In the past 2 weeks, several poultry farms in the Gelderse Valley (the epicentre of Dutch egg production) have been infected with avian influenza. Research by Wageningen Bioveterinary Research (WBVR) seems to indicate that after the introduction by wild birds, the virus has spread between companies in that area.
Almost all of the earlier outbreaks this season were the result of separate infections from wild birds in the area, according to research by WBVR into the bird flu viruses found.
However, the Gelderse Valley is a poultry-dense area where relatively few waterfowl live. The researchers also analysed the viruses from the infections in this area. “This research is aimed at finding out how the recent infections on the farms in Gelderland (province centre-east of the country)came about,” says Nancy Beerens, head of the Netherlands Reference Laboratory for Avian Influenza (AI, bird flu) at WBVR.
To gain insight into this, the genetic code of the highly pathogenic H5N1 bird flu viruses found on poultry farms was determined. A genetic analysis was then performed. “This analysis shows that there are 2 clusters of infections. Within such a cluster, the viruses are very closely related to each other. It is, therefore, likely that 2 companies were infected by wild birds, after which the virus managed to spread to companies in the vicinity,” explains Beerens.
To prevent the further spread of the virus between companies, the Ministry of Agriculture, Nature and Food Quality has tightened up the visitor arrangement in the entire Gelderse Valley region. Poultry farms in the 1-kilometre zone around the outbreaks are culled as a preventive measure. Poultry farmers are called upon to strictly observe hygiene rules and advice.