Difference between revisions of "Classical Swine Fever"
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==Description== | ==Description== | ||
| + | Classical swine fevetr is a highly contagious disease of swine, caused by a Togavirus. The disease may be actue, sub-acute, chronic or persitent and is indistinguishable both clinically and pathologically in the field from African Swine Fever. The acute form is characterised by severe depression, high fever, superficial and internal haemorrhages, and high morbidity and mortality. The chronic form is characterised by anorexia, pyrxia and depression. Transplacental infection results in persistently infected piglets which constitute a major sources of virus spread in endemic situations. | ||
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==Aetiology== | ==Aetiology== | ||
==Signalment== | ==Signalment== | ||
Revision as of 16:07, 6 August 2010
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This article is still under construction. |
Description
Classical swine fevetr is a highly contagious disease of swine, caused by a Togavirus. The disease may be actue, sub-acute, chronic or persitent and is indistinguishable both clinically and pathologically in the field from African Swine Fever. The acute form is characterised by severe depression, high fever, superficial and internal haemorrhages, and high morbidity and mortality. The chronic form is characterised by anorexia, pyrxia and depression. Transplacental infection results in persistently infected piglets which constitute a major sources of virus spread in endemic situations.
Aetiology
Signalment
Pathogenesis
Diagnosis
Clinical Signs
Laboratory Tests
Pathology
Treatment
Prognosis
Antigenicity
- Isolates vary in virulence
- Some antigenic variation
- Best defined by monoclonal antibodies, but no serotypes
Hosts
- Pigs
- Wild boar
Pathogenesis
- Virus enters oropharynx and replicates in palatine tonsil
- Viremia 2-6 days post-infection
Two types of strain:
- Low Virulence:
- Transplacental transmission causes abortion, cerebellar hypoplasia, or growth retardation
- If piglets are born, they are carriers
- High Virulence:
- Leukopenia
- Thrombocytopenia
- Generalized vasculitis
- Hemorrhage of lymph nodes, spleen, bladder, larynx, and skin
- Vasculitis in CNS causes tremors, incoordination and convulsions
Chronic disease:
- Infarction causes button ulcers over Peyer's Patches
Epidemiology
- Recovered animals are immune
- Highly contagious
- Transfer via contact, aerosol, or fomites
- Swine fever was once endemic worldwide but has now been eradicated from UK, Australia, NZ, USA, and Denmark following vaccination schemes
Diagnosis
- Immunofluorescence of tissues for virus isolation
- DD: Porcine circovirus 2, African swine fever, or bacterial septicemia
Control
- NOTIFIABLE disease
- Vaccination (live attenuated) in endemic countries:
- Parts of EU are using vaccinated bait to control spread in wild boar population
- Vaccination does not curtail spread: marker vaccine needed to distinguish virus exposure from vaccine-induced antibody
- Pestivirus invades vascular endothelium and macrophages
- Leads to infarcted lesions
- In spleen
- "Button ulcers" in colon and caecum.
- Ulcers are seen as discrete circular areas of haemorrhage and necrosis with dry, yellow centres