African Swine Fever (ASF) has had a global impact during 2019. Last month the alert status was raised within Germany as the disease reached the West of Poland. The Polish Army has been deployed to the border region to prevent further spread of the disease which also threatens Polish pig meat exports, along with the ASF free status of Germany. The disease also continues to spread in Asia, in Vietnam 5.8 million pigs are dead, the Philippines has also seen outbreaks and the virus is likely to be in Indonesia.
Given the scale of the economic impact its easy to see why ASF is classified as a potential agent of agroterrorism. ASF is caused by the African swine fever virus, a DNA Asfivirus in the family Asfaviridae. ASF is a severe contagious hemorrhagic viral disease that exclusively affects pigs. In its acute form, it causes fever, vomiting, diarrhea, and death in wild and domestic pigs, with the mortality rate in domestic pigs approaching 100% in most outbreaks.
The Chinese pig sector – the Worlds largest in terms of numbers of head is being particularly badly impacted and this is having a global impact in terms of pork prices and trade. ASF has been reported in every province of China and some are forecasting that China could lose up to half of its pigs by the end of 2019. Figures for June 2019 indicate that the total Chinese pig herd was down by 26% year on year. So far almost 1.2 million pigs in China have been culled and retail pork prices in August were up by 47%, with the overall food price index reported to be 10% up. This is already having significant impacts in terms of the meat sector, but will also impact on animal feed markets given Chinese imports of Soya. Chinese pig rations are on average 75% soya and China accounts for 50% of World oilseed imports and ASF is forecasts to have a considerable impact on World oilseed prices. The losses will certainly impact on production in the short term – however it is likely that the outbreak will speed up the process of restructuring and modernization within China and elsewhere in the long term with many so called ‘back yard’ producers disappearing.
Pork is a staple in the Chinese diet, and it is likely that there will be a consumer shift towards other forms of protein, most likely fish and poultry meat. The USDA are forecasting that China will import 3.5 million tonnes of pork in 2020, 35% up on 2019, also with increased imports of chicken and beef to fill the protein gap.
A vaccine or cure is currently not available and early detection is the key to controlling the spread of the disease along with biosecurity – in particular controlling and restricting contact between domestic pigs and wild boar populations. There also needs to be a greater awareness of the threat of ASF amongst travellers – over the Summer traces of ASF were detected within illegally imported meat being taken into Northern Ireland. In the Philippines, the authorities have installed the country’s first modern and automated road bath disinfection facility for animal transport carrier vehicles and a biosecurity and quarantine checkpoint to curtail ASF spread. The authorities have also intercepted several ASF-positive pork packages from China.
Researchers are increasing efforts to develop an effective vaccine with three different approaches being tried. Firstly a live vaccine, consisting of the actual flu virus but with some genes deleted so that the virus is attenuated so it can’t cause disease. The USDA have recently stated that tests conducted on Plum Island using a live attenuated vaccine have proved to be 100% effective. According to Douglas Gladue, senior scientist at the USDA’s Agricultural Research Service (ARS).
“It has been 100% effective. All the animals that have been vaccinated are protected,”
It is not yet clear how quickly this vaccine can be commercialised and made available.
The second approach is to use subunit vaccines – that is to use the parts of the virus to induce an immune response but not a whole live virus. The third approach is using viral vectors – that is putting the gene or genes for ASF into another virus e.g. an Adenovirus. This virus would be safe so that pigs or humans don’t get sick but an immune response to ASF is triggered. VIDO-InterVac in collaboration with the CFIA (Canadian Food Inspection Agency) has been using this approach with partners in Africa to develop a vaccine which is undergoing trials on live pigs in Canada.
Despite these efforts an effective commercially available vaccine could still be some way off and the impact of this global outbreak will be felt for some time to come.