Health officials in Germany have reaffirmed that the virus behind African swine fever isn’t likely to endanger humans, even if they eat meat from infected animals. However, the reassurance comes in the wake of the virus recently being found on several pig farms within the country, a troubling development, since ASF is highly contagious and fatal in domestic pigs.
The African swine fever virus is named after the disease it causes. It’s the only DNA virus known to spread through arthropods, in this case, the bite from certain species of soft ticks (the genetic material of a virus can be either RNA or DNA). The virus is endemic in sub-Saharan Africa, where it doesn’t seem to gravely sicken its native hosts of ticks and various species of feral swine. But when ASF infects domestic pigs, it can cause a severe, Ebola-like hemorrhagic fever with a nearly 100% mortality rate. Though ticks are normally the primary method of transmission, the virus can also survive for a long time in the meat and bodily fluids of infected pigs, including in feces, allowing it to spread easily enough through close contact on a farm.
Since its discovery in the 1920s, ASF has periodically caused devastating (and sometimes mysterious) outbreaks of illness and death among domestic pigs where it’s been introduced. The threat of ASF is so profound that countries will routinely cull entire populations of possibly exposed pigs and ban imports from affected countries to prevent further spread. But it hasn’t stopped the virus from possibly becoming endemic in parts of Russia and Europe. Since 2018, the largest epidemic of ASF to date has been ongoing throughout Asia, leading to the deaths of millions of pigs and wreaking havoc on the global pork economy.
Germany’s recent discovery of ASF within its borders is therefore distressing. Last September, German officials confirmed the presence of ASF in wild boars, and on July 15, it became the latest country to report local cases of ASF, found among pigs living on two farms. Just yesterday, a third case was confirmed, on a small farm close to the other two locations. Following the discovery of ASF last year, many countries temporarily banned imports of German pork, which may limit the further spread of ASF from the region.
ASF is a potentially serious problem whenever it’s found, but there is at least a silver lining: There’s never been a suspected case of human illness tied to the virus, even though it can remain viable in meat for months, and even after it’s been preserved, frozen, or cooked.
“As the pathogen is not dangerous to humans, the consumption of foods originating from infected animals does not pose a health risk to consumers,” Germany’s Federal Institute for Risk Assessment stated in its most recently updated FAQ on the ASF outbreak.
Still, there is room for bleak pessimism if you’re looking hard enough. ASF is the only known member of its viral family, called Asfarviridae. But last December, an international group of researchers claimed to find evidence of DNA sequences from one or more unknown viruses possibly related to ASF in blood samples taken from people in the Middle East as well as from sewers in Spain.
“Detection of these sequences suggests that greater genetic diversity may exist among asfarviruses than previously thought and raises the possibility that human infection by asfarviruses may occur,” they wrote. Just some food for thought.