Comprendre les enjeux de l'agriculture
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Since 2018, the African swine fever epidemic has been rife in Asian countries. Although harmless to people, this viral disease decimates more herds than any other and represents a major loss of earnings for the pork industry. As China forecasts a 50% drop in production volumes, leading to fears of disruptions to supplies and a worsening of food security on a global scale, the attention of researchers is focused on studying the genotype of the virus.

Asia has lost 10% of its pig population in one year

  African swine fever (ASF) has devastating symptoms. Previously confined to sub-Saharan Africa, this highly contagious viral disease has recently spread to eastern Europe and Asia. China is the biggest victim with over 1.2 million pigs either dead or voluntarily slaughtered for preventive reasons. No less than 126 family farms spread across 32 Chinese provinces have been affected. Cases of swine fever have also been reported in the pig farms of Laos, Vietnam, Mongolia, North Korea and Cambodia. More worrying still is the speed with which the disease has spread. According to figures published by the FAO, 5 million pigs have already disappeared from the farms of Asia since the appearance of ASF in August 2018. This figure is equivalent to 10% of the pig population on the continent.

France is not out of harm’s way

Harmless to people, the virus is highly infectious, virulent and extremely lethal to pigs. According to Professor Helen Roberts at the British Department for Environment, Food and Rural Affairs, the virus is incredibly resistant. “It survives for months at glacial temperatures and it is capable of surviving for months or even years in frozen meat. As wild boar, as well as domestic pigs, can spread it, containing the parasite is not easy”, said the political advisor to the G7 for the control of exotic diseases. Travelling thousands of kilometres through exports, the migrations of wild boar and aeroplane passengers who secretly carry pork products in their luggage, the virus patiently awaits the right moment to enter a living animal and set to work.

The French Ministry of Agriculture has not attempted to conceal its concern, saying “this battle is by no means won”. Despite biosecurity measures, mankind cannot possibly monitor the movements of every wild boar. The virus survives in contaminated areas of forest. All it needs is an opportunity to find a potential carrier and the game is up! The Minister remains prudent and appeals to producers “not to lower their guard”, knowing nevertheless that the disease will inevitably arrive at France’s borders. As there is currently no vaccine or effective treatment, the immediate slaughter of the entire herd is the only way of halting further contamination.

China loses its status as leader of the pork industry

For the time being, the eyes of the international community are firmly fixed on China, for whom the epidemic has been a complete catastrophe. Before the epidemic, the Middle Kingdom was the number one in the pork industry. It occupies pole position among producer countries, ahead of the United States, Brazil, the European Union and Canada. Furthermore, half of the global pig population is Chinese. The FAO has stated in a press release that a little less than one third of the pig population in China (200 million pigs) will have disappeared by the end of 2020, a number that is broadly equal to the entire pig population of Europe. How to reintroduce stability into the global trade in proteins, and more particularly animal foodstuffs, that is the question.

The end of the Chinese monopoly is set to usher in a new era in the international meat trade. To meet its population’s demand, China has raised its quotas for imports from Europe by about 30%. A Chinese person with an average income consumes about 30 kg of pork meat per annum. France, the United Kingdom and Germany enjoy the lion’s share of this vast market. Belgium is not in the running, insofar as tests have revealed that 700 wild boar are carriers of the ASF virus. Others are luckier: breeders in Brazil, Canada and Australia will doubtless be happy to seize the opportunity; the Americas and Oceania have been declared free of the disease. The United States are less enthusiastic: the third biggest global exporter is subject to duties of 62%, due to its trade war with Peking.

Economists expect to see new models of consumption in the coming years. It may soon be the case that we see Chinese consumers developing a taste for beef and poultry. Fish, seafood and vegetables could compensate for lower consumption of pork. Case in point, Chinese imports of chicken jumped by 70% in 2019.

A coup de grâce for small family farms

In rural society, pigs are a means of accumulating savings and are only slaughtered during festive periods and on exceptional occasions. Robust studies undertaken in poor rural communities in Africa and Asia have shown the link between small scale husbandry and family nutrition. Raising pigs helps to make ends meet, offsets the dramatic risks of a failed harvest and finances the big expense involved in the next food crop. Due to the effects of swine fever, small Chinese, Vietnamese and Burmese producers are not only losing money, even worse, they are losing their survival insurance.

“Some farmers have lost their entire herd because of swine fever”, says Lubroth, a senior vet at the FAO, “and it might take years for the worst affected countries to recover from the social and economic effects of the epidemic“. Unlike industrial scale farming, these farmyard pig are fed on leftovers; disinfection of clothing, shoes and tools is neglected and the line between domestic pigs and wild board is often not very clear. Just so many opportunities for the parasite.

The ASF epidemic will certainly have a negative effect on the breeders’ finances, but it will also take us a little further away from the “zero hunger” target and the reduction of poverty.

Encouraging results from Chinese research

While the new paradigm of the global demand for protein is keeping the agricultural authorities busy, science is interested in reading the virus’s genotype. Researchers at the Biophysical Institute of the Chinese Academy of Sciences, in collaboration with the Veterinary Research Institute of Harbin, have succeeded in doing just that. They have isolated the strain of the ASF virus after spending 4 months collecting data:

  • the virus is a double-strand DNA,
  • it has a highly developed nucleic architecture (the genome is contained in a core shell, which is in turn protected by a dual layer inner membrane, a capsid and an outer membrane),
  • it is remarkably large (10 times bigger than the Hepatitis A virus),
  • and it contains over 30,000 protein sub-units.

The conclusion is perfectly clear: the parasite derives its power to infect from its structure. It brings complex chemical processes into play between the amino acids to overcome the host’s immune system. According to Rao Zihe, one of the directors of the research, “scientific knowledge of African swine fever was almost zero in comparison to other viruses. Decoding the structure of the virus represents the first major step on the long path to attacking this disease”, he says. The study has indeed revealed the presence of protective antigens that could be exploited for medical purposes to produce antibodies. More in-depth research has yet to be undertaken in order to understand the host-parasite relationship and develop an effective vaccine.

John Mah’rav