"Epidemiology "
"Radiographic features "
"Treatment and prognosis "
"Differential diagnosis "
"Lethargy, reduced consciousness, coma, generalised weakness, hemi-/paraplegia, facial palsy, ataxia, meningism and seizures are commonly reported 4. Once infected, the likelihood of then developing neuroinvasive disease, namely aseptic meningitis and meningoencephalitis, is unknown."
"Due to its high mortality rate (10-15%) and high incidence of permanent neurological deficits, Powassan virus disease is a nationally notifiable condition in Canada and the USA 1,2,13."
"Ticks of the Ixodes genus, namely Ixodes cookei and Ixodes scapularis serve as both reservoirs and vectors of this neuroinvasive tibovirus in North America and the Russian Far East 2. The incidence of Powassan virus disease has increased by approximately 671% since 1999, with 39 cases of neuroinvasive disease reported to the CDC in 2019 1,4. Cases peak in the spring and autumn months 5."
"The Powassan virus is a small, enveloped tibovirus of the Flaviviridae family 12."
"West Nile virus"
"Saint Louis encephalitis virus"
"Japanese encephalitis virus"
"Eastern equine encephalitis virus"
"Western equine encephalitis virus"
Expected headings
"Epidemiology "
"Radiographic features "
"MRI"
"Treatment and prognosis "
"Differential diagnosis "
"Seroprevalence rates suggest the majority of infections are undetected 4. The incubation period may be up to 34 days 4. Symptoms of viral infection, such as fever, rash, malaise and gastrointestinal disturbance, as well as a history of outdoor activity and/or a tick bite, precede the development of neurological symptoms 5."
"Lethargy, reduced consciousness, coma, generalised weakness, hemi-/paraplegia, facial palsy, ataxia, meningism and seizures are commonly reported 4. Once infected, the likelihood of then developing neuroinvasive disease, namely aseptic meningitis and meningoencephalitis, is unknown."
"At low titres of Powassan viraemia, tick saliva may enhance transmission and dissemination of the infection into the CNS 8. This results in spongiform encephalopathy, neuronal necrosis, and reactive gliosis mainly at the cerebellum, brainstem and spinal cord 9,10."
"However, a tick may well go unnoticed. The history, examination and MRI findings may also cause one to consider related pathogens:"
"Lethargy, reduced consciousness, coma, generalised weakness, hemi-/paraplegia, facial palsy, ataxia, meningism and seizures are commonly reported 4. Once infected, the likelihood of then developing neuroinvasive disease, namely aseptic meningitis and meningoencephalitis, is unknown."
"MRI is the modality of choice for viral encephalitis. Imaging findings are non-specific and similar to those of the other endemic encephalitides; the presence of Powassan-specific IgM in the CSF or serum is required for confident diagnosis."
"cortical lesions are uncommon 5; reversible restricted diffusion throughout the cortex has been reported in one patient 5"
"Supportive treatment is the mainstay of care, with avoidance of ticks the primary mechanism of prevention. The mortality is reported as 10-15%; permanent neurological deficits are seen in 50% of patients 5. There are currently no vaccines available 9."
"Supportive treatment is the mainstay of care, with avoidance of ticks the primary mechanism of prevention. The mortality is reported as 10-15%; permanent neurological deficits are seen in 50% of patients 5. There are currently no vaccines available 9."
"Supportive treatment is the mainstay of care, with avoidance of ticks the primary mechanism of prevention. The mortality is reported as 10-15%; permanent neurological deficits are seen in 50% of patients 5. There are currently no vaccines available 9."