TONDER, Denmark — Trying to halt the spread of a disease that can wipe out domestic pig populations, Denmark intends to build a fence along its border with Germany to keep out the pigs’ wild cousins. There are just a few wrinkles to the plan.
To the government’s frustration, many Danes see the fence as being about more than just swine. Depending on their backgrounds and political stripes, people have called it a possible step toward blocking refugees, a detriment to wildlife, a reminder of painful history, or a violation of the European Union ethos of invisible borders and free movement.
Oh, and there is little scientific evidence to suggest that it will work.
“We have to enter the imagination of a pig,” said Bent Rasmussen, the chief forest manager for the area, who is in charge of the project. “It’s not easy.”
The African swine fever virus poses a serious threat to production of pork, a major export for Denmark. It spreads readily and is highly resilient, capable of surviving for months in pork products and feces. There is no vaccine or treatment, and the only way to contain an outbreak is to cull the population, as Romania did recently, killing 230,000 pigs.
The virus is usually harmless to its traditional hosts, African animals like warthogs and bushpigs, as it is to people. But in domestic pigs and wild boars, it causes a hemorrhagic fever that is often lethal. In recent years, it has become widespread in Russia, and outbreaks have become increasingly frequent in other parts of Europe and Asia. In just the last few months, they have been reported in Romania, Belgium, Bulgaria and seven provinces of China.
Denmark’s $20 million answer includes a public awareness campaign, expanded permission to kill wild boar, and a fence about five feet tall along the 42-mile land border, across the neck of the Jutland peninsula, from the North Sea to the Baltic. In France, regional officials this week revealed plans for fences along parts of the country’s border with Belgium, also to block African swine fever, but details and timing remained unclear.
The Danish Parliament has approved the fence, and work is expected to begin early next year, though environmentalists have appealed to the European Union to stop it.
But there are holes in the plan — or, more precisely, holes in the planned fence, which will have openings for 15 official border crossings, five waterways and passages for local farmers. It has to comply with an array of European Union rules and other international strictures protecting wildlife habitat and the movement of people and goods.
“My job is to disturb the wild boar as much as possible and humans and other wildlife as little as possible,” Mr. Rasmussen said during a drive along a reed-covered ditch separating Danish farmland from a German village.
The hope is that animals like deer and otters will still be able to cross the border, but boar will be deterred. Critics ask why that would work, given that the wild pigs are smart and curious, and regularly forage over long distances.
In a report this summer, the European Food Safety Authority concluded that “there is no evidence that large fences have been effective for the containment of wild suids,” using a word for the pig animal family.
Hans Kristensen, a hunter and founder of a Facebook group opposed to the fence, said, “It’s like creating your retirement fund by buying a lottery ticket.” He said there was no reason to think it would keep out German boars.
Then there is the matter of Flensborg Fjord, an arm of the Baltic that forms the eastern part of the international boundary. A floating barrier would extend the fence into the waterway, to about 100 feet from shore. But the fjord is more than 15 miles long and less than a mile wide in places — and wild boar, which venture readily into water, are strong swimmers, even when they are young.
Experts note that the Belgian outbreak of African swine fever occurred far from any others, indicating that people, not pigs, transported the virus into the country.
“Long-distance spread of A.S.F. can happen anytime all over Europe,” said Dr. Klaus Depner of the Federal Research Institute for Animal Health in Germany. “Fences cannot prevent such events.”
Vittorio Guberti, a leading wildlife disease epidemiologist, said the fence was likely to “reduce the speed at which wild boar move,” but he, too, said that unwitting humans were the main factor in spreading the disease.
The Danish plan includes putting wildlife cameras where roads cut through the fence, to record how often boars circumvent it.
Some politicians have called for reinstatement of border controls to stop the flow of migrants into Denmark, and they see a value to the boar fence and cameras that is not what the center-right government intended.
“Hooray, we’re getting a fence on the Danish-German border,” Kenneth Kristensen Berth, a spokesman on European Union affairs for the right-wing Danish People’s Party, wrote on Facebook. “We should add a couple of meters so the fence not just keeps German wild boar away, but also illegal immigrants, asylum seekers and adventurers!”
The party has also asked the minister of justice about possibly “striking two birds with one stone” and using the wildlife cameras to look for people crossing the border illegally.
Such talk angers Henrik Refslund Hansen, a farmer. He vehemently supports anything that might protect his pigs and says that talk of refugees just muddies the issue.
“It’s indecent,” he said. “It’s not a border fence; I don’t want to hear any of that. It’s a veterinary fence made to protect our animals.”
Mr. Hansen knows what is at stake. In the 1980s, as a teenager, he watched as an outbreak of pseudorabies, another viral disease, forced his family to cull thousands of pigs, and he retains the chilling memory of earth-moving equipment removing the carcasses.
But along the border, the planned fence is a source of unease for Denmark’s ethnic German minority, about 15,000 people who maintain German-language schools and publish a newspaper in German.
Jorgen Popp Petersen, a pig farmer and local representative of the minority’s political party, recalls “fanatics” in his childhood resisting intercommunity marriages and calling for a redrawing of the border, which has changed several times over Danish history, often through warfare. The fanatics and their views are gone, he said, but sensitivities over ethnic divisions and national boundaries remain.
The fence, he said, is a way to say that Denmark is fixing things by leaving Germany “to sink or swim” with the virus. “We can’t solve any problems by holing up.”
Denmark’s minister of environment and food, Jakob Ellemann-Jensen, said he understood that sensitivity, adding that he almost choked on his coffee when he first heard the idea of a border fence.
“It’s very un-European to build fences and boundaries between countries,” he said. “I fight for free movement in every other context. When it’s right in this context it’s because such a large part of exports is at risk.”