June 9, 2025
African swine fever circulating in Europe linked to earlier introduction, not new outbreak
A study in Genome Biology and Evolution by Oxford University finds that the African swine fever virus, currently circulating in Europe, is not the result of a recent introduction.
Instead, the virus has been present in the region since 2007. Its current dramatic spread appears to be driven largely by people within Europe traveling longer distances. The paper is titled "Exploiting viral DNA genomes to explore the dispersal history of African swine fever (ASF) genotype II lineages in Europe."
ASF virus is a highly virulent DNA virus that causes a severe haemorrhagic disease of the same name, affecting both domestic pigs and wild boars. The disease is characterised by high mortality rates, leading to significant economic losses in the pork industry.
According to estimates from the Food and Agriculture Organisation, the virus has led to approximately US$2.1 billion in direct economic losses over the past 17 years. Additionally, the outbreak has destroyed many small and medium-sized farms, contributing to structural transformations in agricultural markets, notably in China. Currently, there is no vaccine against the virus available widely.
Initially limited to the sub-Saharan African region, the virus (specifically genotype II) spread globally and is now a major concern in Africa, Europe, Asia, the Pacific and, more recently, the Caribbean. In 2024, the World Organisation for Animal Health reported ASF virus outbreaks in seven European countries, with over one million pigs lost since 2022.
The researchers here analysed ten samples from domestic pigs and wild boar, collected between July 26, 2016, and August 23, 2019, as part of the State Food and Veterinary Service of the Republic of Lithuania surveillance activities in Lithuania. From these samples, they generated complete genome sequences of ASF virus.
Researchers used these new sequences to expand the existing dataset of ASF virus genomes genotype II and study the spread of the virus across the European continent.
The analysis shows the ASF Virus genotype II now circulating in Europe shares a single common ancestor with those circulating in Africa, with no evidence of recent viral exchanges between the two continents. Sequences from Europe are closely related to each other and some countries, particularly Poland, Lithuania, Ukraine, and Germany, appear to have played important roles in the regional spread of the virus across the continent.
"ASF virus continues to threaten domestic pig and wild boar populations in Europe," said the paper's lead author, Christopher Netherton. "Each viral genome we sequence helps to deepen our understanding of the virus's circulation dynamics."
- Oxford University Press
