Generally, the peak of bird flu is in the winter and then disappears again in the summer. This year it was different: bird flu has been frequent among birds all summer and millions of chickens had to be destroyed. Experts are holding their breath for next winter.

Avian flu usually arrived in autumn with birds migrating to winter in the Netherlands. Through their feces, among other things, it ended up in chicken sheds and infected chickens.

Over the years, chicken houses have sometimes had to be gutted in the fall and winter. Since spring, the number of bird flu cases has decreased and bird flu disappeared from our country by summer. There were also winters when bird flu did not reach the poultry sector.

This year is a turning point. The virus spreads from waterfowl that overwinter here to birds such as the sandwich tern that stay here during the summer. Bird flu did not go away because of this.

This week 200,000 animals were slaughtered at a poultry farm in Trento. At the beginning of September, more than two hundred establishments were closed to traffic due to an infected poultry farm in Barneveld.

‘Bird flu is present all year round’

“The forecast for the winter is not good,” says Nancy Behrens, a bird flu expert at Wageningen University and Research (WUR). “The winter visitors come this way in October, and they’re all waterfowl.”

“Water is the best transmission of the virus. The upward trend of recent months is likely to continue. This will be the case throughout the year.”

This year only in May the incidence of bird flu has decreased. In June, July and August, the number of infections in the poultry sector increased again. “It is now very serious, the situation is no longer tenable,” concludes epidemiologist and poultry veterinarian Francisca Welkers.

Avian flu is also spreading rapidly in other European countries. According to Beerens, it was “the largest explosion ever seen in Europe”.

Waterfowl are important vectors of bird flu.

Vaccine research

So the EU is desperately looking for a solution. It could be the vaccine. Wageningen Bioveterinary Research (WBVR) is investigating three potential vaccines.

If the vaccine proves to be appropriate, the agreements reached in the EU will have to be adjusted. At present, the trade of vaccinated chickens is not allowed, says Behrens.

“But many member states are ready to reconsider it. In Italy vaccines are being tested on turkeys, in France on ducks and here on chickens,” he continues.

The first results of the studies are expected at the end of December. If the vaccine is suitable, chickens cannot be vaccinated immediately. “This season (fall and winter months, ed.) it doesn’t work anymore, and I doubt it will work next season,” says Behrens.