The West Nile Virus > Chapter 5

Chapter V. Prevention Information and Guidance for Clinicians

  • No human vaccine against West Nile virus (WNV) is currently available.
  • Education about reducing the risk of infection is important for all persons in transmission areas, but especially in the higher-risk populations (persons more than 50 years old and persons who are immunocompromised).
  • The primary prevention step recommended is the use of mosquito repellent when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or another EPA-registered repellent will give extra protection. These repellents are the most effective and the most studied.
  • Generally, the more active ingredient a repellent contains the longer it can protect from mosquito bites.
  • Repellents containing permethrin are not approved for direct application on the skin. Repellent should not be sprayed on the skin under clothing. For detailed information about using repellents, see Insect Repellent Use and Safety.
  • Other options include wearing protective clothing (long sleeves, socks, and long pants) when outdoors.
  • The primary mosquito-biting hours for many of the species that are important vectors of WNV are from dusk to dawn. It is advisable to either stay indoors during these hours or use protective clothing and repellent.
  • Household mosquito-source reduction is also important. Standing water should be removed from outdoor receptacles in the periresidential environment.
  • Integrated mosquito management can be another important factor in controlling mosquito populations. (See Q & A: Pesticides Used in Mosquito Control.)

Clinical Practice

The following website is linked from the CDC webite and may contain information useful to the healthcare practitioner:

The Physicians' Information & Education Resource Guidance Statement Information on West Nile Virus Disease

Instructions for Sending Diagnostic Specimens to the DVBID Arbovirus Diagnostic Laboratory

1. CDC Submission Form

Complete a CDC submission form (CDC 50.34). Copies of this form may be obtained from:

NOTE: Testing will not be initiated without the inclusion of:

  • date of onset of symptoms
  • date of specimen collection NOTE: If the specimen collection occurs within 8 days after the onset of symptoms, a convalescent specimen will be requested.
  • any pertinent travel history (3 months prior to the date of symptom
  • onset)
  • the patient's name (REQUIRED for submitting specimens)

2. Shipping

For information regarding shipping packages and applicable regulations, please refer to CDC's Scientific Resources Program for specific information:

3. Specimen types and amounts

  • Acute and convalescent specimens, if available, should be sent together.
  • Ideal timing of specimens for serology:

    Specimen Timing
    Acute 3 to 10 days after onset of symptoms
    Convalescent 2-3 weeks after acute sample

  • At least 0.5 mL of serum and/or 1.0 mL of CSF is required for serology testing. CSF specimens are routinely tested undiluted and therefore require larger amounts. Whole blood will not be accepted for serology testing.
  • For serology testing, the specimen should be kept cold or frozen. The sample may be placed in an insulated container with blue ice packs. Additional blue ice packs should be used in the summer to ensure specimen integrity in hot weather.
  • For virus isolation and/or nucleic acid amplification testing, acceptable specimens are fresh frozen tissue, serum, or cerebrospinal fluid. Tissue specimens should be approximately 1 cm, frozen as soon as possible at -70C, and shipped on enough dry ice so that specimens remain frozen until received. Formalin-fixed specimens are not tested at DVBID and can be submitted to the Special Pathogens Laboratory in Atlanta, GA for immunohistochemistry:

    Infectious Disease Pathology Activity
    Centers for Disease Control and Prevention (MS-G32)
    1600 Clifton Rd, NE
    Atlanta, GA 30333

4. Testing Results

Test results are normally available 4 to 14 days after specimen receipt. Reporting times for test results may be longer during summer months when arbovirus activity increases. Receipt of a hard copy of the results will take at least 2 weeks after testing is completed. Initial serological testing will be performed using IgM capture ELISA and IgG ELISA. If the initial results are positive, further confirmatory testing may delay the reporting of final results. ALL RESULTS WILL BE SENT TO THE APPROPRIATE STATE HEALTH DEPARTMENT. Notify your state health department of any submissions to CDC.

5. Shipping Address

Send all specimens to:

ATTENTION: Arbovirus Diagnostic Laboratory, DRA
3150 Rampart Road
Fort Collins, C0 80521

6. Further assistance

Additional assistance may be obtained from the DVBID Arbovirus Diagnostic and Reference Laboratory at 970-221-6445.

Fight The Bite!

Avoid Mosquito Bites to Avoid Infection

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:

  • Avoid bites and illness;
  • clean out the mosquitoes from the places where you work and play;
  • help your community control the disease.

Something to remember: The chance that any one person is going to become ill from a single mosquito bite remains low. The risk of severe illness and death is highest for people over 50 years old, although people of all ages can become ill.

Avoid Mosquito Bites

Use Insect Repellent on exposed skin when you go outdoors. Use an EPA-registered insect repellent such as those with DEET, picaridin or oil of lemon eucalyptus. Even a short time being outdoors can be long enough to get a mosquito bite. For details on when and how to apply repellent, see Insect Repellent Use and Safety in our Questions and Answers pages. See also Using Insect Repellent Safely from the EPA.

Clothing Can Help Reduce Mosquito Bites
Get double protection: wear long sleeves during peak mosquito biting hours, and spray repellent directly onto your clothes. When weather permits, wear long-sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or another EPA-registered repellent will give extra protection. Don't apply repellents containing permethrin directly to skin. Do not spray repellent on the skin under your clothing.

Be Aware of Peak Mosquito Hours
The hours from dusk to dawn are peak 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.

Mosquito-Proof Your Home

Drain Standing Water
Drain standing water
from around your home
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. Need examples? Learn more on the Prevention of West Nile Virus Question and Answer page.

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.

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. State and local agencies have different policies for collecting and testing birds, so check the Links to State and Local Government Sites page to find information about reporting dead birds in your area. Click here for more info about reporting dead birds and dealing with bird carcasses.

Mosquito Control Programs

Check with local health authorities to see if there is an organized mosquito control program in your area. If no program exists, work with your local government officials to establish a program. The American Mosquito Control Association can provide advice, and their book Organization for Mosquito Control is a useful reference.

A report overview of Public Health Confronts the Mosquito: Sustainable State and Local Mosquito Control Programs by the Association of State and Territorial Health Officials is located on this website, including "what you can do" about mosquito control. The entire final report from the Mosquito Control Collaborative is also online.

More questions about mosquito control? A source for information about pesticides and repellents is the National Pesticide Information Center, which also operates a toll-free information line: 1-800-858-7378 (check their Web site for hours).

Clean Up

Mosquito breeding sites can be anywhere. 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 throughout the neighborhood.

Find out more about local prevention efforts

Find state and local West Nile virus information and contacts on the Links to State and Local Government Sites page.
Question No.19. What is the most important risk factor for developing serious WNV illness?

a. Age
b. Gender
c. Weight
d. Diet

Question No.20. Education about reducing the risk of infection is important for all persons in transmission areas.

a. True
b. False

The West Nile Virus > Chapter 5
Page Last Modified On: October 2, 2015, 01:16 PM