African Swine Fever: an Increasing Threat for Europe

African Swine Fever (ASF) is a highly contagious disease, which has no vaccine and often leads to 100 per cent mortality. With Russia unable to control its rapidly spreading ASF outbreak, the threat of this devastating disease in Europe is growing.

2 December 2011

4 minute read

By: Chris Haris

Russia announced at the 2011 World Pork Congress in Germany, that it is struggling to cope with the spread of ASF throughout the country.

Following the spread of ASF from Georgia to Russia, the Russian Veterinary Service noted; "there is an immediate risk of it spreading further".

This article provides the current information issued by OIE on the history, spread, clinical signs and prevention of the disease.

What is African Swine Fever?

ASF is a highly contagious disease of all pigs, warthogs, European wild boar and American wild pigs, often killing 100 per cent of the herd and leading to mass slaughtering.

The ASF virus is characterised by high fever, loss of appetite, haemorrhages in the skin and internal organs, and death in two to 10 days on average.

Mortality rates are often as high as 100 per cent.

ASF is caused by a DNA virus of the Asfarviridae family.

Following outbreaks of ASF in Spain, Portugal and Sardinia in the 1960s, Europe's most recent outbreak reported to the OIE was in Georgia in 2007.

ASF is now a listed disease with the World Organisation for Animal Health (OIE) and any outbreaks must be reported to the OIE under Chapter 1.1 – Notification of Diseases and Epidemiological Information.

Occurrence and Prevalence

ASF is generally found, and is mostly endemic, in countries of sub-Saharan Africa.

In Europe, ASF remains endemic only in Sardinia, the disease was eradicated from Portugal and Spain in 1993 and 1995, respectively.

Outbreaks have occurred outside of Africa, including the outbreaks in Georgia in 2007 and in some Caribbean countries.

Transmission and Spread

The warthog has been reported as a carrier of the virus without being itself being affected. The virus is then spread via the soft tick Ornithodoros moubata, which transfers the disease via blood.

The virus is found in all body fluids and tissues of infected domestic pigs.

Pigs can also become infected by direct contact with infected pigs or by ingestion of rubbish containing unprocessed infected pig meat or pig meat products.

ASF can also be spread through; biting flies, ticks, contaminated premises, vehicles, equipment and clothing.

ASF, however, is not a human health threat.

Clinical Signs of ASF?

Severe cases of the disease are characterised by a high fever and death in two to 10 days on average.

Other clinical signs may include loss of appetite, depression, redness of the skin of the ears, abdomen, and legs, respiratory distress, vomiting, bleeding from the nose or rectum and sometimes diarrhoea.

Moderate forms of the virus produce less intense symptoms, though mortality can still range from 30 to 70 per cent.

Chronic disease symptoms include loss of weight, intermittent fever, respiratory signs, chronic skin ulcers and arthritis.

Diagnosis

ASF may be suspected based on clinical signs and confirmation must be made through prescribed laboratory tests, particularly to differentiate this disease from Classical Swine Fever (CSF).

Prevention and Control

So far, there is no published treatment for or vaccine against ASF.

Prevention in countries free of the disease has been down to strict importation policies, ensuring that neither infected live pigs nor pork products enter into areas free of ASF.

This includes ensuring proper disposal of waste food from aircraft, ships or vehicles coming from infected countries.

In endemic areas, it has proved difficult to eliminate the disease in warthogs; however, control of the soft tick vectors is important in preventing the disease.

It is also important to ensure that meat from warthogs or infected animals is not fed to susceptible pigs.

All successful eradication programmes have involved the rapid diagnosis, slaughter and disposal of all animals on infected premises, thorough cleaning and disinfection, disinsectisation, movement controls and surveillance.