West Nile Virus

West Nile VurisWest Nile encephalitis is an inflammation of the brain caused by the mosquito-borne West Nile Virus (WNV). WNV is a close relative of St. Louis encephalitis, and first appeared in the New York City area in 1999. West Nile Virus is most common in Africa, the Middle East, and West and Central Asia. It is not known how the virus entered the United States.

Disease Transmission

West Nile encephalitis is transmitted through the bite of a mosquito that is carrying WNV. Mosquitoes become infected with the virus by biting a wild bird that has the virus. Though birds are the primary host of West Nile Virus, it is not transmitted directly from birds to people, or through person-to-person contact.

Symptoms of West Nile Encephalitis

The majority of people who are infected with West Nile Virus show no symptoms. Some may experience mild sickness, headache, or fever before making full recovery. However, WNV can cause serious disease that affects the brain in some individuals, particularly the elderly. This disease can cause permanent neurological damage, resulting in death. Symptoms of West Nile Virus infection can be as mild as headache, slight fever, swollen lymph glands, rash or as severe as high fever, disorientation, stiff neck, muscle weakness, paralysis, coma or death.

Who is at Risk of Contacting West Nile Encephalitis?

The chance of contracting WNV is higher in persons over 50 years of age, however any individual living in areas where West Nile Virus has been detected is at risk. In a 1999 survey of New York City residents, 3% of residents had been infected with West Nile Virus, most showed no symptoms or only a mild illness. The case fatality rate is between 3 and 15 percent. Horses are also susceptible to West Nile Virus.

Diagnosis and Treatment

West Nile Virus has no specific therapy or treatment. To date there are no prophylactic treatments such as vaccines to protect against infection. However, the symptoms and complications resulting from infection can be treated. In severe cases, intensive supportive therapy are needed, such as hospitalization and nursing care, airways management and respiratory support, intravenous (IV) fluids, and prevention of secondary infections such as pneumonia.

Prevention and Control - Municipal Level

Prevention and ControlControl of West Nile Virus requires an extensive Integrated Mosquito Management plan.

Key components to the plan include:

  • Bird surveillance to detect and monitor for WNV activity (Substantial amounts of dead crows may be an indicator of WMV).
  • Mosquito surveillance to detect and monitor for WMV activity and to identify vectors
  • Community education
  • Larviciding before transmission occurs in all possible
    • breeding areas, including:
    • Catch basins
    • Floodwater sites
    • Sewage treatment plants
    • Roadside ditches
    • Wetland areas
  • Effective mosquito adultciding to reduce potential vector populations.

Prevention Control - Residential Level

You can help reduce the number of mosquitoes in your community by simply eliminating standing water, where mosquitoes breed.

  • Dispose of any waste that could hold water, such as cans, containers and tires.
  • Drill holes in the bottom of trash receptacles and recycling bins.
  • Clean your home’s roof gutters frequently, and check storm drains and window wells.
  • Empty standing water from boats, trailers, toys, wheelbarrows, and pots. Turn them over when not in use.
  • Do not allow water to stagnate in swimming pools, water gardens, ornamental pools or birdbaths.
  • Ornamental pools should be aerated or stocked with fish.
  • Swimming pools should be cleaned and chlorinated when not in use.
  • Inspect and change the landscape of your property to eliminate any standing water. Remember that in warm weather, mosquitoes can breed in a puddle of water.

Protecting Yourself

Now that you’ve eliminated the mosquitoes’ breeding grounds, here are some ways to protect yourself and family from being bitten by mosquitoes.

  • Inspect all window and door screens to be sure they are "bug-tight".
  • Stay indoors at the times when mosquitoes are most prevalent: morning, dusk and early evening. When you are outdoors, cover up with long pants and a long-sleeved shirt.
  • Use insect repellent. Repellents deter mosquitoes from biting when applied properly to exposed skin and clothing. Especially important is the use of repellant containing DEET (N, N-diethyl-meta-toluamide), Picaridin, (KBR 3023), synthesized Oil of Lemon Eucalyptus (PMD) or IR3535 when mosquitoes are active. For more information about repellents visit the CDC's page at: CDC West Nile Repellent

DuPage County Health Department's Personal Protection Index (PPI)

The DuPage County Health Department has developed this Personal Protection Index (PPI) as part of a public health education campaign to help inform residents of current local WNV activity as well as steps we should follow to protect ourselves and others. This
PPI widget is set to update weekly on Wednesdays at 3:00PM based on the Health Department's most recent review of mosquito surveillance and reported human cases. The PPI is easily recognizable, simple to understand, and viewable across many governmental and public websites.

For additional information about the PPI index, visit the Health Department at this link   PPI on the DuPage County Health Department

How to Report Dead and Dying Birds

Crows, blue jays, and hawks appear highly sensitive to West Nile Virus. Informing your local health department of dead bird sightings could provide an early warning for detecting WNV activity in your community, and would allow health officials to alert residents of the disease. If you find a bird that appears to have died of natural causes within the last 48 hours, between April and late October, you should notify the Health Department at DuPage County. Please read the brief summary at the Health Deprtment's link to know which birds to report and when, then use their convenient on-line reporting tool.  DuPage County Health Dept WNV bird reporting link

Other Valuable Links:
CDC West Nile page

WNV on the Illinois Department of Health website page