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.
Espinosa Seoane D, Riley CB, Kenney DG, Spencer A, Arroyo LG.To describe common bacterial isolates cultured from sick neonatal foals and their antimicrobial susceptibility and resistance patterns. Unassigned: Medical records of foals ≤ 30 days of age, admitted to the Ontario Veterinary College from 2020 to 2023, and with a positive aerobic bacterial culture and susceptibility testing performed (Kirby-Bauer method) were included. A descriptive analysis of species isolated and antimicrobial and multidrug resistance profiles was performed. Unassigned: 62 samples from 60 predominantly Thoroughbred (42% [25 of 60]) neonatal foals (median age, 8 days) yield...
Šarkūnas M, Schwahn A, Suleimanova K.The aim of present study was to examine the potency of moxidectin solution (Cydectin 1 %; Zoetis) and commercially available oral moxidectin gel (Equest®; Zoetis) to suppress the excretion of strongyle eggs in horses over a 6-week period. The horses naturally infected with strongyle nematodes (>500 eggs/g of feces) were divided into two comparable groups according age, sex and weight. On day 0 of the study, horses in Group OT (oral treatment; N=5) were dewormed with moxidectin gel (Equest®; Zoetis; 0.4 mg/kg of b.w.) according to the manufacturer's instructions, and horses in Group IT (intra...
Vasconcelos AB, França DA, Prado ACD, Yamauchi DH, Silva ACAD, Barros IO, Valença SRFA, Lucheis SB, Bosco SMG.Pythiosis is an underestimated and neglected disease in Brazil, both in horse breeders and in horses. The molecular detection of in horses in the Brazilian Northeast represents a milestone in the epidemiology of equine pythiosis in the country. This study reports novel cases of equine pythiosis, diagnosed by molecular methods, in five states of Northeastern Brazil. Clinical samples were submitted to microbiological culture, DNA extraction, and nested-PCR for molecular detection of . The nested-PCR successfully detected in four out of five equine lesion samples, demonstrating higher sensitivi...
Rimayanti R, Khairullah AR, Mustofa I, Utomo B, Lestari TD, Utama S, Akintunde AO, Mulyati S, Hernawati T, Dawood AQ, Riady G, Khan IU, Rasad SD.... is a protozoan parasite that causes the sexually transmitted disease known as "dourine" in horses. This chronic illness is directly spread from one animal to another during mating. Doflein proposed the name in 1901. Despite being distributed worldwide, the broad use of artificial insemination technology over the past three decades has resulted in only a few cases being documented. The condition is typically fatal and is characterized by gradual emaciation, nervous system involvement, and edematous lesions of the genitals. The incubation period between exposure and the onset of clinical sympt...
Jelocnik M, Hall C, Dennis S, Mitchell K, Blishen A, Mashkour N, Anstey SI, Jenkins C, Jeffers K, El-Hage C, McMillan D, Gilkerson J.Infectious diseases significantly impact equine health and welfare, causing illness and death, and loss of productivity globally. One such disease is 'strangles', a highly contagious upper respiratory condition in horses caused by Streptococcus equi subspecies equi (SEE). Diagnostic methods for this pathogen include sensitive molecular assays and less reliable bacterial isolation and biochemical testing. However, the presence of closely related streptococci, such as Streptococcus equi subspecies zooepidemicus (SZOO), may confound diagnosis. Rapid assays for SEE are crucial for outbreak control...
Studzińska M, Klockiewicz M, Szczepaniak K, Demkowska-Kutrzepa M, Roczeń-Karczmarz M, Tomczuk K.The resistance of strongyles to pyrantel pamoate has been reported in publications worldwide. There is no data on its efficacy in horses in Poland. Therefore, the aim of this study was to evaluate the effectiveness of pyrantel pamoate to control strongyle invasions in young horses. The study involved horses of both sexes, aged 1 to 2 years, and was conducted in two seasons (spring and the end of summer). Feces were collected 24 hours before and 14 days after deworming, and they were then examined using McMaster's and combined sedimentation-flotation methods. Results revealed that in spring, th...
Motta D, Pedrosa J, Lilenbaum W.Leptospirosis is a zoonotic disease caused by pathogenic bacteria of the genus Leptospira. A lesser-known form, equine genital leptospirosis (EGL), has been identified as a chronic and often silent infection involving the colonisation of the mare's genital tract. Despite its potential impact, EGL remains underdiagnosed and poorly understood, particularly in its association with reproductive inefficiency. This study showed the presence of Leptospira spp. DNA by lipL32-PCR in the genital tract of mares with a history of reproductive disturbances. Cervicovaginal mucus samples were collected from ...
Angwin CJ, de Assis Rocha I, Reed SM, Morrow JK, Graves A, Howe DK.Equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona is one of the most important neurological diseases of horses in the Americas. While seroprevalence of S. neurona in horses is high, clinical manifestation of EPM occurs in less than 1 % of infected horses. Antemortem diagnosis has proven challenging as serum antibodies against S. neurona are an indicator of infection but not necessarily disease. Factors governing the occurrence of EPM are largely unknown, although horse immunity might contribute to EPM pathogenesis. Immunoglobulin G is the predominant antibody class in eq...
Countrymann K, Ruby R, Miller AD.Equine meningoencephalomyelitis is an important cause of morbidity and mortality and is associated with a wide variety of infectious etiologies. Because of the lack of large retrospective studies, the prevalence and incidence of these diseases are unknown. Here we describe 171 cases of meningoencephalomyelitis in horses submitted to the Section of Anatomic Pathology at the New York State Animal Health Diagnostic Center (Cornell University, Ithaca, NY, USA) from 1996-2023. Neuroinflammatory disease was identified in 5.4% of submitted horses with a wide breed, age, and sex distribution. A parasi...
Wickenden H, Lightbody KL, Peczak N, Stevens KB, Pollard D, Blake DP, Austin CJ, Matthews JB, Fox MT.Anoplocephala perfoliata is the most common equine tapeworm infection. This parasite is found at the small/large intestinal junction and has been associated with colic. The cestode has an indirect lifecycle involving oribatid mite intermediate hosts, though little is known of its epidemiology. This study aimed to monitor seasonal fluctuations in pasture oribatid mite numbers and the presence of Anoplocephala spp. DNA in mite samples collected from three equine premises in the UK. Exposure to infection in resident horses was assessed by measuring tapeworm-specific salivary antibodies. The data ...
subsp. (SEZ) is a bacterium that primarily affects horses but can also infect other animals and humans. In 2021-2022, two SEZ outbreaks occurred in Abruzzo, Italy: one in humans linked to unpasteurized cheese (37 cases) and another in donkeys (4 deaths). These events led researchers to investigate SEZ in horses, donkeys, and a mule in the regions of Abruzzo and Molise, focusing on antibiotic resistance and genetic traits. A total of 490 nasal and genital swabs were collected from equids and analyzed for SEZ presence, with 61 positive samples. Isolated strains underwent antimicrobial suscepti...
Carey KJ, Smith I, Hartley CA, Bailey KE, McIntosh K, Broder CC, Gilkerson JR.Hendra virus (HeV) is a high consequence pathogen that causes severe respiratory and/or neurological disease in both horses and humans with high mortality. The equine vaccine, Equivac® HeV, is a recombinant soluble version of the G glycoprotein of HeV (HeV-sG) that elicits a potent HeV-neutralising antibody response in adult horses and also provides indirect protection for humans. Maternally derived HeV-G specific antibodies could interfere with subsequent foal vaccination, although other factors such as foal age and the suitability of vaccination protocols that have been optimised for adult ...
Whitlock F, Newton R, King S, Ionescu AM, Higgins S.With the geographical distribution of West Nile virus expanding, there is growing concern about the potential for an incursion to the UK. Here, Fleur Whitlock, Richard Newton, Simon King, Andra-Maria Ionescu and Sara Higgins provide a timely reminder of key aspects of the virus' biology.
Poci Palumbo MI, Maciel Cavalcante R, Martins Amorim R, De Vasconcelos Machado VM, Sousa Rocha N, Garcia Ribeiro M, Cagnini DQ, Secorun Borges A.Bacterial infection of the equine central nervous system is rare. This report describes the clinical features, computed tomography (CT) findings, and postmortem results of a 3-month-old female Quarter Horse with an intracranial abscess. Clinical signs included seizures, depression, and bilateral blindness. CT imaging demonstrated a large space-occupying lesion in the left cerebral hemisphere, associated with a frontal bone fracture. Necropsy and histopathology confirmed the presence of an abscess secondary to head trauma. Bacterial culture identified Streptococcus equi subsp. zooepidemicus as...
Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J....The growing problem of antimicrobial resistance also affects equine veterinarians with increasing frequency. Antimicrobial stewardship and responsible prescribing are essential for a future in which effective antimicrobials are available, as it is unlikely that new antimicrobials will become available for use in horses. While antimicrobials are commonly used to treat equine infections, complications with therapy are also relatively common. Antimicrobial-associated diarrhoea, immune-mediated diseases, and nephrotoxicity have been reported as sequelae of antimicrobial therapy in equine practice....
Dong-Ha L, Eun-Bee L, Jong-Pil S, Eun-Ju K.Despite routine vaccination, equine influenza outbreaks occur due to disparities of virus strains between vaccine and field, and immunity gaps between vaccinations. Objective: To evaluate whether a combination of adjuvants can enhance immune responses to equine influenza virus (EIV) vaccines. Methods: In vivo experimental study. Methods: Eight mixed-breed horses were immunised intramuscularly with a recombinant canarypox-based EIV vaccine, either alone or in combination with monophosphoryl lipid A (MPL) and polyinosinic-polycytidylic acid (poly I:C). A single vaccine dose was administered, and...
Samuels AN, Collins NM, Hanlon K, Bartish C, Kelly P, Kamr AM, Toribio RE.Early and accurate identification of septicemia in neonatal foals improves survival. In human medicine, the neutrophil-to-lymphocyte ratio (NLR), neutrophil-to-monocyte ratio (NMR), monocyte-to-lymphocyte ratio (MLR), and plasma cell-free DNA (cfDNA) aid in early bacteremia detection. This study evaluated the diagnostic utility of these markers in conjunction with other clinical and hematological parameters in hospitalized foals < 5 days old to predict positive blood culture at admission and to distinguish between Gram-positive, Gram-negative, or polymicrobial bacteremia. A total of 391 foal...
Nemoto M, Kawanishi N, Kamei R, Furusho K, Kawauchi K, Yabuuchi Y, Oue Y, Uchida Y, Nishiura H, Reedy SE, Chambers TM, Li F, Bannai H, Yamanaka T....In April and May 2025, outbreaks of equine influenza occurred for the first time in 17 years in Japan. Equine influenza virus (EIV) of the H3N8 subtype was mainly detected in heavy draft horse populations in Kumamoto Prefecture and the Tokachi area of Hokkaido. In total, 10 EIVs were isolated from infected horses and then were used for genetic and serological analyses. Phylogenetic analysis of all eight genes revealed that all Japanese isolates were clustered with the Florida sublineage clade 1 (Fc1) viruses and were closely related to North American Fc1 viruses detected in 2024-2025. The resu...
Şahinkesen İ, Bilge-Dağalp S.Equine herpesvirus 1 (EHV-1) and Equine herpesvirus 4 (EHV-4) are major viral pathogens of horses that contribute to respiratory disease, abortion, and neurological disorders, leading to economic losses in the equine industry. Accurate serological diagnosis is critical for disease surveillance and control. This study aimed to develop and validate an in-house enzyme-linked immunosorbent assay (ELISA) for detecting antibodies against EHV-1 and EHV-4 in horse sera. Serum samples previously confirmed by virus neutralization test (VNT) and a commercial ELISA were used to optimize the assay. Cut-off...
Hacilarlioglu S, Bilgic HB, Karagenc T, Aydin HB, Toker H, Kanlioglu H, Pekagirbas M, Bakirci S.Equine piroplasmosis (EP), caused by and , is a tick-borne disease posing significant threats to equine health and the horse industry worldwide. Other vector-borne blood parasites, including , spp., and spp., can also infect horses; however, their prevalence remains poorly characterized in Türkiye. This study aimed to determine the molecular prevalence of , , , spp., and spp. in equids from the Western Aegean Region of Türkiye. Blood samples were collected from 388 clinically healthy equines across İzmir, Aydın, Denizli, and Muğla provinces. Species-specific PCR assays were performed...
Turcotte G, O'Sullivan TL, Rossi TM, Spence KL, Winder CB, Greer AL.Horses are frequently transported, creating opportunities for the spread of pathogens. Disease transmission models for equine infectious diseases face limitations on their generalizability due to challenges in describing equine movement and the structure of their contact networks beyond simplistic assumptions. This study aimed to combine a stochastic, agent-based, SEIR model for equine influenza disease dynamics with an observed Ontario, Canada equine contact network structure to quantify the potential magnitude of equine influenza outbreaks in Ontario competition horses under different condit...
Khan A, Jose-Cunilleras E, Hyde E, Olajide E, Polo MC, Goehring LS.Equid alphaherpesvirus 1 (EHV-1) remains a major concern for the equine industry, with recent outbreaks at international equestrian events highlighting the need for improved surveillance during competitions. Objective: To investigate EHV-1 and -4 presence in shared airspaces and environmental surfaces in direct contact with horses at international equestrian events; and to evaluate air sampling as a surveillance alternative to individual horse testing. Methods: Cross-sectional field study. Methods: Air (37) and surface samples (205) were collected from temporary stabling facilities across six ...
Vitale V, Bindi F, Bertelloni F, Sala G, Cingottini D, Bonelli F, Sgorbini M.Bacterial contamination of intravenous catheters in hospitalized horses may pose risks for both patient care and public health due to potential antimicrobial resistance and zoonotic transmission. This prospective clinical study aimed to evaluate the incidence of catheter contamination in equine patients admitted to a Veterinary Teaching Hospital between 2020 and 2021. All horses requiring intravenous catheterization were included, and data were collected on patient signalment, clinical status, duration of catheterization, treatments, and outcomes. Two catheter types were used: 5 cm polytetrafl...
Chinyere CN, Ajaebili AC, Peter-Ajuzie IK, Galadima HB, Daodu OB, Fatola OI, Okolo CC, Alaba BA, Akinniyi OO, Omoniwa DO, Edeh ER, Olorunfemi AB....African horse sickness (AHS) is a severe, infectious arthropod-borne disease of equids caused by the AHS virus (AHSV). It is endemic in Sub-Saharan Africa, and several sporadic outbreaks of the disease have been reported in Nigeria in the past 5 decades. Following a recent outbreak of the disease in Lagos State, this study was conducted to investigate the prevalence of (AHSV) antibodies in apparently healthy horses and some selected wildlife sampled in four geographical regions of Nigeria. Using a competitive enzyme-linked immunosorbent assay, 575 serum samples collected from horses in five ...
Graham AE, Colgate VA, Floyd EF.Geographical specific data is required to guide empirical antimicrobial selection in equine neonates. Objective: Evaluate antibiograms and survival in foals from a United Kingdom (UK)-based hospital to guide antimicrobial selection. Methods: Blood and synovial fluid samples from 208 foals ≤ 30 days old admitted to Rossdales Equine Hospital from 2018 to 2023. Methods: Retrospective cohort study. Antimicrobial susceptibility was assessed by disc diffusion method. Bacterial culture and susceptibility and foal survival were recorded. The effects of the presence of positive culture or multi...
Kuzmina TA, Königová A, Burcáková L, Syrota Y, Babják M, Várady M.Strongylids and parascarids are the most widespread equine parasites worldwide; however, up-to-date data from Slovakia remain limited. This work bridges that gap by examining the prevalence and level of gastrointestinal helminth infections in Slovak horses. In the study, 392 fecal samples from horses on 24 farms were analyzed using the McMaster method with a sensitivity of 50 eggs per gram (EPG) for detecting nematode eggs and a double-centrifugation/combined sedimentation-flotation protocol for detecting Anoplocephala spp. eggs. Information on the age and breed of horses, management condition...
Schwarzer A, Ziegler U, Fertey J, Kreuz M, Vahlenkamp TW, Groschup MH, Ulbert S.West Nile virus (WNV), Usutu virus (USUV) and tick-borne encephalitis virus (TBEV) are worldwide endemic zoonotic orthoflaviviruses, often co-circulating in the same areas. Serological studies in animals, mostly birds and horses, are important means to monitor the spread of these viruses and the infection risks for humans. However, cross-reactive antibodies to these structurally similar flaviviruses frequently impact serological differentiation in enzyme-linked immunosorbent assays (ELISAs), hence time-consuming virus neutralization tests (VNTs) have to be employed in laboratories with high bi...
Ganbaatar O, Ganzorig S, Tseren-Ochir EO, Suzuki Y, Takai S.In 2024, 90 soil samples and 11 fecal samples were collected from nine Mongolian provinces. Using NANAT selective agar, R. equi was successfully isolated from 23 soil samples (25.6%) across five provinces and from three fecal samples (27.3%) collected in two provinces. A total of 122 isolates were identified as R. equi via choE-targeted polymerase chain reaction (PCR) and subsequently screened for virulence-associated genes (vapA, vapB, and vapN) by PCR. Of these, 17 isolates tested positive for the vapA gene, while the remaining 105 isolates were negative for both vapB and vapN. Plasmid prof...
O'Sullivan JD, Allworth AM, Paterson DL, Snow TM, Boots R, Gleeson LJ, Gould AR, Hyatt AD, Bradfield J.In September, 1994, an outbreak of severe respiratory disease affected 18 horses, their trainer, and a stablehand in Queensland, Australia. Fourteen horses and one human being died. A novel virus was isolated from those affected and named equine morbillivirus (EMV). We report a case of encephalitis caused by this virus. Results: A 35-year-old man from Queensland had a brief aseptic meningitic illness in August, 1994, shortly after caring for two horses that died from EMV infection and then assisting at their necropsies. He then suffered severe encephalitis 13 months later, characterised by unc...
Williamson MM, Hooper PT, Selleck PW, Gleeson LJ, Daniels PW, Westbury HA, Murray PK.To determine the infectivity and transmissibility of Hendra virus (HeV). Methods: A disease transmission study using fruit bats, horses and cats. Methods: Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second experiment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experiment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horse...
van Dinten LC, den Boon JA, Wassenaar AL, Spaan WJ, Snijder EJ.Equine arteritis virus (EAV) is a positive-strand RNA virus that uses a discontinuous transcription mechanism to generate a nested set of six subgenomic mRNAs from which its structural genes are expressed. A stable bacterial plasmid (pEAV030) containing a full-length cDNA copy of the 12.7-kb EAV genome was constructed. After removal of a single point mutation in the replicase gene, RNA transcripts generated in vitro from pEAV030 were shown to be infectious upon electroporation into BHK-21 cells. A genetic marker mutation was introduced at the cDNA level and recovered from the genome of the pro...
Sangioni LA, Horta MC, Vianna MC, Gennari SM, Soares RM, Galvão MA, Schumaker TT, Ferreira F, Vidotto O, Labruna MB.We compared the rickettsial infection status of Amblyomma cajennense ticks, humans, dogs, and horses in both Brazilian spotted fever (BSF)-endemic and -nonendemic areas in the state of Sao Paulo, Brazil. Most of the horses and few dogs from BSF-endemic areas had serologic titers against Rickettsia rickettsii antigens. In contrast, no dogs or horses from BSF-nonendemic areas had serologic titers against R. rickettsii antigens, although they were continually exposed to A. cajennense ticks. All human serum samples and ticks from both areas were negative by serologic assay and polymerase chain rea...
Wise LN, Kappmeyer LS, Mealey RH, Knowles DP.Equine piroplasmosis is caused by one of 2 erythrocytic parasites Babesia caballi or Theileria equi. Although the genus of the latter remains controversial, the most recent designation, Theileria, is utilized in this review. Shared pathogenesis includes tick-borne transmission and erythrolysis leading to anemia as the primary clinical outcome. Although both parasites are able to persist indefinitely in their equid hosts, thus far, only B. caballi transmits across tick generations. Pathogenesis further diverges after transmission to equids in that B. caballi immediately infects erythrocytes, wh...
Mansfield KL, Hernández-Triana LM, Banyard AC, Fooks AR, Johnson N.Japanese encephalitis virus (JEV) is a significant cause of neurological disease in humans throughout Asia causing an estimated 70,000 human cases each year with approximately 10,000 fatalities. The virus contains a positive sense RNA genome within a host-derived membrane and is classified within the family Flaviviridae. Like many flaviviruses, it is transmitted by mosquitoes, particularly those of the genus Culex in a natural cycle involving birds and some livestock species. Spill-over into domestic animals results in a spectrum of disease ranging from asymptomatic infection in some species t...
Kinney RM, Johnson BJ, Welch JB, Tsuchiya KR, Trent DW.Nucleotide sequence analysis of cDNA clones covering the entire genomes of Trinidad donkey (TRD) Venezuelan equine encephalitis (VEE) virus and its vaccine derivative, TC-83, has revealed 11 differences between the genomes of TC-83 virus and its parent. One nucleotide substitution and a single nucleotide deletion occurred in the 5'- and 3'-noncoding regions of the TC-83 genome, respectively. The deduced amino acid sequences of the nonstructural polypeptides of the two viruses differed only in a conservative Ser(TRD) to Thr(TC-83) substitution in nonstructural protein (nsP) three at amino acid ...
Whitlock GC, Estes DM, Torres AG.Burkholderia mallei, the etiologic agent of the disease known as glanders, is primarily a disease affecting horses and is transmitted to humans by direct contact with infected animals. The use of B. mallei as a biological weapon has been reported and currently, there is no vaccine available for either humans or animals. Despite the history and highly infective nature of B. mallei, as well as its potential use as a bio-weapon, B. mallei research to understand the pathogenesis and the host responses to infection remains limited. Therefore, this minireview will focus on current efforts to elucida...
de Vries AA, Chirnside ED, Horzinek MC, Rottier PJ.We have recently shown that the genome of equine arteritis virus (EAV) contains seven open reading frames (ORFs). We now present data on the structural proteins of EAV and the assignment of their respective genes. Virions are composed of a 14-kDa nucleocapsid protein (N) and three membrane proteins designated M, GS, and GL. M is an unglycosylated protein of 16 kDa, and GS and GL are N-glycosylated proteins of 25 and 30 to 42 kDa, respectively. The broad size distribution of GL results from heterogeneous N-acetyllactosamine addition since it is susceptible to digestion by endo-beta-galactosidas...
Murgue B, Murri S, Zientara S, Durand B, Durand JP, Zeller H.On September 6, 2000, two cases of equine encephalitis caused by West Nile (WN) virus were reported in southern France (Hérault Province), near Camargue National Park, where a WN outbreak occurred in 1962. Through November 30, 76 cases were laboratory confirmed among 131 equines with neurologic disorders. The last confirmed case was on November 3, 2000. All but three cases were located in a region nicknamed "la petite Camargue," which has several large marshes, numerous colonies of migratory and resident birds, and large mosquito populations. No human case has been confirmed among clinically ...
Seyedmousavi S, Guillot J, Arné P, de Hoog GS, Mouton JW, Melchers WJ, Verweij PE.The importance of aspergillosis in humans and various animal species has increased over the last decades. Aspergillus species are found worldwide in humans and in almost all domestic animals and birds as well as in many wild species, causing a wide range of diseases from localized infections to fatal disseminated diseases, as well as allergic responses to inhaled conidia. Some prevalent forms of animal aspergillosis are invasive fatal infections in sea fan corals, stonebrood mummification in honey bees, pulmonary and air sac infection in birds, mycotic abortion and mammary gland infections in ...
Viana D, Blanco J, Tormo-Más MA, Selva L, Guinane CM, Baselga R, Corpa J, Lasa I, Novick RP, Fitzgerald JR, Penadés JR.Staphylococci adapt specifically to various animal hosts by genetically determined mechanisms that are not well understood. One such adaptation involves the ability to coagulate host plasma, by which strains isolated from ruminants or horses can be differentiated from closely related human strains. Here, we report first that this differential coagulation activity is due to animal-specific alleles of the von Willebrand factor-binding protein (vWbp) gene, vwb, and second that these vwb alleles are carried by highly mobile pathogenicity islands, SaPIs. Although all Staphylococcus aureus possess c...
Habarugira G, Suen WW, Hobson-Peters J, Hall RA, Bielefeldt-Ohmann H.West Nile virus (WNV) is an important zoonotic flavivirus responsible for mild fever to severe, lethal neuroinvasive disease in humans, horses, birds, and other wildlife species. Since its discovery, WNV has caused multiple human and animal disease outbreaks in all continents, except Antarctica. Infections are associated with economic losses, mainly due to the cost of treatment of infected patients, control programmes, and loss of animals and animal products. The pathogenesis of WNV has been extensively investigated in natural hosts as well as in several animal models, including rodents, lagom...
Wang LF, Yu M, Hansson E, Pritchard LI, Shiell B, Michalski WP, Eaton BT.An outbreak of acute respiratory disease in Hendra, a suburb of Brisbane, Australia, in September 1994 resulted in the deaths of 14 racing horses and a horse trainer. The causative agent was a new member of the family Paramyxoviridae. The virus was originally called Equine morbillivirus but was renamed Hendra virus (HeV) when molecular characterization highlighted differences between it and members of the genus Morbillivirus. Less than 5 years later, the closely related Nipah virus (NiV) emerged in Malaysia, spread rapidly through the pig population, and caused the deaths of over 100 people. W...
Barlough JE, Madigan JE, DeRock E, Bigornia L.A nested polymerase chain reaction for detecting Ehrlichia equi in horses and ticks (Ixodes pacificus) was developed. A major second-round PCR product of 928 bp could be readily visualized in ethidium bromide-stained agarose minigels. An internal probe was used to verify the identity of the amplified product by non-radioactive (digoxigenin-based) Southern blotting; additional confirmation was provided by DNA sequence analysis. A dilution study testing the sensitivity of the PCR indicated that DNA derived from 3 infected neutrophils was sufficient to generate a PCR signal. The specificity of t...
Nugent J, Birch-Machin I, Smith KC, Mumford JA, Swann Z, Newton JR, Bowden RJ, Allen GP, Davis-Poynter N.Equid herpesvirus 1 (EHV-1) can cause a wide spectrum of diseases ranging from inapparent respiratory infection to the induction of abortion and, in extreme cases, neurological disease resulting in paralysis and ultimately death. It has been suggested that distinct strains of EHV-1 that differ in pathogenic capacity circulate in the field. In order to investigate this hypothesis, it was necessary to identify genetic markers that allow subgroups of related strains to be identified. We have determined all of the genetic differences between a neuropathogenic strain (Ab4) and a nonneuropathogenic ...
van Kasteren PB, Bailey-Elkin BA, James TW, Ninaber DK, Beugeling C, Khajehpour M, Snijder EJ, Mark BL, Kikkert M.Protein ubiquitination regulates important innate immune responses. The discovery of viruses encoding deubiquitinating enzymes (DUBs) suggests they remove ubiquitin to evade ubiquitin-dependent antiviral responses; however, this has never been conclusively demonstrated in virus-infected cells. Arteriviruses are economically important positive-stranded RNA viruses that encode an ovarian tumor (OTU) domain DUB known as papain-like protease 2 (PLP2). This enzyme is essential for arterivirus replication by cleaving a site within the viral replicase polyproteins and also removes ubiquitin from cell...
Weese JS.Methicillin-resistant Staphylococcus aureus (MRSA) is a critically important human pathogen that is also an emerging concern in veterinary medicine and animal agriculture. It is present in a wide range of animal species, including dogs, cats, rabbits, horses, cattle, pigs, poultry, and exotic species, both as a cause of infection and in healthy carriers. Identification of MRSA in various species and in food has led to concerns about the roles of animals, both pets and livestock, in the epidemiology of MRSA infection and colonization in humans. There is evidence of the role of food animals in h...
Murray KO, Mertens E, Despres P.Zoonotic West Nile virus (WNV) circulates in natural transmission cycles involving certain mosquitoes and birds, horses, humans, and a range of other vertebrates are incidental hosts. Clinical infections in humans can range in severity from uncomplicated WNV fever to fatal meningoencephalitis. Since its introduction to the Western Hemisphere in 1999, WNV had spread across North America, Central and South America and the Caribbean, although the vast majority of severe human cases have occurred in the United States of America (USA) and Canada. By 2002-2003, the WNV outbreaks have involved thousa...
Bunning ML, Bowen RA, Cropp CB, Sullivan KG, Davis BS, Komar N, Godsey MS, Baker D, Hettler DL, Holmes DA, Biggerstaff BJ, Mitchell CJ.A total of 12 horses of different breeds and ages were infected with West Nile virus (WNV) via the bites of infected Aedes albopictus mosquitoes. Half the horses were infected with a viral isolate from the brain of a horse (BC787), and half were infected with an isolate from crow brain (NY99-6625); both were NY99 isolates. Postinfection, uninfected female Ae. albopictus fed on eight of the infected horses. In the first trial, Nt antibody titers reached >1:320, 1:20, 1:160, and 1:80 for horses 1 to 4, respectively. In the second trial, the seven horses with subclinical infections developed Nt a...
Komar N, Clark GG.West Nile virus (Flavivirus: Flaviviridae; WNV) has spread rapidly throughout the Caribbean Basin since its initial detection there in 2001. This report summarizes our current knowledge of WNV transmission in tropical America. Methods: We reviewed the published literature and consulted with key public health officials to obtain unpublished data. Results: West Nile virus infections first appeared in human residents of the Cayman Islands and the Florida Keys in 2001, and in apparently healthy Jamaican birds sampled early in 2002. Serologic evidence of WNV infection in 2002 was detected in horses...
Timoney JF.Streptococci pathogenic for the horse include S. equi (S. equi subsp. equi), S. zooepidemicus (S. equi subsp. zooepidemicus), S. dysgalactiae subsp. equisimilis and S. pneumoniae capsule Type III. S. equi is a clonal descendent or biovar of an ancestral S. zooepidemicus strain with which it shares greater than 98% DNA homology and therefore expresses many of the same proteins and virulence factors. Rapid progress has been made in identification of virulence factors and proteins uniquely expressed by S. equi. Most of these are expressed either on the bacterial surface or are secreted. Notable e...
Cai W, Ryan U, Xiao L, Feng Y.Giardia duodenalis is a common intestinal parasite in various hosts, with the disease giardiasis being a zoonosis. The use of molecular typing tools has improved our understanding of the distribution and zoonotic potential of G. duodenalis genotypes in different animals. The present review summarizes recent data on the distribution of G. duodenalis genotypes in humans and animals in different areas. The dominance of G. duodenalis assemblages A and B in humans and common occurrence of host-adapted assemblages in most domesticated animals suggests that zoonotic giardiasis is probably less common...
Guy JS, Breslin JJ, Breuhaus B, Vivrette S, Smith LG.A coronavirus was isolated from feces of a diarrheic foal and serially propagated in human rectal adenocarcinoma (HRT-18) cells. Antigenic and genomic characterizations of the virus (isolate NC99) were based on serological comparison with other avian and mammalian coronaviruses and sequence analysis of the nucleocapsid (N) protein gene. Indirect fluorescent-antibody assay procedures and virus neutralization assays demonstrated a close antigenic relationship with bovine coronavirus (BCV) and porcine hemagglutinating encephalomyelitis virus (mammalian group 2 coronaviruses). Using previously des...
Snijder EJ, Wassenaar AL, Spaan WJ.To study the proteolytic processing of the equine arteritis virus (EAV) replicase open reading frame 1a (ORF1a) protein, specific antisera were raised in rabbits, with six synthetic peptides and a bacterial fusion protein as antigens. The processing of the EAV ORF1a product in infected cells was analyzed with Western blot (immunoblot) and immunoprecipitation techniques. Additional information was obtained from transient expression of ORF1a cDNA constructs. The 187-kDa ORF1a protein was found to be subject to at least five proteolytic cleavages. The processing scheme, which covers the entire OR...
Rogers GN, Pritchett TJ, Lane JL, Paulson JC.Human and animal (avian and equine) influenza A virus isolates of the H3 serotype exhibit marked differences in their ability to bind specific sialyloligosaccharide sequences that serve as cell surface receptor determinants (G. Rogers and J. Paulson, 1983, Virology 127, 361-373). Whereas human isolates of this subtype strongly agglutinate enzymatically modified human erythrocytes containing the terminal SA alpha 2,6Gal sequence, avian and equine isolates preferentially agglutinate erythrocytes bearing the SA alpha 2, 3Gal sequence. As shown in this report, a glycoprotein found in horse serum, ...
Dick LK, Bernhard AE, Brodeur TJ, Santo Domingo JW, Simpson JM, Walters SP, Field KG.The purpose of this study was to examine host distribution patterns among fecal bacteria in the order Bacteroidales, with the goal of using endemic sequences as markers for fecal source identification in aquatic environments. We analyzed Bacteroidales 16S rRNA gene sequences from the feces of eight hosts: human, bovine, pig, horse, dog, cat, gull, and elk. Recovered sequences did not match database sequences, indicating high levels of uncultivated diversity. The analysis revealed both endemic and cosmopolitan distributions among the eight hosts. Ruminant, pig, and horse sequences tended to for...
Dutkiewicz J, Mackiewicz B, Kinga Lemieszek M, Golec M, Milanowski J.Pantoea agglomerans, a bacterium associated with plants, is not an obligate infectious agent in humans. However, it could be a cause of opportunistic human infections, mostly by wound infection with plant material, or as a hospital-acquired infection, mostly in immunocompromised individuals. Wound infection with P. agglomerans usually follow piercing or laceration of skin with a plant thorn, wooden splinter or other plant material and subsequent inoculation of the plant-residing bacteria, mostly during performing of agricultural occupations and gardening, or children playing. Septic arthritis ...
Garmashova N, Atasheva S, Kang W, Weaver SC, Frolova E, Frolov I.The encephalitogenic New World alphaviruses, including Venezuelan (VEEV), eastern (EEEV), and western equine encephalitis viruses, constitute a continuing public health threat in the United States. They circulate in Central, South, and North America and have the ability to cause fatal disease in humans and in horses and other domestic animals. We recently demonstrated that these viruses have developed the ability to interfere with cellular transcription and use it as a means of downregulating a cellular antiviral response. The results of the present study suggest that the N-terminal, approxima...
Baldacchino F, Desquesnes M, Mihok S, Foil LD, Duvallet G, Jittapalapong S.Tabanids are nuisance pests for people and livestock because of their painful and irritating bite, persistent biting behavior, and blood ingestion. About 4400 tabanid species have been described; they are seasonally present in all kinds of landscapes, latitudes, and altitudes. High populations have a significant economic impact on outdoor activities, tourism, and livestock production. Tabanids are also vectors of animal disease agents, including viruses, bacteria and parasites. However, tabanids have received little attention in comparison with other hematophagous Diptera. Here, we highlight t...
