Dr Nambinga sheds light on African swine fever (ASF)
As a result of the recent outbreak of African swine fever in the Northern regions of Namibia, I felt the need to shed some light on the disease and provide information I think will be necessary to pig farmers as well as prospective pig farmers. I hope this information will be useful to the reader.
What is African swine fever?
African swine fever is a highly contagious hemorrhagic viral disease of both wild and domestic pigs, which is responsible for serious economic and production losses.
Transmission and spread
The Epidemiology of ASF is complex and varies depending on the environment, types of pig production systems, the presence or absence of competent tick vectors, human behaviour, as well as the presence of wild pigs. The major routes of transmission include: • Direct contact with infected domestic or wild pigs • Indirect contact through ingestion of contaminated
material (e.g food waste, feed or garbage) • Contaminated fomites or biological vectors e.g.
Ornithodoros soft ticks
Public health risk
ASF is not a risk to human health.
Clinical signs: Clinical signs and mortality rates can vary according to the
virulence of the virus and the type/species of pig:
Acute forms of ASF are characterised by high fever, depression, anorexia(Not eating) 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 (death) rates may be as high as 100%. Subacute and chronic forms 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. Different types of pigs may have varying susceptibility to ASF
virus infection. African wild suids may be infected without showing clinical signs allowing them to act as reservoirs. Prevention and control • There is currently no approved vaccine or treatment for
ASF. • Avoid introducing new pigs to pigsties during an outbreak. • Avoid visiting other people’s pigsties during an outbreak • Avoid feeding pigs garbage that is not well cooked • Keep the pigs housed at all times.
• Ensure tick control by dipping for pigs with an appropriate, registered dip. • Clean and disinfect pigsties regularly. • The disease causes very serious economic and production
losses; hence, when in doubt, do not hesitate to contact the nearest veterinarian.