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− | {{unfinished}} | + | {{OpenPagesTop}} |
| + | Also known as: '''''Equine Flu''''' |
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− | {{toplink
| + | == Introduction == |
− | |linkpage =Viruses
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− | |linktext =VIRUSES
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− | |sublink1=Orthomyxoviridae
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− | |subtext1=INFLUENZA
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− | |pagetype =Bugs
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− | }}
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− | <br>
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− | ===Subtypes===
| + | There are two subtypes of Equine Influenza described in the world today. These are: |
− | *Two subtypes of Equine Influenza have been described:
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− | **H7N7 (Equine 1), which was prevalent in the UK between 1963-1977
| + | *H7N7 (Equine 1), which was prevalent in the UK between 1963-1977 |
− | **H3N8 (Equine 2), or the European strains, have been circulating since 1965
| + | *H3N8 (Equine 2), or the European strains, have been circulating since 1965. |
− | *Some drift has occurred, causing outbreaks of North-American-like strains of H3N8 in 1998 (EU) and 2003 (South America)
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− | ===Pathogenesis===
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− | *Aerosol and fomite transmission infects the epithelium of the upper respiratory tract, resulting in cell necrosis
| + | Aerosol and fomite transmission infects the epithelium of the upper respiratory tract, resulting in cell necrosis, which then manifests as [[Bronchiolitis|bronchiolitis]] and serous exudation. There is a 1 - 3 day incubation period, with excretion of the virus in nasal secretions peaking at 3-4 days and finishing by 10 days. |
− | *This manifests a bronchiolitis and serous exudation
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− | *1-3 day incubation period
| + | The disease usually occurs as an outbreak with many horses on the yard becoming infected. The most common age to encounter the disease is around 2 years and stress is a predisposing factor, so this disease is most commonly seen in racing yards. |
− | *Excretion of the virus in nasal secretions peaks at 3-4 days and finishes by 10 days
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− | *Clinical signs:
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− | **Harsh dry cough
| + | == Clinical Signs == |
− | **Pyrexia (103-106F)
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− | **Depression
| + | There will be a harsh dry cough with pyrexia (39-41<sup>0></sup>C / 103-106F). The horse will appear generally depressed with a loss of appetite and decreased activity. Submandibular lymph nodes will be enlarged on physical examination. Secondary bacterial infection can follow defective muco-ciliary transport, eg ''[[Streptococcus zooepidemicus]]''. |
− | **Loss of appetite
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− | **Enlarged submandibular lymph nodes
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− | *Secondary bacterial infection can follow defective muco-ciliary transport, eg ''Streptococcus zooepidemicus''
| + | == Diagnosis == |
− | *For more, see [[Respiratory Viral Infections - Pathology#Equine influenza|here]]
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− | ===Diagnosis===
| + | Virus isolation by deep nasal swabs (12 inches) deposited into 10ml of transport medium and transported at 4<sup>0</sup>C. An antigen detection [[ELISA testing|ELISA]] should then be performed. Blood samples for serology should also be taken on day one of the disease (acute phase) and then two weeks later (convalescent stage). A 4-fold increase of haemaglutination inhibition (HI) must be shown to confirm diagnosis. |
− | *Virus isolation: Deep nasal swabs (12 inches) deposited into 10ml of transport medium and transported at 4C
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− | *Antigen detection via ELISA: tests for type A nucleoprotein
| + | == Treatment and Control == |
− | *Serology provides a retrospective diagnosis by '''Haemagglutination Inhibition (HI)''':
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− | **Acute and Convalescent (2 weeks post-acute) samples are tested from the same animal
| + | Isolate coughing horses at once to minimize spread and perform thorough disinfection of all shared tack, stables, vehicles, boot and feed buckets. Treat any secondary bacterial infections with suitable antibiotics. |
− | **4-fold increase of HI must be shown to confirm diagnosis
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− | ===Control=== | + | Control for this disease is by [[Vaccines|vaccination]]. All vaccines include H7 and varieties of the current circulating strains of H3. There are strict rules from the Jockey Club regarding timing of vaccinations: Horses must be certified as completing a vaccination course of 3 injections at least 8 days prior to racing. The course consists of a primary inoculation followed by a second within '''21-92 '''days and a third after a further '''150-215 '''days. Boosters are given annually on or before the anniversary of the third injection to maintain immunity, and in the event a year is missed, the initial course of three injections must be repeated. |
− | *Isolate coughing horses to minimize spread
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− | *Vaccination:
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− | **All vaccines include H7 and varieties of the current circulating strains of H3
| + | == References == |
− | **'''Inactivated''' egg-grown vaccine is produced with alhydrogel as an adjuvant
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− | **'''Live''' vaccines using purified haemagglutinin do not require adjuvants
| + | Brown, C.M, Bertone, J.J. (2002) The 5-Minute Veterinary Consult- Equine', Lippincott, Williams & Wilkins |
− | **UK Jockey Club rules regarding timing:
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− | ***Horses must be certified as completing a vaccination course of 3 injections at least 8 days prior to racing
| + | Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students University of Liverpool |
− | ***The course consists of a primary inoculation followed by a second within 21-92 days and a third after a further 150-215 days
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− | ***Boosters are given annually to maintain immunity, and in the event a year is missed the initial course of three jabs must be repeated
| + | Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders. |
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| + | {{review}} |
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| + | {{OpenPages}} |
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| + | {{Learning |Vetstream = [https://www.vetstream.com/equis/Content/Disease/dis00586.asp Equine Influenza]}} |
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| + | [[Category:Orthomyxoviridae]] [[Category:Horse_Viruses]] [[Category:Expert_Review - Horse]] [[Category:Respiratory_Viral_Infections]] [[Category:Respiratory_Diseases_-_Horse]] |