Classical Swine Fever
CSF is a highly contagious disease of pigs of all
ages. It is caused by a RNA-virus belonging to the
family Flaviviridae, genus Pestivirus. The virus is
relatively stable in moist excretions of infected pigs,
pig carcasses and fresh pig meat. It is readily
inactivated by detergents, lipid solvents, proteases
and common disinfectants. It is transmitted through
direct contact, swill-feeding, transplacentally, and
through mechanical transmission (such as needles
during treatments). Only one serotype exists
although
strains
with
different
virulence
characteristics have been identified. CSF is not a
threat to human health.
Weak and ataxic pig
Clinical Signs: The incubation period varies from 2-14 days. Pigs may die after a short febrile illness and
before other clinical signs develop. Pigs become depressed, recumbent, have difficulty breathing, stop
eating, and huddle together.
Acute: Fever (41°C), cyanotic skin haemorrhages (especially at extremities), conjunctivitis, anorexia, ataxia,
paresis, convulsions, sometimes vomiting, diarrhoea or constipation. Death usually occurs within 5-15 days
after clinical signs develop. Mortality depends on the virulence of strain and age of the animal, with young
animals are more vulnerable than adults.
Chronic: Initial signs are similar to acute infection and progress to non-specific signs (intermittent fever,
chronic enteritis, wasting). Skin haemorrhages are absent. Death after several months of disease. Virus is
constantly shed.
Congenital: Transplacental transmission can result in abortion, resorption, mummification, and stillbirth of
piglets. Surviving piglets may be clinically normal at birth but are consistently viraemic and shed the virus
until death. Weakness, tremor and poor growth sometimes leading to death.
Pathological Findings
Acute: No lesions if death soon after infection. Enlarged and haemorrhagic lymph nodes, encephalomyelitis.
Multi-focal infarctions along the margin of the spleen. Widespread haemorrhage in skin, lymph nodes, larynx,
bladder, kidney, ileocaecal junction
Chronic: Button ulcers in caecum and large intestines, generalized depletion of lymph tissue. Haemorrhagic
lesions often absent.
Differential Diagnosis
African Swine Fever, Porcine Dermatitis Nephropathy Syndrome, Bovine Viral Diarrhea virus: Similar gross
pathology. Laboratory differential diagnosis is essential.
Bacterial diseases such as erysipelas, salmonellosis, and pasteurellosis usually respond to antimicrobials
and have lower morbidity and mortality rates.
Infected pigs huddle together
Haemorrhage in lymph nodes of acutely infected pig
Splenic infarcts in acutely infected pig
Control of Classic Swine Fever
Prevention:
►
Pig farmers and field personnel should know the dangers of CSF and be
able to suspect the disease.
►
Contain pigs within pig sties with controlled entry/exit points
►
Do not allow visitors in without changing their boots and clothes
►
Have a boot bath to wash and disinfect boots regularly
►
Control and monitor movement of pigs within the country and especially
across international borders
►
Swill should not contain remains of pigs and should be boiled for 30
minutes and allow to cool before feeding
►
Vaccines can be used to protect swine from disease (attenuated and
sub-unit).
►
Infected sows can transmit the disease to piglets during pregnancy and
should be eliminated from the herd.
During an outbreak:
►
infected and suspected infected farms must be placed under quarantine
►
-no movement of pigs or any products of pig origin should be allowed
Humane killing and proper burial
of infected pigs
►
-all infected and in-contact pigs must be humanely slaughtered
►
-carcasses, animal products and bedding must be burnt or buried
deeply on site
Sentinel pigs contained in a
sty with controlled entry
►
-personnel should ensure that shoes, clothes vehicles and equipment
are disinfected between farms
►
-farms should not be restocked until after proper cleaning and
disinfection is completed. Sentinel pigs might be used.
►
If using vaccine, only healthy non-infected pigs should be vaccinated.
Reference Experts and Laboratory Contacts:
Veterinary Laboratories Agency (VLA) – Weybridge
New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
Tel: +44 (0) 1932 341111
Email: enquiries@vla.defra.gsi.gov.uk
Foreign Animal Disease Diagnostic Laboratory
Plum Island Animal Disease Center USA
Tel: +1 631 323 3256 Fax: +1 631 323 3366
Email: nvsl.concerns@usda.aphis.gov
Institut für Virologie Tierärztliche Hochschule
Bünteweg 17, D-30599 Hannover GERMANY
Tel.: +49 511 953 8840 Fax: +49 511 953 8898
Email: moennig@viro.tiho-hannover.de
Friedrich-Loeffler-Institut
Bundesforschungsinstitut für Tiergesundheit
Suedufer 10, D-17493 Greifswald-Insel Riems GERMANY
Tel: +49 38351 7-0 Fax: +49 38351 7-219
If the shipping of samples to an OIE or FAO reference laboratory is required,
FAO may be able to assist in the shipment; offering IATA transport boxes
and arranging the shipment with a specialized transport company. For
requests, please contact: empres-shipping-service@fao.org
Disinfectants:
Inactivated by cresol, sodium
hydroxide (2%), formalin (1%),
sodium carbonate (4%
anhydrous or 10% crystalline,
with 0.1% detergent), ionic
and non-ionic detergents,
strong iodophors (1%) in
phosphoric acid
Samples: Label all samples and provide
epidemiological information and history
-Tissue from tonsils, lymph nodes
(pharyngeal, mesenteric, maxillary, renal),
spleen, kidney and distal ileum collected
aseptically and kept separate and chilled
(never frozen).
-Aseptic blood samples in EDTA from live
animals, serum from recovered and
affected animals.
Disinfecting boot bath at entrance to farm