Is it still important to send in dead wild birds for bird flu surveillance?

Bird flu is still present among wild birds in the Netherlands. The virus is now endemic in wild bird populations and still causes mortality, although fortunately less than last summer. Some birds have built up partial protection (immunity) against the disease, which means they die less quickly but are also sick for a longer time. This makes detecting the virus more complicated.

The collected birds are tested for bird flu by taking a swab from both the cloaca and trachea, and examining those swabs. A bird only excretes virus for the first seven days of infection (on average). If a bird is sick for a longer period of time before they are tested, the swabs may be negative, while the bird may still have bird flu. It is therefore possible that birds that are symptomatic for the disease (tremors, walking in circles, unable to fly, etc.) test negative on the swabs.

Symptoms fitting of bird flu can also be caused by other diseases, thus research remains necessary. For example, a mute swan that showed neurological symptoms but tested negative for bird flu was recently found to have a parasitic infection (worms) that had caused severe encephalitis and a blind eye.

In collaboration with other national institutions, DWHC is investigating into better methods of detecting bird flu in dead wild birds. In the meantime, is it still relevant to offer dead wild birds to DWHC for bird flu research? Yes, it is still very important!

Your reports are very important to understand the changing dynamics of the disease in wild birds, even if the reported animal is not collected for research. The information of your report will be included in our overview of reported animals. We use this for research into mortality among wild birds in the Netherlands.

Please also include the symptoms and details of each case on the form. Your descriptions will be read and are valuable to us in improving our surveillance.

Stay involved and please keep reporting!