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The West Nile Virus - Steven M. Zien
West Nile virus (WNV)
is a serious disease that is spread to humans by infected mosquitoes and
this threat has many people very concerned. We must become aware of the risks
involved and what we can do to protect ourselves and our families; but we
must also put this problem in perspective. There is no reason for panic or
to start applying toxic pesticides to your home and family.
The U.S. Center for Disease Control (CDC) states: “Even in areas where the
virus is circulating, very few mosquitoes are infected with the virus. Even
if the mosquito is infected, less than 1% of people who get bitten and become
infected will get severely ill. The chances you will become severely ill
from any one mosquito bite are extremely small.”
Approximately 4 out of 5 people infected with WN will not show
any symptoms and remain perfectly healthy. It is estimated that about 20%
of those infected will develop West Nile fever (symptoms include fever, headache,
tiredness and body aches, occasionally accompanied with a skin rash and even
swollen lymph glands). Only one in 150 infected people will develop more serious
symptoms (headache, high fever, neck stiffness, stupor, disorientation, coma,
tremors, convulsions, muscle weakness and paralysis). Symptoms generally last
for several days, but they can last for several weeks. The most susceptible
people are those over 50 years of age and those with compromised immune systems.
In 2004 only 779 cases of WNV were reported to the U.S. Center for Disease
Control (CDC) from California. It is likely that many more went unreported
and of those few that were reported, less than 4% died.
In addition to mosquitoes becoming infected by feeding on infected birds
and then passing the virus on, people can also become infected through transplanted
organs and blood transfusions. These two areas are now being screened for
WNV prior to use.
West Nile virus is a bird disease, primarily affecting corvids. In Northern
California that includes the American crow, common raven, yellow-billed magpie,
Steller’s Jay, and the western scrub-jay (for pictures go to http://169.237.206.160/corvids.htm).
These birds are highly susceptible to the disease and will usually die when
infected. Dead birds are an indicator that an area has a WNV problem and
mosquito control districts use dead bird reports to monitor for the disease.
If you find a dead bird you should report to the proper authorities.
In California call toll-free: 1-877-WNV-BIRD (1-877-968-2473). Operators
are available 8 am -5 pm / 7 days a week. After 5 pm, please leave a message.
You can also report the occurrence by posting it on line at http://cvecdata.ucdavis.edu/deadbird2.cfm.
West Nile virus is now well established in Sacramento and Yolo Counties.
As of the first week of July 2005 the Sacramento-Yolo Mosquito and Vector
Control District (SYMVCD) [<www.fightthebite.net>
(916-685-1022 and 800-429-1022)] has sent out postcards to residents of particular
neighborhoods because there are indications that those areas in the
district may have problems. This action was based on numerous monitoring
tools. The district is stepping up their work to control the population before
the mosquitos become adults and can bite. Members of the community must also
step up. If both the district and community work hard, it will not be necessary
to spray pesticides in these neighborhoods to combat adult mosquitoes.
It should be noted that the SYMVCD is working very hard to manage this pest
using organic products and techniques.
By following the “Seven D’s,” as recommended by the SYMVCD, residents can
reduce the number of adult mosquitoes and likely prevent the need for pesticide
applications to kill them. Prevention is the key.
- DRAIN any standing water that may produce mosquitoes.
- DAWN and DUSK are times to avoid. These are when mosquitoes are most active.
- DRESS appropriately if you need be out when mosquitoes are active. Long sleeves and pants will cover unprotected skin.
- DOOR and window screens should be in good condition to prevent mosquitoes from entering your home, and finally:
- DEFEND
yourself against mosquitoes by using an effective repellent, such as DEET,
Picaridin Oil of Lemon Eucalyptus, or 2% soybean oil. Make sure
you follow label directions! (See more below about repellants!)
- DISTRICT personnel are on hand to help address any mosquito problem you may be experiencing.
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How important is draining standing water?
A coffee can with an inch of water can produce over 1,000 mosquitoes every
seven days. You can reduce mosquito breeding sites around the home. Remove,
turn over, or drill holes in the bottom of any container that can hold water,
such as tin cans, buckets, ceramic pots, plastic covers, and toys. Old tires
should be recycled or stored inside a garage or shed. Change water often (don’t
just add more to keep it full) in birdbaths, fountains, wading pools, pet
water dishes, and potted plant trays (at least once a week). Empty water from
wheelbarrows and boats. Turn these items over if possible. Cover large boats
to prevent the accumulation of water and keep drains open. Make sure roof
gutters drain properly and clean them in the spring and fall. Fix leaky outdoor
faucets and sprinklers. Drain (or fill with dirt) unneeded or unwanted pools
or puddles. Walk around your home, landscape and garden weekly looking for
places where water can accumulate and eliminate those spots.
If you are uncertain as to how to deal with standing water ask the SYMVCD
for assistance. They will visit your property free of charge and make recommendations
on how to maintain the body of water and still not have a mosquito breeding
area. They may offer to stock your pond with mosquito fish or other biological
control options. You can also go to most local nurseries and purchase a biological
and organic pest control product often referred to as Mosquito dunks. These
are small disks that you place in the water about once a week. They
contain a minute organism known as Bacillus thuringiensis israelensis (Bti),
which is a naturally occurring disease of mosquitoes. For smaller bodies
of water Bti is also available in little pellets. Always read and follow
label directions!
If you will be outside at dawn or dusk and unable to wear protective clothing
to cover your skin, wear a repellent. The most recommended repellent is Deet
since it is very effective. The stronger the formulation you use, the longer
it lasts. Deet has been used successfully for years with fairly good results;
however, there are some concerns that may lead you away from Deet and
seek alternatives.
Deet is not organic. Health problems from the use of Deet include irritation
of eyes, skin blisters (followed by severe scarring in some cases), and toxic
encepalopathy. Symptoms of the toxic encepalopathy, which occurs mainly in
children who have been “intensively treated,” include headaches, irritability,
loss of consciousness, and seizures. The United States Environmental Protection
Agency (EPA) recommends that “great caution should be exercised in using
Deet on children” and that “applications should be limited to exposed areas
of skin, using as little repellent as possible and washing off after use.”
Deet is absorbed through the skin. It crosses the placenta in pregnant women
and has been found in breast milk.
Consumer Reports printed an article entitled “Protection at a Price- Deet's
DOWNSIDE (July 1993, pg. 453). The article stated that "Deet is readily absorbed
into the bloodstream, and medical reports have shown that absorption of Deet
sometimes has serious consequences.”
Deet can also damage plastics, rayon, spandex, other synthetic fabrics, leather,
and painted or varnished surfaces. So when you go for that bike ride with
your bicycle shorts on, before you leave realize that there may not be much
left of those shorts when you get home.
The amount of protection does not increase with the percentage of Deet you
are using. However, the amount of time you are protected does increase.
At concentrations of about 7% you will have about 2 hours of protection.
At concentrations of about 24% you can have up to 5 hours of protection.
There are natural alternative repellents that you can use and still have
protection similar to standard concentrations of Deet (7%). The U.S. Center
for Disease Control (CDC) found that oil of lemon eucalyptus and a
2% soybean oil achieved similar levels of effectiveness as 7% Deet.
Other products such as citronella and eucalyptus may provide some protection but, probably, not for very long.
Several products are available on the market that contain these ingredients.
Note that even though these products are natural, you can still have allergic reactions.
When using repellents the U.S. Center for Disease Control and Environmental Protection Agency both recommends:
- Apply repellents only to exposed skin and/or clothing (as directed on the product label.) Do not use repellents under clothing.
- Never use repellents over cuts, wounds or irritated skin.
- Do not apply to eyes or mouth and apply sparingly around ears.
When using sprays, do not spray directly on face—spray on hands first
and then apply to face.
- Do not allow children to handle the product. When using on children,
apply to your own hands first and then put it on the child. You may not want
to apply to children’s hands.
- Use just enough repellent to cover exposed skin and/or clothing.
Heavy application and saturation are generally unnecessary for effectiveness.
If biting insects do not respond to a thin film of repellent, then apply
a bit more.
- After returning indoors, wash treated skin with soap and water
or bathe. This is particularly important when repellents are used repeatedly
in a day or on consecutive days. Also, wash treated clothing before wearing
it again. (This precaution may vary with different repellents—check the product
label.)
- If you or your child get a rash or other reaction from an insect
repellent, stop using the repellent, wash it off immediately with mild soap
and water, and call a local poison control center for further guidance. If
you go to a doctor because of the repellent, take the repellent with you
for reference.
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The Sacramento-Yolo Mosquito and Vector Control District is working very
hard to avoid spraying our neighborhoods with pesticides to control adult
mosquitoes. However, if we as a community do not do our part, adult
mosquitoes could get out of hand and the SYMVD would feel compelled to spray.
If that does become a reality, current plans are to use natural pyrethrum
for this purpose. While this might be considered organically acceptable,
the formulation they will use also contains piperonyl butoxide, which
is not allowed in organic production.
If your neighborhood gets sprayed, take the following steps to protect you and your family:
- Children and pregnant women should take care to avoid exposure whenever possible
- Remain inside or avoid the area whenever spraying takes place
and for about 30 minutes after spraying. That time period will greatly reduce
the likelihood of your breathing in pesticides from the air.
- Close windows and doors and turn off window air-conditioning
units or close their vents to circulate indoor air before spraying begins.
Windows and air-conditioner vents can be reopened about 30 minutes after
spraying.
- If you come in direct contact with pesticide spray, protect your
eyes. If you get pesticide spray in your eyes, immediately rinse them with
water. Wash exposed skin. Wash clothes that come in direct contact with spray
separately from other laundry.
- Consult your health care provider if you think you are experiencing health effects from spraying.
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Steps you may want to take:
- If spraying just occurred, minimize your contact with outdoor
surfaces and wash skin that has come in contact with these surfaces.
- Pick homegrown fruits and vegetables you expect to eat soon before
spraying takes place. Rinse homegrown fruits and vegetables (in fact, all
produce) thoroughly with water before cooking or eating.
- Cover outdoor tables and play equipment before spraying or wash them off with detergent and water after they have been sprayed.
- Bring laundry and small toys inside before spraying begins(wash
with detergent and water if exposed to pesticides during spraying).
- Bring pet food and water dishes inside. Cover ornamental fishponds to avoid direct exposure.
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Pets occasionally get West Nile virus from mosquito bites but seldom get
sick. While horses are susceptible to WNV and can, die there is a vaccine
for horses. However it must be used well before infection for it to be effective.
Data indicates that most horses do recover from the infection.
Remember - you can help prevent the need for spraying! Drain all sources
of standing water. Avoid spending time outside at dawn and dusk. Dress to
protect wearing long pants and long sleeves. Defend yourself with repellents.
Door and window screens need to be well maintained. And finally, get
free help from the SYMVCD if you have questions or problems.
The following are websites that can provide additional information about
mosquito control, West Nile virus, Deet and related information.
This information was compiled by Steven M. Zien,
President of Living Resources Company, an organic landscape maintenance firm
serving the Sacramento area (www.organiclandscape.com 916-726-5377). To reprint or use in any manner, first contact the author for permission.
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West Nile Virus