West Nile Virus
Overview
West Nile virus (WNV) in Wisconsin is a virus that is transmitted by
mosquitoes. Birds are mainly affected, but the virus may be spread
to humans and other animals such as horses. There is no human to
human spread of WNV.
An estimated that 80% of people infected by West Nile virus never
experience symptoms. Most of the remaining 20% will experience relatively mild
illness, with symptoms such as fever, headache, muscle pains, a skin rash, swollen lymph nodes, nausea and vomiting.
Less than one percent (approximately one of every
150 people) infected with WNV become seriously ill.
Older persons are at an increased risk of severe illness from WNV.
Severe symptoms include a sudden onset of a high fever, neck stiffness,
extreme muscle weakness, tremors, convulsions, or disorientation. Hospitalization and death may occur as a result of serious illness from
WNV.
There is no specific
treatment or vaccine for humans infected with WNV but physicians treat
patients to minimize symptoms of the infection. If you think you may
have been infected with WNV, contact your health care provider.
Surveillance Methods
West Nile Virus Surveillance Plan (includes wild bird surveillance)
(PDF, 15 KB)
Prevention
Some tips to protect yourself include:
- Use effective mosquito repellant and apply according to the label
instructions. More information on CDC web site West
Nile Virus prevention (Exit
DHS).
- Wear long-sleeved shirts, long pants, socks, and shoes.
- Mosquitoes may bite through thin clothing, so spraying clothes
with a repellent containing permethrin or DEET will give extra
protection. These repellants are the most effective and most
studied.
- Avoid being outside during times of high mosquito activity,
specifically around dawn and dusk.
- Keep window screens repaired so that mosquitoes cannot enter your
home.
- Dispose of discarded tires, cans, or plastic containers left
outside that may contain standing water.
- Drain standing water from pool or hot tub covers.
- Turn over plastic wading pools and wheel barrows when not in use.
- Change the water in bird baths, pet dishes and wading pools every
3-4 days.
- Keep drains, ditches and culverts clean of trash and weeds so
water will drain properly.
- Clean gutters to ensure they drain properly.
Insect
repellent products, use, and safety information (Exit DHS)
Role
of pesticides in mosquito control (Exit DHS)
Information for Health Professionals
West
Nile virus is reportable in Wisconsin
WNV
Clinical characteristics (Exit DHS)
Risk
Factors for WNV infections (Exit DHS)
Laboratory
Guidance
We
will continue to confirm all presumptive positive laboratory results
reported by physicians and private laboratories at the
Wisconsin State Laboratory of Hygiene (WSLH).
Physicians should order the arboviral panel testing due to cross
reactivity among the agents.
Available
diagnostic tests at the WSLH include IgM capture enzyme immunoassays
(IgM CEIA) that will identify IgM antibodies in serum and cerebrospinal
fluid (CSF) specific to La Crosse (LAC) encephalitis virus, and Eastern
Equine encephalitis (EEE) virus. A microsphere immunoassay is used to
test serum and CSF for IgM specific to WNV and St. Louis encephalitis (SLE)
virus. Clinicians should
also consider enterovirus PCR and culture testing of the CSF (WSLH test
code 1507 pcr) for patients with apparent aseptic meningitis.
Confirmatory testing: The
WSLH will no longer perform the Plaque Reduction Neutralization assay (PRNT)
on equivocal results, but will send them to CDC for confirmation.
The decision to perform confirmatory testing will require
approval of the Division of Public Health (DPH) or the WSLH.
Confirmatory testing for other arboviruses (LAC, EEE, SLE) will continue
to be performed by the CDC.
Wisconsin
Local Health Departments - Regional Offices - Tribal Agencies
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WNV Home | Overview |
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Last Revised: May 01, 2012
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