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West Nile Virus
(WNV) Information
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Confirmed 2009 West Nile Virus Infections in Orange County |
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Human |
Birds |
Equine |
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last updated:
7/2/09 |
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West Nile Virus Case Information
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| West Nile Virus
(WNV) is endemic in Orange County and is expected to be a public health concern
indefinitely. WNV first reached Orange County in 2003
when a few dead birds tested positive. In 2004, Orange
County had its first human cases with 64 confirmed human WNV
infections. Since 2004, there have continued to be human WNV
infections reported each year. Because it is not
possible to accurately predict the impact WNV will have on
people in Orange County each year, all residents and
visitors are urged to continue to take precautions against WNV
infection every year. Recommended actions can be found in the How
to Reduce Your West Nile Virus Risk section below, and in the
information materials that can be downloaded from this site. |
Q.
What is West Nile Virus?
A. West Nile
virus (WNV) is a virus that is most commonly spread by the bite of
an infected mosquito. It affects the central nervous system and can
cause a potentially serious illness with varying symptoms as
described below (What are the symptoms of West Nile Virus
infection?). People who spend a lot of time outdoors are
more likely to be bitten by an infected mosquito, and people older
than 50 years of age are at increased risk for severe disease if
bitten by an infected mosquito. In a very small
number of cases, WNV was spread through blood transfusions, organ
transplantations, from mother-to-baby (during pregnancy and through
breastfeeding), and through work exposures (animal handling or
laboratory). Animals can also be infected with WNV and certain birds in
particular play an important part in the life cycle and spread of
the virus although birds do not directly spread the infection to
humans. There is no treatment except supportive care for WNV
infection, although experimental therapies are currently being
studied. Avoiding mosquito bites is the #1 way to prevent WNV
infection.
WNV was first
seen in the United States in New York in August 1999 and has since
spread south and westward, with WNV activity reported in all 48
states in the Continental United States.
Q.
What are the symptoms of West Nile Virus Infection?
A. West Nile Virus infection is uncommon, even in
areas with infected mosquitoes and animals. Infection occurs in
less than 1% of people bitten by an infected mosquito. If infection
occurs, symptoms begin 2-14 days after the mosquito bite and
include:
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No Symptoms in
Most People.
Approximately 80 percent of people who are infected with WNV will
not show any symptoms at all.
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Mild to Moderate Symptoms in
Some People.
Up to 20 percent of the people who become infected will display
symptoms, which may include fever, headache, and body aches,
nausea, vomiting, and sometimes swollen lymph glands or a skin
rash on the chest, stomach and back. Symptoms typically last a few
days and it is not necessary to seek medical attention unless
there is no improvement, more serious symptoms develop, or you are
pregnant or breastfeeding.
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Serious Symptoms
in a Few People.
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, and some neurological
effects may be permanent.
- Apply insect repellent containing DEET (N,N-diethyl-metatoluamide), picaridin, oil of lemon eucalyptus, or IR3535 (3-[N-Butyl-N-acetyl]-aminopropionic acid, ethyl ester) to exposed skin whenever you go outdoors. Be sure to follow the product directions for use.
- Wear long-sleeves, long pants and socks when outdoors,
whenever possible. Spray thin clothes with repellant to provide
extra protection but do not spray repellants containing permethrin
directly on the skin and do not spray DEET under the clothing.
- Avoid outdoor activities from dusk to dawn, which are peak
mosquito biting times. If you must go outdoors in the evening and
early morning, be sure to use repellant and protective clothing as
described above.
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Drain standing water (which serve as mosquito breeding sites) around your
home. This includes empty containers, flowerpots, bird baths,
and pet dishes.
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Install or repair tight fitting screens on your windows and
doors to keep the mosquitoes out.
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Arrange or participate in neighborhood clean-up days to pick up
empty containers, tires, and other standing water sources to
eliminate mosquito-breeding sites in your community.
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Report dead
birds (if they have been dead less than 24 hours) to Orange County
Vector Control (714) 971-2421 or to the State of California
1-877-WNV-BIRD. Some birds may be tested for WNV
infection. Dead birds may indicate that WNV is circulating in the
area.
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Interested in
a speaker about West Nile Virus prevention for your group or
organization? Please call Howard Sutter of the Health Care
Agency at (714) 834-5109 to schedule a presentation.
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Mosquito Control
Information on
mosquito control is available on the Orange County Vector Control
District’s Web site at www.ocvcd.org.
Reporting Dead
Birds
The reporting
of dead birds can provide important information about WNV activity
and is part of the overall WNV surveillance process.
Dead Bird Disposal Options:
- Orange County Vector Control District (OCVCD)
may be able to collect dead birds if suitable for West Nile
Virus testing. If a dead bird is found and it appears to have
died within the last 24 hours and is in good condition,
carefully and without touching the bird, place the carcass in a
plastic bag by inverting the bag over it, and put in a cool or
shady place, then thoroughly wash your hands and contact OCVCD
at 714-971-2421 x117.
- If you find a dead bird and wish to dispose
of it yourself, carefully and without touching the bird, place
the carcass in a plastic bag by inverting the bag over it, tie
the bag, and dispose of the carcass in your trash container, do
not place the bird in your green waste or recyclable materials
container, then thoroughly wash your hands.
- Though disposal of dead animals is very
unlikely to transmit West Nile Virus, proper handling of the
carcass and hand washing is recommended to minimize the
possibility of transmitting of other diseases.
- If a citizen is uncomfortable with disposing
of the bird, contact your local animal care services provider
who under certain circumstances may dispose of the bird.
Between 7:00
am
and 4:30 pm on Monday through Thursday, or 7:00 am and 3:30 pm on Friday, please contact Orange County Vector
Control District at (714) 971-2421 extension 117 or
wnsurv@ocvcd.org. Please be aware that there is a
limit to the number of birds that Vector Control can test,
especially from areas in which WNV has already been detected. In
some cases, you may be asked to dispose of the bird carcass.
After regular
business hours or on weekends, you may also report dead birds through the
Internet to www.westnile.ca.gov
or call (877) WNV-BIRD.
For more
information on West Nile Virus, see:
www.cdc.gov/ncidod/dvbid/westnile
For current
information about the extent of WNV in the United States, please
click on this link:
www.cdc.gov/ncidod/dvbid/westnile/surv&control.htm.
WNV Internet Resources
Below is a
list of documents that provide information on some of the most
commonly asked questions about West Nile Virus, as well as a list of
links to other sources of WNV information.
about
downloading files
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Additional
Information |
Click on icon to
Download |
Tree Squirrels: A New
Surveillance Tool for WNV
Department of Health
Services - Division of Communicable Disease Control |
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How do I choose an insect
repellent?
Centers for Disease
Control and Prevention |
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Information about insect
repellents
Centers for Disease
Control and Prevention |
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Remember the “Five D’s” to
defend yourself against West Nile virus poster
English |
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Espaņol |
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Vietnamese |
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Korean |
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I've Been Bitten By A Mosquito ... Should I Be Concerned About West Nile Virus?
Health Care Agency • Animal Care Services |
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Question & Answers about West Nile Virus (WNV)
Health Care Agency • Public Health Services (ADA Compliant) |
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Blood donation and West Nile Virus Infection |
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Q&A about West Nile Virus (WNV) for pets
Health Care Agency • Animal Care Services |
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Question & Answers about
West Nile Virus for horses
Health Care Agency • Animal Care Services |
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