Surveillance of H5 Avian Influenza Virus in Wild Birds Found Dead

Wild birds are suspected to play a role in the spread of avian influenza H5N1; however, much remains unknown about the ecology and epidemiology of H5N1 in wild birds. Lake Constance is an important wetland area and was a focus for surveillance of dead wild birds between February and June 2006. Dead wild birds collected from the lake and surrounding regions were tested for avian influenza H5. This article provides a descriptive and spatial analysis of the data collected during this period and includes discussion of the strengths and limitations of this type of surveillance. The sampling of dead birds may provide a rapid and cost-effective means of detecting the presence of H5N1; however, such sampling is prone to certain biases and lacks sensitivity in detecting asymptomatic infections. The benefit of such surveillance will be enhanced by detailed ornithologic information, greater accuracy of spatially referenced data, and quantification of surveillance effort.