What is the latest West Nile virus news?
Surveillance for West Nile virus (WNV) is over for the winter. This disease is not a threat without mosquito activity. WNV testing
of dead birds and mosquitoes will likely start again in the spring of 2008, see "Why are dead birds important?" below.
In the summer of 2007, Snohomish Health District sent 49 birds and sent 223 pools of mosquitoes in for testing. Eleven horses were
also tested in Snohomish County. No WNV was detected in Snohomish County this summer. However, eight horses and one bird were found
positive for the virus that summer in Yakima County.
What is West Nile virus?
Spread by mosquitoes, West Nile virus (WNV) is a bird disease that sometimes affects people and certain animals,
such as horses. Although WNV can cause a potentially serious illness, the risk is low for most people. When someone
is infected with West Nile virus (WNV) they will typically have one of three outcomes: No symptoms (most likely),
West Nile fever (WNF in about 20% of people) or severe West Nile disease, such as meningitis or encephalitis
(less than 1% of those who get infected). If you develop a high fever with severe headache, consult your health
care provider. The WNV is closely related to both St. Louis encephalitis and dengue viruses. WNV first appeared
in the United States on the East Coast in 1999. Since then, the virus has spread steadily across the United States.
How do people get West Nile virus?
WNV is spread to humans by the bite of an infected mosquito. Not all mosquitoes carry WNV, but species that are
known to carry it live in Snohomish County. Mosquitoes get the virus when they feed on infected birds. Animals
such as chickens and horses can not spread the virus to humans or other animals. WNV is not spread from person-to
person or animal-to-person.
What is the health risk from West Nile virus?
Although the risk of getting WNV is low, all residents in areas where the virus is active are at risk. Only a
small number of people who become infected will develop any symptoms, usually 3 to 14 days after exposure.
Persons over 50 years of age are more at risk for getting symptoms than children or pets. The median age of
death is 78, so it is particularly important for older persons to take personal protective measures. However,
everyone should take precautions to prevent mosquito bites. If you use repellant for your family, make sure it
is suitable for children and follow the label instructions. In 2003, 9858 WNV illness were reported across the
United States. Of the cases reported, 262 people died. By comparison, more than 24,000 Americans have died
from flu and its complications in a year. Unlike the flu, there is no vaccine against WNV. Therefore, people
should take precautions to reduce your risk of exposure to it.
What are the symptoms of West Nile virus?
Although WNV affects the central nervous system, symptoms can vary. Approximately 80 percent of people who are infected
with WNV will not show any symptoms at all. However, up to 20 percent of the people who become infected will
display mild symptoms, including fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph
glands or a skin rash on the chest, stomach and back. Symptoms last a few days to weeks. About one in 150 people
infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness,
stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These
symptoms may last several weeks to months, and neurological effects may be permanent.
How can residents help reduce their risk of getting West Nile virus?
There are some simple steps you can take to reduce risk. The best way to minimize the threat of WNV is to control
mosquito populations and prevent exposure to mosquitoes. To control the mosquito population, empty old tires,
buckets, plastic covers, toys and other containers around your home where water can accumulate and serve as a
breeding ground for mosquitoes. Change water every week in birdbaths, fountains, wading pools and animal troughs.
To protect yourself from mosquito bites, wear long-sleeved shirts and long pants when in mosquito-infested areas.
Consider using a
mosquito repellant containing DEET. (N,N-diethyl-m-toluamide). Other repellents registered with the EPA
include Picaridin (KBR 3023) and Oil of lemon eucalyptus [active ingredient: p-menthane 3,8-diol (PMD)], a plant-based
repellent. In two recent scientific publications, when oil of lemon eucalyptus was tested against mosquitoes found in
the US it provided protection similar to repellents with low concentrations of DEET.
Measures can reduce the risk of exposure to mosquitoes that transmit West Nile virus:
Get rid of old tires and other containers around your home
where water can accumulate and serve as a breeding ground
for mosquitoes.
Make sure the screens on all doors and windows are working
properly.
Schedule outdoor activities away from dusk and dawn when
mosquitoes are most active.
Use mosquito repellents containing DEET, picaridin, or oil
of lemon eucalyptus; follow the directions on the container.
Wear long-sleeved shirts and long pants when in mosquito
infested areas.
Why are dead birds important?
Snohomish Health District is collecting reports of dead birds and testing some of them for WNV, in cooperation with the
Washington State Department of Health and Washington State University. Observing dead birds is one of the important monitoring
systems to detect WNV activity in our county. However, resources only allow us to collect and test certain dead birds. Crows,
ravens, blue jays and raptors are of interest because they are particularly susceptible to WNV and frequently die from it.
Therefore, only these types of birds will be collected for testing and only if they are not damaged.
If I see a dead bird, what should I do?
To report dead birds, call the West Nile virus line at (425) 339-8720. Please only report birds without damage or trauma.
Note: Other agencies may be interested in domestic poultry or migratory birds because of
the avian influenza surveillance (AvianFlu.gov).
For information on testing sick or dead domestic poultry, please call the Washington State Department of Agriculture at 360.902.1878.
You may also call the United States Department of Agriculture toll free at 866.536.7593. Although Snohomish Health District is not
testing birds for avian influenza, if several wild migratory water fowl are reported dead in an area we will forward the information
to the Washington State Department of Fish & Wildlife.
Birds that cannot be transported to Snohomish Health District for WNV testing within 48 hours after death should be disposed of, unless
the bird is frozen (one week maximum). People should use gloves and double-wrap the bird in plastic bags for disposal or testing.
Dead birds can then be placed in the outside trashcan for disposal. Dead birds will only be accepted for testing if they are placed
in two clear “zip-lock” freezer bags with a paper towel placed between the bags. The following information will be useful when reporting
dead birds:
A description and condition of the bird.
Date and time you saw the dead bird.
Mosquito problems in the area should also be reported.
About You
Your Name
Day telephone number
E-mail address
About the Dead Bird
Date you found the bird
Approximate length of time the bird has been dead
Address/location where you found the bird (include city and ZIP code)
Description of the bird (size, color, etc.)
Click here if you find a crow with a colored band on its leg.
Are dead birds a hazard?
WNV is transmitted by the bite of an infected mosquito. However, people should still use precautions when handling dead
animals. People should use gloves and double-wrap the bird in plastic bags, dead birds can then be placed in the outside
trash can.
Why should I worry about old tires and birdbaths when there is a wetland in my neighborhood?
The Snohomish Health District mosquito survey has identified 23 different types of mosquitoes in Snohomish County, seven of which
are known to test positive for WNV in other parts of the country. However, one type of mosquito, the Culex pipiens
(AKA "the house mosquito"), is of most concern because they are known transmitter of WNV. Culex larvae grow in water-filled
containers found in urban areas. Experts report that healthy wetlands provide some deterrent for mosquito development, because
of native fish, frogs, toads, newts, salamanders and other mosquito predators. However, some artificial features such as tires,
birdbaths and storm water retention ponds may provide significant mosquito-breeding opportunities. Tires are a particular problem
because they hold water and their black color provides warmth. Nevertheless, any object that holds stagnant water, except a
chlorinated pool, can produce thousands of mosquitoes.
What is being done about mosquito control?
Snohomish Health District has no specific authority to control mosquitoes. We do encourage all landowners to evaluate
their mosquito situation. If there is a history of mosquito problems in certain areas, landowners in those areas should
take steps to control mosquito larvae. BEFORE applying pesticides to water on your property, you need a
permit. That permit requires a person
who is licensed by the state to follow strict pesticide label requirements. Contact WADOH for their guidance and permit
process.
It is likely that there will be no mosquito control in many areas of the County this summer. The Snohomish Health
District continues to advise residents to take precautions to guard against mosquito bites, including:
If outside during evening, nighttime, and dawn hours when mosquitoes are most active and likely to bite,
children and adults should wear protective clothing such as long pants, long-sleeved shirts, and socks.
Consider the use of an insect repellant containing 10% or less DEET for children and no more than 30%
DEET for adults.
Use DEET according to manufacturer’s directions.
Make sure that doors and windows have tight-fitting screens. Repair or replace screens that have
tears or holes.
What is the latest West Nile virus news?