Powassan Virus—A New Reemerging Tick-Borne Disease

Abstract

Powassan virus is a neurovirulent flavivirus consisting of two lineages causing meningoencephalitis. It is the only member of the tick-borne encephalitis serogroup which is present in mainland North America. With a total number of 27 cases from 1958 to 1998 and 98 cases from 1999 to 2016, reported cases have increased by 671% over the last 18 years. Powassan infection is transmitted by different tick species in different geographical regions. Ixodes scapularis is the primary vector that transmits the virus on the East Coast of US and Ixodes cookei in the Midwest and Canada, while Hemaphysalis longicornis is the vector in Russia. Powassan has no singular pathognomonic finding and presents with a wide spectrum of symptoms including severe neurological symptoms. The clinical challenge lies within the management of the disease as there is no standard diagnostic protocol and most cases are only diagnosed after a patient goes through an extensive workup for other infectious disease. The diagnosis is established by a combination of imaging and serologic tests. In case of Powassan meningoencephalitis, computed tomography scan and magnetic resonance imaging show vascular insults, which are also seen in cases of tick-borne encephalitis virus, another flavivirus of medical importance. Serologic tests are the gold standard for diagnosis, although testing is not widely available and only state health departments and Center for Disease Control and Prevention can perform Powassan-specific IgM antibody testing utilizing enzyme-linked immunosorbent assay and immunofluorescence antibody. Powassan is also of veterinary medical importance. Wildlife animals act as a reservoir to the pathogens, hence possessing threat to humans and domestic animals. This review highlights Powassan’s neurotropic presentation, epidemiology, diagnostic challenges, and prevalence. Strong emphasis is placed on establishing diagnostic protocols, widespread Powassan-specific IgM testing, role of the vector in disease presentation, and necessary preventive research.

Nanoscale Structure Determination of Murray Valley Encephalitis and Powassan Virus Non-Coding RNAs

“…Viruses 2019, 12,190 5 of 18 14.5 mL) for each RNA and analyzed them using Urea-PAGE ( Figure 2B). As demonstrated in Figure 2B, RNAs migrate similarly and are highly pure, devoid of any aggregation or degradation, except minor degradation of MVEV 5' TR.…”

“…PowV is the only member of the tick-borne encephalitis serogroup that is currently present in North America [11]. There has been a drastic increase in PowV over the last 18 years as compared to the previous 40 years with an increase of 671% of infections in humans [12]. It was first identified in Powassan, Ontario in 1958 [13] and has become endemic in the upper Midwest and the Northeastern United States, but there have also been cases reported in eastern Russia [14].…”

Dissecting Flavivirus Biology in Salivary Gland Cultures from Fed and UnfedIxodes scapularis(Black-Legged Tick)

“…This may be suggestive of the possibility that the two lineages of POWV may multiply differently in I. scapularis and that the results may reflect differences in transmission efficiency. This is an interesting observation since I. scapularis is considered a natural vector for POWV-L2 (8,(16)(17)(18)(19)(20)(21), whereas other ixodid tick species (H. longicornis, I. spinipalpis, I. cookei, and I. marxi) are implicated in maintenance of POWV-L1 (8)(9)(10)(11)(12)(13)(14). POWV-L2 has been found in natural populations of D. andersoni (20,22), but the natural transmission cycle of POWV with this tick species remains unclear.…”

“…The lineages are suggested to have different ecological life cycles, including different tick vectors, mammalian hosts, and habitats (6,8). POWV-L1 has been isolated from Haemaphysalis longicornis, Ixodes spinipalpis, Ixodes marxi, and Ixodes cookei (8)(9)(10)(11)(12)(13)(14). POWV-L2 has been isolated from the black-legged tick, Ixodes scapularis (15)(16)(17)(18)(19)(20)(21) and the Rocky Mountain wood tick, Dermacentor andersoni (20,22).…”

Nanoscale Structure Determination of Murray Valley Encephalitis and Powassan Virus Non-coding RNAs

“…PowV is the only member of the tick-borne encephalitis serogroup that is currently present in North America [10]. PowV has seen a drastic increase in the last 18 years, compared to the previous 40 with an increase of 671% [11]. It was first identified in Powassan, Ontario in 1958 [12] and has become endemic in the upper Midwest and the Northeastern United States, but cases have also been reported in eastern Russia [13].…”