African Horse Sickness
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This article is still under construction. |
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Antigenicity
- 9 serotypes
Hosts
- Clinical: horses, mules, donkeys
- Subclinical: african donkeys, zebras
Pathogenesis
- Virus oscillates between horses and midges
- Replicates in the salivary glands of biting midges, and occurs where they breed
- Pantropic virus: infects endothelium and myocardium
- Peracute: causes sudden death with pyrexia before the onset of clinical signs
- Two forms:
- Acute cardac-pneumonic form:
- Interlobular pulmonary oedema
- Pericarditis
- Hemorrhage and oedema of the viscera
- Death within 5 days
- Subacute cardiac form:
- Milder clinical signs but still a high mortality rate
- Acute cardac-pneumonic form:
Diagnosis
- Clinical signs
- Differential: Equine Adinovirus
- EAV causes oedema in the legs, which AHS does NOT
- Suckling mouse inoculation
- Virus serotype identification
- Serology
- RT-PCR will be used in future outbreaks
Control
Control measures are largely preventative:
- Slaughter or immediate isolation of sick animals
- Mandatory and immediate vaccination with appropriate serotype
- Restricted movement of susceptible animals
- Protection zones and Surveillance zones set in place around outbreaks
- Control of vector: ectoparasiticides, etc.
Current Relevance
- Once only found in Africa, but since 1987 has recurred in Spain and Portugal
- Not present currently in the UK but global warming may expand midge breeding grounds