Difference between revisions of "Equine Influenza"
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| − | {{ | + | {{unfinished}} |
| − | |||
| − | == | + | {{toplink |
| + | |linkpage =Viruses | ||
| + | |linktext =VIRUSES | ||
| + | |sublink1=Orthomyxoviridae | ||
| + | |subtext1=INFLUENZA | ||
| + | |pagetype =Bugs | ||
| + | }} | ||
| + | <br> | ||
| − | + | ===Subtypes=== | |
| − | + | *Two subtypes of Equine Influenza have been described: | |
| − | *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) | |
| − | + | ===Pathogenesis=== | |
| − | 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 |
| − | + | *This manifests a bronchiolitis and serous exudation | |
| − | + | *1-3 day incubation period | |
| − | + | *Excretion of the virus in nasal secretions peaks at 3-4 days and finishes by 10 days | |
| − | + | *Clinical signs: | |
| − | + | **Harsh dry cough | |
| − | + | **Pyrexia (103-106F) | |
| − | + | **Depression | |
| − | + | **Loss of appetite | |
| − | + | **Enlarged submandibular lymph nodes | |
| − | == Diagnosis == | + | *Secondary bacterial infection can follow defective muco-ciliary transport, eg ''Streptococcus zooepidemicus'' |
| − | + | *For more, see [[Respiratory Viral Infections - Pathology#Equine influenza|here]] | |
| − | Virus isolation | + | ===Diagnosis=== |
| − | + | *Virus isolation: Deep nasal swabs (12 inches) deposited into 10ml of transport medium and transported at 4C | |
| − | == | + | *Antigen detection via ELISA: tests for type A nucleoprotein |
| − | + | *Serology provides a retrospective diagnosis by '''Haemagglutination Inhibition (HI)''': | |
| − | Isolate coughing horses | + | **Acute and Convalescent (2 weeks post-acute) samples are tested from the same animal |
| − | + | **4-fold increase of HI must be shown to confirm diagnosis | |
| − | + | ===Control=== | |
| − | + | *Isolate coughing horses to minimize spread | |
| − | + | *Vaccination: | |
| − | + | **All vaccines include H7 and varieties of the current circulating strains of H3 | |
| − | + | **'''Inactivated''' egg-grown vaccine is produced with alhydrogel as an adjuvant | |
| − | + | **'''Live''' vaccines using purified haemagglutinin do not require adjuvants | |
| − | + | **UK Jockey Club rules regarding timing: | |
| − | + | ***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 to maintain immunity, and in the event a year is missed the initial course of three jabs must be repeated | |
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Revision as of 14:46, 17 September 2009
 |
This article is still under construction. |
|
Subtypes
- Two subtypes of Equine Influenza have been described:
- H7N7 (Equine 1), which was prevalent in the UK between 1963-1977
- 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)
Pathogenesis
- Aerosol and fomite transmission infects the epithelium of the upper respiratory tract, resulting in cell necrosis
- This manifests a bronchiolitis and serous exudation
- 1-3 day incubation period
- Excretion of the virus in nasal secretions peaks at 3-4 days and finishes by 10 days
- Clinical signs:
- Harsh dry cough
- Pyrexia (103-106F)
- Depression
- Loss of appetite
- Enlarged submandibular lymph nodes
- Secondary bacterial infection can follow defective muco-ciliary transport, eg Streptococcus zooepidemicus
- For more, see here
Diagnosis
- Virus isolation: Deep nasal swabs (12 inches) deposited into 10ml of transport medium and transported at 4C
- Antigen detection via ELISA: tests for type A nucleoprotein
- Serology provides a retrospective diagnosis by Haemagglutination Inhibition (HI):
- Acute and Convalescent (2 weeks post-acute) samples are tested from the same animal
- 4-fold increase of HI must be shown to confirm diagnosis
Control
- Isolate coughing horses to minimize spread
- Vaccination:
- All vaccines include H7 and varieties of the current circulating strains of H3
- Inactivated egg-grown vaccine is produced with alhydrogel as an adjuvant
- Live vaccines using purified haemagglutinin do not require adjuvants
- UK Jockey Club rules regarding timing:
- 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 to maintain immunity, and in the event a year is missed the initial course of three jabs must be repeated