Fight the bite the west nile virus updated and current as of 17 july 2003
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Fight the Bite! The West Nile Virus Updated and current as of 17 July 2003 PowerPoint PPT Presentation

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Fight the Bite! The West Nile Virus Updated and current as of 17 July 2003. Infection Area so far in 2003 as of July 16, 2003. Human cases in the U.S. in 2003. Human Cases in the U.S. in 2002. Human cases in Ohio in 2002. Montgomery County. Background.

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Fight the Bite! The West Nile Virus Updated and current as of 17 July 2003

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Fight the bite the west nile virus updated and current as of 17 july 2003

Fight the Bite!The West Nile VirusUpdated and current as of 17 July 2003

Infection area so far in 2003 as of july 16 2003

Infection Area so far in 2003 as of July 16, 2003

Fight the bite the west nile virus updated and current as of 17 july 2003

Human cases in the U.S. in 2003

Human cases in the u s in 2002

Human Cases in the U.S. in 2002

Human cases in ohio in 2002

Human cases in Ohio in 2002

Montgomery County



  • Since West Nile virus (WNV) was first isolated in 1937, it has been known to cause asymptomatic infection and fevers in humans in Africa, West Asia, and the Middle East.

  • Human and animal infections were not documented in the Western Hemisphere until 1999.

  • In 1999 and 2000, outbreaks of WNV encephalitis (inflammation of the brain) were reported in persons living in the New York City metropolitan area, New Jersey, and Connecticut. In these two years, 83 human cases of West Nile illness were reported; 9 died.

  • In 2001, human infection with WNV occurred in 10 states with 66 cases and 9 deaths.

  • In 2002, WNV activity spread to 44 states, with 4,156 human cases and 284 deaths.



  • WNV is transmitted to humans through mosquito bites. Mosquitoes become infected when they feed on infected birds that have high levels of WNV in their blood. Infected mosquitoes can then transmit WNV when they feed on humans or other animals.

  • WNV is not transmitted from person to person and there is no evidence that a person can get infected by handling live or dead infected birds. But, to add a further level of safety, if birds or other potentially infected animals must be handled, a protective barrier (e.g., gloves, inverted plastic bags) should be used.



  • Most WNV infected humans have no symptoms.

  • A small proportion develops mild symptoms that include fever, headache, body aches, skin rash and swollen lymph glands.

  • Less than 1% of infected people develop more severe illness that includes meningitis (inflammation of the spinal cord) or encephalitis.

  • The symptoms of these illnesses can include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis.

  • Of the few people that develop encephalitis, a small proportion die but, overall, this is estimated to occur in less than 1 out of 1000 infections.



  • There is no specific treatment for WNV infection or vaccine to prevent it.

  • Treatment of severe illnesses includes hospitalization, use of intravenous fluids and nutrition, respiratory support, prevention of secondary infections, and good nursing care.

  • Medical care should be sought as soon as possible for persons who have symptoms suggesting severe illness.

Reducing exposure

Reducing Exposure

  • Individuals can reduce their contacts with mosquitoes by taking these actions:

  • When outdoors, wear clothing that covers the skin such as long sleeve shirts and pants,

  • Apply effective insect repellent to clothing and exposed skin, and

  • Curb outside activity during the hours that mosquitoes are feeding which often includes dawn and dusk.

  • In addition, screens should be applied to doors and windows and regularly maintained to keep mosquitoes from entering the home.

Q and a from the cdc

Q and A from the CDC

  • Symptoms of West Nile Virus

  • Q. What are the symptoms of West Nile virus infection?

  • A. Most people who are infected with the West Nile virus will not have any type of illness. It is estimated that 20% of the people who become infected will develop West Nile fever: mild symptoms, including fever, headache, and body aches, occasionally with a skin rash on the trunk of the body and swollen lymph glands.

  • The symptoms of severe infection (West Nile encephalitis or meningitis) include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. It is estimated that 1 in 150 persons infected with the West Nile virus will develop a more severe form of disease.

  • Q. What is the incubation period in humans (i.e., time from infection to onset of disease symptoms) for West Nile encephalitis?

  • A. Usually 3 to 14 days.

  • Q. How long do symptoms last?

  • A. Symptoms of mild disease will generally last a few days. Symptoms of severe disease may last several weeks, although neurological effects may be permanent.

Avoiding exposure fight the bite

Avoiding Exposure - fight the bite

  • When dealing with West Nile virus, prevention is your best bet. Fighting mosquito bites reduces your risk of getting this disease, along with others that mosquitoes can carry. Take the commonsense steps below to reduce your risk, and you'll:

  • Avoid bites and illness;

  • Clean out the mosquitoes from the places where you work and play;

  • Help your community control the disease.

Reduce your risk 3 ways

Reduce your risk 3 ways

Step 1 avoiding bites

Step 1 - Avoiding bites

  • Avoid Mosquito Bites

  • Apply Insect Repellent Containing DEET

  • (Look for: N,N-diethyl-meta-toluamide) to exposed skin when you go outdoors. Even a short time being outdoors can be long enough to get a mosquito bite. Always follow the manufacturer indications for use, and note that repellants are recommended for small children.

  • Clothing Can Help Reduce Mosquito Bites

  • When possible, wear long-sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or DEET will give extra protection. Don't apply repellents containing permethrin directly to skin. Do not spray repellent containing DEET on the skin under your clothing.

  • Be Aware of Peak Mosquito Hours

  • The hours from dusk to dawn are peak mosquito biting times for many species of mosquitoes. Take extra care to use repellent and protective clothing during evening and early morning -- or consider avoiding outdoor activities during these times.

Step 2 mosquito proof your home

Step 2 - Mosquito-Proof Your Home

  • Mosquito-Proof Your Home

  • Drain Standing Water

  • Mosquitoes lay their eggs in standing water.Limit the number of places around your home for mosquitoes to breed by getting rid of items that hold water.

  • Install or Repair Screens

  • Some mosquitoes like to come indoors. Keep them outside by having well-fitting screens on both windows and doors. Offer to help neighbors whose screens might be in bad shape.

Step 3 help your community

Step 3 - Help Your Community

  • Help Your Community

  • Report Dead Birds to Local Authorities

  • Dead birds may be a sign that West Nile virus is circulating between birds and the mosquitoes in an area. Over 130 species of birds are known to have been infected with West Nile virus, though not all infected birds will die. It's important to remember that birds die from many other causes besides West Nile virus.

  • By reporting dead birds to state and local health departments, you can play an important role in monitoring West Nile virus. Keep in mind that state and local agencies have different policies for collecting and testing birds. Also be sure to handle dead birds with gloves.

  • Clean Up

  • Mosquito breeding sites can be everywhere. Neighborhood clean up days can be organized by civic or youth organizations to pick up containers from vacant lots and parks, and to encourage people to keep their yards free of standing water. Mosquitoes don't care about fences, so it's important to control breeding sites anywhere in the neighborhood.

  • Find out more about local prevention efforts

  • Find out what state and local officials are doing to help control West Nile virus.

Mosquito control with pesticides

Mosquito Control with Pesticides

1. Larvicides can be used to control mosquitoes in the aquatic stage before they become biting adults. This type of control generally has the least effect on non-target species and the environment.

  • Microbial larvicides such as Bacillus thuringiensis var. israelensis and Bacillus sphaericus can be used successfully in a broad range of freshwater habitats.

  • Biochemical larvicides (insect growth regulators - IGRs) such as methoprene can also be used in a variety of habitats.

  • Mono-molecular surface film larvicides can be used in polluted or artificial habitats, but should not be used where non-target insects are important resources.

    2. Mosquito adulticides should be considered the least desirable method of control and only used when isolations of virus and/or evidence of disease has been established. These materials have strengths and drawbacks that will influence which material is most appropriate for a given situation, and all must be applied according to label directions. Currently available adulticides include organophosphates, pyrethrins, and pyrethroid-based insecticides. These may be applied by hand-held, or backpack, foggers, or fixed-wing or rotary-wing aircraft.

  • Application of adulticides by truck-mounted foggers, fixed-wing or rotary-wing aircraft is usually done by government agencies or private contractors. Those who apply pesticides in these ways must be licensed, have their equipment properly calibrated, and adhere to the label directions.



  • The U.S. Centers for Disease Control and Prevention (CDC),

    • see website

  • The U.S. Geological Survey (USGS)

    • See website

  • The Ohio Department of Health

    • See website

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