Powassan (POWV) virus infection
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Powassan virus (POWV) infection is a rare tickborne arbovirus
infection, transmitted by the bite of infected deer/blacklegged tick (Ixodes
the same tick that causes other tickborne diseases in Wisconsin,
including Lyme disease. POWV is the only tickborne virus that is part of
the arbovirus group (including West Nile virus) occurring in Wisconsin
and other parts of North America (Maine, Michigan, Minnesota, New Jersey,
New York, Vermont, and Canada). The presence of POWV has been documented
in several ticks species (Ixodes spp., Dermacentor andersoni) and
small and medium-sized mammal species (rodents, woodchucks, and skunks).
The first case of Powassan identified in Wisconsin was in 2003.
People who are infected with POWV may experience a variety of
symptoms from mild illnesses to life threatening complications; some
people may not have any symptoms. Symptoms of illness usually begin 7-14
days (range 8-34 days) after being exposed to an infected tick bite.
Signs and symptoms include acute onset of fever, muscle weakness,
confusion, headache, nausea, vomiting, and stiff neck. Severe illness
can include confusion, paralysis, speech difficulties, memory loss, and
meningoencephalitis (inflammation of the brain and meninges).
Tickborne infections home
Data and statistics
Information for health professionals
This is a Wisconsin disease surveillance category II disease:
the patient's local public health department electronically, through the Wisconsin
Electronic Disease Surveillance System
(WEDSS), by mail or fax using an Acute and Communicable Disease case
report F-44151 or by other means within 72 hours
upon recognition of a case.
Information on communicable disease reporting
Wisconsin case reporting and public health follow-up
case report (PDF, 531 KB)
- Laboratory Guidance
- Because POWV is part of the arbovirus group, symptoms of Powassan
virus infection are similar to other arboviral infections and can be
difficult to differentiate. Blood tests can detect antibodies to POWV
but are not readily available in commercial laboratories. However,
testing can be requested through the Wisconsin State Laboratory of
Hygiene for the arbovirus panel (West Nile, California/La Crosse, St.
Louis, Eastern, and Western equine encephalitis virus) including
Powassan virus testing. Confirmation for POWV will be performed at the
Centers of Disease Control and Prevention (CDC).
The Wisconsin State Laboratory of Hygiene (WSLH) performs arbovirus
screening by a combination of tests including IgM capture enzyme
immunoassays (IgM CEIA) and Microsphere Immunoassay for IgM antibodies
performed on serum and cerebrospinal fluid (CSF). The WSLH will forward
positive samples to CDC for confirmatory testing by Plaque Reduction
Neutralization assay (PRNT). The WSLH offers arbovirus panel testing for
fee-for-service. Meeting clinical criteria is not required to submit
serum or CSF specimens to the WSLH for fee-for-service arboviral
- The Wisconsin Division of Public Health (DPH) continues to monitor
for POWV as part of our enhanced arbovirus surveillance. Testing for
POWV as part of the DPH investigation may be fee-exempt. Please contact
the Vectorborne Disease Epidemiologist at 608-267-0249 for fee-exempt
- Fee-exempt arboviral testing criteria
Fee-exempt testing for arbovirus infection including Powassan virus will
be offered to clinicians whose patients meet one of the following
- Request for confirmatory testing of positive IgM and IgG
commercial test results (performed at laboratories other than the
- POWV is the suspected agent causing illness and testing for other
arboviruses (West Nile, California/La Crosse, St. Louis, Eastern
equine, and Western equine encephalitis) demonstrated negative IgM
- The patient has signs and symptoms of meningitis (fever, headache,
and stiff neck) or encephalitis (fever, headache, and altered mental
status ranging from confusion to coma), or acute flaccid paralysis
(AFP) with no other laboratory diagnosis
- The patient has a diagnosis of Guillain-Barré syndrome and no
other laboratory diagnosis
- The local health department may request fee-exempt testing be
performed if the case-patient lacks insurance coverage or the
ability to pay.
- Collection and shipping of clinical specimens to the WSLH
- Specimens submitted to the WSLH for fee-exempt testing must
include the WSLH - Enhanced Wisconsin Arbovirus Surveillance Form
provided by the Vectorborne Epidemiologist.
- Specimens submitted for fee-for-service testing must use the
WSLH CDD Requisition Form B). Please contact the WSLH-Clinical Stock Orders, for ordering of kits and WSLH CDD
Requisition Form B at 1-800-862-1088 or 608-265-2966.
- At least 3-7 mls of serum and/or >1ml of CSF in sterile
screw-capped vials should be submitted on cold packs.
- It is essential that the lab requisition forms be as complete as possible
including the patient name, city, date of birth, specimen type,
submitting agency, onset date, signs and symptoms, and collection
Note: Testing for POWV may be delayed on specimens with laboratory
forms missing the above requested data until information is available.
Local Health Departments - Regional offices - Tribal agencies
Diep Hoang Johnson
Vectorborne Disease Epidemiologist
Wisconsin Division of Public Health
Bureau of Communicable Diseases
(Phone 608-267-0249) (Fax 608-261-4976)
August 20, 2014