the number of transfused foals developing R equi pneumonia compared with the untreated foals. The time required for recovery from pneumonia between the 2 groups was not significantly different.
Gunshot injuries in horses: 22 cases (1971-1993). Twenty-two horses were examined because of firearm injuries. Nine had been shot with .22-caliber bullets, 2 with BB pellets, 6 with buckshot, 1 with a .35-caliber bullet, and 1 with an airgun pellet. Injury was confined to the skin or skeletal muscles in 8 horses. Of these, 7 returned to their previous use. In 14 horses, injuries to additional structures were incurred, including the sinus and pharynx (n = 2), mandible (n = 1), tooth (n = 1), aorta (n = 1), eye (n = 3), tibia (n = 1), gastrointestinal tract (n = 3), joint (n = 1), and trachea (n = 1). The 3 horses that had only eye injuries wer...
Equine viral arteritis with abortions: serological and virological evidence in Germany. An outbreak of clinical disease with abortions, suspected to be equine viral arteritis in Germany was examined serologically and virologically. Three of five animals tested seroconverted to EAV, and EAV was isolated from an aborted fetus. In view of the significant increase in seropositive horses, the need for control measures is emphasized.
Outbreak of trypanosomosis due to Trypanosoma evansi in horses of Pantanal Mato-grossense, Brazil. This paper reports an outbreak of trypanosomosis due to Trypanosoma evansi in horses of the Pantanal Mato-grossense region of Brazil. Forty-eight horses died (51% mortality) and abortion in one mare was recorded. The clinical signs observed were fever, anemia, conjunctivitis, edema of the legs and lower parts of the body, progressive weakness, loss of condition, and loss of appetite. The diagnosis was confirmed by morphological and biometrical studies.
Analyses of restriction fragment patterns (RFPs) and pathogenicity in baby mice of equine herpesvirus 1 and 4 (EHV-1 and EHV-4) strains circulating in Danish horses. Twenty-five strains of equine herpesvirus 1 (EHV-1) and one strain of equine herpesvirus 4 (EHV-4) isolated from material from various clinical cases in Denmark, together with reference EHV-1 and EHV-4 strains, were compared by restriction fragment pattern (RFP) analysis and inoculation of baby mice. The RFP analyses revealed that all EHV-1 strains belonged to genome type Ip. Four fetal isolates exhibited genomic characteristics that have been suggested as specific markers of the attenuated strain Rac H, widely used as a live vaccine. As the use of five vaccines against EHV-1 and EHV-4 has nev...
Equine pulmonary disease: a case control study of 300 referred cases. Part 1: Examination techniques, diagnostic criteria and diagnoses. Three-hundred adult horses, referred from 1990 to 1993 inclusively, for pulmonary examination were assessed using standardised history taking and clinical, intrapleural pressure, arterial blood gases and pH, bronchoscopic and tracheal and broncho-alveolar lavage fluid (BALF) cytological examinations. Two-hundred and thirty-five cases were referred with overt signs of pulmonary disease and the remaining 65 cases were referred for pulmonary examination because of reduced exercise (usually racing) performance or prolonged dyspnoea after racing. No pulmonary disease was detected in 30 cases. The 2...
Epidemiologic evidence for clustering of equine motor neuron disease in the United States. To examine the regional variations in the distribution of equine motor neuron disease (EMND) in the United States and the factors that might explain those variations. Methods: Cluster investigation and case-control study. Methods: The study population consisted of 97 horses with histopathologically confirmed EMND and 698 controls with diagnosis of other spinal cord disorders at 21 US veterinary teaching hospitals participating in the Veterinary Medical Data Base. Methods: The total horse population of the United States was divided into 21 regions, and the regional incidence rates of EMND from ...
Venezuelan equine encephalitis–Colombia, 1995. An outbreak of Venezuelan equine encephalitis (VEE) that began in northwestern Venezuela in April 1995 has spread westward to the Guajira peninsula and to Colombia (Figure 1), resulting in an estimated minimum of 13,000 cases in humans and an undetermined number of equine deaths. Governments of both countries have initiated efforts to control the spread of this outbreak by quarantining and vaccinating equines and applying insecticides. This report summarizes the ongoing investigation of the outbreak in Colombia.
Detection of Trichinella spiralis muscle larvae in naturally infected horses. Human trichinellosis outbreaks related to horsemeat consumption have been reported in France and Italy in recent years. In order to determine if Trichinella is present in horses slaughtered at an abattoir in the State of Mexico, diaphragm muscle tissue samples (22-37 g) from 80 horses were examined by artificial digestion. Four of these samples had larvae that were characterized as Trichinella sp. by morphological criteria and as Trichinella spiralis by the polymerase chain reaction.
Antibacterial susceptibility patterns for microbial isolates associated with infectious keratitis in horses: 63 cases (1986-1994). Seventy-three aerobic bacterial isolates were cultured from 64 eyes of 63 horses with infectious keratitis. Forty-two (58%) of the organisms isolated initially were gram-positive (g+, 10 genera) and 31 (42%) were gram-negative (g-, 5 genera). After local antimicrobial treatment, repeat cultures from samples obtained from 15 eyes of hospitalized horses yielded 21 secondary bacterial isolates. Staphylococci spp and Streptococci spp were the most common g(+) isolates and accounted for 79% of g(+) organisms isolated initially. Antibiograms revealed ticarcillin to be the most efficacious antibiotic...
Proteolytic cleavage of VP2, an outer capsid protein of African horse sickness virus, by species-specific serum proteases enhances infectivity in Culicoides. Purified African horse sickness virus (AHSV) was fed, as part of a blood meal, to adult females from a susceptible colony of Culicoides variipennis, established in the insectories at the Institute for Animal Health, Pirbright Laboratory, UK. The meal consisted of heparinized blood obtained from ovine, bovine, equine (horse and donkey) or canine sources spiked with AHSV serotype 9 (AHSV9). The infectivity levels observed for C. variipennis varied significantly, according to the source of the blood sample. Comparison of the protein profiles obtained from AHSV9 incubated with the individual serum...
The use of African horse sickness virus NS3 protein, expressed in bacteria, as a marker to differentiate infected from vaccinated horses. Segment 10 of the double-stranded RNA (dsRNA) genome from African horse sickness virus serotype 4 (AHSV-4) was cloned and sequenced. The sequence of the coding region showed a total length of 667 bp. Nucleotide comparisons showed a 95% sequence similarity between serotypes 4 and 9, and 76% between serotypes 4 and 3. cDNA clones containing the coding region were cloned in the vector pET3xb and expressed in Escherichia coli. The NS3 gene product was synthesised at very high level as an insoluble fusion protein. The recombinant protein was used in a differential ELISA to distinguish horses that w...
Enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Anoplocephala perfoliata in horse sera. A scolex antigen of the horse tapeworm Anoplocephala perfoliata containing at least 14 different proteins was employed in an enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to A. perfoliata in equine sera. The assay was applied to sera from 426 slaughtered horses with different numbers of worms and with varying degrees of intestinal lesions. As measured by the ELISA, there was a very strong effect on the antibody levels both from the number of tapeworms present and from the intestinal lesion score. However, considerable individual variation was observed between horses wit...
