Maine CDC Health Advisory
June 29, 2021
Human Powassan Case and Arbovirus Update for Healthcare Providers in Maine
The purpose of this health advisory is to alert clinicians to the potential for human arboviral disease activity in Maine and to consider testing for arboviruses in patients presenting with unexplained encephalitis, meningitis or high fever (100.4F or 38C) during the summer and fall.
Maine CDC identified a human case of Powassan encephalitis in a Maine resident who resides in midcoastal Maine. The individual was symptomatic in late June and hospitalized. CDC Fort Collins confirmed the Powassan result in this individual by neutralization testing.
This individual likely acquired this Powassan encephalitis infection in the state of Maine. There are two types of Powassan virus in the United States. The first type, often called lineage 1 Powassan virus is associated with Ixodes cookei or the woodchuck tick. Lineage 2 POW, sometimes called Deer tick virus, is associated with Ixodes scapularis or the deer tick. Both can cause human disease. Powassan encephalitis is a member of the flavivirus genus which includes arboviruses like Dengue virus, West Nile virus (WNV), Yellow Fever virus, and Zika virus.
Arboviral diseases, including Eastern equine encephalitis (EEE), Jamestown Canyon virus (JCV), and WNV, are serious infections that are transmitted by the bite of an infected mosquito. Maine reported one human case of WNV in 2020. Additionally, Powassan virus is an arboviral disease transmitted by the bite of an infected tick. Maine identified one case of Powassan virus disease in residents during 2020. Although rare, these diseases have potentially severe and even fatal consequences for those who contract them.