How likely will west nile virus cause severe muscle weakness?

Unlikely: A very small minority of patients who develop west nile infection are left with widespread muscle weakness that is much like poliomyelitis.

Depends: Muscle weakness is usually seen proportional to the coalescence of the illness. Your recovery with take twice as long as the illness, unless there was neurological injury of a permanent type, which may take longer. A rehabilitation physician can help you with recovery.