Classical swine fever
Encyclopedia
Classical swine fever or hog cholera (also sometimes called pig plague based on the German word Schweinepest) is a highly contagious disease of pig
s and wild boar.
, skin lesions, convulsions and usually (particularly in young animals) death
within 15 days.
The signs are indistinguishable from those of African swine fever.
, Central
and South America
, and parts of Europe
and Africa
. It was believed to have been eradicated in the United Kingdom
by 1966 (according to the Department for Environment, Food & Rural Affairs), but an outbreak occurred in East Anglia
in 2000. It was eradicated in the USA by 1978, according to the United States Department of Agriculture
.
Other regions believed to be free of CSF include Australia, Canada (1962), Ireland, New Zealand and Scandinavia.
The infectious agent responsible is a virus
CSFV (previously called hog cholera virus) of the genus Pestivirus
in the family Flaviviridae
. CSFV is closely related to the ruminant pestiviruses which cause Bovine Viral Diarrhoea (BVDV) and Border Disease (BDV).
The effect of different CSFV strains varies widely, leading to a wide range of clinical signs. Highly virulent strains correlate with acute, obvious disease and high mortality, including neurological signs and hemorrhages within the skin.
Less virulent strains can give rise to subacute or chronic infections that may escape detection, while still causing abortions and stillbirths. In these cases herds in high-risk areas are usually serologically tested on a thorough statistical basis.
Infected piglets born to infected but subclinical sows help maintain the disease within a population. Other signs can include lethargy, fever, immunosuppression, chronic diarrhoea and secondary respiratory infections. The incubation period of CSF ranges from 2 to 14 days, but clinical signs may not be apparent until after 2 to 3 weeks. Preventive State Regulations usually assume 21 days as the outside limit of the incubation period. Animals with an acute infection can survive 2 to 3 months before their eventual death.
Eradicating CSF is problematic. Current programmes revolve around rapid detection, diagnosis and slaughter. This may possibly be followed by emergency vaccination (ATCvet codes: for the inactivated viral vaccine, for the live vaccine). Vaccination is only used where the virus is widespread in the domestic pig population and/or in wild or feral pigs. In the latter case a slaughter policy alone is usually impracticable. Possible sources for maintaining and introducing infection include the wide transport of pigs and pork products, as well as endemic CSF within wild boar and feral pig populations.
Pig
A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
s and wild boar.
Clinical Signs
Swine fever causes feverFever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, skin lesions, convulsions and usually (particularly in young animals) death
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
within 15 days.
The signs are indistinguishable from those of African swine fever.
Epidemology
The disease is endemic in much of AsiaAsia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, and parts of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. It was believed to have been eradicated in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
by 1966 (according to the Department for Environment, Food & Rural Affairs), but an outbreak occurred in East Anglia
East Anglia
East Anglia is a traditional name for a region of eastern England, named after an ancient Anglo-Saxon kingdom, the Kingdom of the East Angles. The Angles took their name from their homeland Angeln, in northern Germany. East Anglia initially consisted of Norfolk and Suffolk, but upon the marriage of...
in 2000. It was eradicated in the USA by 1978, according to the United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
.
Other regions believed to be free of CSF include Australia, Canada (1962), Ireland, New Zealand and Scandinavia.
Virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
CSFV (previously called hog cholera virus) of the genus Pestivirus
Pestivirus
Pestivirus is a genus of viruses that belong to the family Flaviviridae. Viruses in the genus Pestivirus infect mammals, including members of the family Bovidae and the family Suidae .-Virus Genetics and Structure:Pestivirus viruses have a single strand of...
in the family Flaviviridae
Flaviviridae
The Flaviviridae are a family of viruses that are primarily spread through arthropod vectors . The family gets its name from Yellow Fever virus, a type virus of Flaviviridae; flavus means yellow in Latin...
. CSFV is closely related to the ruminant pestiviruses which cause Bovine Viral Diarrhoea (BVDV) and Border Disease (BDV).
The effect of different CSFV strains varies widely, leading to a wide range of clinical signs. Highly virulent strains correlate with acute, obvious disease and high mortality, including neurological signs and hemorrhages within the skin.
Less virulent strains can give rise to subacute or chronic infections that may escape detection, while still causing abortions and stillbirths. In these cases herds in high-risk areas are usually serologically tested on a thorough statistical basis.
Infected piglets born to infected but subclinical sows help maintain the disease within a population. Other signs can include lethargy, fever, immunosuppression, chronic diarrhoea and secondary respiratory infections. The incubation period of CSF ranges from 2 to 14 days, but clinical signs may not be apparent until after 2 to 3 weeks. Preventive State Regulations usually assume 21 days as the outside limit of the incubation period. Animals with an acute infection can survive 2 to 3 months before their eventual death.
Eradicating CSF is problematic. Current programmes revolve around rapid detection, diagnosis and slaughter. This may possibly be followed by emergency vaccination (ATCvet codes: for the inactivated viral vaccine, for the live vaccine). Vaccination is only used where the virus is widespread in the domestic pig population and/or in wild or feral pigs. In the latter case a slaughter policy alone is usually impracticable. Possible sources for maintaining and introducing infection include the wide transport of pigs and pork products, as well as endemic CSF within wild boar and feral pig populations.
Diagnosis
- Direct immunofluorescenceImmunofluorescenceImmunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on biological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows...
- detection of virus in histological edges - Indirect immunofluorescence - detection of specific antibodies from sera
- ELISAELISAEnzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...
- Histology of the brain shows vasculo-endothelial proliferation and peri-vascular cuffing (cuffing is highly suggestive when accompanied by other signs but is not pathonomonic for the disease).
External links
- CSF page of Pig Disease Information Centre (UK)
- CSF page of World Organisation for Animal Health
- European Commission Animal Health & Welfare on CSF
- The Institute of Virology (Hannover) Reference Laboratory for CSF
- Department for Environment Food and Rurual Affairs (UK) on CSF
- International Veterinary Training talks about CSF
- The USDA's APHIS on CSF
- The Pig Site talks about swine fevers
- Vetgate CSF notes & resources
- Animal viruses