Topic:Disease Transmission
Disease transmission in horses refers to the spread of infectious agents such as bacteria, viruses, fungi, and parasites among equine populations. These pathogens can be transmitted through various routes, including direct contact, vector-borne transmission, or environmental exposure. Factors influencing disease transmission include horse density, management practices, and biosecurity measures. Understanding the mechanisms and conditions that facilitate the spread of diseases is essential for developing effective prevention and control strategies. This page compiles peer-reviewed research studies and scholarly articles that investigate the modes of transmission, risk factors, and management practices related to infectious diseases in horses.
[Three cases of virus isolation from horse fetuses diagnosed with equine arteritis virus (EAV) abortion from stud farms with different breeds]. Three cases of abortions were diagnosed as caused by Equine Arteritis Virus (EAV) by isolation and typing of this virus from the respective fetuses. All 3 abortions were single cases, one occurring on a stud with Iceland Ponies, one with Warmbloods, one with Lipizzaner horses. On each stud horses of the respective breed were kept exclusively, therefore there existed no epidemiologic link. By means of seroneutralization tests performed on in contact horses it could be shown, that EAV had only been introduced recently into the stud with the Iceland Ponies. An extraneous mare stabled temporarily ...
Equine arteritis virus: an overview. The causative agent of the respiratory disease equine viral arteritis is a small, single-stranded RNA virus with a genome organization and replication strategy related to that of coronaviruses and toroviruses. Clinical signs of infection in horses vary widely and severe infection can lead to pregnant mares aborting. Infected horses generally make good recoveries but stallions may become semen shedders of equine arteritis virus (EAV). These carrier stallions play an important role in the dissemination and perpetuation of EAV. Laboratory tests exist to detect virus and the equine immune response...
Association between serum cytotoxicity and selected clinical variables in 240 horses admitted to a veterinary hospital. A total of 378 serum samples from 240 hospitalized horses and 47 sera from healthy control horses were assayed for growth effects on actinomycin D-treated L929 cells. On average, patient and control sera stimulated cell growth; however, mean percentage of the relative growth index (RGI) of sera from clinical cases was significantly (P less than 0.001) lower than that of control sera. Approximately 35% of patient sera and 6% of control sera had tumor necrosis factor-like cytotoxic activity for L929 cells (ie, RGI less than 100%). Sera from horses with either peritoneal leakage of gastrointestin...
Epizootiological aspects of type 1 and type 4 equine herpesvirus infections among horse populations. The dissemination of equine herpesvirus types 1 (EHV-1) and 4 (EHV-4) among various horse populations in Japan was investigated through the isolation and typing of virus strains from horses with respiratory diseases. Type specific monoclonal antibody pools were used for the typing of isolates. The 42 strains of EHV-1 and 64 strains of EHV-4 were isolated from 4593 nasal swabs and/or blood plasma samples collected from 3326 horses during a period from 1979 to 1990. All the strains of EHV-1 were isolated from racehorses only and during the winter season exclusively, when the epizootic of respira...
Venereal disease. Equine venereal infections of concern in the United States include EHV-3, T. equigenitalis, P. aeruginosa, and K. pneumoniae. Stallions may also harbor EAV in the genital tract and transmit the virus to mares during coitus. With the exception of EHV-3, the stallion generally remains asymptomatic while transmitting infections to mares during breeding. Methods for diagnosis, treatment, and control of these infections are discussed.
[Comparative plasmid profile analysis of Salmonella typhimurium var. Copenhagen strains from a Salmonella outbreak in hospitalized horses]. From April 1990 through June 1991 clinical salmonellosis and asymptomatic faecal excretion of Salmonella spp. were seen in hospitalized horses at two veterinary hospitals. 76 Salmonella strains from hospitalized horses and 18 strains from horses without any clinical contact were characterized by serotyping and plasmid profile analysis. From April 1990 through January 1991 97.8% of the hospitalized horses were infected with strains of S. typhimurium var. Copenhagen, which were closely related according to their similar plasmid patterns. Other strains of S. typhimurium var. Copenhagen and seroty...
The spectrum of antibiotic resistance in human and veterinary isolates of Escherichia coli collected from 1984-86 in northern India. This study was undertaken to assess the spectrum of drug resistance prevalent in Escherichia coli isolates from human and animal populations in Northern India. Three hundred and two isolates of Escherichia coli isolated from various infections of humans (47 from diarrhoea; 101 from urinary tract infection) and veterinary animals (17 from poultry septicaemia; 75 from bovine diarrhoea; 14 from ovine diarrhoea and 48 from equine metritis) were studied for their susceptibility to ampicillin, cephaloridine, amoxycillin, cloxacillin, oxytetracycline, doxycycline, chloramphenicol, gentamicin, and tri...
Transmission and diagnosis of equine babesiosis in South Africa. The transmission and prevalence of Babesia equi and B. caballi are being studied. Rhipicephalus evertsi mimeticus an ixodid tick from Namibia was identified as a new vector of B. equi, however, R. turanicus, previously reported to be a vector, failed to transmit both B. equi and B. caballi in the laboratory. The accurate diagnosis of B. caballi is being investigated because the nature of its low level parasitaemia does not allow easy detection in thin blood smears, routinely used for diagnosis, by clinicians. Consequently its role as a pathogen remains obscure. The importance of identifying in...
Alkaloids of Stipa robusta (sleepygrass) infected with an Acremonium endophyte. Stipa robusta (= Stipa vaseyi) is a perennial grass found in certain areas of the southwestern United States. It is commonly known as sleepygrass, as horses that ingest this grass may become profoundly somnolent or stuporous for periods of time lasting up to several days. In an attempt to determine the active principle(s), fractionation of a methanolic extract of sleepygrass infected with an Acremonium endophyte has yielded lysergic acid amide (20 micrograms/g dry wt), isolysergic amide (8), 8-hydroxylsergic acid amide (0.3), ergonovine (7), chanoclavine-I (15), and N-formylloline (18). Relate...
Evolutionary pattern of the H 3 haemagglutinin of equine influenza viruses: multiple evolutionary lineages and frozen replication. The nucleotide and deduced amino acid sequences of the haemagglutinin genes coding for the HA 1 domain of H3N8 equine influenza viruses isolated over wide regions of the world were analyzed in detail to determine their evolutionary relationships. We have constructed a phylogenetic model tree by the neighbour-joining method using nucleotide sequences of 15 haemagglutinin genes, including those of five viruses determined in the present study. This gene tree revealed the existence of two major evolutionary pathways during a twenty five-year period between 1963 to 1988, and each pathway appeared t...
[Epidemiology of encephalitis caused by arbovirus in the Brazilian Amazonia]. An overview of ecological, epidemiological and clinical findings of potential arthropod-borne encephalitis viruses circulating in the Amazon Region of Brazil are discussed. These viruses are the Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE), St. Louis Encephalitis (SLE), Mucambo (MUC) and Pixuna (PIX). These last two are subtypes (III and IV) of Venezuelan Equine Encephalitis virus. The areas of study were the highways and projects of development, as well as places where outbreaks of human diseases caused by arboviruses had been detected. These viruses are widespread in ...
Neutralization of HIV-1: a paradox of humoral proportions. The production of immunoglobulin capable of neutralizing the infectivity of a virus represents one of the most remarkable molecular accomplishments of the host's available immune defenses. It should be no surprise that a virus that has existed in the parenchyma of the immune system has evolved as an equally dynamic molecule (i.e., viral envelope) for survival. Neutralizing immunoglobulin (Ig) can best serve the host under conditions where the invading pathogen requires a well-defined cell-free state for establishing an infection or transmission. Evidence for a controlling and therefore protect...
Diagnosis and prevalence of leptospira infection in aborted and stillborn horses. A study was conducted to evaluate a recently available fluorescent antibody test (FAT) conjugate for the detection of leptospires in tissues of aborted and stillborn horses, to determine the leptospira antibody titers and compare serologic test results with FAT results, and to determine the prevalence of leptospira-induced abortions and stillbirths in the equine population of central Kentucky. From July 1, 1988 through June 30, 1989, 15 (2.5%) of 594 submissions (fetuses, stillborn foals, and/or placentas) were diagnosed as leptospirosis by the FAT (14 of 15 tested) and/or microscopic agglutin...
An assessment of the biological capacity of a Sacramento Valley population of Aedes melanimon to vector arboviruses. Daily survivorship, duration of the gonotrophic cycle, absolute abundance and season-long relative abundance were estimated for Aedes melanimon in the Sacramento Valley of California in 1987 and 1988 using mark-release-recapture (MRR) techniques and by monitoring changes in the abundance and parity rate of the native population. One objective of these studies was to determine the extent to which A. melanimon was biologically capable of serving as a horizontal arbovirus vector. Daily survivorship was estimated to be 0.90 and 0.84 in MRR studies conducted in September 1987 and August 1988, 0.89 ...
A rare GC mutant in horses disclosed by isoelectric focusing and subsequent immunoprinting. An apparent incompatibility in the GC/DBP system in a mare and her colt was found after classification by polyacrylamide gel electrophoresis. Because of this observation an analysis of the equine GC/DBP system by isoelectric focusing and subsequent immunoprinting was initiated. Further GC subtypes, however, were not encountered: the three phenotypes GC F, FS and S were also delineated by this method. The GC types in the case of disputed descent were dissolved: GC S was found in the mare and GC FS in her colt as well as in another of her male offspring. It is proposed that a rare GC mutant is r...
Equine infectious anemia virus derived from a molecular clone persistently infects horses. A full-length molecular clone of equine infectious anemia virus (EIAV) was isolated from a persistently infected canine fetal thymus cell line (Cf2Th). Upon transfection of equine dermis cells, the clone, designated CL22, yielded infectious EIAV particles (CL22-V) that replicated in vitro in both Cf2Th cells and an equine dermis cell strain. Horses infected with CL22-V developed an antibody response to viral proteins and possessed viral DNA in peripheral blood mononuclear cells, as determined by polymerase chain reaction assays. In addition, horses infected with CL22-V became persistently infe...
Strangles in horse studs: incidence, risk factors and effect of vaccination. A questionnaire survey of 179 horse studs in New South Wales was conducted to estimate the incidence of strangles during 1985 to 1988, to identify risk factors for strangles outbreaks and to assess the effect of strangles vaccination. Forty-nine of the studs (27.4%) had at least one strangles outbreak during this period and 62 studs (34.6%) had at least one case of strangles. The average incidence of strangles was 2.1 cases per 100 horses per year. The risk of strangles increased progressively with the total horse population and rose markedly when more than 100 mares had been served in the 198...
An outbreak of trypanosomiasis caused by Trypanosoma evansi on the island of Madura, Indonesia. During an outbreak of trypanosomiasis in cattle, buffalo and horses on the island of Madura, a survey was conducted to determine the prevalence of Trypanosoma evansi in the region. Blood samples were collected from 130 cattle and 147 buffalo in 5 villages, whole blood was examined for trypanosomes by the microhaematocrit (MHCT) method and serum samples were subjected to an enzyme linked immuno absorbent assay to detect T. evansi antibodies. T. evansi was detected by MHCT in 50% of the buffalo examined and 13% of the cattle, while antibodies were detected in 47% of the buffalo and 30% of the ca...
Haemoparasites of equines: impact on international trade of horses. The geographical distribution of Babesia equi and Babesia caballi and their tick vectors is discussed. Control of infections with these protozoa is hampered by the lack of a suitable antiprotozoal drug and a reliable serological test. No vaccine is available. Ehrlichia risticii (the causal agent of Potomac horse fever) and E. equi are rickettsial parasites which are difficult to control. Little is known of their geographical distribution and vectors. Early diagnosis is required for tetracycline therapy to be effective and there is a need for a rapid test to provide an early diagnosis.
Serosurvey of horses with evidence of equine monocytic ehrlichiosis. In August 1986, an extensive serosurvey for prevalence of IgG and IgM antibodies against Ehrlichia risticii, the causative agent of equine monocytic ehrlichiosis (EME), was performed at 2 Ohio racetracks, River Downs (RD) and Beulah Park (BP). Of 840 horses at RD and 574 at BP, 13 and 20%, respectively, were IgG antibody-positive (by indirect fluorescent antibody test results), with antibody titer ranging from 1:20 to 1:10,240. The titer observed at highest frequency at both racetracks was 1:80. A higher proportion of horses was ill at RD (operating during the summer months) than at BP (winter...
[Serologic studies of the occurrence of Borrelia burgdorferi in domestic animals in Berlin (West)]. The prevalence of B. burgdorferi, the causative agent of Lyme Borreliosis in humans, was determined in domestic animals living in Berlin. 189 dogs, 29 cats, 224 horses and 194 cows were investigated. Using the indirect immunofluorescence test (IFT) 5.8% of the dogs and 24.5% of the cows investigated showed a positive reaction at titres of 1:128 or higher. Horses and cats gave negative results. ELISA was more sensitive than IFT. 10.1% of the dogs, 16.1% of the horses and 66% of the local cows showed positive reaction. Domestic animals seem to be in contact with B. burgdorferi and can be a reser...
Neospora caninum (Apicomplexa) in an aborted equine fetus. Tachyzoites of Neospora caninum were found in sections of lung of an equine fetus aborted 2 mo before term. Individual tachyzoites were approximately 3-5 x 2-3 microns, divided by endodyogeny, and stained positively with anti-N. caninum serum but not with anti-Toxoplasma gondii serum. Toxoplasma gondii antibody was not found in the mare's serum. This is the first report of N. caninum in a horse and indicates that N. caninum can be transmitted transplacentally in equids.