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.
DOLL ER, WALLACE E, RICHARDS MG.Manninger and Csontos reported that mares inoculated with equine abortion virus developed a transient fever 2 to 4 days after pharyngeal or intravenous inoculation and that an uninoculated horse in contact with the experimentally inoculated mares contracted a febrile disease resembling equine influenza. Also, mares that had aborted virus-infected fetuses were resistant to inoculation with equine influenza virus. From these observations, they proposed that virus abortions were a manifestation of infection of pregnant mares by the equine influenza virus. In reports on equine virus abortions, Kre...
CRAWFORD M.This disease has a very long history, with the earliest written description by Vegetius in the fourth century A.D. It has many names, such as periodic ophthalmia, recurrent ophthalmia, iridocyclitis, uveitis, moon-blindness, etc. Periodic ophthalmia is perhaps the name more generally used, but I prefer to use recurrent iridocyclitis because (a) there is no definite fixed period between the recurrent attacks and (b) because the essential lesion is iridocyclitis.
HAMMON WM, REEVES WC.In three cases of encephalitis in humans that occurred in the area where the newly described California virus was isolated from mosquitoes, serological evidence seemed to indict the California virus as the etiological agent. In the case of an infant with very severe disease, the serological evidence was convincing; the evidence was almost as strong in the case of a seven-year-old boy; the results in an adult were equivocal. Inapparent infection in man is quite common as indicated by neutralization tests on the sera of nearly 600 residents of California, but encephalitic manifestations of infec...
Dong J, Bao H, Mang L.Rhinoestrus sp. (Diptera: Oestridae) is an economically important parasite that can cause severe nasal myiasis in equids and can also affect humans. The ultrastructure of all Rhinoestrus sp. larval instars from Mongolian horse was examined by light and scanning electron microscopy to characterize the features of Rhinoestrus. The structure of the anterior region, posterior region, and the spines of the third segment was analyzed for 10 specimens in each larval stage. Additionally, 34 third-instar (L3) larvae of Rhinoestrus sp. from Mongolian horse were subjected to molecular characterization by...
León B, González G, Nicoli A, Rojas A, Pizio AD, Ramirez-Carvajal L, Jimenez C.Venezuelan Equine Encephalitis virus (VEEV) is an arboviral pathogen in tropical America that causes lethal encephalitis in horses and humans. VEEV is classified into six subtypes (I to VI). Subtype I viruses are divided into epizootic (IAB and IC) and endemic strains (ID and IE) that can produce outbreaks or sporadic diseases, respectively. The objective of this study was to reconstruct the phylogeny and the molecular clock of sequences of VEEV subtype I complex and identify mutations within sequences belonging to epizootic or enzootic subtypes focusing on a sequence isolated from a mare in C...
Asmundsson T, Gunnarsson E, Johannesson T.Blood samples were taken from 18 healthy horses (Group A), 15 horses clinically diagnosed to have "haysickness" ("farmer's lung") (Group B), 10 closely related horses (Group C) and 14 inbred horses (Group D). Precipitins in sera were measured by double gel diffusion test against Micropolyspora faeni, Thermoactinomyces vulgaris, Aspergillus fumigatus, Alternaria, Penicillium and Rhizopus species. In Group A, all the horses were precipitin negative except one with a faint reaction to Rhizopus species. In Group B all had precipitin against M faeni. One horse also had precipitins against Rhizopus ...
Chen X, Zhao Y, Su L, Wang L, Ma X, Zhang B, Su Y.Strangles, which is caused by Streptococcus equi subspecies equi, is one of the most prevalent equine infectious diseases and poses heavy economic losses worldwide. Although various vaccines have been used for decades, they seemed to be sub-optimal to demonstrate effective protection, and the antigen component of vaccines against S. equi remains to be optimized. In the present study, three target antigens (M-like protein, α2-macroglobulin and IgG-binding protein, and glyceraldehyde-3-phosphate dehydrogenase) were selected and expressed. Mice were immunized and challenged, and their immune res...
Mashin VV, Sergeev AN, Martynova NN, Oganov MD, Sergeev AA, Kataeva VV, Zagidullin NV.Equine blood plasma/serum and intermediates must be monitored for the presence of live viruses pathogenic in humans during production of equine immunoglobulins. Information concerning low-cost and simple methods for the detection of live horse viruses pathogenic and non-pathogenic to humans was gained using data of modern domestic and foreign literature. These methods are based on cultivation of these viruses on sensitive biosystems. The presented information can be used to set up blood plasma/serum control of horses at different stages of immunoglobulin production, i.e., when taking blood fro...
Rodriguez JY, Finneburgh BM, Lewis BC, Flanagan J, Snowden KF.Heterobilharzia americana is a trematode parasite (family: Schistosomatidae) of mammalian wildlife that occasionally infects domestic dogs and horses in the southeastern United States. This report presents the first case of H. americana infection in a Grant's zebra (Equus burchelli boehmi). The parasite was diagnosed post mortem as an incidental finding by histopathologic identification of H. americana eggs in the liver parenchyma after the zebra succumbed in an accidental traumatic death. Molecular analysis of a portion of the parasite small subunit ribosomal RNA gene demonstrated 100% identi...
Ma Y.Equine rotavirus (ERV) strain L338 (G13P[18]) has a unique G and P genotype. However, the evolutionary relationship of L338 with other ERVs is still unknown. Here whole genome analysis of the L338 ERV strain was independently performed. Its genotype constellations were determined as G13-P[18]-I6-R9-C9-M6-A6-N9-T12-E14-H11, confirming previous genotype assignments. The L338 strain only shared the P[18] and I6 genotypes with other ERVs. The nucleotide sequences of the other 9 RNA segments were different from those of cogent genes of all other group A rotavirus (RVA) strains including ERVs and fo...
Schultheiss PC, Collins JK, Carman J.An indirect immunoperoxidase (IP) procedure using the avidin-biotin-peroxidase complex detection technique was developed to detect viral equine herpesvirus-1 (EHV-1) antigen in formalin-fixed paraffin-embedded tissues from aborted equine fetuses. The procedure was applied to liver, lung, and other tissues from 20 cases of confirmed or suspected EHV-1-induced abortions. Specific staining was observed in tissue sections from EHV-1-infected fetuses. Positive IP staining was present in tissues of 7 cases that were also positive by fluorescent antibody (FA) and virus isolation (VI) and that had typ...
Hébert L, Cauchard J, Doligez P, Quitard L, Laugier C, Petry S.There is great concern about the potential pathogen contamination of horse manure compost spread in the same fields horses graze in. To ensure that pathogen destruction occurs, temperatures need to be sufficiently high during composting. Here, we investigated the survival rate of two marker organisms, Rhodococcus equi and Parascaris equorum eggs, exposed to temperatures potentially encountered during horse manure composting. Our results show that the time required to achieve a 1 log10 reduction in R. equi population (D-value) are 17.1 h (+/-1.47) at 45 degrees C, 8.6 h (+/-0.28) at 50 degrees ...
Dolan M, Cargill C, Martin F, Davenport P, Franks D, Lightfoot J.A bacteriological and serological survey for evidence of contagious equine metritis (CEM) was made during the 1980 breeding season on 3 horse studs in South Australia with a history of previous infection. Swabs from the clitoral sinus and the cervix were cultured for Haemophilus equigenitalis and serum was screened for antibody using the complement fixation test (CFT) and the enzyme-linked immunosorbent assay (ELISA). The specificity of both tests was greater than 0.99 but the ELISA was more sensitive in detecting antibody in infected mares. On the evidence presented it was concluded that H. e...
Tamin A, Rota PA.Hendra virus (HeV) and Nipah virus (NiV) are the causative agents of emerging transboundary animal disease in pigs and horses. They also cause fatal disease in humans. NiV has a case fatality rate of 40 - 100%. In the initial NiV outbreak in Malaysia in 1999, about 1.1 million pigs had to be culled. The economic impact was estimated to be approximately US$450 million. Worldwide, HeV has caused more than 60 deaths in horses with 7 human cases and 4 deaths. Since the initial outbreak, HeV spillovers from Pteropus bats to horses and humans continue. This article presents a brief review on the cur...
Katz J, Geer P.An enzyme-linked immunosorbent assay (ELISA) was developed for the serodiagnosis of contagious equine metritis (CEM), a sexually transmitted disease caused by Taylorella equigenitalis. Antigen preparation was simple, and antigens derived from both classical and atypical forms of T. equigenitalis enabled detection of antibody responses elicted in horses experimentally exposed to either form of the bacterium. Sera serially obtained from these horses from 0 to 63 days postexposure were tested by the traditional complement fixation test (CFT) for CEM and with the ELISA, using both antigens separat...
Kalemkerian PB, Metz GE, Peral-Garcia P, Echeverria MG, Giovambattista G, Díaz S.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...
Fernández H, Notario R, Gambande T, Borda N, Rivera S.A semiprepared medium containing horse globular lysate was evaluated for the isolation of Campylobacter under two incubation atmospheres (5% O2 and candle jar). Studying 19 known strains of C. jejuni, 151 human and 230 animal fecal samples. They were seeded on conventional medium (MC) and on the new medium (MLG) and incubated at 42 degrees C for 24 and 48 h. Campylobacter strains grew better in 5% O2 atmosphere after 48 h of incubation. All the strains that grew or were isolated on MC, could also grow in MLG incubation in candle jar. Campylobacter was isolated from human fecal samples with the...
Yu MH, Kasem S, Yoshizaki N, Pagamjav O, Yamaguchi T, Ohya K, Fukushi H.EUL47 is a major component of the tegument of equine herpesvirus 1 (EHV-1). To determine its function, we used Red/ET cloning to delete its gene (gene 13) from EHV-1 strain Ab4p inserted into a bacterial artificial chromosome (BAC), yielding Ab4pattBΔ13. We also examined the reverted virus (Ab4pattB13R). Ab4pattBΔ13 replicated in rabbit kidney (RK)-13 cells, indicating that ORF13 is dispensable for virus replication in cell culture. Its intracellular and extracellular titers were about 10- and 100-fold lower than those of the revertant and parent strains, respectively. In addition, the plaqu...
Sugiura T, Nakajima H.An indirect hemagglutination was developed for the diagnosis of equine infectious anemia using sheep red blood cells coated with group specific virus antigen which had been highly purified by affinity chromatography. The presence of indirect hemagglutination antibodies was demonstrated in horses with equine infectious anemia since the cells were specifically agglutinated by all the serum samples obtained from experimentally infected horses. Antibodies appeared within 35 days after inoculation, and development of which coincided well with that of precipitating and complement fixing antibodies. ...
Craig MI, Barrandeguy ME, Fernández FM.Equine herpesvirus 2 (EHV-2) was isolated from healthy animals; therefore, the association between EHV-2 infection and respiratory disease raises the question of the role of this agent in this pathology. To date, there are no reports that relate viral excretion to health, this study then analysed 153 nasal swabs from horses in different age groups (older and younger than 1 year old) and state of health (clinically healthy and with respiratory symptoms). Results showed that the percentage of horses with viral excretion was higher within the clinically healthy group, being significative (p < 0.0...
Fernández-Garayzábal JF, LaFrentz S, Casamayor A, Abarca E, Mohammed HH, Cuming RS, Arias CR, Domínguez L, Vela AI.Twenty-two unidentified Gram-positive, rod-shaped organisms were recovered from the conjunctival surface of apparently healthy horses and subjected to a polyphasic taxonomic analysis. Based on cellular morphology and biochemical criteria, the isolates were tentatively assigned to the genus , although they did not match any recognized species. Comparative 16S rRNA gene sequencing studies demonstrated that all of the isolates were phylogenetically members of the genus The isolates shared 99.4 to 100% 16S rRNA gene sequence similarity among the strains and 96.5% similarity with 2385/12, which w...
Gabal MA, Mohammed KA.An enzyme-linked immunosorbent assay was evaluated for the detection of antibody in sera of equine naturally infected with Histoplasma farciminosum 'epizootic lymphangitis'. Ten sera from naturally infected horses were tested. A hydrogen peroxide ABTS mixture constituted the substrate. The reactions were read as the absorbance values measured at 405 nm using a spectrophotometer. The standard deviation and the average percentage of the absorbance values of the different serum samples were considered in the interpretation of the results. All sera were proved positive with variations in the diffe...
Kumar S, Rakha NK, Goyal L, Goel P, Kumar R, Kumar A, Kumar S.Theileria equi merozoite surface antigens have been an important candidate for development of diagnostics. We developed ELISA based on EMA-1 recombinant antigen, so as to widen our diagnostic confidence in detection of antibodies against T. equi in sero-surveillance studies. The 547 bp EMA-1 gene fragment encoding high hydrophilic antigenic region was expressed with glutathione-S-transferase tag in prokaryotic system and purified protein (43 kDa) was used for development of ELISA (EMA-1t/ELISA). The EMA-1t/ELISA clearly differentiated T. equi-infected from Babesia caballi-infected horse sera o...
Wallace FJ, Emery JD, Cripps AW, Husband AJ.The ability of mucosally administered antigen to provide protection against Streptococcus equi ('Strangles') infections in horses was examined. First, an enzyme linked immunosorbent assay (ELISA) was developed to detect the immune status of horses to S. equi. This assay was used to select Strangles-naive horses for the study and also to monitor their response to immunisation. Potential vaccine candidates were: (a) orally administered paraformaldehyde killed S. equi; (b) intraperitoneally (IP) administered paraformaldehyde killed S. equi in a non-inflammatory adjuvant; (c) orally administered l...
Guimarães AM, Bruhn FRP, Ribeiro MJM, Rosa MHF, de Mello Garcia A, da Rocha CMBM, de Assis Rocha I.Theileria equi, a protozoon in the phylum Apicomplexa, is the causative agent of equine theileriosis. The aim of this cross-sectional study was to determine the prevalence of IgG antibodies against T. equi, by using the indirect fluorescent antibody test (IFAT) reaction and correlating the serostatus with some epidemiological variables relating to the way in which Mangalarga Marchador horses are raised in southern Minas Gerais, Brazil. In this study, 506 horses were used, all clinically healthy, on 53 horse farms distributed across 27 municipalities in southern Minas Gerais. The statistical te...
Byars TD, Dainis CM, Seltzer KL, Rantanen NW.The formation of cranial thoracic masses (CTM) as a sequel to infectious pleuropneumonia is described. Using ultrasound, masses were diagnosed subjectively as abscesses or loculations. Eight of 99 cases with pleuropneumonia had CTM. Clinical signs associated with the presence of a CTM included increased heart rate, jugular distention, forelimb 'pointing' and caudal displacement of the heart. Techniques used for diagnostic ultrasonographic examination of the cranial thorax are described. Five of the eight horses with CTM responded to conservative medical management; the other three required per...
Ma X, Wang C, Zhang B, Xia L, Su Y.Strangles is a highly prevalent, extremely contagious, and occasionally lethal infectious disease affecting horses worldwide. Prophylactic antibiotics are ineffective in prevention of disease but are recommended for exposed horses at the first sign of fever and any horse obviously ill from strangles or with complications and there is an urgent need of a cost-effective, safe, efficacious vaccine. In the present study, we sought to develop effective vaccines by fusing the Streptococcus equi subspecies equi (S. equi) antigen SeM with the flagellin of Salmonella abortus equi FljB. We also explored...
Holguin-Rocha AF, Calle-Tobon A, Vásquez GM, Astete H, Fisher ML, Tobon-Castano A, Velez-Tobon G, Maldonado-Ruiz LP, Silver K, Park Y....Ticks are obligatory hematophagous ectoparasites that transmit pathogens among various vertebrates, including humans. The composition of the microbial and viral communities in addition to the pathogenic microorganisms is highly diverse in ticks, but the factors driving the diversity are not well understood. The tropical horse tick, , is distributed throughout the Americas and it is recognized as a natural vector of and , the causal agents of equine piroplasmosis. We characterized the bacterial and viral communities associated with partially-fed females collected by a passive survey on hors...
Powers JD, Powers TE, Varma KJ, Gabel AA, Spurlock SL.Quantification of the clinical manifestations of a disease has been a serious problem particularly as related to clinical trials or drug efficacy studies. Historically, this quantification has been limited to categorizing each patient into one of three or four groups, e.g. worse, no improvement, improved. This problem becomes serious when an investigation utilizes an experimentally induced animal disease model. A health index, which quantifies the clinical state of horses which have an experimentally induced beta-hemolytic streptococcal infection, is described. Aspects of experimental design a...
Lamarque D, Haessler C, Champion R, Granga D, Bendina , Steinmetz P, Guelina A, Maurice Y.An epidemic of human and animal anthrax raged in Chad mainly in the Department of Chari Baguirmi from September to December 1988, infesting more than 50% of donkeys and horses. 716 human cases have been reported, with 88 deaths. Thanks to a geographical distribution of animal and human prevalence, one sees immediately the interdependency between sanitary state of live-stock and public health. An unusual means of transmission from donkey to donkey by insects as the vector is suggested to explain the intensity of animal epidemics. Two strains of B. anthracis were isolated and described. Systemat...
Dos-Santos MC, Yamaguchi IK, Caricatti CP, Higashi HG, Dias-da-Silva W.Equines (2 horses and 2 donkeys) immunized with whole Crotalus durissus terrificus venom or its phospholipase A2 component either presented an increased survival time determined 3 days after challenge or were totally resistant to a challenging lethal dose of 200 mg crude venom 270 days after the initial immunization or 90 days after the last booster injection. The resistance was demonstrable on the basis of a good correlation with antibody titers determined by the ELISA method but not with the flocculation and neutralization assays. Since phospholipase A2 is essentially nontoxic, it can be use...
Onen EA.The aim of this study was to evaluate formalin-inactivated autovaccination to treat cutaneous papillomatosis and to perform molecular typing of the papillomavirus in four horses (two foals, one 3-year-old filly and a 5-year-old stallion). Methods: Histopathological slides of lesions were prepared and stained with haematoxylin and eosin (H&E) to establish a diagnosis that was based on observation koilocytosis, which is a pathognomonic cytopathic change that is associated with papillomatosis, using light microscopy. Polymerase chain reaction (PCR) and DNA sequencing were performed using the ...
Cervantes DT, Ball JM, Edwards J, Payne S.Equine infectious anemia virus (EIAV) causes lifelong infections ranging from acutely fatal, to chronic, to asymptomatic. Within infected animals, EIAV is found as a quasispecies. Many experimental studies on EIAV, carried out in the U.S. over the past 70 years, have used either the highly virulent Wyoming (EIAVWYO) field strain or various derivatives of that strain. These infections have provided insights into the variety of genetic changes that accumulate in the env gene and LTR in experimentally infected horses. In the current study, we obtained EIAV sequences from blood samples collected f...
