This training bulletin provides information about West Nile virus for police officers, including that it is spread through mosquito bites, most people infected have no symptoms but some develop mild flu-like symptoms and rarely more serious neurological issues, and the best prevention is using insect repellent containing DEET and avoiding being outdoors at dawn and dusk when mosquitos are most active. It notes that while serious cases are rare, the elderly and immunocompromised are most at risk.

1. 012th
District Training Bulletin
West Nile Virus
by Lt. Joe Serb
Issue 02-01 21 September 2002
As a police officer who spends a
good deal of time on the out on the streets
you may be concerned about West Nile
Virus. This training bulletin will address the
issues and give you what you need to know
about the virus.
What is the West Nile Virus?
West Nile Virus is an organism
technically known as a “flavivirus” which is
closely related to St. Louis encephalitis.
What are the symptoms of the West Nile
Virus?
Most people who become infected
have no symptoms. 20% develop mild
symptoms which may include fever, head
and body aches. Occasionally, these are
accompanied by a skin rash on the trunk of
the body or swelling in the lymph glands.
More serious cases can involve
encephalitis, meningitis or
meningoencephalitis. Encephalitis involves
swelling of the brain, meningitis is an
inflammation of the membrane around the
brain, and meningoencephalitis is a
combination of both encephalitis and
meningitis. The symptoms of these these
may include headache, high fever, neck
stiffness, stupor, disorientation, coma,
tremors, convulsions, muscle weakness, and
paralysis.
It is estimated by the Center for
Disease Control that the odds of having a
serious case are only 1 in 150.
How long will the effects of the virus last?
Symptoms of mild cases may last
only a few days. More serious infections
may last weeks or months, and neurological
effects may be permanent.
How is the Virus spread?
The virus is spread through mosquito
bites. There are no records of the virus
being spread through any kind of social
contact. It is thought that West Nile may be
transmitted through organ donation or
blood transfusion.
What is the incubation period?
The incubation period is listed by the
CDC as 3 - 14 days.
Who is most effected?
Anyone who is bitten by an infected
mosquito can be effected. People over 60 or
those with depressed or undeveloped
immune systems are most at risk. Also at
risk are the very young who have not had
their immune systems fully develop.
What do I do if I think I have West Nile
Virus?
If you think you have West Nile see
your doctor as soon as possible!
How do I protect myself from becoming
effected?
The best way to prevent becoming
infected with the virus is to not be bitten by
mosquitos.

2. Since mosquitos feed most during the
hours just before or after dawn and dusk try
to avoid being outside during these times.
Choosing clothing which offers more
coverage can greatly reduce the potential for
being bitten. Avoid wearing very bright
clothing. Perhaps the best and most practical
step you can take is keeping a good insect
repellent with you and using it when needed.
How do insect repellents work?
Female mosquitos bite to get protein
from blood which they need to develop their
eggs. Mosquitos find animals to feed on (us)
by skin odors and sensing the carbon dioxide
which we exhale.
The only repellent recommended by
the CDC is N,N-diethyl-m-toluamide,
commonly known as DEET. This chemical
repels mosquitos by making the person using
it unattractive for feeding or in effect making
it difficult for the mosquitos to find them.
DEET is not designed to kill mosquitos. As
a result, if you use a repellent and still see
mosquitos but are not being bitten, there is
no need to apply more repellent.
More about repellents
The concentration of DEET in a
product has more to do with how long it will
last then how effective it is. A product with
23% DEET will protect for up to five hours,
while a product with 4.75% will only provide
protection for about 1 ½ hours.
Repellents which use active
ingredients other the DEET do not provide
long lasting protection and are not
recommended by the CDC.
The amount of protection a product
gives will depend to a large extent on what
you are doing. If you are sweating a lot, you
will need to apply repellent more often.
Products with a high concentration of
DEET may remove water repellent, damage
some nylon, and the very high concentration
may damage plastics like watch crystals.
Once you no longer need protection,
be sure to shower or wash off the repellent.
The Good News.
The human body reacts to a virus by
producing a defense against it. If you are
exposed to the West Nile Virus when you
recover your body will continue to have an
immunity. This immunity will last for years
and possibly for a natural lifetime.
Special Thanks to Dr. Lin of the UIC
Medical Center E.R., Dr. Bokhar of Cook
County Hospital E.R., and Marli Serb R.N.
for their assistance with the production of
this report.
Information for this report was obtained
from, and further information is available
from the following Center for Disease
Control web pages:
http://www.cdc.gov/ncidod/dvbid/westnile/
http://www.cdc.gov/ncidod/dvbid/westnile/q
a/overview.htm
http://www.cdc.gov/ncidod/dvbid/westnile/q
a/transmission.htm
http://www.cdc.gov/ncidod/dvbid/westnile/q
a/symptoms.htm
http://www.cdc.gov/ncidod/dvbid/westnile/q
a/insect_repellent.htm
http://www.cdc.gov/do/oc/media/wncount.ht
m
http://www.cdc.gov/ncidod/dvbid/westnile/q
a/who_risk.htm