Deer Tick Virus (DTV) is an arbovirus closely related to Powassan Virus (POWV) but has a different vector and range of vertebral hosts.
The Powassan Virus is Lineage I POWV.
DTV is Lineage II POWV.
Genus: Flavivirus
Vector: Ixodes scapularis (deer tick), Dermacentor andersoni
Usual hosts: white-footed mice, fox, opossum, woodchucks, raccoons
Distribution: northeastern United States, north central United States, Canada
Incubation period: 1 to 5 weeks
Clinical findings:
(1) fever
(2) myalgia with weakness
(3) encephalitis (decreased level of consciousness, memory loss, seizures, focal neurological findings)
(4) skin rash
(5) gastrointestinal symptoms (vomiting)
(6) acute flaccid paralysis
(7) severe neurological disease with death
Laboratory findings:
(1) CSF pleocytosis (up to 700 per µL)
(2) variable mild thrombocytopenia
The diagnosis is made based on:
(1) isolation of virus
(2) IgM antibodies on ELISA, confirmed by plaque neutralization test
(3) CSF IgM antibodies to Powassan antigen
(4) 4-fold rise in titer
(5) molecular method
A tick infected with DTV may also spread Lyme's borreliosis.
