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.
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.
Arriaga C, Yépez-Mulia L, Viveros N, Adame LA, Zarlenga DS, Lichtenfels JR, Benitez E, Ortega-Pierres MG.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.
Long MT, Goetz TE, Kakoma I, Whiteley HE, Lock TE, Holland CJ, Foreman JH, Baker GJ.Fetal infectivity of Ehrlichia risticii was investigated in 19 ponies that were E risticii negative on the basis of results of an indirect fluorescent antibody (IFA) test. Thirteen pregnant ponies were infected by IV administration of E risticii between 90 and 180 days of gestation. Six pregnant ponies served as noninfected controls. Each infected pony had clinical signs of equine monocytic ehrlichiosis, was confirmed to be ehrlichemic, and developed an IFA titer to E risticii. Two infected ponies became recumbent, were unresponsive to supportive care, and were euthanatized. After recovery fro...
Monzón CM, Jara A, Nantulya VM.The sensitivity of an antigen detection enzyme immunoassay (Ag-ELISA) based on a Trypanosoma brucei group-specific monoclonal antibody was evaluated to detect circulating Trypanosoma evansi antigen in horse sera. Three horses and 2 mules were experimentally infected with T. evansi. Circulating antigens were detected on 7 and 21 days postinfection. Antigen levels increased during the course of the illness and remained high even when parasitemia was low or when parasites could not be detected. Antigens were cleared from serum when drug treatment was effective but persisted when it was not. In 6 ...
Moore CP, Collins BK, Fales WH.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...
Marchi PR, Rawlings P, Burroughs JN, Wellby M, Mertens PP, Mellor PS, Wade-Evans AM.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...
Laviada MD, Roy P, Sánchez-Vizcaíno JM, Casal JI.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...
The Journal of nutritionOctober 1, 1995
Volume 125, Issue 10 2711-2716 doi: 10.1093/jn/125.10.2711
Greiwe-Crandell KM, Kronfeld DS, Gay LA, Sklan D.Vitamin A influences growth and reproduction in horses. A retinol dose response (RDR) test for retinol has been shown to be better than serum retinol concentration for assessing vitamin A status in other species, so we have compared these two methods in the horse. Forty-five Thoroughbred broodmares were assigned randomly to three groups fed pasture and hay (PH), pasture, hay and vitamin A-free concentrate (PHC), or hay and concentrate (HC) in early summer (May 1991). Mares in pasture groups produced 23 foals (March through June) that had access to their dam's diets and were also studied. In th...
Rames DS, Miller DK, Barthel R, Craig TM, Dziezyc J, Helman RG, Mealey R.Ocular contents from a horse with a 4-week history of severe unilateral uveitis were submitted for histopathologic examination. A severe unilateral granulomatous chorioretinitis with intralesional Halicephalobus deletrix was diagnosed. The horse developed progressive neurologic signs several days following the surgery to remove ocular contents and implant a prosthesis and was subsequently euthanatized. A severe multifocal granulomatous encephalitis with intralesional H. deletrix, localized primarily to the optic chiasm, thalamus, and brain stem, was diagnosed from tissues acquired at necropsy....
Monzón CM, Jara GA, Hoyos CB.The microhaematocrit (MH) technique was used to study the survival of Trypanosoma evansi in blood from two herds of naturally-infected horses. A comparison was made between samples treated with ethylenediaminetetraacetic acid and sodium citrate (alone or with 1% glucose), and sent to the laboratory packed in ice. In general, the number of samples yielding positive results by the MH technique showed the least variation during the first 24-36 h after sample collection. Survival varied with the anticoagulant used, but it declined rapidly from 48 h after collection, although live parasites were st...
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...
Glaser AL, de Vries AA, Dubovi EJ.Three murine monoclonal antibodies (MAbs) that neutralize equine arteritis virus (EAV) infectivity were identified and characterized. The antibodies, 93B, 74D(B) and 38F, recognized the major envelope glycoprotein (GL) encoded by open reading frame (ORF) 5 in immunoblots and by immunoprecipitation. All three MAbs were used to compare the Bucyrus isolate of EAV and MAb neutralization-resistant (NR) escape mutants with the vaccine virus and 19 independent field isolates of EAV by virus neutralization. The different abilities of the MAbs to neutralize virus isolates indicated that they recognize ...
Crabb BS, Studdert MJ.A series of truncated equine herpesvirus 1 (EHV1) glycoprotein C (gC) molecules was examined for use as serodiagnostic antigens for EHV1 and EHV4. Small regions of EHV1 glycoprotein C, an immunodominant EHV1 glycoprotein, were expressed in Escherichia coli as glutathione S-transferase (GST) fusion proteins using the bacterial expression vector pGEX-2T. Sera obtained from horses, including sera from specific-pathogen-free (SPF) foals, following exposure to either EHV1, EHV4 or both viruses were used. Several of the fusion proteins were shown to encompass EHV1 specific epitopes while others enco...
Tantawichien T, Benjavongkulchai M, Wilde H, Jaijaroensup W, Siakasem A, Chareonwai S, Yountong C, Sitprija V.The high cost of postexposure prophylaxis for rabies is one reason that treatment is inadequate in developing countries. This problem has kindled interest in the use of equine rabies immune globulin, which is a less expensive, yet effective, substitute for human rabies immune globulin. Fatal anaphylaxis is a feared complication of the administration of heterologous serum; therefore, authoritative sources recommend prior skin testing. However, recommendations for methods of administering such a skin test and for its interpretation vary greatly. We embarked on a long-term study to develop guidel...
Fodor L, Szenci O, Peters M, Varga J, Szemerédi G, Wyszoczky F.A total of seven Bacteroides ureolyticus strains were isolated from the cervix and the clitoral fossa of mares with vaginal discharge. No other bacteria capable of causing metritis or vaginitis were isolated from the samples. The isolated strains resembled Taylorella equigenitalis. Both species are catalase, oxidase and alkaline phosphatase positive, but, in addition to these characteristics, B. ureolyticus strains produced urease and they could not tolerate 10% O2. They also failed to be agglutinated in a hyperimmune serum raised against T. equigenitalis; however, B. ureolyticus and T. equige...
Monzón CM, Hoyos CB, Jara GA.Tests on 257 blood samples from 21 herds of horses in Formosa Province of Argentina, using the technique of centrifuging microhaematocrit capillary tubes, revealed Trypanosoma evansi in 90 of 137 animals in eight herds. Application of the direct agglutination test to serum samples from the same animals revealed antibodies to T. evansi in 107 horses. Antibody was also detected in nine horses from two herds where the parasite was not detected. Outbreaks of 'mal de caderas' occurred in the humid (eastern) and sub-humid (central) zones of Formosa. More than 95% of the equine population of the prov...
Bertone AL.Infectious tenosynovitis is treated similarly to infectious arthritis. The principles of treatment include an early diagnosis and immediate therapy. Therapy should include use of systemic and local antimicrobials and sheath lavage and drainage. Fibrosis and adhesions can be minimized with passive range of motion exercises, intrathecal hyaluronate, and phenylbutazone therapy. Restrictive fibrosis may be treated successfully by annular ligament resection.
Nakamura Y, Kishi M, Nakaya T, Asahi S, Tanaka H, Sentsui H, Ikeda K, Ikuta K.Borna disease (BD) is a progressive poliomeningoencephalomyelitis which occurs naturally in horses and sheep. Here, peripheral blood mononuclear cells (PBMC) derived from 57 healthy horses in Japan were examined by a nested reverse transcription-polymerase chain reaction to determine the prevalence of BD virus (BDV) infection. Seventeen (29.8%) of the samples were positive by this examination and the specificity of the amplified product was confirmed by hybridization with authentic oligomer probes. About 60% of the BDV RNA-positive individuals also showed seropositivity by Western blotting. Th...
Moulay S, Zientara S, Sailleau C, Cruciere C.In order to develop a non-radioactive dot-blot hybridization assay, for the detection of African-horse sickness virus (AHSV), genome segment 7 from 9 serotypes was amplified by RT-PCR. The resulting PCR products were denatured, immobilized on nylon membranes and then hybridized to a non-radioactive digoxigenin-labelled probe. This probe (265 bp in length) was generated by nested-PCR using genome segment 7 of AHSV, serotype 4 as a template. The dot-blot was visualized by chemiluminescence. Positives were obtained from the PCR products amplified from all 9 AHSV serotypes, but not from any other ...
Vaid RK, Shanmugasundaram K, Anand T, Bera BC, Tigga M, Dedar R, Riyesh T, Bardwaj S, Virmani N, Tripathi BN, Singh R. is a well-known Gram-negative bacterial pathogen causing a plethora of diseases in different animals. Although its infection has been reported from pigs and dogs in India, no report of B. bronchiseptica from horses is described. We report for the first time, isolation, identification and characterization of strains of B. bronchiseptica from respiratory infection in horses from different states in India. The antimicrobial susceptibility testing showed resistance to penicillins, ceftazidime, and chloramphanicol. The virulence capability of the strains was confirmed by sequencing genes such as a...
MacMillan AP, Baskerville A, Hambleton P, Corbel MJ.Five mares, one stallion and a colt foal were inoculated intraconjunctivally with Brucella abortus strain 544. No clinical signs of disease developed except mild pyrexia. Intermittent bacteraemia was detected in the mares but not in the stallion or foal. Antibodies to B abortus became detectable from the second week after inoculation. Titres in the serum agglutination and complement fixation tests declined substantially after six to eight weeks but reactions to the Coombs antiglobulin, 2-mercaptoethanol and immunodiffusion tests were maintained. No consistent changes in biochemical or haematol...
Papapetrou MA, Arroyo LG, Meister TL, Baird JD, Steinmann E, Lillie BN.Equine parvovirus-hepatitis (EqPV-H) was first reported from the serum and liver tissue of a horse diagnosed with Theiler's disease in the United States in 2018. Theiler's disease, also known as equine serum hepatitis, is a severe hepatitis with fulminant hepatic necrosis. The disease has most frequently been reported following the administration of equine-origin biological products; however, it has also been reported in in-contact horses with no prior biologic administration. EqPV-H has been detected in clinically healthy horses in North America (USA, Canada), Europe (Germany, Austria, Sloven...
Romo-Sáenz CI, Tamez-Guerra P, Olivas-Holguin A, Ramos-Zayas Y, Obregón-Macías N, González-Ochoa G, Zavala-Díaz de la Serna FJ....Equine infectious anemia (EIA) is a highly infectious disease in members of the family, caused by equine infectious anemia virus (EIAV). The disease severity ranges from subclinical to acute or chronic, and causes significant economic losses in the equine industry worldwide. Serologic tests for detection of EIAV infection have some concerns given the prolonged seroconversion time. Therefore, molecular methods are needed to improve surveillance programs for this disease. We attempted detection of EIAV in 6 clinical and 42 non-clinical horses in Nuevo Leon State, Mexico, using the agar gel immu...
Cruz F, Fores P, Mughini-Gras L, Ireland J, Moreno MA, Newton R.Equine viral arteritis (EVA), a disease caused by infection with the equine arteritis virus (EAV), is present in many European countries. In Spain, the last confirmed outbreak was reported in 1992 and there is a paucity of seroprevalence studies. The disease has a major impact on the equine breeding industry, which is mainly represented by Spanish Purebred (SP) horses in Spain. Objective: To estimate the seroprevalence of EAV in the breeding SP horse population in central Spain and identify potential horse and studfarm level factors associated with seropositivity to EAV. Methods: Cross-section...
Yin X, Guo M, Gu Q, Wu X, Wei P, Wang X.Tetherin is an interferon-inducible host cell factor that blocks the viral particle release of the enveloped viruses. Most knowledge regarding the interaction between tetherin and viruses has been obtained using the primate lentiviral system. However, much less is known about the functional roles of tetherin on other lentiviruses. Equine infectious anemia virus (EIAV) is an important macrophage-tropic lentivirus that has been widely used as a practical model for investigating the evolution of the host-virus relationship. The host range of EIAV is reported to include all members of the Equidae ...
Matera MG, Calzetta L, Sanduzzi A, Page CP, Cazzola M.It has been demonstrated in mammals that the airway hyper-responsiveness, which accompanies viral infections, is the result of increased reflex bronchoconstriction due to inhibition of muscarinic prejunctional receptors, which belong to M2 subtypes. Multiple mechanisms account for virus-induced M2 receptor dysfunction. Viral neuraminidase may deglycosylate the M2 receptor, decreasing acetylcholine affinity. Equine influenza remains a common viral respiratory disease of horses worldwide, which results in loss to the equine industry, by decreasing performance, convalescence time and loss of peak...
Zahoor J, Kashif M, Nasir A, Bakhsh M, Qamar MF, Sikandar A, Rehman A.Trypanosomiasis is one of the severe pathogenic infections, caused by several Trypanosoma species, affecting both animals and humans, causing substantial economic losses and severe illness. The objective of this study was to determine the molecular diagnosis and the risk factors associated with trypanosomiasis in District Jhang, Punjab, Pakistan. For this purpose, blood samples were randomly collected from 200 horses. A predesigned questionnaire was used to collect data on risk factors before the sample collection. The microscopy examination through Giemsa staining, formol gel test and PCR tec...
Fikrig E, Magnarelli LA, Chen M, Anderson JF, Flavell RA.Enzyme-linked immunosorbent assays (ELISA) and immunoblots using either whole-cell lysates of Borrelia burgdorferi or an antigenic region of flagellin (41-G) as the antigen were performed, and the abilities of the two assays to detect antibodies to this spirochete in dog, cottontail rabbit, and horse sera were compared. Assays using whole-cell B. burgdorferi lysates as the antigen were more sensitive for detecting antibodies. ELISA with 41-G as the antigen were specific for Borrelia antibodies but were not as sensitive as the assays with whole-cell lysates coated to the solid phase. Use of rec...
Bochkova NG, Koreshkova GV, Pogodina VV.A total of 5227 serum specimens from humans, horses and swine collected in the seasons of 1968--1976 in 15 administrative areas of the Primorskiy Kray were examined with antigens of a number of mosquito-borne arboviruses: Japanese encephalitis (JE), West Nile (WN), Getah, and Sindbis. Both independent and combined circulation of these viruses in the region was established. Sindbis virus was found to be circulating separately most frequently, West Nile virus the least frequently. According to the results of the serological analysis, the conditions for combined circulation are most closely relat...
Hudson LC, Weinstock D, Jordan T, Bold-Fletcher NO.Twelve naive and nine test-vaccinated horses which developed clinical signs of rabies as a result of the required protocol of a vaccine trial were prospectively observed. Nineteen of the 21 cases were confirmed positive for rabies infection of the brain by fluorescent antibody test. The two horses with negative results had ganglioneuritis of the trigeminal ganglion or lymphocytic perivascular cuffing in the brain stem in addition to clinical signs. Average incubation period was 12.3 days and average morbidity was 5.5 days. Naive animals had significantly shorter incubation and morbidity period...
Volkmann DH, Williams JH, Henton JH, Donahue JM, Williams NM.Since the late 1980s a distinct form of focally-extensive mucoid to mucopurulent uterine body chronic placentitis,caused by nocardioform organisms, hasbeen recognised in horses in the USA state of Kentucky and possibly in other areas. This disease has led to increasing numbers of foal losses from late abortions, still-births, prematurity, or early neonatal deaths. The foals are usually not infected, but may be small or emaciated. Modes of infection and transmission are as yet unknown. Nocardia spp. and related nocardioform bacteria as causes of equine infertility, endometritis and foal death a...
Skipper L, Pusterla N.The purpose of this study was to establish if peak serum amyloid A (SAA) concentrations can be used to determine an appropriate immune response to a vaccine containing West Nile Virus (WNV) antigen. A pilot study with 20 clinically healthy horses was performed to identify peak SAA concentration postvaccination with a commercial multivalent WNV vaccine. Blood was collected for SAA at 0, 24, 48, 72, 96, 168 hours postvaccination. Serum for WNV serum neutralization antibody testing was obtained immediately prior to and 30 days postvaccination. An additional 40 horses underwent the study protocol,...
Zhang P, Sun Y, Tan C, Ling M, Li X, Wang W, Cong Y.To prevent and control H3N8 subtype equine influenza, we prepared virus-like particles (VLPs) comprising the HA, NA and M1 proteins of H3N8 equine influenza virus (EIV) through the insect cell-baculovirus expression system. The results of Western blot and hemagglutination analyses demonstrated that the constructed VLPs comprising HA, NA and M1 proteins have good hemagglutination activity. Immunoelectron microscope revealed that the VLPs share similar morphology and structure with natural virus particles. The hyperimmune serum from horses immunized with the VLPs were injected into mice by means...
Coffman EA, Abd-Eldaim M, Craig LE.A pregnant 18-year-old Quarterhorse mare presented with fever, anorexia, tachycardia, tachypnea, and gastrointestinal hypermotility at day 68 of gestation. Potomac horse fever was diagnosed based on polymerase chain reaction (PCR) analysis of whole blood and a high antibody titer to Neorickettsia risticii. The mare made a rapid clinical recovery following antibiotic therapy, but aborted 98 days later. Necropsy on the aborted fetus revealed lymphohistiocytic colitis, lymphadenitis, myocarditis, and hepatitis. The placenta was grossly and histologically normal. Formalin-fixed lymph node, thymus,...
Azab W, El-Sheikh A.Equine herpesvirus 4 (EHV-4) is an important equine pathogen that causes respiratory tract disease among horses worldwide. Glycoprotein K (gK) homologues have been identified in several alphaherpesviruses as a major player in virus entry, replication, and spread. In the present study, EHV-4 gK-deletion mutant has been generated by using bacterial artificial chromosome technology and Red mutagenesis to investigate the role of gK in EHV-4 replication. Our findings reported here show that gK is essential for virus replication in vitro and that the gK-negative strain was not able to be reconstitut...
Tamekuni K, Toledo Rdos S, Silva Filho Mde F, Haydu VB, Pacheco RC, Cavicchioli JH, Labruna MB, Dumler JS, Vidotto O.Brazilian spotted fever (BSF) is an emerging disease most likely caused by Rickettsia rickettsii. The objective of the present study was to estimate the seroprevalence of BSF rickettsia infections in equines from six horse farms located in Londrina County, Paraná, Southern Brazil. Six owners of horse farms situated in Cambé, Santa Fé, Guaraci and Londrina municipalities participated in the study. All farms were located in areas where BSF has not been reported. A total of 273 horses were sampled and their sera were tested by indirect immunofluorescence assay (IFA) using R. rickettsii and R. ...
Castagnetti C, Veronesi MC.In the foal, the most common neonatal diseases are responsible for an high non-survival rate. Since intensive care for neonatal foals is usually very expensive an early prognosis for survival at admission or during hospitalization is recommended, as well as a prognosis for future athletic potential. Therefore, prognostic factors for prematurity, septicaemia, other infectious diseases and hospitalized foals are revised and discussed on the base of literature and authors experiences. The advantages and limitations of retrospective and perspective prognostic factors is also presented, and the pos...
Pauwels FE, Wigley SJ, Munday JS, Roe WD.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...
Stasiak K, Dunowska M, Trewick S, Rola J.Equid herpesvirus 5 (EHV-5) is one of two γ-herpesviruses that commonly infect horses worldwide. The objective of the study was to estimate the genetic variability within EHV-5 viruses circulating among horses in Poland. Partial glycoprotein B (gB) sequences from 92 Polish horses from 13 studs throughout Poland were compared to each other and to three EHV-5 sequences from other countries. Despite the overall high level of conservation, considerable variability was observed around the putative furin cleavage site. Based on phylogenetic analysis, the viruses clustered within two major lineages ...
Duthie S, Mills H, Burr P.Infection with equine arteritis virus is a notifiable disease with sporadic occurrence in the UK. As stallions may harbour the virus after infection, horses are screened for exposure by serological testing prior to breeding. The virus neutralisation test is considered the 'gold standard' serological screening test, but it is time-consuming and labour intensive; consequently there is a move towards more rapid screening methodology. In this study, a commercially available EVA antibody ELISA is assessed. The ELISA performed poorly with a specificity [corrected] of 26% and a sensitivity [corrected...
Saklou N, Pleasant S, Lahmers K, Funk R.Equine Herpesvirus type 1 (EHV-1) typically causes mild respiratory disease, but it can also cause late-term abortion, neonatal foal death and neurologic disease. Once a horse is infected, the virus concentrates to local lymphoid tissue, where it becomes latent. The virus can be reactivated during times of stress, which can lead to the initiation of devastating outbreaks. Understanding the carriage rate of latent EHV-1 in different geographic regions is essential for managing the disease. The objective of the current study was to estimate the prevalence of latent EHV-1 and compare the frequenc...
Yao Q, Ma J, Wang X, Guo M, Li Y, Wang X.Tetherin (BST-2) is an important host restriction factor that can inhibit the release of a diverse array of enveloped viruses from infected cells. Conversely, to facilitate their release and spread, many viruses have evolved various strategies to overcome the antiviral effect of tetherin in a species-specific manner. During the development of an attenuated equine infectious anemia virus (EIAV) vaccine in our laboratory, we found that serial passage of a field-isolated virulent EIAV strains in horse and donkey as well as the cultivated donkey cells, produces several typical EIAV strains, includ...
Mitchell SW, Moran RA, Elbourne LDH, Chapman B, Bull M, Muscatello G, Coleman NV.Antimicrobial resistance in bacteria is a threat to both human and animal health. We aimed to understand the impact of domestication and antimicrobial treatment on the types and numbers of resistant bacteria, antibiotic resistance genes (ARGs), and class 1 integrons (C1I) in the equine gut microbiome. Antibiotic-resistant fecal bacteria were isolated from wild horses, healthy farm horses, and horses undergoing veterinary treatment, and isolates (9,083 colonies) were screened by PCR for C1I; these were found at frequencies of 9.8% (vet horses), 0.31% (farm horses), and 0.05% (wild horses). A co...
McLean RG.The epidemic strain of Venezuelan equine encephalitis virus (VEE) 1B invaded south Texas in 1971. The success of the eventual containment and control of the virus invasion was the early recognition and immediate detection, cooperation, coordination, and participation among multiple federal agencies. There were 4739 wild vertebrate animals trapped on a ranch in the area with only 1 VEE virus isolation from a Virgina opossum (Didelphis virginiana). A large number of mosquitoes were also collected on the ranch and tested, resulting in 240 VEE virus isolations. Virus isolations were obtained from ...
Pusterla N, Barnum SM, Byrne BA.Polymerase chain reaction (PCR)-based detection assays for Streptococcus equi subspecies equi often overestimate the prevalence of samples containing viable organisms. The objective of this study was to determine if viability could be determined using genome quantitation and detection of messenger RNA (mRNA) transcripts for the SeM gene of S. equi in pre- and post-cultured samples. Nasal secretions collected from 42 horses with suspected strangles were tested by culture and by quantitative PCR (qPCR) before and 24 hours after a culture step. Viable S. equi was determined based on the detecti...
Zehetner V, Cavalleri JV, Klang A, Hofer M, Preining I, Steinborn R, Ramsauer AS.There is strong evidence that equine parvovirus-hepatitis (EqPV-H) is associated with the onset of Theiler's disease, an acute hepatic necrosis, in horses. However, the impact of this virus on other hepatopathies remains unknown. The objective of this retrospective study was to evaluate the prevalence and quantify the viral loads of EqPV-H in formalin-fixed, paraffin-embedded equine and donkey livers with various histopathologic abnormalities. The pathologies included cirrhosis, circulatory disorders of the liver, toxic and metabolic hepatic diseases as well as neoplastic and inflammatory dise...
Adams RJ, Mollenkopf DF, Mathys DA, Whittle A, Ballash GA, Mudge M, Daniels JB, Barr B, Wittum TE.To estimate the prevalence of extended-spectrum cephalosporin-, carbapenem-, and fluoroquinolone-resistant bacteria of the family Enterobacteriaceae in the feces of hospitalized horses and on hospital surfaces. Methods: Fecal and environmental samples were collected from The Ohio State University Galbreath Equine Center (OSUGEC) and a private referral equine hospital in Kentucky (KYEH). Feces were sampled within 24 hours after hospital admission and after 48 hours and 3 to 7 days of hospitalization. Methods: Fecal and environmental samples were enriched, and then selective media were inoculate...
Fritsch H, Pereira FM, Costa EA, Fonseca V, Tosta S, Xavier J, Levy F, Oliveira C, Menezes G, Lima J, Santos L, Silva L, Nardy V, Astete MKG....During these past years, several studies have provided serological evidence regarding the circulation of West Nile virus (WNV) in Brazil. Despite some reports, much is still unknown regarding the genomic diversity and transmission dynamics of this virus in the country. Recently, genomic monitoring activities in horses revealed the circulation of WNV in several Brazilian regions. These findings on the paucity of genomic data reinforce the need for prompt investigation of WNV infection in horses, which may precede human cases of encephalitis in Brazil. Thus, in this study, we retrospectively scr...
Medica DL, Sukhdeo MV.Infective larvae (L3) of Strongylus vulgaris have limited energy stores for host finding and for infection. For transmission to occur, the larvae must have sufficient energy to (a) migrate onto grass, where they are ingested by their equine host (host finding), and (b) penetrate into the host gut. This study is designed to test the hypothesis that L3 larvae of S. vulgaris partition their energy stores between locomotory activity (used in host finding) and infection activity (penetration). Chronic locomotory activity was stimulated by incubating S. vulgaris L3 larvae at a constant temperature (...
