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Powassan virus
Epidemiology:
- found in the warm climate across Eurasia
- also exists in North America
- Northeastern & North central U.S.
- transmitted by ticks of the Genus Ixodes & Dermacentor ticks
- transmitted by Ixodes scapularis tick [2]
- maintained in a rodent reservoir [2]
- ~60 cases in the United States reports 2005-2015 [2]
- 5 cases in northern New England & 13 cases in Massachusetts were reported from 2013-2016 [2]
Pathology:
- rare cause of viral encephalitis
- cerebral edema
- involvement of the basal ganglia & thalamus are common
Clinical manifestations:
- fever
- headache
- vomiting
- weakness
- confusion
- seizures
- memory loss
- Parkinsonism
Laboratory:
- Powassan virus serology*
- Powassan virus IgM in serum*
- Powassan virus IgM in CSF*
- Powassan virus IgG in serum
- Powassan virus RNA
- plaque reduction neutralization test (confimatory)
* detection of the virus in blood or CSF with PCR is generally feasible only during the prodromal phase, thus diagnosis usually relies on serology [2]
* IgM serology 1st line, bur false positives due to cross-reactivity with other flaviviruses [2]
Complications:
- long-term neurologic problems may occur [2]
Management:
- intravenous fluids
- respiratory support as needed
- glucocorticoids as needed to reduce cerebral edema
- prevention:
- insect repellant (repells ticks)
- inspect for ticks after travelling through bushy &/or wooded areas
Interactions
disease interactions
General
arbovirus
flavivirus
viral encephalitis
Properties
KINGDOM: virus
GENOME-TYPE: RNA
SINGLE-STRANDED
NEGATIVE-STRAND
GENOME-SIZE: 10 kB
ENVELOPE: PRESENT
CAPSID-SYMMETRY: ICOSAHEDRAL
References
- Wikipedia: Powassan virus
https://en.wikipedia.org/wiki/Powassan_virus
- Rothaus C
A Woman with Fever, Headache, and Progressive Encephalopathy
NEJM Resident 360. Jan 23, 2019
https://resident360.nejm.org/content_items/a-woman-with-fever-headache-and-progressive-encephalopathy
- Centers for Disease Control & Prevention (CDC)
Powassan Virus
http://www.cdc.gov/powassan/