By Samuel
African Swine Fever (ASF) is a highly contagious haemorrhagic viral disease of domestic pigs, caused by a large DNA virus of the Asfarviridae family
The disease which affects pigs of any age can result in a high mortality rate and is responsible for the recent production and economic losses in some pig farms across Lagos.
Transmission
Depending on the environment and the type of pig production systems, among others, the transmission is generally through direct contact. Direct contact with bodily discharges, faeces, and vomit of infected pigs.
Other transmission modes include:
• Introduction of affected pigs to the herd
• Indirect contact, through ingestion of contaminated material (e.g. food waste, feed, or garbage);
• Biological vectors such as bites from soft-bodied ticks, lice, and flies.
• Use of contaminated surgical equipment and syringes.
Clinical Signs
This varies according to the virulence of the virus and/or the species of pig:
• Acute forms of ASF are characterised by high fever, anorexia and loss of appetite, haemorrhages in the skin (redness of skin on ears, abdomen, and legs), abortion in pregnant sows, cyanosis, vomiting, diarrhoea and death within 6-13 days (or up to 20 days). Mortality rates may be as high as 100%.
• Subacute disease symptoms are caused by moderately or low virulent viruses, which produce less intense clinical signs that can be expressed for much longer periods. Mortality rates are lower, but can still range from 30-70%.
• Chronic disease symptoms include loss of weight, intermittent fever, respiratory signs, chronic skin ulcers and arthritis.
Prevention
• Implementation of appropriate import policies
• Adoption of biosecurity measures
• Preventing infected live pigs from being introduced into ASF-free zones
• In cases of early detection, infected pigs should be killed followed by proper disposal of carcasses and waste
• Thorough cleansing and disinfection and movement controls of herds.
Treatment
There is no treatment or approved vaccine for ASF but in cases of early detection, the infected animals must be isolated and removed from the herd immediately.