Novel viruses in birds: Flying through the roof or is a cage needed?

Emerging viral diseases continue to have a major global impact on human beings and animals. To be able to take adequate measures in case of an outbreak of an emerging disease, rapid detection of the causative agent is a crucial first step. In this review, various aspects of virus discovery are discussed, with a special focus on recently discovered viruses in birds. Novel viruses with a potential major impact have been discovered in domestic and wild bird species in recent years using various virus discovery methods. Only a few studies report the detection of novel viruses in endangered bird species, although increased knowledge about viruses circulating in these species is important. Additional studies focusing on the exact role of a novel virus in disease and on the impact of a novel virus on bird populations are often lacking. Intensive collaboration between different disciplines is needed to obtain useful information about the role of these novel viruses.