  We present a model for the growth of West Nile virus in mosquito and bird
populations based on observations of the initial epidemic in the U.S. Increase
of bird mortality as a result of infection, which is a feature of the epidemic,
is found to yield an effect which is observable in principle, viz., periodic
variations in the extent of infection. The vast difference between mosquito and
bird lifespans, another peculiarity of the system, is shown to lead to
interesting consequences regarding delay in the onset of the steady-state
infection. An outline of a framework is provided to treat mosquito diffusion
and bird migration.
