Der IHT schrieb gestern:

As new outbreaks of bird flu have peppered Europe and Africa in the last few weeks, experts are realizing that they do not fully understand how migrating birds disseminate the H5N1 virus, leaving the continents vulnerable to unexpected outbreaks. Just after new scientific research clarified the role of wild birds in spreading H5N1 out of its original territory in southern China, the virus promptly moved into dozens of locations in Europe and Africa, following no apparent pattern and underlining how little scientists actually know.