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Animalborne
Disease > West
Nile Virus Information
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The Yakima Health District has compiled answers to the questions we most commonly receive about West Nile virus (WNV) below. If you don’t see the answer to your particular question, please feel free to contact our program staff.
Click on your question of interest:
I found a dead bird(s). What should I do?
*** IMPORTANT ***
As of 2009, the Yakima Health District will no longer be testing dead birds for West Nile virus (WNV). Use the list below to determine whether the dead bird(s) you found needs to be reported or view our bird reporting algorithm.
If you found 1 or 2 dead birds that ARE NOT birds of prey (hawk, owl, falcon, eagle):
- YOU DO NOT NEED TO REPORT IT.
- You may safely dispose of the dead bird(s) yourself as outlined below:
- Do not touch the dead birds with your bare hands.
- Pick the dead bird(s) up with a shovel or plastic gloves.
- Double bag them in regular trash bags.
- Put the bags out with your normal trash.
- Always remember to wash your hands thoroughly afterwards.
- If you found 1 or 2 dead birds that ARE birds of prey (hawk, owl, falcon, eagle):
- Please contact Marsha Flamm of The Raptor House Rehabilitation Center at 509-945-7334.
- If you found 3 or more dead birds in the same place at the same time:
- Please call the Washington Department of Fish and Wildlife’s Dead Bird Reporting line at 1-800-606-8768. This is a message line. If they are interested in testing the birds or want more information, they will get back with you within 24 hours. If you do not hear back from them, you may dispose of the birds as outlined above.
What is West Nile virus?
West Nile virus (WNV) is a flavivirus (germ) known to infect birds, mosquitoes, horses, humans, and other animals. It was first found in the United States in New York in 1999. WNV was not found in Washington until 2002. West Nile virus can make some people sick, although the majority of people never fall ill even after being infected with the virus. Of those that do get sick, most develop a mild illness much like a cold. A very small number of people develop a serious and even life-threatening illness after being infected with West Nile virus.
Have there been cases of WNV in Yakima County?
YES!!! West Nile Virus has been found circulating in the environment in Yakima County consistently from 2005-2008. Environmental positives were also found in 6 of the 8 counties that closely border Yakima County in 2008. Therefore, it is reasonable to assume that WNV is circulating throughout the entire County even if there have not been positives in your immediate area.
The summary of WNV positives for Yakima County in 2008 was as follows:
- 2 humans (locally acquired)
- 26 horses
- 5 birds
- 41 mosquito pools.
How is West Nile virus spread?
WNV is spread by mosquito bites. Mosquitoes become infected by taking a blood meal from a bird that is carrying the virus. Once WNV grows to high enough levels in the mosquito, they can pass it humans and other animals when they bite them.
Remember – WNV is almost always spread by mosquitoes! Humans and other animals that become infected with WNV do NOT spread it to others through normal day-to-day contact. Although very unlikely, WNV has been passed from human to human through blood transfusions, organ transplants, pregnancy, through breast feeding, and in lab settings.
There are mosquitoes where I live. Are they carrying WNV?
Even in areas like Yakima County where WNV is known to be circulating in the environment, scientists estimate only about 1% of mosquitoes will be infected with the virus at any given time. Even though the risk is low, all it takes is one bite form one infected mosquito to get sick, so be sure to protect yourself and your family!
I was bitten by a mosquito. Am I going to get sick? What symptoms should I look for?
Most people never get symptoms - About 80 percent of people bitten by a mosquito carrying WNV will never show symptoms of WNV illness. In other words, most people will never know even know they were exposed to WNV.
Some people get mild symptoms (West Nile fever) – Only about 1 in 5 people (20 percent) who get bitten by a mosquito carrying WNV develop noticeable symptoms of illness. Over 99 percent of these people get a mild illness much like the common cold 2-15 days after they are bitten. Symptoms of mild illness include fever, headache, body aches, nausea, and vomiting. Some people may also get swollen lymph glands or a rash on the chest, stomach, and/or back. Most cases of mild WNV illness go away after a few days without the need for medical attention.
Very few people develop severe symptoms (West Nile neuroinvasive disease) – About 1 in 150 of the people who get sick from WNV will develop a very serious, potentially life-threatening illness. Symptoms of severe illness include a high fever, severe headache, neck stiffness, stupor (daze), disorientation (confusion), tremors (shivers), convulsions (uncontrollable shaking), muscle weakness, vision loss, numbness, paralysis, and coma. Some of these symptoms can have very long lasting effects or be permanent. Approximately 3-15 percent of people who develop severe WNV illness die of complications resulting from their illness. People over the age of 50 are more likely to develop the more serious form of WNV illness.
I think I may have WNV. What should I do?
People with a history of mosquito bites should watch for symptoms that may indicate WNV illness. Symptoms of mild illness include fever, headache, body aches, nausea, vomiting, swollen lymph glands, and rash. West Nile fever typically resolves on its own so medical attention may not be necessary unless desired. Consult your regular medical provider if mild illness worsens or lasts longer than a few days.
Anyone experiencing symptoms of West Nile neuroinvasive disease - high fever, severe headache, neck stiffness, stupor (daze), disorientation (confusion), tremors (shivers), convulsions (uncontrollable shaking), muscle weakness, vision loss, numbness, paralysis or coma should seek immediate medical care.
Who is at risk for West Nile virus infection?
Anyone who lives in, works in, plays in, or passes through an area where WNV has been detected and mosquitoes are active is at risk for WNV. If you are going to be in area where WNV is known to be circulating, protect yourself:
- Avoid being outside at dusk and dawn when mosquitoes are most active
- Stay away from mosquito infested areas
- If you must go into areas with many mosquitoes, wear long pants and long sleeves
- Use EPA-registered mosquito repellents, following manufacturer instructions for use
- Equip doors and windows with screens to keep mosquitoes out of your home
- If outdoors with infants and toddlers, cover their stroller or carrier with mosquito netting
WNV is not passed from person to person through normal everyday contact, but there are a few other ways that WNV has been spread. Although very rare, WNV has been passed from human to human through blood transfusions, organ transplants, pregnancy, through breast feeding and in lab settings.
I know someone sick with West Nile virus illness. Can I get WNV from them?
WNV is not passed from person to person through normal everyday contact. WNV is almost always spread by the bite of an infected mosquito.
I’m pregnant. Am I at higher risk for being infected with West Nile virus?
Pregnant women are not more likely to develop WNV illness than those who are not pregnant. However, there have been two cases where a mother infected with WNV passed the virus to her child. One of these cases occurred from mother to baby before birth and the other through breast feeding.
According to the CDC, mosquito repellents are safe for use by pregnant women as long as they are used in a safe manner according to the “directions for use” on the manufacturer’s label. (See What are the DOs and DON’Ts for using mosquito repellents safely?)
Is it true people over 50 are more susceptible to severe West Nile Virus illness?
Yes. People over the age of 50 who develop symptoms of WNV illness are more likely to develop the more serious form of the illness (West Nile neuroinvasive disease). The fatality rate of severe WNV illness is also highest in those 50 and older.
How can I prevent becoming infected with West Nile virus?
Since we know that WNV is circulating throughout Yakima County, it is important that you protect yourself and your family from mosquitoes. Use these tips to help prevent mosquito bites and infection with WNV:
- When possible, remain inside at dawn & dusk when mosquitoes are most active
- Wear long pants and long sleeved shirts when going into mosquito infested areas
- Equip doors and windows with screens to keep mosquitoes out of your home
- If outdoors with infants and toddlers, cover their stroller or carrier with mosquito netting
- Apply repellent following the DOs and DON’Ts of using mosquito repellent safely
What are the DOs and DON’Ts for using mosquito repellents safely?
- #1 DO: ALWAYS APPLY REPELLENTS ACCORDING TO THE LABEL’S DIRECTIONS FOR USE!!!
- DO apply mosquito repellent if you are going to be in areas with mosquitoes.
- DO choose a product that contains one of these EPA-registered repellents for mosquitoes:
- DEET, Picaridin, Oil of Lemon Eucalyptus (as ingredient, not pure) or PMD, IR535
- DO choose a repellent appropriate for your child’s age
- DO apply mosquito repellent to exposed skin and/or clothing (as indicated on product label).
- DO apply a light spray of repellent to skin. DON’T apply heavily or saturate skin.
- DO re-apply repellent if you start to get mosquito bites, or move to a different area with no mosquitoes.
- DON’T spray mosquito repellents indoors or in enclosed areas.
- DON’T apply to skin covered by clothing.
- DON’T apply to cuts, wounds or irritated skin.
- DON’T allow children to apply repellent themselves.
- DON’T spray onto children. DO use your hands to apply repellent to exposed skin of children.
- DON’T apply to eyes or mouth.
- DON’T spray directly onto the face.
- DO apply to hands first then rub on face and neck.
- Some repellents like Permethrin can be applied to clothing. DON’T apply these to skin! DO follow label instructions.
- Once indoors, DO wash bodily areas where mosquito repellent was applied with soap and water.
DEET can be used safely in conjunction with sunscreens. Generally, the sunscreen would be applied first and then the repellent, but refer to labels of specific products as they may vary. Because the timeframes for reapplying sunscreen and mosquito repellents are different, products that combine both are not recommended by the CDC. More information on DEET can be found at the EPA DEET page.
Which insect repellents are most effective in preventing mosquito bites?
Mosquitoes that bite humans are females seeking nourishment to complete the development of eggs. It is thought that mosquitoes are attracted to the carbon dioxide that humans exhale and also to odors on skin. When applied, effective mosquito repellents will make human skin less appealing to the females looking to take a blood meal.
There are four active ingredients registered with the EPA that have demonstrated effectiveness in repelling mosquitoes. They are broken down into two categories by the EPA: conventional repellents and biopesticide repellents.
Conventional repellents
- DEET (also known as N,N-diethyl-m-toluamide or N,N-diethyl-3-methyl-benzamide)
- Picaridin (also known as KBR 3023 or 2-(2-hydroxyethly)-1-piperidinecarboxylic acid 1-methylpropyl ester)
Biopesticide repellents – derived from natural ingredients
- Oil of Lemon Eucalyptus or PMD (also known as para-Menthane-3,8-diol)
- Labels of products containing Oil of Lemon Eucalyptus indicate it should not be used on children under the age of 3.
- Use products containing Oil of Lemon Eucalyptus, NOT the oil in its pure form
- IR535 (also known as 3-[N-Butyl-N-acetyl]-aminopropionic acid, ethyl ester)
Products with any of the active ingredients listed above are known to be effective in preventing mosquito bites. People often assume that products with a higher concentration of active ingredient will repel mosquitoes better. This is untrue. As a general rule, the higher the concentration of any active ingredient, the longer the product will offer protection once applied. Information from a 2002 study (Fradin and Day, 2002) indicates:
Some products also come in a controlled release or encapsulated form. Even at lower concentrations, these products may last longer than their unencapsulated counterparts. The effectiveness of mosquito repellents can depend on air temperature, sweat, exposure to water (like swimming), and inadvertent rubbing off. Effectiveness can also depend on the species of mosquitoes the area.
Are mosquito repellents safe to use on children or women who are pregnant or nursing?
Children. Labels of products containing Oil of Lemon Eucalyptus indicate it should not be used on children under the age of 3.
The American Academy of Pediatrics (AAP) Committee on Environmental Health has updated their recommendation for use of DEET products on children in 2003, citing: "Insect repellents containing DEET (N,N-diethyl-m-toluamide, also known as N,N-diethyl-3-methylbenzamide) with a concentration of 10% appear to be as safe as products with a concentration of 30% when used according to the directions on the product labels."
The AAP also recommends that repellents with DEET NOT be used on infants less than 2 months old. For information on DEET alternatives, visit the AAP’s webpage on DEET Alternatives Considered to be Effective Mosquito Repellents.
As a general rule, if there are age restrictions for any repellent, it must be specifically stated on a product’s label. If there is no warning or restriction in regards to age, the EPA has not required a restriction on the use of the product.
Pregnant or lactating women. According to the CDC, mosquito repellents are safe for use by pregnant women as long as they are used in a safe manner according to the “directions for use” on the manufacturer’s label. (See What are the DOs and DON’Ts for using mosquito repellents safely?)
You should always consult a mosquito repellent’s product label to determine if there are special precautions for a product’s use on children or other special populations. Always follow the manufacturer’s “Directions for Use” on the product label.
How can I help eliminate mosquitoes around my home?
The most important step to protect yourself and your family from WNV is to reduce mosquito breeding areas around your home and to prevent mosquito bites.
Mosquitoes need still water to breed and grow. It doesn't take much water or time. Anything that can hold water for a week or more can provide a breeding ground for mosquitoes. Here’s what you can do around your own home to eliminate mosquito breeding grounds:
- Change water in birdbaths, wading pools, and animal troughs or dishes at least once per week
- Empty anything that holds standing water at least 1-2 times each week –
- Examples: swimming pool covers that puddle water and empty flower pots, buckets, barrels, and cans
- Store containers that can collect rain and sprinkler water upside down when not in use
- Dispose of used tires and other discarded items properly
- Fix leaky outdoor faucets & sprinklers so they don’t create puddles
- Clean clogged roof gutters to drain properly
Can pets and wild animals become infected with West Nile virus?
Yes.
Birds. Birds are known carriers of WNV. Some types of birds (crows, ravens, jays, magpies, hawks, and other birds of prey) are highly susceptible to WNV infection and usually succumb to the disease. This is the main reason these birds have been used for WNV surveillance in the past.
Horses. In 2008 alone, there were 26 cases of WNV diagnosed in horses in Yakima County. On average, 1 in 3 (33%) horses that become ill with WNV die or require euthanasia due to complications from their symptoms. Vaccinations for horses and other equines are available through your local veterinarian’s office. Horse owners in Yakima County should highly consider vaccinating their horses against WNV. The vaccine regimen consists of 2 doses the first year, and yearly boosters (recommended in early spring) in subsequent years. For more information, visit the USDA’s website on horses and WNV or the CDC’s Question and Answer page for West Nile Virus and Horses.
Dogs. One dog was diagnosed with WNV in White Swan in 2007. This is the only dog diagnosed with WNV in Washington. Dogs become infected with WNV after being bitten by an infected mosquito. It is very rare for WNV to cause disease in dogs because the virus typically cannot replicate itself to levels high enough in the blood to cause noticeable symptoms. There is no need to destroy the animal, as full recovery from WNV infection in dogs would be likely, according to the CDC. There is no WNV vaccine for dogs. For more information, visit the CDC’s web page for West Nile Virus and Dogs & Cats.
Cats. Like dogs, it is very rare for WNV to replicate to levels where it would cause noticeable symptoms in cats. Cats are typically infected by a mosquito carrying the virus, although there are laboratory studies that suggest they could also become infected after eating infected mice. There is no need to destroy the animal, as full recovery from WNV would also be expected for cats, according to the CDC. There is no WNV vaccine for cats. For more information, visit the CDC’s web page for West Nile Virus and Dogs & Cats.
Game birds and mammals. Since birds and mammals are known to be susceptible to WNV infection, there is a possibility that wild game birds and mammals killed by hunters may be infected with WNV in areas where mosquitoes are active and WNV has been identified in the environment. There have been no documented cases of WNV being transmitted to hunters or others who eat game meat. As an added safety precaution, it is always highly recommended that all wild game meat be properly handled and thoroughly cooked before consumption to prevent potential food-borne illness.
Squirrels. Although not common, some squirrels have tested positive for WNV in the past.
Just like humans infected with WNV, animals infected with WNV cannot pass the virus to humans or other animals through normal, day-to-day contact. The disease is almost always transmitted through the bite of an infected mosquito.
Should I vaccinate my horse against West Nile virus?
Horse owners in Yakima County should vaccinate their horses against WNV. The vaccine regimen consists of 2 doses the first year, and yearly boosters (in early spring) in subsequent years. Vaccinations for horses and other equines are available through your local veterinarian’s office. For more information, visit the USDA’s website on horses and WNV or view the USDA’s flyer about the vaccination available for horses.
Why won’t the city or county spray for mosquitoes in my area?
A very small portion of Yakima County is covered by Mosquito Control Districts (MCDs). The voters in these regions have gone through the petition process, approved a tax and pay to cover the expense of providing mosquito control services specifically in their area. In Yakima County, there are two groups that work with mosquito control: Yakima County Mosquito Control District #1 and the Benton County Mosquito Control District.
Those living in areas outside the established boundaries of existing MCDs who wish to have mosquito control capabilities in their areas could consider petitioning for the formation of new districts in their area. Information about the petitioning process can be found in RCW 17.28 Mosquito Control Districts.
If you are dealing with a mosquito control problem in your neighborhood, please attempt to work with your neighbors to control mosquitoes in your community for the health and safety of everyone.
What is the current WNV activity for Washington State?
For up-to-date information on WNV activity in Washington State for the current and prior years, visit the Washington Department of Health’s West Nile Virus Surveillance Page.
NOTE: Due to decreases in funding for WNV surveillance, other counties like Yakima that have demonstrated WNV is active in their jurisdiction may discontinue environmental surveillance in 2009. Therefore, there could be a drop in the number of positives reported on the DOH WNV Surveillance website, although environmental activity for WNV in the state is likely to remain the same if not increase.
Read WNV Press Releases
Links to other West Nile virus resources
References & Information on WNV:
http://www.cdc.gov/ncidod/dvbid/westnile/index.htm
http://www.doh.wa.gov/ehp/ts/Zoo/WNV/WNV.html
http://www.aap.org/family/wnv-jun05.htm
http://agr.wa.gov/foodanimal/animalhealth/diseases/westnilevirus/default.aspx
http://awic.nal.usda.gov/nal_display/index.php?info_center=3&tax_level=3&tax_subject=170&topic_id=1565&level3_id=6601&level4_id=0&level5_id=0&placement_default=0
Surveillance maps:
http://www.doh.wa.gov/ehp/ts/Zoo/WNV/Surveillance09.html
http://www.cdc.gov/ncidod/dvbid/westnile/Mapsactivity/surv&control08Maps.htm |
