Statistics & Maps
Human Powassan (POW) virus infections have been recognized in the United States, Canada and Russia. In the United States, cases of POW virus disease have been reported primarily from northeastern states and the Great Lakes region. These cases occur primarily in the late spring, early summer and mid-fall when ticks are most active.
POW virus disease is a nationally notifiable condition. Cases are reported to CDC by state and local health departments using standard case definitions [PDF - 148 pages]. POW virus disease cases are rare but the reported number of cases have increased in recent years.
All residents of and visitors to areas where POW virus activity has been identified are at risk of infection. People who engage in outdoor work and recreational activities in endemic areas are at increased risk of infection.
*Neuroinvasive disease includes cases reported as encephalitis or meningitis.
Data table: From 2001 through 2012, POWV neuroinvasive disease cases have been reported in Maine (2), Michigan (1), Minnesota (19), New York (13), Pennsylvania (1), Virginia (1), and Wisconsin (10).