Which type of disease would be most challenging to prevent from entering the U.S.?

The selection of a disease of various species with wild birds as a reservoir reflects the complexities involved in preventing such diseases from entering the U.S. This is primarily due to the migratory patterns and wide-ranging movements of wild birds, which can easily traverse vast distances across international borders.

Wild birds can carry pathogens without showing symptoms, making it difficult to identify and control the spread of diseases they may harbor. Additionally, the natural behaviors of these birds allow them to reach diverse habitats, facilitating the mixing of different wildlife populations and increasing the chances of disease transmission to domestic poultry and other wildlife.

In contrast, diseases with mammalian intermediate hosts or those exclusive to reptiles may have more defined pathways of transmission or be limited geographically by the habitats of their hosts. Diseases spread through contaminated water might also be detectable and managed at water sources. Therefore, the widespread distribution and silent transmission of diseases associated with wild birds pose significant challenges in terms of monitoring and prevention, making them particularly challenging to control.