摘要 : Powassan virus is a tick-borne flavivirus that circulates widely throughout parts of North America and eastern Russia. Closely related to tick-borne encephalitis virus, Powassan virus was first identified in an encephalitic child ... 展开 Powassan virus is a tick-borne flavivirus that circulates widely throughout parts of North America and eastern Russia. Closely related to tick-borne encephalitis virus, Powassan virus was first identified in an encephalitic child from Powassan, Ontario, in 1958 (though was later retrospectively identified in ticks from northern Colorado from 1952). Powassan virus has 2 distinct genetic lineages that are clinically and serologically indistinguishable: lineage 1 (prototype Powassan virus) and lineage 2 (also known as deer tick virus). The primary vectors of Powassan virus are Ixodes species of ticks including Ixodes cookei (lineage 1), Ixodes marxi (lineage 1), and Ixodes scapularis or the black-legged/deer tick (lineage 2). Small- to medium-sized forest rodents are thought to be amplifying hosts. In the United States, there have been 125 human cases of Powassan virus disease reported from 2008 to 2017, mostly from the Northeast and Great Lakes regions. Minnesota (n = 32), Wisconsin (n = 22), New York (n = 16), and Massachusetts (n = 16) reported the highest number of cases during this time period, possibly due to increased burden of disease and/or enhanced surveillance in these states. Most cases of Powassan virus disease occur from mid-spring through late fall (peaking in May and June), coinciding with when Ixodes species of ticks are most active. While all ages groups and both sexes can be affected, there appears to be a male predilection. Powassan vims disease has been historically underrecognized, though recognition may be improving with increased arboviral surveillance and education. 收起