The situation in the Netherlands could be quite explosive because of the huge concentration and numbers of poultry. It is worse than in other countries.

Cat-to-human transmission is theoretically possible and not to be excluded.

Swans fly no more than 50km a day. Looking at the way the disease has spread ­ one day it's in Italy, a day later it's in the north of Germany ­ that makes us believe that there are other bird species spreading the disease.

There is little you can do about the wild birds, especially the migratory ones, it's very difficult to do anything there and probably it's not possible or even desirable. The most important thing is to now, as much as possible, to have the poultry flocks indoors.

I think it is a worrisome situation, especially because we think that swans could be an indicator species, meaning that swans are relatively susceptible and so it could well be that other aquatic birds could be infected. Now we have seen it in Greece and Italy and now Germany. It is spreading all over Europe.

If we see what is happening in Europe at this moment, I think we have to be worried. We see dead swans and we know that swans are highly susceptible [to H5N1]. And they share their ponds, the places where they swim, with other birds as well that are less susceptible, for instance ducks. And they might have actually infected the swans, so I think we have to be prepared in Europe, especially since the bird migration is about to start.