The Swine Fevers

Other names	Swine Fever - Hog Cholera, CSF, Swine Fever African Swine Fever - ASF
Causal agent	Classical Swine Fever - Virus - a Flaviviridae, genus Pestivirus. Enveloped RNA virus African Swine Fever - Virus - Enveloped DNA virus related to Poxviruses
Age group	Any age group of pig can be infected with CSF or ASF
Clinical signs
	It is not possible clinically to distinguish between CSF and ASF
Naive herds Piglet with multiple haemorrhages over the skin	Initially a few pigs appear drowsy and less active, with some anorexia and they may appear chilled
	Within days, pigs will present with a marked fever (41-42•C), sometimes with a reddening of the skin
	The pigs develop a conjunctivitis and constipation leading to yellowish diarrhoea
	The pigs appear chilled and will huddle together
	A few pigs may convulse before they die
	Pigs start to die with a spreading purple discoloration of the skin. Death often occurs some 10 to 20 days post-infection
	Pigs which survive will be chronically affected with severe retardation of growth and often present with arched backs
	In the adult herd, returns, abortions, and an increase in mummified and stillborn piglets
On established herds
Congenital infection	Piglets infected from their mothers during pregnancy can result in abortion, mummification, malformations (may present with a congenital tremor with cerebral hypoplasia with Classical Swine Fever), stillbirths and weak born piglets. Piglets born from CSF infected mothers may remain healthy but continually spread the disease through out their lives
Rest of the herd	An almost in apparent infection can also be present on chronically infected herd. These herds can be very difficult to identify
Diagnosis
	Your vet and the government vets must be informed of any suspicious clinical signs If you are suspicious samples should not be taken, discuss with the government. In positive countries, samples can be obtained from tonsilar swabs using Dacron swabs
Treatment
	None
Prevention
	Prevent any pork products entering the farm and being fed to the pigs
	Prevent any infected pigs entering the farm
	All pigs from infected herds are slaughtered and destroyed and the farm intensely disinfected
	In ASF areas, control ticks and flies that may transmit the disease
	In endemic parts of the world vaccines are available
Common differentials
	PDNS, Salmonellosis, Acute pasteurellosis, Erysipelas, Acute septicaemic streptococcal infections, PDNS, Thrombocytopaenia, Warfarin poisoning. Haemophilus parasuis. Reproductive diseases. Other causes of congenital tremor.

Infectivity
Both	The virus is able to survive in uncooked and cured pork and pork products for months
	The introduction of new animals or pork products from infected herds, into a herd is the most likely source of infection
	The diseases can be carried on boots, vehicles, clothing, and also pets and birds
	The diseases can be carried by wild boar
Classical Swine Fever	The virus is quite resistant in the environment, surviving a couple of days
	The virus is quite readily inactivated by approved disinfectants
	Other members of the Pestivirus genus can cause disease in pigs, notably Bovine Viral Diarrhoea and Border’s Disease.
	The virus is excreted from pigs for 10-20 days post-infection in large amounts
African Swine Fever	The virus is very resistant in the environment, surviving for months
	The disease can be spread by ticks (Ornithodoros species in Africa)
	Recovered animals remain infective for at least 6 months
	The virus is inactivated by approved disinfectants
Post-mortem Lesions
Peracute	The pigs may die so rapidly that there are few post-mortem signs
Acute	Multiple haemorrhages through out the carcase
	Swollen, oedematous and haemorrhagic lymph nodes
	Infarction of the spleen (large areas where the blood supply has been cut off resulting in blood filled blebs on the surface of the spleen)
Chronic	In CSF ulceration (button ulcers) can be seen in the large intestine
Button ulcers in the large intestine		Haemorrhages in the bladder	Haemorrhages on the epiglottis and larynx
Splenic infarcts		Petechial haemorhages kidney

Note the feeding of waste feed, including household scraps, unless it is cooked in a plant operating under a licence is prohibited in many countries.

Several countries have now banned the feeding of any waste feed containing mammalian meat proteins