The wild bird enigma: what role do wild birds play in the highly pathogenic avian influenza epizootic?

Since 1997, poultry holdings world-wide face an increasing risk of infection with the highly pathogenic avian influenza virus H5N1 Asia (HPAIV H5N1). Due to its zoonotic potential, this virus also constitutes a risk of infection for humans who come into direct contact with the agent. Since 2005, HPAIV H5N1 has also beet? detected frequently in various wild bird species. These finding have sparked a controversial discussion about the role of wild birds, especially water birds, for the maintenance, transmission, and worldwide spread of HPAIV H5N1. In this article, we summarize the current scientific knowledge and perception of the role of wild birds in the highly-pathogenic avian influenza epidemic. We argue that the scientific evidence so far suggests that wild birds play a role amongst other factors the transmission and world wide spread of HPAIV H5N1 and that measures are required to reduce the risk of transmission between captive and wild bird populations to a minimum.