Francesc Accensi: "The plague virus may have traveled on the wheels of a truck or on a piece of meat; perhaps we will always have that doubt."

BarcelonaResearchers at the Animal Health Research Center (IRTA-CReSA) are sequencing and isolating the virus detected in wild boars that died in the Collserola Natural Park after being infected with African swine fever. They are searching for the virus's genome to compare it with those circulating in other countries and pinpoint its origin. Francesc Accensi, an IRTA-CReSA researcher and Vice Dean of the Faculty of Veterinary Medicine at the Autonomous University of Barcelona (UAB), explained to ARA that the most likely scenario is that an animal came into contact with contaminated food or material transported by a human. However, he cautioned, "We may always be left wondering how it got here. Once we have the sequence, we can see where it came from and determine if it closely resembles the virus circulating in Italy, Poland, Germany, Romania, Russia, or China. But we won't know exactly how it arrived, whether it was on tires." If it were in food, remember that this would have affected wild boar, but not humans or other animal species.

"What has happened here, appearing like mushrooms in Collserola, already occurred in 2018 in Belgium. Also in Sweden. In these two cases, they were able to eliminate it because they only had cases in wild boar and they acted quickly and very well," explains the researcher. He adds that in cases where the virus has made these geographical "jumps," the reasons have often not been determined. "The only explanation is human action, that someone, through carelessness, carries contaminated food or hasn't changed their boots. It could be a thousand things." That's why, he says, the restriction on walking or doing activities in the area where infected animals have been found makes sense: "You might unintentionally step in a little blood or vomit from an infected wild boar, carry the virus on your shoes, and the next day go somewhere else, Alesh."

In Africa, swine fever is transmitted through ticks that are not found in Catalonia, explains Accensi. Therefore, he narrows down the hypotheses about the origin of the contagion to contact between infected animals—which he considers unlikely, because it would imply that a sick wild boar had walked from another country to Collserola—or to contact between an animal and infected food or material, which he considers the most likely: "The virus could have traveled on the wheels of a bicycle, due to human activity."

If the wild boar ate contaminated sausage or meat, Accensi points out, it would have had to have been produced elsewhere because there are currently no cases of African swine fever in farm animals in Catalonia. In fact, the researcher adds, the first time the virus left Africa was because contaminated food scraps were transported and used to feed pigs. However, protocols are currently in place to prevent these situations, and in fact, this is one of the reasons why importing meat from non-EU countries is not permitted.

"We've been preparing since 2018"

"We've been preparing since 2018," he says, referring to the isolated outbreak in Belgium. Since then, authorities have been working on a contingency plan and were on high alert for the possibility of African swine fever cases. For example, following the infections in Belgium, a protocol was implemented in Catalonia whereby whenever someone reported seeing a dead wild boar in the woods or on the road, blood samples were taken to rule out the virus. Until recently, all the tests had come back negative. Knowing all the precautions that have been taken for years, Accensi is optimistic that the infections will remain confined to wild boars and not reach pig farms. He also explains that it has been mandatory for farms for years to have a double fence, which is regularly inspected, to prevent wild boars from coming into contact with the animals inside. Biosecurity measures have also been established to prevent the virus from entering the farms, such as requiring workers to change their clothes and prohibiting them from bringing certain foods: "You can take a potato omelet sandwich or a tuna sandwich, but not a whip sandwich, to prevent it from happening under any circumstances."