African Swine Fever (ASF) is a hot topic for the pig industry at the moment with the death toll in Asia rising by the day. In the UK the focus is on preventing its entry into the country’s pig farms.
African Swine Fever (ASF) was first discovered in East Africa in the early 1900s and was thought to originate from a persistently infected population of wild warthogs and soft ticks, which act as a reservoir for disease. The virus can survive in the tick population for up to four years.
The highly contagious virus affects pigs of all ages, and clinical signs include the onset of fever with lethargy and loss of appetite about four to five days after infection, death usually follows within seven days.
Other symptoms include vomiting, dullness, breathing difficulties, diarrhoea, coughing, nasal and ocular discharges, and redness of the skin, especially on the ears, tail, feet and abdomen. Abortion and still birth is often seen in pregnant sows.
High morbidity and mortality rates as high as 100 per cent are associated with ASF. However, chronic illness can result in anorexia, lameness and skin ulceration.
On May 30, 2019, the Food and Agriculture Organisation of the United Nations (FAO) confirmed 1.1 million pigs have been slaughtered to date in China in an effort to control its spread. There have also been confirmed cases in Hong Kong, Mongolia, Vietnam, and Cambodia where a combined 1.75 million pigs have been slaughtered. There have also been reports of new cases in North Korea and further spread across Europe.
Louise Blenkhorn, independent pig consultant says: “Pigs can contract the virus directly from another pig, eating infected meat or meat products or via contact with contaminated fomites - people, clothing, vehicles and equipment, but it is important to point out that ASF poses no threat to humans or food safety.
Data from China shows that 34 per cent of ASF cases were as a result of feeding swill to pigs, 62 per cent as a result of vehicles and workers without disinfection and 19 per cent from transport of live pigs and products across other regions.
In the UK it is illegal to feed catering waste, kitchen scraps, meat or meat products to farmed animals, including pigs kept as pets. The APHA says too few people are aware of the risks posed to livestock and threat of disease by doing so.
Mrs Blenkhorn says: “The biggest threat to the UK is introduction via infected meat products being fed to pigs. The education of the general public never to feed outdoor pigs is essential."
Some forecasting models have predicted that if ASF was to enter the UK it may be up to 40 days before confirmation of diagnosis, resulting in the possibility of extensive spread via pig movements. There is also a huge threat posed by possible infection of the wild boar population.
Mrs Blenkhorn says: “It would be devastating for the UK pig industry if ASF was to enter the country. Pig farmers have to get good at biosecurity now.
“ASF is a notifiable disease and, if confirmed in the UK, would trigger movement restrictions, compulsory slaughter on affected farms and testing and surveillance of surrounding farms. There is currently no treatment for ASF and the notifiable status of the virus is the main mechanism for its control."
The development of a vaccine as a means of control for ASF has not so far been successful. More than 40 years ago, a vaccine using inactive viruses, as is the case for many vaccines, proved unsuccessful. Development has been repeated since with newer knowledge and technology but was unable to sustain protection once the animal was faced with disease challenge.
The National Pig Association has recently launched its #MuckFreeTruck campaign aimed at encouraging all producers, processors and hauliers to do everything they can to keep lorries clean.
This will be vital to reduce the potential impact of ASF spread via vehicles if the virus were to reach the UK.