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Topic:Disease Outbreaks
Disease outbreaks in horses refer to the occurrence and spread of infectious diseases within equine populations. These outbreaks can be caused by various pathogens, including bacteria, viruses, and parasites, and can lead to significant health issues in affected horses. Common diseases that may result in outbreaks include equine influenza, equine herpesvirus, strangles, and equine infectious anemia. The transmission of these diseases can occur through direct contact, environmental exposure, or vectors such as insects. Disease outbreaks can have substantial impacts on horse health, welfare, and the equine industry as a whole. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, transmission dynamics, and management strategies associated with disease outbreaks in equine populations.
Genomic and antigenic comparison of an equine herpesvirus 1 (EHV 1) isolate from the 1983 Lippizan abortion storm with EHV 1 reference strains. An EHV 1 isolate from the Lippizan Stud at Piber, which caused the abortion and paresis outbreak in 1983, was investigated using 3 known subtype 1 and 2 subtype 2 strains for comparison. Broad-scale restriction enzyme analysis as well as cross-neutralization with hyperimmune sera produced in rabbits were performed, and SDS-PAGE of infected cell proteins was conducted on a limited scale. The Piber isolate was clearly classified as a subtype 1 strain of EHV 1, and showed closest resemblance in its restriction patterns with a British EHV 1 strain, which originated from an outbreak with paretic sy...
Emergence of antibiotic-resistant Salmonella agona in horses in Kentucky. Eighty-seven of 283 isolates of salmonellae recovered from horses in Kentucky by the Livestock Disease Diagnostic Center from July 1, 1980 through June 30, 1984 were Salmonella agona. No isolations of S agona were made from Jan 1, 1972 through June 30, 1980. Salmonella agona was isolated from horses on 56 farms and most of the isolations were made in the spring. All age classes of horses were involved. Clinical forms of salmonellosis observed were diarrhea, septicemia, infertility, and abortion. Antibiotic susceptibilities were determined for 83 of the 87 isolates, and 79 were resistant to mul...
Acute postoperative diarrhoea in colic horses. A retrospective study on surgical cases of colic in horses (n = 216) revealed that 42 (19.4%) developed post-surgical diarrhoea. Salmonella spp. were isolated in 6 (16.2%) of the cases (n = 37) exhibiting diarrhoea. In 35.7% of the cases (n = 42) recovery from surgery was disturbed by other complications; 23.8% (10/42) died, 2 of which from primary acute diarrhoea due to salmonellosis. Most of the outbreaks of diarrhoea occurred in winter and spring. From the associated variables examined, the duration of colic signs revealed a significant difference between the cases which developed acute pos...
Isolation of eastern equine encephalitis virus from Aedes sollicitans during an epizootic in southern New Jersey. Eastern equine encephalitis virus (EEE) was isolated from the salt marsh mosquito, Aedes sollicitans, collected from coastal areas of New Jersey on 3 occasions during the late summer and fall of 1982. The isolations were made at a time when local Culiseta melanura were either undergoing a population increase or exhibiting high levels of EEE virus. Although no human cases were reported during the epizootic period, the data lend support to the hypothesis that Ae. sollicitans is capable of functioning as an epidemic vector in the coastal areas of New Jersey where human cases of EEE have been most...
American dog tick (Acari: Ixodidae), summer activity on equine premises enzootic for Potomac horse fever in south-central Maryland. The American dog tick, Dermacentor variabilis (Say), was the only ixodid tick found feeding on horses in Montgomery County, Md., from May to August. Average tick burdens were low (less than one tick per horse per week), but >80% of 33 horses examined weekly were exposed to tick feeding during the summer. Of the 98 ticks collected, 78% were attached to the tail and 12% were present in the mane. Host-seeking adult D. variabilis were active on vegetation in pastures from May to early August, with most specimens along hedgerows, woods margins, and horse paths.
Salmonellosis in hospitalized horses: seasonality and case fatality rates. Salmonellosis was studied during an 11-year period (July 1971 through June 1982) in 245 hospitalized horses. Ten years' data (207 cases) were analyzed in a time series study. Peak seasonality of the disease was from June through September. The cycle curve revealed 3 major outbreaks, with no apparent periodicity. Eighteen Salmonella serotypes caused clinical salmonellosis in horses, but 84% of the cases and 90% of the deaths were caused by 5 serotypes: Salmonella typhimurium, S typhimurium var copenhagen, S anatum, S kottbus, and S saint-paul. Overall, the case fatality rate was 44.9%. Excludin...
An outbreak of suspected equine infectious anaemia in Guyana. An outbreak of suspected equine infectious anaemia (EIA) among a population of 678 horses from 16 farms occurred in the Rupununi Savannahs of Guyana. Clinical signs of EIA were detected in 110 horses. Agar gel immunodiffusion (AGID) tests on 92 sera examined showed positive serological evidence of EIA in 67 (72·8%). The mean packed cell volume of 50 horses studied was 0·178
and the mean red blood cell count was 3·7 × 1012/l with the mean white blood cell count 4·1 × 109/l.
The morbidity rate of the disease was 14·0% and the mortality rate 11·1%. The majority (78%) of all seroposi...
Salmonella serotypes from animals in New York State, 1978-1983. The salmonella serotypes isolated during 1978 to 1983 at the diagnostic and clinical laboratories of the New York State College of Veterinary Medicine from animal sources in New York state were reviewed and compared to earlier data from New York state animals and to national data for both human and animal sources. A total of 255 salmonella strains were studied from the six year period and included 33 serotypes. Salmonella enteritidis ser Typhimurium continued to be the most commonly reported serotype followed by serotype Anatum. Generally serotypes from New York state animals reflected nationa...
Equine herpesvirus type 1 (EHV-1) induced abortions and paralysis in a Lipizzaner stud: a contribution to the classification of equine herpesviruses. Out of 30 cases of abortion and perinatal deaths in a Lipizzaner stud in Austria 10 mares died after having shown central nervous system disturbances, ataxias and paralysis. The etiological agent of this "abortion storm" was equine herpesvirus type 1 (EHV-1). The restriction enzyme pattern of the DNA from 5 isolates recovered from fetuses has been analyzed and compared with the known reference strains of EHV-1, -2, -4 and an Austrian vaccine strain. The DNA restriction profiles of the Lipizzaner isolates as well as of the vaccine strain could be identified as being typical of abortigenic strai...
A retrospective study of equine infectious anemia based on the canadian control program. Equine infectious anemia in Canada was reviewed for the period January 1976 to December 1981. The human and ecological factors prevailing in Canada are deemed instrumental with respect to the evolution of the disease. The natural spread of the disease on a large scale has not been influenced by the Federal program. Reactors with signs of the disease are important for it's propagation. The author underlines the necessity of cooperation with private practising veterinarians to control it.
Investigations of the vertebrate hosts of eastern equine encephalitis during an epizootic in Michigan, 1980. A study was undertaken to investigate an increase in reported cases of clinical encephalitis due to eastern equine encephalitis (EEE) virus in horses and to determine the natural vertebrate hosts of that virus. Horses, birds, and small mammals were sampled at sites in a contiguous area in St. Joseph and Kalamazoo counties, Michigan, from 25 August to 5 September 1980. Serum samples from four horses acutely ill with encephalitis and 16 of 39 pasture mates of ill horses had neutralizing (N) antibody against EEE virus (46.5%); no viruses were isolated from these 43 sera. None of 24 draft horses f...
Lymphadenopathy-associated virus: from molecular biology to pathogenicity. Recent data indicate that the lymphadenopathy-associated virus (LAV) is morphologically similar to animal lentiviruses, such as equine infectious anemia and visna viruses. This finding, together with the cross-reactivity of the core proteins of LAV with those of the equine infectious anemia virus and a similarity in genome structure and biological properties, allows LAV to be placed in the retroviral subfamily of Lentivirinae. Molecular data indicate a high degree of genetic variation of the virus, especially in the envelope gene, which have important implications for the origin of the virus (...
Arbovirus investigations in Argentina, 1977-1980. I. Historical aspects and description of study sites. This is the introductory paper to a series on the ecology of arboviruses in Argentina. Epizootics of equine encephalitis have occurred since at least 1908, principally in the Pampa and Espinal biogeographic zones, with significant economic losses; human cases of encephalitis have been rare or absent. Both western equine and eastern equine encephalitis viruses have been isolated from horses during these epizootics, but the mosquitoes responsible for transmission have not been identified. A number of isolations of Venezuelan equine encephalitis (VEE) virus were reported between 1936 and 1958 in ...
Salmonella shed by horses with colic. Salmonella was isolated from 13 of 100 colicky horses admitted to a referral hospital. Seven horses were shedding the microorganism at or soon after hospital admission. A unique serotype was introduced into the hospital by a horse not shedding Salmonella at admission. It was concluded that 8 horses were infected before admission. Whether the remaining 5 horses were infected before or after admission could not be determined. Salmonella senftenberg was the most commonly isolated serotype from colicky horses and from horses with salmonellosis that were not colicky on hospital admission during the...
Serum bactericidal responses to Streptococcus equi of horses following infection or vaccination. An indirect test based on horse blood was used to study bactericidal responses of the horse to Streptococcus equi following infection or vaccination. Bactericidal antibody appeared in convalescent sera between two and four weeks and high titres were usually attained by eight weeks. Infection without clinical evidence of abscessation was also effective in eliciting strong bactericidal responses. Serum bactericidal activity of horses either recovered from strangles or immunised with commercial bacterin had declined eight months after vaccination. However, horses that developed strangles eight to...
A review and some observations on stringhalt. A review of the literature on stringhalt in horses is presented, including the aetiology, clinical signs, pathology and treatment of this disease. Three New Zealand outbreaks of stringhalt are reported and discussed. The occurrence of these (and most previously reported outbreaks) in the late summer and autumn, and the association of the disease with various weeds, indicates a likely toxic aetiology.
Prevalence of equine onchocerciasis in southeastern and midwestern United States. Of 664 horses reported to have originated in southeastern and midwestern United States, 341 (51.4%) were positive for Onchocerca cervicalis cutaneous microfilariasis. The highest prevalence of 68.8% was recorded for horses from Virginia. Horses with the highest concentrations of microfilariae (as high as 19,770 microfilariae/mg in 1 horse) were from the Southeast (Georgia, Florida, Tennessee, and Alabama). For horses from South Carolina, the prevalence of infection was 57.1%; from the Midwest (Kentucky, Illinois, Ohio, and Indiana), 54.4%; from North Carolina, 45.5%; from Pennsylvania, 7.7%; a...
