Equis ISSN 2398-2977

Coronavirus

Contributor(s): Nicola Pusterla, Rachael Conwell

Introduction

Classification

Taxonomy

  • Order: Nidovirales.
  • Family: Coronaviridae.
  • Genus: Betacoronavirus.
  • Group affiliation: Group 2a.
  • Species: coronavirus.

Etymology

  • Corona refers to the peplomers embedded in the envelope; these peplomers give the virus its crown-like morphology.

Active Forms

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Clinical Effects

Epidemiology

Habitat

  • Replicates in crypt epithelial cells of the small and large intestine of equids (horses and donkeys).
  • Can be detected by qPCR in clinically and asymptomatically infected equids.
  • Appears to circulate at high frequency in foals with and without signs of diarrhea.

Lifecycle

  • Persistent or chronic infection has yet not been reported.
  • ECoV is maintained in horse population through clinical and asymptomatic infected equids.

Transmission

  • Transmission occurs via the ingestion of fecal contaminated feed and/or water.
  • Respiratory infection is very unlikely to occur, due to the very low frequency of ECoV detection in nasal secretions of horse with clinical ECoV infection.

Pathological effects

  • Very short incubation period of 48-72 h following exposure to ECoV-containing feces.
  • ECoV infected equids displayed mild to moderate diffuse enteritis with villus attenuation, crypt necrosis, extravasation of neutrophils and fibrin into the small intestinal lumen and microthrombosis.
  •  Fecal shedding of ECoV under natural conditions ranges between 3-25 days.
  • Mortality has been attributed to disruption of the gastrointestinal barrier leading to septicemia Systemic inflammatory response syndrome, endotoxemia Endotoxemia: overview and/or hyperammonemia-induced encephalopathy.

Control

Control via animal

  • ECoV is highly contagious and its spread can be minimized by obeying to stringent biosecurity protocols aimed at reducing the introduction or spread of ECoV at any horse-based premise (boarding facility, show ground, veterinary hospital).
  • Due to the highly contagious nature of ECoV, any horse developing or presenting with significant fever, anorexia and lethargy with or without enteric signs (colic, diarrhea) should be strictly isolated until a diagnosis is secured.

Control via chemotherapies

  • Depending on the magnitude of the general clinical signs (lethargy, anorexia and elevated rectal temperature), infected horses will benefit from the administration of non-steroidal anti-inflammatory drugs Therapeutics: anti-inflammatory drugs in order to improve their overall wellbeing, appetite, feed and water intake. NSAIDs should be used judiciously and in light of adequate hydration status and uncompromised renal function.
  • ECoV infected horses with more severe enteric signs may benefit from enteral or parental fluid administration in order to maintain their hydration status.
  • The use of antimicrobials Therapeutics: antimicrobials should be restricted to horses with clinical or laboratory evidence of endotoxemia Endotoxemia: overview and/or septicaemia Systemic inflammatory response syndrome.

Control via environment

  • Following the laboratory confirmation of ECoV infection, proper biosecurity Biosecurity protocols, including use of foot-baths and personal protective equipment should be instituted.
  • Further adequate hygiene and cleanliness should be maintained in order to reduce environmental contamination with ECoV.  
  • Separate equipment, tack, bedding and feedstuffs should be used in the care of ECoV infected equids. The equipment should be cleaned and disinfected on a daily basis.
  • Only designated personnel should be allowed to care for sick horses.
  • If exposed, asymptomatic horses need to be exercised, such activity should be restricted to dedicated areas or performed at times when non-exposed horses are not present in the area.
  • Riders should wear protective clothing and always clean and disinfect equipment that was used with such horses.  
  • Horses returning from shows or extended traveling events should be isolated according to their particular circumstances.
  • All horse transportation vehicles should be cleaned and disinfected after their use.

Vaccination

  • The use of modified-live commercially available BCoV vaccines is routinely used in the livestock industry to prevent winter dysentery.
  • Despite the close antigenic relationship of ECoV with BCoV, the use of BCoV vaccines in horses for the prevention of ECoV infection has yet not been investigated and cannot be recommended at this time due to the lack of safety and efficacy data.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Kooijman L J, James K, Mapes S M, Theelan M J P & Pusterla N (2017) Seroprevalence and risk factors for infection with equine coronavirus in healthy horses in the USA. Vet J 220, 91-94 PubMed.
  • Kooijman L J, Mapes S M & Pusterla N (2016) Development of an equine coronavirus-specific enzyme-linked immunosorbent assay to determine serologic responses in naturally infected horses. J Vet Diag Invest 28 (4), 414-418 PubMed.
  • Pusterla N, Vin R, Leutenegger C et al (2016) Equine coronavirus: an emerging enteric virus of adult horses. Equine Vet Educ 28 (4), 2176-223 VetMedResource.
  • Fielding C L, Higgins J K, Higgins J C et al (2015) Disease associated with equine coronavirus infection and high case fatality rate. J Vet Intern Med 29 (1), 307-310 PubMed.
  • Giannitti F, Diab S, Mete A et al (2015) Necrotizing enteritis and hyperammonemic encephalopathy associated with equine coronavirus infection in equids. Vet Pathol 52 (6), 1148-1156 PubMed.
  • Nemoto M, Oue Y, Higuchi T et al (2015) Low prevalence of equine coronavirus in foals in the largest thoroughbred horse breeding region of Japan 2012-2014. Acta Vet Scandinavia 57, 53 PubMed.
  • Nemoto M, Oue Y, Murakami S, et al (2015) Complete genome analysis of equine coronavirus isolated in Japan. Arch Virol 160 (11), 2903-2906 PubMed.
  • Pusterla N, Holzenkaempfer N, Mapes S & Kass P (2015) Prevalence of equine coronavirus in nasal secretions from horses with fever and upper respiratory tract infection. Vet Rec 177 (11), 289 PubMed.
  • Miszczak F, Tesson V, Kin N et al (2014) First detection of equine coronavirus (ECoV) in Europe. Vet Microbiol 171 (1-2), 206-209 PubMed.
  • Slovis NM, Elam J, Estrada M et al (2014) Infectious agents associated with diarrhoea in neonatal foals in central Kentucky: a comprehensive molecular study. Equine Vet J 46 (3), 311-316 PubMed.
  • Pusterla N, Mapes S, Wademan C et al (2013) Emerging outbreaks associated with equine coronavirus in adult horses. Vet Microbiol 162 (1), 228-231 PubMed.
  • Oue Y, Ishihara R, Edamatsu H et al (2011) Isolation of an equine coronavirus from adult horses with pyrogenic and enteric disease and its antigenic and genomic characterization in comparison with the NC99 strain. Vet Microbiol 150 (1-2), 41-48 PubMed.
  • Zhang J, Guy J S, Snijder E J et al (2007) Genomic characterization of equine coronavirus. Virology 369 (1), 92-104 PubMed.

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