ShapeShapeauthorShapechevroncrossShapeShapeShapeGrouphamburgerhomeGroupmagnifyShapeShapeShaperssShape

Swine fevers: African and Classical

Background and history

Swine fever is one of the most important virus diseases of pigs. It is notifiable in most countries of the world. .

The pig is the only natural host. The virus is spread from infected or carrier pigs via discharges from the nose, mouth, urine and faeces or infected semen and it is highly contagious. The virus survives in frozen carcasses for long periods of time

Control is by slaughter or as a last resort by vaccination. African swine fever (ASF) and Classical Swine fever are caused by very similar viruses which are only distinguishable by laboratory testing.

Clinical signs

Piglets

  • Huddled.
  • Chilled.
  • Vomiting.
  • Diarrhoea.
  • Incoordination.
  • Conjunctivitis.
  • High fever.
  • Death sudden.
  • Piglet malformations.
  • Very weak piglets at birth showing trembling (congenital tremor).

Sows

  • When first introduced into the breeding herd it causes inappetence and high fevers.
  • The virus can cross the placenta to invade the foetuses.
  • Returns 18 23 days.
  • Foetal death with mummification.
  • Embryo death.
  • Dog sitting position.
  • Nervous signs
  • Abortions.
  • Increases in stillbirths.
  • Convulsions may occur with death within a few hours.
  • Sows may lose the use of their legs.
  • The disease in the acute form will have dramatic effects on reproduction through abortions and embryo and foetal deaths.

Weaners and growers

  • Pigs dejected - hang their heads.
  • Not eating.
  • Pigs chilled - huddled together.
  • Diarrhoea.
  • Eye discharge - heavy.
  • High persistent fever.
  • Nervous signs - incoordination, swaying on the legs.
  • Blue discolouration of the skin.
  • High mortality.

Call your veterinarian immediately if you have the above symptoms.

Diagnosis

ASF and CSF are fast-spreading diseases with high mortality. There are characteristic post-mortem changes with haemorrhagic lymph nodes, dead patches in the spleen, multiple small haemorrhages in the kidneys and so-called "button ulcers" in the gut. Laboratory tests include the identification of viral antigen, isolation of the virus and the presence of antibodies in serum.

Prevention

There is no live or attenuated vaccine for the prevention of ASF therefore control of the virus is reliant on strict biosecurity.

  • Do not feed domestic pigs food waste; this is illegal in the UK, other EU regions and some states within the US
  • Where ‘permitted garbage feeding’ is legal in US states, pigs fed this way are prohibited from exportation.
  • Do not leave food waste exposed for wild swine species to access. Dispose of food waste properly.
  • Abide by strict biosecurity rules. Do not take pig meat onto farms, or restrict all food (and consumption of food) to a canteen. All staff on farm should be inducted onto a strict programme of hand and equipment sanitisation before and after contact with pigs.
  • Follow rules and regulations on disposal of food waste at ferry ports and airports.
  • Provide the means for staff and visitors to thoroughly sanitise their hands and equipment.
  • Ensure that wild boar, warthogs and wild pigs, and materials potentially contaminated by such wild species do not come into contact with domestic pigs.
  • Check infected regions before import of goods that could potentially be contaminated.
  • Advise and educate people on the risks of bringing back pork products from infected regions.

Treatment

There is no treatment.