West Nile Virus

State of Wisconsin
Department of Health and Family Services
Jim Doyle, Governor
Karen E. Timberlake, Secretary

June 25, 2008
For Immediate Release

Contact: Stephanie Marquis, Department of Health and Family Services (608) 266-1683
Bob Wakeman, Department of Natural Resources (262) 574-2149

Take Steps to Reduce Mosquito Populations
Protect yourself against bites

Following June's heavy rains and flooding across the state, State health and environmental officials urge residents to take simple steps to reduce exposure to mosquitoes.

Mosquitoes that carry West Nile virus tend to breed in places where there is standing, stagnant water with a high concentration of organic content. Containers that hold water for an extended period of time, such as birdbaths and gutters, are breeding sites for these mosquitoes because they lack the natural predators found in wetlands and lakes. According to the Department of Natural Resources, even a single discarded tire can produce 500 mosquitoes.

Mosquito larvae must live in still water for five or more days to complete their growth before changing into adult mosquitoes capable of transmitting disease. Effective ways to prevent your home from becoming a mosquito breeding site include:

Properly dispose of items that hold water such as tin cans, plastic containers, ceramic pots or discarded tires.
Clean roof gutters and downspouts for proper drainage.
Turn over wheelbarrows, wading pools and canoes when not in use.
Change the water in birdbaths and pet dishes at least every three days.
Clean and chlorinate swimming pools, outdoor saunas and hot tubs; drain water from pool covers.
Trim tall grass, weeds and vines since mosquitoes use these areas to rest during hot daylight hours.
Plug tree holes.

The State does not recommend individual application of larvicides—chemicals that kill mosquito larvae—to standing bodies of water on your property. Application of larvicides is a complex, expensive technique that is ineffective unless carried out as part of a comprehensive, integrated mosquito control program. In addition, a DNR permit is required to apply larvicides to any body of water belonging to the state (i.e. ponds, lakes, rivers). To apply for the necessary permit, contact the Wisconsin Department of Natural Resources.

Below are effective steps to protect yourself from mosquito bites:

Make sure window and door screens are in good condition to prevent mosquito entry.
Limit time spent outside at dawn and dusk, when mosquitoes are most active.
Avoid shaded areas where mosquitoes may be resting.
Wear pants and long sleeves shirts when outdoors. Light clothing may reduce the attraction of mosquito and loose fitting clothing may help prevent mosquitoes from biting through to the skin.
Apply insect repellant to skin and clothing. The Centers for Disease Control and Prevention recommends using products that contain active ingredients approved and registered by the U.S. Environmental Protection Agency.

For information about mosquito control or WNV infection and surveillance visit the Department of Health and Family Services http://dhfs.wisconsin.gov/ Department of Natural Resources http://www.dnr.wi.gov/ or Centers for Disease Control and Prevention http://www.cdc.gov/

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WISCONSIN DIVISION OF PUBLIC HEALTH
Department of Health & Family Services

West Nile Virus Infection
(West Nile Encephalitis, West Nile Fever)

CDC West Nile Informational Flyer www.cdc.gov/westnile

Disease Fact Sheet Series

What is a West Nile virus infection?

It is an infection caused by West Nile virus, which is spread to people by the bite of a mosquito infected with the virus. Viruses that are spread by mosquitoes are called arboviruses. In temperate climates, West Nile virus infections generally occur during warm weather months when mosquitoes are active.

Is West Nile fever a new disease?

No. This virus was first identified in 1937 in Uganda, Africa. Prior to 1999, the virus had only been identified in Africa, Europe, the Middle East, and Asia. West Nile virus was first detected in the United States in 1999, when 62 cases of illness and seven deaths from West Nile virus were reported in the New York City area. West Nile virus has spread across the U.S. and into Canada and Latin America since that time. The virus was found in Wisconsin for the first time in 2001 in infected wild birds. The first human infections of West Nile virus in Wisconsin were documented in 2002.

How is West Nile virus spread?

This virus is spread primarily through mosquitoes. Mosquitoes get infected with West Nile virus by feeding on infected birds. Once infected with the virus, a mosquito will transmit the virus to other animals or birds when they take another blood meal. In 2002, there were rare cases of West Nile virus infections that were transmitted to people by blood transfusions or organ transplants from donors unknowingly infected with West Nile virus.

Who gets West Nile virus?

Anyone can get infected with West Nile virus. Older persons are at an increased risk of severe disease from the virus.

What are the symptoms of a West Nile virus infection?

Approximately 80% of people infected with West Nile virus do not become ill. Most of the remaining 20% of infected people may experience a mild illness that can present with fever, headache, eye pain, muscle aches, joint pain, a rash on the trunk, swollen lymph nodes, nausea and vomiting. Less than 1% of people infected with West Nile virus will become severely ill. Symptoms of severe illness

include extreme muscle weakness, inflammation of the brain (encephalitis), paralysis, and coma. In rare cases the infection may be fatal, particularly in the elderly and people with other medical conditions.

How soon after being bitten by a West Nile virus infected mosquito do symptoms occur?

Symptoms usually occur 3 to 14 days after a West Nile virus infected mosquito bites a person.

Does past infection with this virus make a person immune?

Yes. Prior infection with West Nile virus can provide prolonged to lifelong immunity to the virus.

What is the treatment for West Nile virus infection?

There is no specific treatment for West Nile virus infection. A physician may provide treatment to relieve the symptoms of the illness. In severe cases hospitalization may be required.

What can be done to prevent an infection with West Nile virus?

Preventing mosquito bites will prevent West Nile virus infection. To decrease exposure to mosquitoes and the viruses they may carry; personal protective measures include:

limiting the time spent outdoors at dawn and dusk during mosquito season (June to September) or other times mosquitoes are active
wearing shoes, socks, long sleeve shirts and long pants when outdoors
applying insect repellents containing an EPA-registered ingredient, such as DEET, to exposed skin when outdoors
spraying clothing with insect repellents since mosquitoes may bite through thin clothing
making sure your home window and door screens are in good repair to prevent mosquito entry.

Reducing mosquito populations will also reduce mosquito bites. In some communities, public funded surveillance and control programs reduce mosquito populations by eliminating mosquito breeding habitat, mosquito larvae or adults.

You can also take action to eliminate or reduce mosquito breeding sites and sources of standing water on your own property:

Dispose of tin cans, plastic containers, ceramic pots or similar water-holding containers.
Remove all discarded tires.
Drill holes in the bottoms of recycling containers that are kept outdoors.
Make sure roof gutters drain properly and clean clogged gutters.
Change water in birdbaths regularly.
Turn over wheelbarrows, wading pools, and boats when not in use.
Clean and chlorinate swimming pools, outdoor saunas and hot tubs.
Drain water from pool covers.
Use landscaping to eliminate standing water that collects on your property.

DEVELOPED BY THE DIVISION OF PUBLIC HEALTH,
BUREAU OF COMMUNICABLE DISEASE
COMMUNICABLE DISEASE EPIDEMIOLOGY SECTION
PPH 42104 (Rev. 07/06)

Additional Information: CDC West Nile Informational Flyer
www.cdc.gov/westnile