Avian influenza virus in aquatic habitats: what do we need to learn?

Although aquatic habitats utilized by wild and domestic birds potentially can provide a bridge for avian influenza virus (AIV) transmission among many diverse hosts, the factors controlling environmental persistence and transmission via these habitats are poorly understood. AIV has been detected in water samples collected in the field, and under experimental laboratory conditions, these viruses can remain infective in water for periods of time that would be consistent with an environmental reservoir. However, the application of laboratory results to field realities is complicated by the complexity and scale of these systems. In this brief review, we present a summary of existing research on the environmental tenacity of AIV, provide an example of the challenges associated with the application of laboratory results to the field realities associated with detection of AIV from environmental sources, and identify gaps in our current understanding of the factors potentially affecting AIV infectivity in the environment, specifically from aquatic habitats utilized by wild birds.