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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 ...
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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.
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Arboviruses are arthropod-borne viruses transmitted by the bite of mosquitoes, ticks, or other arthropods. Arboviruses are a common and an increasing cause of human illness in North America. Powassan virus, Chikungunya virus, and ...
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Arboviruses are arthropod-borne viruses transmitted by the bite of mosquitoes, ticks, or other arthropods. Arboviruses are a common and an increasing cause of human illness in North America. Powassan virus, Chikungunya virus, and Zika virus are arboviruses that have all recently emerged as increasing causes of neurologic illness. Powassan virus almost exclusively causes encephalitis, but cases are rare, sporadic, and restricted to portions of North America and Russia. Chikungunya virus has spread widely across the world, causing millions of infections. Encephalitis is a rare manifestation of illness but is more common and severe in neonates and older adults. Zika virus has recently spread through much of the Americas and has been associated mostly with microcephaly and other congenital neurologic complications. Encephalitis occurring in infected adults has also been recently reported. This review will discuss the neuropathogenesis of these viruses, their transmission and geographic distribution, the spectrum of their neurologic manifestations, and the appropriate method of diagnosis.
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We describe a patient with severe and progressive encephalitis of unknown etiology. We performed rapid metagenomic sequencing from cerebrospinal fluid and identified Powassan virus, an emerging tick-borne flavivirus that has been ...
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We describe a patient with severe and progressive encephalitis of unknown etiology. We performed rapid metagenomic sequencing from cerebrospinal fluid and identified Powassan virus, an emerging tick-borne flavivirus that has been increasingly detected in the United States.
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Deer tick virus (DTV), a variant of Powassan virus (POWV), appears to be maintained in nature in an enzootic cycle between Ixodes scapularis ticks and small mammals. Although POWV infection of human beings is rare, a recent report...
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Deer tick virus (DTV), a variant of Powassan virus (POWV), appears to be maintained in nature in an enzootic cycle between Ixodes scapularis ticks and small mammals. Although POWV infection of human beings is rare, a recent report suggests increasing incidence and the possibility that POWV may be an emerging tick-borne zoonosis. Therefore, we assessed the long-term stability of the POWV transmission cycle in northwestern Wisconsin. Adult I. scapularis and Dermacentor variabilis were collected from Hayward and Spooner, Wisconsin, screened for infection by reverse transcriptase polymerase chain reaction (RT-PCR), and virus was isolated. Seventeen of 1,335 (1.3%) of I. scapularis and 0 of 222 (0%) of D. variabilis ticks were infected. All isolated virus belonged to the DTV genotype of POWV. These findings suggest stable transmission of POWV in this focus over ten years and highlight the potential for this agent to emerge as a public health concern.
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In 2019, a geographically focal cluster of 3 Powassan virus neuroinvasive disease cases occurred in New Jersey. We conducted a serosurvey of 273 adult area residents and estimated that immunoglobulin M seroprevalence was 0.31% (95...
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In 2019, a geographically focal cluster of 3 Powassan virus neuroinvasive disease cases occurred in New Jersey. We conducted a serosurvey of 273 adult area residents and estimated that immunoglobulin M seroprevalence was 0.31% (95% confidence interval [CI], .04%–1.00%) and 23% (95% CI, 7%–100%) of infections result in neuroinvasive disease.
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Background. Powassan virus (POWV) is a tick-transmitted pathogen that may cause severe encephalitis; experimentally, it can be transmitted within just 15 minutes following a tick bite. The deer tick virus subtype of POWV (DTV) is ...
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Background. Powassan virus (POWV) is a tick-transmitted pathogen that may cause severe encephalitis; experimentally, it can be transmitted within just 15 minutes following a tick bite. The deer tick virus subtype of POWV (DTV) is transmitted by the deer tick and is the likely cause of the increase in the number of POWV cases reported in the United States. However, DTV has only been definitively documented in 6 patients by molecular analysis of the virus. Methods. Two patients from Connecticut with encephalitis, who had a recent deer tick bite, were evaluated by the relevant sero-logic tests to determine if they had been infected with POWV. Evaluation also included molecular testing of an adult deer tick that had been removed from one of the patients. Results. We documented neuroinvasive POWV infection in 2 children from Connecticut. Based on the results of testing the tick removed from case 2, this patient was infected by DTV, representing the 7th reported case and the first documented case of DTV infection in a child. Of note, the duration of the tick bites in both cases was very short. Conclusions. We provide the first clinical and epidemiologic evidence that POWV/DTV can be rapidly transmitted to a human host, that is, within hours of tick attachment, which is distinctive when compared to other deer tick-transmitted infections such as Lyme disease.
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In 1958, a 5-year-old boy from Powas-san, Ontario, Canada, died from a severe form of encephalitis. A virus was isolated from brain tissue and named after the hometown where the child resided [l]. Since its original description, f...
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In 1958, a 5-year-old boy from Powas-san, Ontario, Canada, died from a severe form of encephalitis. A virus was isolated from brain tissue and named after the hometown where the child resided [l]. Since its original description, fewer than 100 cases of Powassan virus encephalitis have been reported in North America; in addition, at least 17 cases have been reported from the Primorski Krai region of Russia.
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Background. Powassan virus (POWV) is a rarely diagnosed cause of encephalitis in the United States. In the Northeast, it is transmitted by Ixodes scapularis, the same vector that transmits Lyme disease. The prevalence of POWV amon...
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Background. Powassan virus (POWV) is a rarely diagnosed cause of encephalitis in the United States. In the Northeast, it is transmitted by Ixodes scapularis, the same vector that transmits Lyme disease. The prevalence of POWV among animal hosts and vectors has been increasing. We present 8 cases of POWV encephalitis from Massachusetts and New Hampshire in 2013-2015.
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