Frequently Asked Questions

 

Overview of West Nile Virus 

What is West Nile Virus?
West Nile Virus (WNV) is a mosquito-borne disease. Mosquitoes spread this Virus after they feed on infected birds and then bite people, other birds, and animals. The Virus can infect humans, birds, horses, mosquitoes, and some other mammals according to the Centers for Disease Control and Prevention (CDC).

West Nile is a flavivirus previously only found in Africa, Eastern Europe, and West Asia. It is closely related to St. Louis encephalitis Virus (SLE), which is found in the United States, the Japanese encephalitis Virus from Asia, and to Murray Valley fever Virus from Australia and New Guinea. West Nile Virus can lead to West Nile fever, West Nile that can cause encephalitis, or West Nile encephalitis.

What is encephalitis?
Encephalitis is inflammation (swelling) of the brain tissue.


How long has West Nile Virus been in Wyoming?
West Nile Virus was first detected in Wyoming in August 2002.



Symptoms of West Nile Virus

What are the symptoms of West Nile Virus?
People with mild infections may experience fever, headache, body aches, skin rash and swollen lymph glands. This is called West Nile fever.

People with more severe infections may experience high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, and paralysis. This is called West Nile encephalitis.

 

Transmission of West Nile Virus

How can I get West Nile Virus?
The main route of human infection is through the bite of an infected mosquito. In 2002, additional routes became apparent; however, this represented a very small amount of cases. These routes include receiving transplanted organs and blood transfusions, trans-placental (mother to unborn child) and possibly breastfeeding transmission, and laboratory workers working with West Nile infected products.

 


Prevention of West Nile Virus

What can I do to protect myself from West Nile Virus?
Steps you can take to minimize the probability of infection include remembering the 5 D’s of West Nile Virus prevention:

 

1. DAWN &
2. DUSK
- When possible, avoid spending time outside at dawn and dusk.

 

3. DRESS- Wear shoes, socks, long pants, and a long-sleeved shirt when outdoors for long periods of time or when mosquitoes are most active. Clothing should be light colored and made of tightly woven materials to keep mosquitoes away from the skin.

 

4. DRAIN - Reduce the amount of standing water in or near your property by draining and/or removing it. Mosquitoes may lay eggs in areas with standing water. See below for more information and tips on reducing the amount of standing water in or near your property. For recommendations on how to eliminate potential mosquito breeding sites on your near your property click here.

5. DEET - For additional protection from mosquitoes, use an insect repellent containing DEET (N,N-diethyl-m-toluamide) or picaridin (KBR 3023). Other insect repellents such as oil of lemon eucalyptus and IR3535 are also registered by the EPA but may be less effective than products containing DEET. It is important to follow the product guidelines when using insect repellant.  Please see the Insect Repellant Safety and Use Q&A for more detailed information concerning the use of repellants. 

 

West Nile Virus and Fishers and Hunters

Are fishers and hunters at risk for West Nile Virus?
Yes. Fishers and hunters are outdoors, and they may fish or hunt in areas that have mosquitoes with West Nile Virus. As a result, fishers and hunters are at risk for mosquito bites. It is unknown whether West Nile Virus may be present in wild game.

What can fishers and hunters do to protect against West Nile Virus?
Fishers and hunters can limit time outdoors at Dawn and Dusk, wear shoes, socks, long pants, and long sleeve shirts, and use insect repellant with DEET. For more information on prevention, see How to Protect Yourself. In addition, hunters may consider wearing gloves when handling and cleaning animals to prevent exposure to blood. Meat should be cooked thoroughly.

Who can I contact to learn if West Nile Virus is in a specific geographic area?
Fishers and hunters can view West Nile Virus maps from the US Geological Survey (USGS)  at http://diseasemaps.usgs.gov/wnv_us_human.html

 

West Nile Virus and pets (cats, dogs)

Are my pets (cats, dogs) at risk for West Nile Virus?
According to the Centers for Disease Control and Prevention (CDC), a small number of dogs(less than 40) and one cat were reported to the CDC during 2003. Contact your Veterinarian if you have questions about West Nile Virus in dogs and cats.

 

West Nile Virus and camping or hiking

Am I at risk for West Nile Virus if I camp or hike?
Yes. Campers or hikers may be in or near areas with standing water, areas with no mosquito control, or outside for longer periods of time. Additionally, the risk for mosquito bites and transmission of West Nile Virus increases with warm weather when people are more likely to be outdoors. These factors can greatly increase the risk for mosquito bites among campers and hikers.

What can campers and hikers do to protect against West Nile Virus?
Campers and hikers can limit their time outdoors at Dawn and Dusk, wear shoes, socks, long pants, and long sleeve shirts, and use insect repellant with DEET. For more information on prevention, see How to Protect Yourself. Campers should also check their tents to ensure screens are secure and free of holes or places mosquitoes can enter the tent. Mosquito nets may also be considered.

Who can I contact to learn if West Nile Virus is in a specific geographic area?
Campers and hikers can view West Nile Virus maps from the US Geological Survey (USGS)  at http://diseasemaps.usgs.gov/wnv_us_human.html

 

West Nile Virus and people who work outside

Am I at risk for West Nile Virus if I work outside or spend large amounts of their workday outside?
Yes. The risk for mosquito bites and transmission of West Nile Virus increases with warm weather. Also, working outside in or near areas with standing water and at Dawn and Dusk may increase the risk for mosquito bites.

Agriculture and Natural Resource workers (Farmers, Ranchers, Bureau of Land Management personnel, Forest Service personnel, State Forestry personnel, national and State Park personnel, construction workers that are near a mosquito habitat) may be at higher risk for West Nile Virus. The reason is these individuals may work near a mosquito habitat or spend time outdoors at Dawn and Dusk (when mosquito activity is high). 

What can people who work outside do to protect against West Nile Virus?
People who work outside can limit their time outdoors at Dawn and Dusk, wear shoes, socks, long pants, and long sleeve shirts, and use insect repellant with DEET. For more information on prevention, see How to Protect Yourself.

Additional information on West Nile Virus and work environments (for example, occupational risks of West Nile Virus, questions and answers, and recommendations for protection) can be found on the West Nile Virus pages from the National Institute for Occupational Safety and Health at the Centers for Disease Control and Prevention (CDC).

 


West Nile Virus and outdoor sports (baseball, football, golf, rodeo, soccer, softball, tennis, and other outdoor sports)

Am I at risk for West Nile Virus if I participate in outdoor sports?
Yes. Sports such as baseball, football, golf, rodeo, soccer, softball, or tennis are often held outdoors. The risk for mosquito bites and transmission of West Nile Virus increases with warm weather. In addition, participating in outdoor sports at or near areas with standing water and at Dawn and Dusk may increase the risk for mosquito bites.


Am I at risk for West Nile Virus if I attend outdoor sports events?
Yes. The reason is sports such as baseball, football, golf, rodeos, soccer, softball, tennis, and other outdoor sports events are usually attended in an outdoor setting. The risk for mosquito bites and transmission of West Nile Virus increases with warm weather. In addition, attending outdoor sports at or near areas with standing water and at Dawn and Dusk may increase the risk for mosquito bites.

What can I do to protect myself if I play outdoor sports or attend outdoor sports events?
People who participate in outdoor sports or attend outdoor sports events can limit their time outdoors at Dawn and Dusk if possible, wear shoes, socks, long pants, and long sleeve shirts, and use insect repellant with DEET according to the label. For more information on prevention, see How to Protect Yourself.



West Nile Virus and pregnant women

Can West Nile Virus (WNV) be transmitted from a pregnant mother to her unborn fetus (child)?
In 2002, there was one case of trans-placental (mother to unborn child) transmission of West Nile Virus according to the Centers for Disease Control and Prevention (CDC). See the article in Morbidity and Mortality Weekly Report (December 20, 2002; available at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5150a3.htm)for more information. CDC and state and local health departments followed birth outcomes among women with WNV illness while pregnant. More information can be found at the CDC's Questions and Answers on West Nile Virus, Pregnancy, and breast-feeding.

Information is also available for healthcare providers through the CDC February 2004 MMWR
"Interim Guidelines for the Evaluation of Infants Born to Mothers Infected with West Nile Virus During Pregnancy"


What can pregnant women do to avoid the possibility of trans-placental (mother to unborn child) transmission of WNV?
The CDC recommends pregnant women take precautions to avoid WNV and other mosquito infections. This includes avoiding mosquitoes or areas where mosquitoes may be present, wearing protective clothing (for example, long sleeve shirts and long legged pants) and using insect repellents containing DEET. Pregnant women using insect repellents with DEET should carefully follow the instructions for use and direct any questions regarding the use of DEET in pregnancy to their health care providers. Pregnant women who experience any symptoms of WNV are strongly encouraged to see their health care provider as soon as possible. For questions on insect repellent use, see the CDC's Questions and Answers on Insect Repellent and Safety.


West Nile Virus and Breast-feeding

Can West Nile Virus be transmitted through Breast milk?
In 2002, it appeared West Nile Virus was transmitted through breast milk according to the Centers for Disease Control and Prevention. The CDC reported the infant was most likely infected through breast milk, yet the child was reported healthy and did not have symptoms of West Nile Virus.

Should I breast-feed if I have symptoms of West Nile Virus?
The CDC’s West Nile Virus Questions and Answers on Breast-feeding says because the health benefits of breast-feeding are well established, and the risk for West Nile Virus transmission through breast-feeding is unknown, the new findings do not suggest a change in breast-feeding recommendations. The American Academy of Pediatricians and the American Academy of Family Physicians recommend that infants be breastfed for a full year of life.

Lactating women who are ill or who are having difficulty breast-feeding for any reason, as always, should consult their health care providers.

For more information on breast-feeding and West Nile Virus, see the CDC's West Nile Virus Questions and Answers on Breast-feeding website.


West Nile Virus and Blood transfusions and organ donation

Can West Nile Virus be transmitted by blood transfusion or organ donation?
Yes. For more information on West Nile Virus and blood transfusions, see the Questions and Answers on Blood Transfusions, organ Donation, and Blood Donation Screening Information at the website for the Centers for Disease Control and Prevention (CDC). Additional information on Blood Safety can be found at the Food and Drug Administration Blood Safety and Availability website. 

Can West Nile Virus be transmitted by organ donation?
According to the Centers for Disease Control and Prevention (CDC), transplanted organs were identified as a source for West Nile Virus in 2002. It was unclear how the organ donor became infected with West Nile Virus. CDC also learned of people developing West Nile Virus after blood transfusions in 2002.

 

Using insect repellant safely

Why should I use insect repellent?
Insect repellent helps to reduce a person’s exposure to mosquito bites. This can help reduce a person’s risk for exposure to West Nile Virus and other viruses carried by mosquitoes.

Who should use insect repellent?
People who plan to be outdoors, whether it is for fun or work, should consider using insect repellent to reduce their risk for mosquito bites.

What type of insect repellent should I use?
People should consider using insect repellent that contains the chemical, N,N-diethyl-m-toluamide (DEET). DEET does not kill mosquitoes. It repels the mosquitoes by making a person unattractive for feeding.

The Centers for Disease Control and Prevention (CDC) has suggested that other insect repellents besides DEET may also work. Picaridin (KBR 3023) has also shown a high degree of efficacy of repelling mosquitoes that cause WNV in scientific studies. Two recent publications have also suggested that oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)], a plant based repellent, may also effectively repel mosquitoes and that it provides similar protection to repellents containing low concentrations of DEET.

Furthermore, products containing permethrin may also be used on clothing, shoes, bed nets, and camping gear. Like the other products mentioned above, permethrin is registered with the U.S. Environmental Protection Agency (EPA). Permethrin acts as both a repellent and as an insecticide. However, permethrin is not recommended for use on bare skin.

When should I use insect repellent?
Insect repellent should be used when you will be spending time outdoors and you will be at risk for mosquito bites.

How often should I apply insect repellent?
Follow the directions on the insect repellent. According to the Centers for Disease Control and Prevention (CDC), sweating, perspiration or getting wet may mean that you need to re-apply repellent more frequently. Repellents are effective only at short distances from the treated surface, so you may still see mosquitoes flying nearby. As long as you are not getting bitten, there is no reason to apply more DEET.

Whenever you use an insecticide or insect repellent be sure to carefully read and follow the manufacturer's DIRECTIONS FOR USE, as printed on the pesticide product label. If you have health-related questions or concerns about insect repellents (DEET) or insecticide products used to control mosquitoes in and around the home, contact the National Pesticide Information Center (NPIC) at 800-858-PEST (800-858-7378), or visit the NPIC website.

For more information on insect repellents, see the Questions and Answers on Insect Repellent Use and Safety at the website for the Centers for Disease Control and Prevention (CDC). Additional information can be obtained from the Environmental Protection Association (EPA) website on DEET.

 

Laboratory Submission and Testing

Whom do I contact for information on human testing?
For information about human testing for West Nile Virus, contact your health care provider.

 

Whom do I contact for information on horse sample submissions?
To learn about horse sample submissions, call the Wyoming State Veterinary Laboratory at 1-800-442-8331.