At the beginning of the year, the Italian authorities reported the first case of African swine fever (ASF) in a wild boar found in the Piedmont region, in the northwest of the country. Within a few days, two additional cases were reported, also in wild boar. This is bad news, which shows that this viral disease continues to expand.
In autumn 2020, the European Food Safety Authority (EFSA) launched a campaign, called “Stop the African swine fever”, destined to raise awareness and sensitize to the population and to stop the serious outbreaks that are emerging in south-eastern Europe and that can dangerously threaten the economy of our continent. At the moment the success of the campaign is limited.
A DNA virus without zoonotic potential
African swine fever (ASF) is a devastating viral disease caused by a DNA virus of the family Asfarviridae. It is characterized by hemorrhagic fevers, ataxia, and severe depression. It affects pigs, wild boars and their close relatives, with a fatality rate of up to 100%.
The disease has no zoonotic potential, because it does not affect humans. But despite presenting a limited range of guests, its socio-economic impact is tremendous. It should not be forgotten that pigs are a primary source of domestic income in many countries. Moreover, the meat of these animals is one of the main sources of animal protein, representing over 35% of global meat intake.
According to the World Organization for Animal Health (OIE), the African swine fever (ASF) virus is the most important pathogen affecting the domestic pig population worldwide. The spread of African swine fever around the world has devastated family-run pig farms, often the mainstay of people’s livelihoods and an engine of upward mobility. As a side effect, it has reduced opportunities to access health care and education.
Given these facts, it is understandable the impact that in August 2018 there was a large outbreak of ASF in China, the largest producer and consumer of pork in the world. It killed millions of pigs and led to an economic loss of 0.78% in China’s gross domestic product in 2019. The outbreak forced Chinese producers to cull more than 200 million pigs, which had a major slowing impact on the Chinese economy. It even affected meat markets worldwide, posing a strong threat to the global supply of pork.
Global situation of African swine fever in January 2022
At the moment there is no vaccine
Swine fever currently affects several regions of the world and does not have an effective vaccine. Nothing trivial considering that it not only impedes the health and welfare of animals, but also has detrimental effects on biodiversity and the livelihoods of primary producers.
Over the past decade, African swine fever has grown from a regional disease of sub-Saharan Africa to a considerable and tangible threat to pig farming both in Europe and Asia. Instead of getting better, everything has gotten worse.
Originally, the disease was discovered in Kenya in 1910, and the virus was detected for the first time on the European continent, in Portugal, in 1957. From there the disease spread to Spain in 1960, which caused serious economic damage derived from both of the pigs that died – and of the need to slaughter the animals in the affected areas – as well as of the prohibition of exporting pigs or derived products.
Between 1960 and 1970, African swine fever spread throughout Europe, affecting Italy, the Netherlands, Belgium and France. Fortunately, the disease managed to be eradicated from European territories, except for the Italian island of Sardinia, where African swine fever has been categorized as endemic since 1978.
Currently, the African swine fever virus (an Asfivirus, the only member of its genus) is endemic in several countries in sub-Saharan Africa and Madagascar. There are 24 genotypes described, based on sequencing of the p72 capsid protein gene of the virus. African swine fever virus genotype I is endemic in Sardinia. Unfortunately, genotype II of the virus was introduced in 2007 in Georgia and from there it spread through the Caucasus region, affecting Armenia, Azerbaijan, Russia, Ukraine, Belarus, Lithuania, Latvia, Poland, Estonia, Moldova. , the Czech Republic and Romania, where the virus continues to circulate.
In 2018, three other European countries, Hungary, Bulgaria and Belgium, reported the presence of the African swine fever virus and China warned of outbreaks in its territory. Outbreaks in Africa and Asia and the spread to Europe They haven’t stopped since. The virus appears to be spreading from the affected area of the European Union, moving mainly in a south-westerly direction.
The virus is generally transmitted through contact with infectious animals and fomites, ingestion of contaminated pork products, and tick bites. In sub-Saharan Africa, the disease circulates through a cycle of infection that affects domestic pigs, the river potamoquero (Potamochoerus larvatus), the eastern warthog (Phacochoerus aethiopicus) and several species of soft ticks of the genus Ornithodoros.
In areas of the Caucasus, Eastern Europe, and the Baltic countries, the disease circulates among domestic pigs (Sus scrofa domesticus) and European wild boars (sow), causing similar clinical signs and mortality in both populations.
The case of Poland and wild boars
Poland began reporting outbreaks of African swine fever on February 14, 2014. The first outbreak occurred in a wild boar population in the east of the country, 10 km from the border with Belarus. From February 2014 to the summer of 2021, in Poland they had been confirmed more than 12,764 outbreaks of African swine fever in wild boar and 400 outbreaks of this disease in domestic pigs.
Unfortunately, despite the measures implemented for the eradication of African swine fever, the number of outbreaks in wild boar and domestic pigs is increasing dynamically in recent years. Apparently in Poland there is a massive infection of wild boar causing a slow but steady spread of the disease.
In terms of the multiplicity and population density of wild boars, the current number of these animals on Polish territory is close to 67,000 heads. The Polish authorities have introduced control measures such as reduction of the wild boar population, search and elimination of dead animals, traps or fences among others. But at the moment they do not seem enough.
Given the situation, the German authorities have put up a fence hundreds of kilometers long along the German-Polish border to prevent wild boar from spreading African swine fever to Germany. The fence was agreed with Poland and has been built within German territory at a minimum distance of 5 meters from the actual border with the neighboring country.
Denmark has also built a fence tens of kilometers long along its border with Germany in an effort to control wild boar migration. Not in vain, Denmark is among the world’s largest exporters of pork.
The introduction of the African swine fever virus in countries free of the disease, either through wild boar populations or through the importation and legal and illegal trade of contaminated pig products and waste, is a very serious problem.
What seems indisputable is that the increase in the number of infected countries represents a significant threat. Since the effects of an African swine fever outbreak can be devastating, prevention, detection and information are essential to prevent the spread and to contain the disease.