ASF Germany: a fragile balance at the border

Just over a week ago, the entire German pork industry was holding its breath. Near the city of Potsdam, southwest of the capital Berlin, a suspicious boar carcass was found. To make sure it was a case of African swine fever (ASF), the Brandenburg State laboratory sent the carcass to the national reference laboratory at the Friedrich-Loeffler-Institut (FLI).

In previous situations, the first notifications from the Brandenburg State Laboratory had always been correct, so there was no reason to believe this would be a false alarm. Still, it was – a ‘negative’ result was positive news this time around, and on the morning of Saturday, January 9, my Twitter followers sighed in relief at the post.

FALSE ALARM: The state of Brandenburg in Germany maintenant is now reporting the wild suspect #Swine Fever. So no #ASF jump inside the country. Minister Anna Heyer-Stuffer: “I am very happy and relieved with this result!” #ASPIC

– Vincent ter Beek (@vincenttb) January 9, 2021

ASF virus jumping across distances

While the FLI had reported a “positive” result, a westward jump of over 90 km fitted perfectly into the pattern we have seen over the past 15 years in Eastern and Central Europe. The ASF virus is known to spread at a slow rate when found only in wild boar. Yet humans are known to be the greatest helpers in helping the virus spread over great distances. This is how a 2^nd The Polish cluster was born in Western Poland in 2019, more than 5 years after its introduction in Eastern Poland. And human behavior has most likely caused the emergence of hot spots in Belgium and the Czech Republic.

ASF in the border area: Polish statistics

Despite the false alarm in Potsdam, there are still plenty of reasons to remain vigilant. Let’s take a look at the current situation in the German-Polish border area; my analysis below is based on data available in the early morning hours of January 18, 2021.

As usual in winter, the number of ASF victims is still increasing in wild boars. This winter is no different. It can be seen in Figure 1 below, where the number of cases in western Poland has been plotted and categorized by time of discovery. Information on cases discovered at the end of 2020 has continued to arrive over the past week.

In December 2019, when ASF had just been discovered in western Poland, a total of 126 carcasses were found. The same month, a year later, at least 346 were found. With the more intense months to come, it is clear that the trend is rising.

Western Poland: 2796 infected wild boars

Since November 2019, the Polish authorities have communicated the discovery of 2,796 dead wild boars in the only cluster in the west of the country. Looking at the situation near the German border, it is clear that the number of infections is increasing there. At the end of 2020, many cases were discovered around the Polish border town of Leknica and roughly the same is happening about 120 km north around the border town of Kostrzyn.

Many candidates for infection with ASF virus

It is precisely this pressure that makes Germany nervous, as there are a lot of 4-legged candidates for infection on the German side. Wild boar populations have flourished over the past decade in Germany and the number of slaughtered boars is generally a good indication of the size of the population. Over the past decade, the number of shots has almost doubled. During the last hunting season (April 2019 to March 2020), 856,000 wild boars were slaughtered in Germany, which was the culmination of an upward trend of 440,000 in the 2009/2010 season.

It is therefore good that the German authorities have been very busy building a permanent fence along the Oder and Neisse rivers, jointly forming the border between Poland and Germany. In an earlier stage, sheep fences were placed to prevent wild boars from entering, but in practice they did not form a real obstacle to the migration of wild boars, just as rivers did not constitute a barrier for them.

ASF in the border area: German statistics

There is a need to avoid more infections in Poland, as the current ASF situation in Germany shows an increasing trend. The most recent German data includes the 1^st positive carcass results in 2021, leading to a total of 509 infected wild boars to date. As Table 2 shows, the middle of the 3 states, Brandenburg, is hit the hardest with 492 cases in 3 separate areas. In the south, the state of Saxony has reported “only” 17 victims in an infected area.

The upward trend can be seen in Figure 2. Since mid-November, there have been quite a few weeks with the discovery of more than 40 wild boars per week.

(German authorities are currently in the process of creating white zones around these infected areas, in which all wild boar are slaughtered to give the virus no chance to escape to stray wild boars. Once the white areas are confirmed free of wild boars, hunters will enter the infected zone itself.)

State of Brandenburg: the ASF fence

In Germany, the construction of permanent border fences is not organized at national level but is the responsibility of the 3 border states, from north to south Mecklenburg-Western Pomerania, Brandenburg and Saxony. When completed, the total length of the fence for the state of Brandenburg will be 270 km.

Currently, the state has completed the fence between the border town of Frankfurt an der Oder, to the south towards the border with the state of Saxony, over a stretch of 120 km. North of Frankfurt an der Oder, towards the border with Mecklenburg-Western Pomerania, construction work is underway and around 50 km have already been completed. The authorities have said that it is impossible to predict when this task will be completed.

A wild boar with its litter wandering in a meadow in Europe. – Photo: Jan Vullings

State of Saxony: the ASF fence

The state of Saxony began construction of its permanent fence in mid-November 2020. As the crow flies, the border between Saxony and Poland stretches for 80 km. Seeing that the Neisse border river meanders a lot, the eventual length of the fence here will be longer. This fence will be 1 m high, so deer can jump over it.

Mecklenburg-Vorpommern: the ASF fence

In the northern state of Mecklenburg-Western Pomerania, a fence was put into operation at the end of November 2020. This state has a relatively short border with Poland, only 63 km away, so it was easier to build.

Will the fences protect the ASF virus?

Now the big question is, once the permanent fences are over, will they be enough to keep the virus under control and protect Germany from the emergence of new hot spots? Obviously, you can never be completely sure. The virus can break through in different ways.

A fence will never be 100% waterproof because there will always be (rail) roads that will break it. Additionally, birds of prey or insects could be a mechanical vector of the virus in case they came into contact with an infected carcass before flying across the border. And not to mention the biggest risk: us humans. For them, no fence is too high.

Reduce the risk of ASF infection

Under normal circumstances, however, a permanent fence will significantly reduce the risk of the virus spreading. As demonstrated in Belgium and the Czech Republic, building permanent fences around infected areas, coupled with smart hunting, brought the virus under control – which ultimately had a positive effect on pig markets.

This makes the construction of the remaining fence a real race against time. After all, the discovery of a random boar should no longer make the headlines.