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Topic:Infectious Disease
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.
Genetic heterogeneity and variation in viral load during equid herpesvirus-2 infection of foals. Equine herpesvirus-2 (EHV-2) infection has been implicated as a cause of a variety of clinical disorders in young horses, including upper respiratory tract disease, generalized malaise, fever, pharyngeal lymphoid hyperplasia, and lymphadenopathy. Considerable sequence heterogeneity has been demonstrated previously among EHV-2 strains, and individual horses can be concurrently infected with more than one virus strain. In this study, the temporal variation of the viral load and genomic diversity of the glycoprotein B (gB) gene of EHV-2 in the nasal secretions of a cohort of foals was characteriz...
Equus caballus major histocompatibility complex class I is an entry receptor for equine herpesvirus type 1. In this study, Equus caballus major histocompatibility complex class I (MHC-I) was identified as a cellular entry receptor for the alphaherpesvirus equine herpesvirus type 1 (EHV-1). This novel EHV-1 receptor was discovered using a cDNA library from equine macrophages. cDNAs from this EHV-1-susceptible cell type were inserted into EHV-1-resistant B78H1 murine melanoma cells, these cells were infected with an EHV-1 lacZ reporter virus, and cells that supported virus infection were identified by X-Gal (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside) staining. Positive cells were subjected t...
Survey for tick-borne zoonoses in the state of Espirito Santo, southeastern Brazil. Blood samples collected from 201 humans, 92 dogs, and 27 horses in the state of Espirito Santo, Brazil, were tested by polymerase chain reaction, indirect immunofluorescence assays, and indirect enzyme-linked immunosorbent assay for tick-borne diseases (rickettsiosis, ehrlichiosis, anaplasmosis, borreliosis, babesiosis). Our results indicated that the surveyed counties are endemic for spotted fever group rickettsiosis because sera from 70 (34.8%) humans, 7 (7.6%) dogs, and 7 (25.9%) horses were reactive to at least one of the six Rickettsia species tested. Although there was evidence of ehrlic...
West Nile virus activity – United States, 2009. West Nile virus (WNV) was first detected in the Western Hemisphere in 1999 in New York City and has since caused seasonal epidemics of febrile illness and neurologic disease across the United States, where it is now the leading cause of arboviral encephalitis. This report updates a previous report and summarizes WNV activity in the United States reported to CDC in 2009. A total of 38 states and the District of Columbia (DC) reported 720 cases of WNV disease. Of these, 33 states and DC reported 386 cases of WNV neuroinvasive disease, for an incidence of 0.13 per 100,000 population. The five sta...
Molecular cloning, expression, and initial characterization of members of the CYP3A family in horses. The use of performance-enhancing drugs in the horse racing industry combined with the need for more rational approaches in the use of therapeutic agents in equids necessitates additional studies on the spectrum, content, and catalytic activities of hepatic cytochrome P450 monooxygenases in this species. In this study, three cytochrome P450 (P450) monooxygenases in the 3A family were cloned from, sequenced, and expressed in a baculovirus expression system. The proteins were designated CYP3A89, CYP3A96, and CYP3A97. Expression studies produced various results among the three proteins. CYP3A89 ap...
A reverse genetics system of African horse sickness virus reveals existence of primary replication. African horse sickness virus (AHSV), a member of the orbivirus genus of the family Reoviridae, is an insect-vectored pathogen of horses of concern to the equine industry. Studies on AHSV replication and pathogenesis have been hampered by the lack of reverse genetics allowing targeted mutation of viral genomes. We demonstrate that AHSV single-stranded RNA synthesized in vitro (core transcripts) is infectious and that there are distinct primary and secondary stages of the replication cycle. Transfection with a mixture of core transcripts from two different serotypes or a mixture of core transcri...
The utility of animal surveillance in the detection of West Nile virus activity in Puerto Rico, 2007. After the isolation of West Nile virus (WNV) from humans, mosquitoes, and chickens in 2007, an analysis of animal surveillance involving multiple species (horses, monkeys, sheep, dogs, and birds) used to track WNV transmission from 2006 to 2008 was performed. During this period 13.4% of all the animal samples collected were seropositive by blocking ELISA for WNV. The most complete island-wide sampling was obtained from horses of which 22% were serologically positive and 96% were confirmed as WNV infections by plaque-reduction neutralization test. Our conclusion from this 3-year study is that a...
Molecular investigation of the viral kinetics of equine herpesvirus-1 in blood and nasal secretions of horses after corticosteroid-induced recrudescence of latent infection. Recrudescence of latent equine herpesvirus 1 (EHV-1) with subsequent viral shedding via nasal secretions is a potential source of infection for susceptible horses and has been implicated in outbreaks occurring in closed populations. Objective: To describe the viral kinetics of reactivated EHV-1 in blood and nasal secretions from latently infected horses after administration of corticosteroids, and to study the infectious nature of reactivated EHV-1 to sentinel horses. Methods: Eight healthy horses. Methods: Four horses infected 4 months previously with EHV-1 received dexamethasone on 5 consecu...
Detection and management of an outbreak of equine herpesvirus type 1 infection and associated neurological disease in a veterinary teaching hospital. Because of the serious disease sequelae associated with equine herpesvirus type 1 (EHV-1) infections, awareness and control measures used to control outbreaks are important issues for all horse populations. Objective: Describe the occurrence and management of an outbreak of EHV-1 infection at a veterinary hospital. Methods: Horses hospitalized at a referral veterinary hospital. Methods: A horse with myeloencephalopathy associated with EHV-1 infection (EHM) was admitted for diagnostic evaluation and treatment under strict infection control procedures. We describe the occurrence and management o...
Detection of neuropathogenic strains of Equid Herpesvirus 1 (EHV-1) associated with abortions in Germany. A single nucleotide polymorphism within EHV-1 gene ORF 30, which encodes for the viral DNA polymerase, allows the differentiation of the neuropathogenic (G2254) from non-neuropathogenic genotype (A2254). The aim of our study was to investigate the distribution of the neuropathogenic and non-neuropathogenic genotype of EHV-1 isolates associated with abortions in Germany. To determine the nucleotide sequence at the polymorphic site the amplification product of ORF 30 gene specific nested PCR was digested with restriction enzyme SalI and sequenced. Thirty-two EHV-1 isolates from six abortion outb...
Genetic diversity of equine piroplasms in Greece with a note on speciation within Theileria genotypes (T. equi and T. equi-like). Equine piroplasms in Greece were studied using the reverse line blot hybridization (RLB) assay. Three genotypes consisting of two Theileria (T. equi and T. equi-like) and one Babesia (B. caballi-like) were identified. Of 787 samples tested, 371 (47.14%) hybridised to catchall probe (probe specifically designed to capture any piroplasm species present in a sample), 346 (43.96%) to T. equi probe, 364 (46.25%) to T. equi-like probe, 0 (0%) to B. caballi probe and 3 (0.38%) to B. caballi-like probe. Seven samples gave faint signals with the catchall probe only, indicating the presence of known or ...
REVIEW PAPER: pathology of animal models of alphavirus encephalitis. The encephalitides caused by Venezuelan (VEEV), eastern (EEEV), and western (WEEV) equine encephalitis viruses are important natural diseases of horses and humans and potential agents of biowarfare or bioterrorism. No licensed vaccines or specific therapies exist to prevent or treat human infections with VEEV, EEEV, or WEEV. Well-characterized animal models are needed to support the development of such medical countermeasures under the United States Food and Drug Administration's "Animal Rule." This review focuses on the pathological features and pathogenetic mechanisms of these alphaviral enc...
Detection and sequence analysis of equine gammaherpesviruses from horses with respiratory tract disease in Turkey. The equid herpesvirus 2 (EHV-2) and 5 (EHV-5), identified agents of respiratory infections and keratoconjunctivitis cases in some equids, comprise a high degree of antigenic heterogeneity. Prevalence and genetic characterization of EHV-2 and EHV-5 strains from Turkey were investigated in this study. A total of 73 nasal swabs and 54 blood specimens were sampled from horses with respiratory tract diseases characterized by mucopurulent nasal discharge and occasional coughing. Overall, EHV-2- and EHV-5-specific DNA amplicons were obtained from 19.2% (14/73) and 21.9% (16/73) of horses tested by mu...
Carriage of Clostridium difficile and other enteric pathogens among a 4-H avocational cohort. Clostridium difficile (CD), Salmonella, Campylobacter and enterohemorrhagic Escherichia coli (EHEC) are major causes of morbidity in a variety of enteric diseases in humans and animals, but subclinical carriage in both is probably more common than are clinical cases. Little is known regarding the prevalence of these pathogens in animals raised for exhibit at Michigan county fairs or the frequency with which Michigan citizens raising these animals may have been subclinically colonized. To address these issues, 361 fecal specimens from 158 humans and 203 of their farm animals were cultured for C...
Control of EHV-1 viremia and nasal shedding by commercial vaccines. Equine herpesvirus-1 is a cause of outbreaks of abortion and neurological disease. The pathogenesis of both these diseases depends on establishment of viremia. An experiment was performed to determine the protective efficacy of two commercially available vaccines used with an optimized 3-dose vaccination regime: a modified-live viral (MLV) and a high antigen load killed vaccine licensed for abortion control. The study design was a blinded, randomized challenge trial. Three groups of 8 yearling ponies received one of three treatments: MLV vaccine (Rhinomune, Boehringer Ingelheim Vetmedica, Inc....
Neospora spp. and Toxoplasma gondii antibodies in horses in the Czech Republic. During January 2007, blood samples were collected from 552 healthy horses from nine different regions of the Czech Republic. Sera were tested for serum antibodies to Neospora caninum by a competitive-inhibition enzyme-linked immunosorbent assay and confirmed by an indirect fluorescent antibody test. The same samples were tested for serum antibodies against Toxoplasma gondii by a latex agglutination test. In total, 131 of 552 (24%) horses reacted positively for Neospora antibodies in competitive-inhibition enzyme-linked immunosorbent assay; seven of them had > or =50% of inhibition. Samples wer...
Comparative diagnosis of parasitological, serological, and molecular tests in dourine-suspected horses. Study on comparative sensitivity of parasitological, serological, and molecular tests on 237 horses originating from two dourine-suspected districts of Arsi-Bale highlands of Ethiopia was conducted to determine the prevalence of the disease and degree of agreement of the diagnostic tests. Accordingly, the prevalence of the disease was found to be 4.6%, 36.7%, and 47.6% by parasitological Woo test, RoTat 1.2 and 18S PCR tests, respectively. The seroprevalence of the disease was 27.6% in CATT/Trypanosoma evansi test. In Ethiopia, it was for the first time that trypanosomes from dourine suspected...
Vector competence of Culex (Melanoconion) taeniopus for equine-virulent subtype IE strains of Venezuelan equine encephalitis virus. The mosquito Culex (Melanoconion) taeniopus is a proven vector of enzootic Venezuelan equine encephalitis virus (VEEV) subtype IE in Central America. It has been shown to be highly susceptible to infection by this subtype, and conversely to be highly refractory to infection by other VEEV subtypes. During the 1990s in southern coastal Mexico, two VEE epizootics in horses were attributed to subtype IE VEEV. These outbreaks were associated with VEEV strains with an altered infection phenotype for the epizootic mosquito vector, Aedes (Ochlerotatus) taeniorhynchus. To determine the infectivity for ...
Serosurveillance for equine infectious anaemia in the Ardahan province of Turkey. Equine infectious anaemia is a retroviral infection of horses. All infected horses, including those that are asymptomatic, become carriers and are infectious for life. In this study, blood samples of all equines in the province of Ardahan were collected. The material consisted of 8,947 equines, including 8,769 horses and 178 donkeys, from Ardahan province in northeastern Turkey. Blood was collected from all horses and donkeys and the sera were analysed for the presence of antibodies to equine infectious anaemia virus (EIAV) using an enzyme-linked immunosorbent assay. The results revealed that ...
Excessive sulfate and poor water quality as a cause of sudden deaths and an outbreak of diarrhea in horses. Sudden deaths and an outbreak of diarrhea in horses occurred in southern Saskatchewan in 2006. Five horses died while survivors presented with diarrhea and, in 1 case, acute neurologic signs attributed to hyponatremia. Diagnostic testing of affected horses and environmental testing suggested poor water quality, specifically high salinity and high sulfate concentration as the cause. Des morts soudaines et une éclosion de diarrhée se sont produites chez des chevaux du Sud de la Saskatchewan en 2006. Cinq chevaux sont morts tandis que les survivants ont présenté de la diarrhée et, dans 1 ca...
A case of disseminated infection caused by Streptococcus equi subspecies zooepidemicus. Human infections with Streptococcus equi subspecies zooepidemicus, a group C streptococcus, are very rare and are generally associated with contact with horses, and consumption of unpasteurized milk products, goat cheese or pork. In most cases S zooepidemicus leads to fulminant infections. The case of a middle-aged woman who had sporadic contact with horses is described in the present report. She developed a bacteremia with severe and extensive complications that included meningitis, mitral endocarditis and blindness due to bilateral endophthalmitis. To the authors' knowledge, this is the firs...
The immune response of foals to natural infection with equid herpesvirus-2 and its association with febrile illness. Equid herpesvirus-2 (EHV-2) infection is ubiquitous in horses. Although EHV-2 infection has been associated with several disease syndromes, its true pathogenic significance in horses remains uncertain. Epstein-Barr virus (EBV), another gammaherpesvirus, has been shown to cause febrile illness in humans related to its immunopathologic effects. Thus, the purpose of this study was to describe the ontogeny of the immune response of a cohort of 9 foals to natural infection with EHV-2 by evaluating serial complete blood counts, lymphocyte morphology, cytokine gene expression in peripheral blood mono...
Isolation and characterisation of equine influenza viruses (H3N8) from Europe and North America from 2008 to 2009. Like other influenza A viruses, equine influenza virus undergoes antigenic drift. It is therefore essential that surveillance is carried out to ensure that recommended strains for inclusion in vaccines are kept up to date. Here we report antigenic and genetic characterisation carried out on equine influenza virus strains isolated in North America and Europe over a 2-year period from 2008 to 2009. Nasopharyngeal swabs were taken from equines showing acute clinical signs and submitted to diagnostic laboratories for testing and virus isolation in eggs. The sequence of the HA1 portion of the viral...
In vitro antimicrobial activity of gallium maltolate against virulent Rhodococcus equi. The objective of this study was to determine the in vitro antimicrobial activity of gallium maltolate (GaM) against Rhodococcus equi. A total of 98 virulent bacterial isolates from equine clinical cases were examined, of which 19 isolates were known to be resistant to macrolides and rifampin. Isolates were cultured with various concentrations of GaM and minimal inhibitory concentration (MIC) values were determined after 24 and 48 h. Both the MIC(50) and the MIC(90) after 24h of growth were 558 ng/mL (8 μM) and after 48 h of growth were 2230 ng/mL (32 μM). There were no apparent differences b...
Initial occurrence of Taylorella asinigenitalis and its detection in nurse mares, a stallion and donkeys in Kentucky. In 1998, a newly identified bacterium Taylorella asinigenitalis was isolated from the external genitalia and reproductive tracts of nurse mares, a stallion and donkey jacks in Kentucky. An extensive regulatory effort was implemented to contain the outbreak including the tracing and testing of 232 horses and donkeys on 58 premises. T. asinigenitalis was isolated from the reproductive tract of 10 adult equids, including two donkey jacks, one Paint Quarter-horse stallion and seven draft-type breeding mares. None of the infected horses had clinical signs of reproductive tract disease. The odds of ...
Equine granulocytic anaplasmosis in the Czech Republic. Twelve confirmed cases of equine granulocytic anaplasmosis (EGA) and five additional suspected cases, showing a compatible clinical history and specific IgG titres of 1280 or above, were recorded in the Czech Republic during the period 2002 to 2008. The diagnosis was based on clinical signs, the detection of Anaplasma phagocytophilum morulae in neutrophils in blood smears, serology and molecular methods. Pyrexia (39.8 to 41.3 degrees C), depression, partial or total anorexia, limb oedema and icterus were the most frequently observed clinical abnormalities. Haematological examination revealed t...
Human meningitis from Streptococcus equi subsp. zooepidemicus acquired as zoonoses. Streptococcus equi subsp. zooepidemicus rarely causes meningitis in humans by contact with domestic animals or their unpasteurized products. In this paper we reviewed the literature pertaining to the epidemiological and clinical aspects relating to this infection on previously reported cases of human disease. Additionally, the case of a 51-year-old female who acquired meningitis with this organism after contact with a horse is described. This patient was successfully treated with ceftriaxone, yet penicillin remains the treatment of choice. This aetiological agent should be considered in the pr...
