What is new?
Because of budget reductions, the Snohomish Health District is no longer performing West Nile virus (WNV) environmental
surveillance. These activities included testing and mapping of dead birds and mosquitoes. Positive results would have
triggered enhanced public notification and education activities locally. Next summer we will rely on others for continued
state wide effort to monitor this disease.
If you have questions about WNV surveillance please contact the Washington State Department of Health at 1-360-236-3980,
or go to their web site at: http://www.snohd.org/snoWNileVirus/index.htm
If you have questions about human illness call our communicable disease office at 245.339.5278
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.
If I see a dead bird, what should I do?
Snohomish Health District is no longer collecting information about birds. Please contact the following agencies:
Washington State Department of Agriculture Sick/Dead Bird Reporting:
Sick and dying domestic birds (chickens, domestic waterfowl, and gamebirds)
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.
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 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 new?