| West
Nile Virus |
| |
| Agency
Directive: |
Issued August
12, 2003
West Nile Virus Detected in Arizona
Background:
On August 11, 2003, the Arizona Department of Health Services reported
the first detection of West Nile Virus in Arizona. The positive test was
the result of an ongoing surveillance program that ADHS has been conducting
whereby mosquito traps are placed in various sites around the state. At
this time, there have been no confirmed human or animal cases, although
there is a great likelihood that this will not be true in the future as
health experts expect the disease to spread to other areas of the state.
Undoubtedly, this detection will heighten interest in bird testing. Arizona
Game and Fish Department has participated in this bird surveillance program
and will continue to do so. The following protocol should be used to guide
submissions for this program. Bag and chill if possible and submit to the
environmental health office of your local health department or to the Arizona
Veterinary Diagnostic Lab if the following apply:
· bird is freshly dead <24 hours
· not scavenged, no odor, no maggots
· body not soft and mushy
· not a baby or young bird
· not a pigeon
Avoiding being bitten by mosquitoes is the most effective way to avoid
exposure to West Nile Virus. The following precautions should be taken
to minimize the risk of being bitten.
· Eliminate standing water where mosquitoes can breed. Check for items outside
the home that collect water, such as cans, bottles, jars, buckets, old tires,
drums and other containers.
· Change water in flower vases, birdbaths, planters and animal watering pans
at least twice a week.
· Repair leaky pipes and outside faucets, and move air conditioner drain hoses
frequently.
· Avoid being bitten by mosquitoes when going outside at night by using insect
repellent. Wear lightweight clothing that covers the arms and legs.
CONTACTS FOR ADDITIONAL INFORMATION:
For more information about mosquito-borne viruses and dead bird reporting,
please visit the Arizona Department of Health Services' Web site at www.hs.state.az.us
or call the State Public Health Hotline at (602) 364-4500 or statewide
toll-free at (800) 314-9243.
The following is a listing of contact information for the County Health
Departments in Arizona. |
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| Background |
What
is West Nile virus?
West Nile virus is an arbovirus (short
for arthropod-borne virus) that causes encephalitis
(inflammation of the brain). Blood-feeding
insects such as mosquitoes transmit arboviruses,
including West Nile virus. Most infections
with West Nile virus have been identified in
wild birds, but the virus can also infect humans,
horses, dogs, cats, bats, chipmunks, skunks,
squirrels, domestic rabbits, and domestic birds.
Where did West Nile virus come from?
West Nile virus was first identified
in the West Nile district of Uganda in 1937,
and has since been found in Africa, Eastern
Europe, West Asia, the Middle East, and the
United States. The strain of virus found
in the United States most closely resembles
that found in the Mediterranean and Middle
East.
How is West Nile virus
transmitted?
Mosquitoes draw the virus from infected
birds and transmit it to animals and humans
through bites. West Nile viral encephalitis
develops in animals and humans when the virus
multiplies and crosses the blood-brain barrier.
West Nile virus is not transmitted directly
from person to person, animal to person,
person to animal, or animal-to-animal. Ticks
infected with the virus have been found in
Asia and Africa; however, there are no verified
reports of ticks spreading the virus and
their role in transmission has not been determined.
What clinical signs are associated with West Nile virus infection?
Horses - The most common sign is weakness,
usually in the hindquarters. Weakness may
be indicated by a widened stance, stumbling,
leaning to one side, and toe dragging. In
extreme cases, paralysis may follow. Fever
is sometimes evident, as are depression and
fearfulness. Approximately 40% of cases of
West Nile encephalitis in horses proved fatal
during the 1999 outbreak.
Humans - Most infections in humans are relatively mild, with flu-like symptoms
including fever, headache, body aches and, in some cases, skin rash and
swollen lymph glands. Signs of more severe infections include high fever,
neck stiffness, muscle weakness, convulsions, and paralysis. Death rates
associated with severe infection range from 3% to 15% and are highest among
the elderly.
Other animals - Wild birds infected with West Nile virus in the United
States are most often found dead; therefore, descriptions of clinical signs
in wild birds are not readily available. Nor have clinical signs associated
with West Nile virus infection in dogs, cats, bats, chipmunks, skunks,
squirrels, domestic rabbits, and domestic birds been well described. It
appears that, although they may be infected, many of these latter species
may not develop clinical signs of disease.
How is West Nile viral encephalitis diagnosed and treated?
Diagnosis of West Nile viral encephalitis
is based on a history of exposure, clinical
signs, and results of diagnostic blood tests.
As for all viral diseases, treatment consists of providing support (e.g.,
hospitalization, intravenous fluids, respiratory support, prevention of
secondary infections, and good nursing care) while the affected individual's
immune system responds to the infection.
Can you get West Nile virus directly from birds?
There is no evidence that a person
can get the virus from handling live or dead
infected birds. However, persons should avoid
barehanded contact when handling any dead
animals and use gloves or double plastic
bags to place the carcass in a garbage can.
How many types of
animals have been found to be infected with
West Nile virus?
Although the vast majority of infections have been identified in birds,
West Nile virus has been shown to infect horses, cats, bats, chipmunks,
skunks, squirrels, and domestic rabbits.
What is the incubation
period in humans (i.e., time from infection
to onset of disease symptoms) for West Nile
encephalitis?
Usually 3 to 14 days. |
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| Prevention |
Can
West Nile viral encephalitis be prevented?
| A vaccine
is now available for horses. For other
species, limiting exposure to mosquitoes
is considered effective prevention.
The following actions may reduce the
risk of mosquito bites and possible
exposure to West Nile virus: |
| • |
Check the
integrity of screens around your home,
porch, and patio. |
| • |
During warm
months, avoid outdoor activities at
dusk and dawn. |
| • |
If you must be outdoors
during hours when mosquitoes are most
active, cover up with shoes, socks,
long pants and long-sleeved shirts. |
| • |
Use mosquito repellant
on exposed skin and spray clothing
with repellents containing permethrin
or 35% DEET (N,N-diethyl-meta-toluamide)
since mosquitoes may bite through thin
clothing. When using insecticides or
insect repellants, be sure to read
and following the manufacturer's directions
for use. |
| • |
Eliminate stagnant water
from any receptacles in which mosquitoes
might breed. |
Is DEET safe?
Yes, products containing DEET are very safe when used according to the
directions. Because DEET is so widely used, a great deal of testing has
been done. When manufacturers seek registration with the U.S. Environmental
Protection Agency (EPA) for products such as DEET, laboratory testing regarding
both short-term and long-term health effects must be carried out. Over
the long history of DEET use, very few confirmed incidents of toxic reactions
to DEET have occurred when the product is used properly.
Is there a vaccine
against West Nile encephalitis?
No, but several companies are working towards developing a vaccine. |
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| Risk
To Humans |
Are
game hunters at risk for West Nile virus
infection?
Because of their outdoor exposure, game hunters may be at risk if they
become bitten by mosquitoes in areas with West Nile virus activity. The
extent to which West Nile virus may be present in wild game is unknown.
It appears that birds often die within 48 hours of exposure so birds
that are acting normally pose essentially no risk to hunters.
What should wild
game hunters do to protect against West
Nile virus infection?
Hunters should follow the usual precautions when handling wild animals.
If they anticipate being exposed to mosquitoes, they should apply insect
repellents to clothing and skin, according to label instructions, to
prevent mosquito bites. Hunters should wear gloves when handling and
cleaning animals to prevent blood exposure to bare hands and meat should
be cooked thoroughly.
Who is at risk
for getting West Nile encephalitis?
All residents of areas where virus activity has been identified are at
risk of getting West Nile encephalitis; persons over 50 years of age
have the highest risk of severe disease. It is unknown if immunocompromised
persons are at increased risk for West Nile virus disease.
Additional Information:
Arizona Department of Health Services 24 Hour phone line:
Phoenix Area - 602-364-4500
Elsewhere in Arizona - 800-314-9243
- What You Should Know About West Nile Virus [PDF,
800kb]
Informational Web sites:
Center for Disease Control
(CDC)
American
Veterinary Medial Association (AVMA)
Arizona
Department of Health Services (ADHS)
NOTE: External
sites will open in a new browser window. |
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| Attention
Hunters |
| Doves
Do Not Transmit West Nile Virus |
West Nile
Virus (WNV) is a mosquito-borne virus that
was first detected in the United States in
1999. The majority of people and animals
that are infected with WNV have no symptoms
or only a mild illness, such as a fever or
headache. The Arizona Game and Fish Department
has put this information sheet together to
inform and educate dove hunters about WNV.
All information contained on this sheet was taken from the Arizona Department
of Health Services - West Nile Virus Fact Sheet.
| Here
are some facts to keep in mind as
you go out into the field: |
| • |
People
become infected with WNV only from
the bite of an infected mosquito.
Birds (including doves) and other
animals CANNOT transmit WNV to people. |
| • |
WNV
is not spread by direct person-to-person
or person-to-animal contact. To be
fully safe, wear protective gloves
when handling or cleaning your dove. |
| • |
The
most severe illnesses have been seen
in crows, jays, ravens and horses,
NOT doves. |
| • |
Avoid
standing water where mosquitos may
be living. Avoid being bitten by
mosquitos by using insect repellent
(35% DEET) and/or wearing lightweight
clothing that covers the arms and
legs. |
| • |
Proper
cooking kills the WNV. Consequently,
there is no danger associated with
eating birds that have been properly
cooked. |
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| Related
AZGFD Info |
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