chapter  12
28 Pages

- Powassan Virus

Powassan virus (POWV; family Flaviviridae, genus Flavivirus) is a member of the mammalian tick-borne virus group (Grard et al. 2007). The virus appears to be widely distributed in its enzootic hosts in North America and Far East Asia (Mandl et al. 1993). Remarkable disease is rare (Hoang Johnson et al. 2010), but encephalitis in humans may be associated with signicant neurologic sequelae. The rst case was identied in 1958 in Powassan, Ontario, Canada (McLean and Donahue 1959). The virus appears to be increasing in prevalence in the United States, possibly as a consequence of improved diagnostics leading to increased detection, but equally likely as a consequence of the proliferation of vector tick populations or increased contact

12.1 Introduction .................................................................................................. 261 12.2 Classication and Distribution ..................................................................... 262

12.2.1 Canada ..............................................................................................264 12.2.2 United States .....................................................................................265 12.2.3 Mexico ..............................................................................................265 12.2.4 Russia ................................................................................................265