Westnile virus book2

The West Nile Virus Guide
&
Mosquito Fact Book
Compiled, edited & published by Scott Parat
A Culex quinquefasciatus mosquito on a human finger.
The Culex quinquefasciatus mosquito is proven to be a
vector associated with transmission of the West Nile Virus.

West Nile Virus --- Facts, Resources & Information
I dedicate this book to my loving wife who has endured my
hours of research and constant attempts to publish this
book. A book that I hope makes information regarding the
west nile virus available in a concise, life changing form.
You’ve endured my constant illness and have stood by. I am
indeed a blessed man. Liz, I love you!
Preface
I want to “thank-you” for purchasing the “West Nile Virus
Guide” and hope that you’ll find it very practical and
useful. My goal was to provide you with information that
you need to realize that the west nile virus is a real
threat and I wanted to provide you with the information you
need to protect yourself and loved ones from possibly
contracting this dangerous disease.
If you register your copy of this ebook, I’ll keep you
informed of updates, new resources and new developments
pertaining to west nile virus and mosquito control. Send a
blank email to westnilevirus_guide-28@best-e-book.com and
you’ll be automatically registered.
Anytime you see blue text with a line under it, chances are
that it is a hyper-link, that means if you place your mouse
pointer over it, you’ll be able to click on that link and
if you are connected to the internet, you’ll go straight to
that website. At the time of publishing this ebook all
links were active. I cannot control links that belong to
other people so please don’t send me an email regarding a
link that’s not working… I simply can’t do anything about
it.
I struggled with writing an appropriate introduction to a
book that is so close to my heart. So I decided to approach
the chore from a practical point of view.
I happen to live in a low lying area in Midwestern United
States. I have a river on one end of my property and a
conservation area on the other end..this area floods every
spring and holds 2 to 3 feet of water. It becomes a virtual
“mosquito factory”!
West Nile Virus Guide
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©All Rights Reserved www.WestNileVirusGuide.con Page - 2 -

With the advent of west nile virus, my wife and I became
concerned for the health of our family. During the summer
months you can literally hear the buzz sound of mosquitoes
as twilight approaches.
It’s currently early fall and you won’t believe this but
I’m watching 2 mosquitoes hover around my desklamp. Yep,
they invade the house everytime the door is open.
By now you must be getting the picture. Mosquitoes plus
west nile virus was a reality in our lives. It’s September
and as I listen to the radio another elderly man, 78 just
died from a west nile virus infection.
It’s real..it’s here and you need to protect yourself. As
you read you’ll find out that the virus is traveling across
the United States. If it’s not in your state now..it will
be!
The west nile virus is not restricted to the United States.
As I studied, I discovered the virus has affected much of
the world. This particular book covers issues in the United
States, however, the facts regarding to the virus and
mosquitoes can be applied to anyplace the virus and
mosquitoes are present.
I hope and pray that you, your family and loved ones will
be positively affected by the knowledge you gain from
reading this ebook and applying the facts.
To your health,
Scott Parat
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Note:
The below Table of Contents is live. You can click on
either a description or page number and be taken to that
page. It is a very easy way to navigate and use this book
as a reference guide.
This book was compiled from different US governmental
agencies and is based on current research regarding the
west nile virus and mosquito and their respective control.
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PREFACE..................................................................................................................................................... 2
INTRODUCTION TO THE WEST NILE VIRUS ................................................................................... 7
BACKGROUND: VIRUS HISTORY AND DISTRIBUTION................................................................. 9
HISTORY..................................................................................................................................................... 9
HUMAN CASE AND VIRUS DISTRIBUTION INFORMATION............................................................................ 9
WEST NILE VIRUS: WHAT YOU NEED TO KNOW......................................................................... 10
WHAT IS WEST NILE VIRUS? ................................................................................................................... 10
WHAT CAN I DO TO PREVENT WNV?...................................................................................................... 10
WHAT ARE THE SYMPTOMS OF WNV?..................................................................................................... 10
HOW DOES WEST NILE VIRUS SPREAD? .................................................................................................. 10
HOW SOON DO INFECTED PEOPLE GET SICK?.......................................................................................... 11
HOW IS WNV INFECTION TREATED? ....................................................................................................... 11
WHAT SHOULD I DO IF I THINK I HAVE WNV? ....................................................................................... 11
WHAT IS THE RISK OF GETTING SICK FROM WNV? ................................................................................. 11
WHAT ELSE SHOULD I KNOW?................................................................................................................. 12
LINKS TO STATE AND LOCAL GOVERNMENT WEST NILE VIRUS WEB SITES................... 13
LIST OF STATE AND LOCAL HEALTH DEPARTMENT WEB SITES, BY STATE AND CITY HEALTH
DEPARTMENT WEST NILE VIRUS WEB SITES ........................................................................................... 13
ADD.......................................................................................................................................................... 15
IT'S TIME TO PREPARE FOR WEST NILE VIRUS. ......................................................................... 16
FIVE COMMON MYTHS ABOUT WEST NILE VIRUS.................................................................................... 16
WEST NILE VIRUS TRANSMISSION CYCLE................................................................................................ 18
WHAT YOU NEED TO KNOW ABOUT MOSQUITO REPELLENT ............................................... 22
WHICH MOSQUITO REPELLENTS WORK BEST .......................................................................................... 22
UPDATED INFORMATION REGARDING INSECT REPELLENTS...................................................................... 25
VERTEBRATE ECOLOGY ..................................................................................................................... 27
BIRDS ....................................................................................................................................................... 27
DOGS AND CATS....................................................................................................................................... 27
HORSES .................................................................................................................................................... 28
OTHER VERTEBRATES .............................................................................................................................. 28
ENTOMOLOGY........................................................................................................................................ 28
VIROLOGY: CLASSIFICATION OF WEST NILE VIRUS ................................................................................. 29
PUBLIC HEALTH CONFRONTS THE MOSQUITO: DEVELOPING SUSTAINABLE STATE AND LOCAL MOSQUITO
CONTROL PROGRAMS............................................................................................................................... 30
WHAT YOU CAN DO ABOUT MOSQUITO CONTROL.................................................................................. 31
MOSQUITOES........................................................................................................................................... 33
WHAT KINDS OF MOSQUITOES ARE COMMON IN ILLINOIS? ....................................................................... 33
DO ALL MOSQUITOES CARRY DISEASE? .................................................................................................... 33
WHAT IS THE BEST WAY TO REDUCE POPULATIONS OF MOSQUITOES? ...................................................... 34
HOW CAN PEOPLE PROTECT THEMSELVES FROM MOSQUITO BITES?.......................................................... 35
MOSQUITOES AND ENCEPHALITIS.................................................................................................. 36
DISEASES.................................................................................................................................................. 36
PREVENT MOSQUITOES FROM BREEDING AROUND THE HOME................................................................. 36
PROTECTION FROM MOSQUITO BITES....................................................................................................... 37
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QUESTIONS AND ANSWERS ABOUT MOSQUITO PREVENTION FOR PEOPLE, PROPERTY
AND PETS .................................................................................................................................................. 38
WHAT KINDS OF DISEASES CAN BE CARRIED BY MOSQUITOES?................................................................. 38
WHAT IS ENCEPHALITIS? .......................................................................................................................... 38
HOW CAN I HELP PROTECT MY FAMILY AND MYSELF FROM MOSQUITOES AND THE DISEASES THEY MAY
CARRY? .................................................................................................................................................... 38
QUESTIONS AND ANSWERS ABOUT SPRAYING FOR ADULT MOSQUITOES ...................... 41
WHAT INSECTICIDES ARE USED TO FOG FOR MOSQUITOES? ...................................................................... 42
ARE THE INSECTICIDES USED FOR FOGGING SAFE?.................................................................................... 43
DO I NEED TO WASH HOME-GROWN FRUITS AND VEGETABLES AFTER THE MOSQUITO FOGGING?............. 43
WILL THE FOGGING KILL BIRDS OR OTHER LARGE ANIMALS? ................................................................... 44
THE EPA, PESTICIDES AND MOSQUITO CONTROL..................................................................... 45
HOW ARE MOSQUITOES CONTROLLED WITH PESTICIDES AND OTHER METHODS?................................... 46
WHAT CAN I DO TO REDUCE THE NUMBER OF MOSQUITOES IN AND AROUND MY HOME?..................... 46
THE EPA’S VIEW OF LARVICIDES FOR MOSQUITO CONTROL................................................................... 48
WHAT IS THE MOSQUITO LIFE CYCLE? .................................................................................................... 49
WHAT ARE LARVICIDES?.......................................................................................................................... 49
WHAT ARE MICROBIAL LARVICIDES? ...................................................................................................... 49
INFORMATION ON ARBOVIRAL ENCEPHALITIDES.................................................................... 53
LA CROSSE ENCEPHALITIS ....................................................................................................................... 55
EASTERN EQUINE ENCEPHALITIS.............................................................................................................. 56
WESTERN EQUINE ENCEPHALITIS............................................................................................................. 56
ST. LOUIS ENCEPHALITIS.......................................................................................................................... 57
POWASSAN ENCEPHALITIS ....................................................................................................................... 57
VENEZUELAN EQUINE ENCEPHALITIS....................................................................................................... 57
JAPANESE ENCEPHALITIS.......................................................................................................................... 58
TICK-BORNE ENCEPHALITIS..................................................................................................................... 58
WEST NILE ENCEPHALITIS ....................................................................................................................... 59
QUESTIONS AND ANSWERS ABOUT WEST NILE .......................................................................... 60
OVERVIEW OF WEST NILE VIRUS .................................................................................................... 61
CASES OF WEST NILE HUMAN DISEASE ................................................................................................... 62
UNDERSTANDING THE NUMBERS POSTED FOR WEST NILE VIRUS CASES........................................ 63
WEST NILE VIRUS AND DEAD BIRDS ............................................................................................... 65
WHO'S AT RISK FOR WEST NILE VIRUS ......................................................................................... 65
TRANSMISSION ....................................................................................................................................... 66
WEST NILE VIRUS POLIOMYELITIS ....................................................................................................... 71
PREVENTION............................................................................................................................................. 72
INSECT REPELLENT USE AND SAFETY........................................................................................... 74
GENERAL QUESTIONS............................................................................................................................... 74
ACTIVE INGREDIENTS (TYPES OF INSECT REPELLENT)............................................................................. 74
USING REPELLENTS PROPERLY ................................................................................................................ 76
CHILDREN ................................................................................................................................................ 77
INSECT REPELLENTS CONTAINING DEET AND SUNSCREEN...................................................................... 78
WEST NILE VIRUS VACCINE...................................................................................................................... 79
TESTING AND TREATING WEST NILE VIRUS IN HUMANS UPDATED!................................ 80
QUESTIONS ABOUT COMMERCIAL LABORATORIES................................................................. 81
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WEST NILE VIRUS, PREGNANCY AND BREAST-FEEDING......................................................... 82
BREASTFEEDING....................................................................................................................................... 84
BLOOD TRANSFUSION, ORGAN DONATION AND BLOOD DONATION SCREENING INFORMATION .............. 85
UPDATE ON DETECTION OF WNV IN BLOOD DONATIONS -- FROM MMWR, SEPTEMBER
18, 2003........................................................................................................................................................ 85
GENERAL INFORMATION ON SCREENING OF BLOOD DONATIONS FOR WNV ................. 86
PESTICIDES USED IN MOSQUITO CONTROL................................................................................. 91
WEST NILE VIRUS AND DOGS AND CATS ....................................................................................... 93
WEST NILE VIRUS AND HORSES........................................................................................................ 94
WEST NILE VIRUS AND SQUIRRELS .......................................................................................................... 95
WEST NILE VIRUS AND WILD GAME/MEAT ............................................................................................. 96
RECOMMENDATIONS FOR PROTECTING OUTDOOR WORKERS FROM WEST NILE
VIRUS EXPOSURE................................................................................................................................. 103
Recommendations for employers of Outdoor Workers ..................................................................... 103
RECOMMENDATIONS FOR WORKERS....................................................................................................... 104
RECOMMENDATIONS FOR PROTECTING LABORATORY, FIELD, AND CLINICAL
WORKERS FROM WEST NILE VIRUS EXPOSURE....................................................................... 105
Occupational Risk............................................................................................................................. 105
Recommendations for employers ...................................................................................................... 106
Recommendations for workers.......................................................................................................... 106
.......................................................................................................................................... 107CONCLUSION
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Introduction to the West Nile Virus
West Nile virus emerged in the United
States in the New York metropolitan area
in the fall of 1999. Since then, the virus,
which can be transmitted to humans by
the bite of an infected mosquito, has
quickly spread across the country.
In Illinois, West Nile virus was first
identified in September 2001 when
laboratory tests confirmed its presence in
two dead crows found in the Chicago
area. The following year, the state's first
human cases and deaths from West Nile
disease were recorded and all but two of
the state's 102 counties eventually
reported a positive human, bird, mosquito or horse case. By the end of 2002, Illinois had counted
more human cases (884) and deaths (67) than any other state in the nation. In 2003, the
epicenter of West Nile disease moved westward. Colorado reported the highest number of cases
(2,947), easily surpassing the caseload record for the mosquito-borne disease set the previous
year by Illinois. The number of West Nile human cases in Illinois fell dramatically with just 54
reported and only one death. Illinois' caseload in 2004 was slightly higher than the previous year
with 60 reported cases and four deaths. For the second consecutive year, the country's western
states had the most cases with California leading the way with 771, followed by Arizona with 391
and Colorado with 276. In 2005, Illinois' first human cases were reported on July 29.
Most state Public Health services maintain a sophisticated disease surveillance system to monitor
animals and insects that can potentially carry the virus: dead crows, robins, blue jays, mosquitoes
and horses. Mosquitoes can either carry the virus or get it by feeding on infected birds. The
surveillance system also includes infectious disease physicians, hospital laboratory directors and
infection control practitioners, local health departments and laboratory staff, environmental health
and infectious diseases divisions who test for and report suspect or confirmed cases of various
diseases that can be caused by mosquito-borne viruses.
Mild cases of West Nile infections may cause a slight fever or headache. More severe infections
are marked by a rapid onset of a high fever with head and body aches, disorientation, tremors,
convulsions and, in the most severe cases, paralysis or death. Usually symptoms occur from
three to 14 days after the bite of an infected mosquito. Persons at the highest risk for serious
illness are those 50 years of age or older.
The best way to prevent West Nile encephalitis and other mosquito-borne illnesses is to reduce
the number of mosquitoes around your home and neighborhood and to take personal precautions
to avoid mosquito bites.
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Background: Virus History and Distribution
Introduction
West Nile virus (WNV) has emerged in recent years in temperate regions of Europe
and North America, presenting a threat to public and animal health. The most
serious manifestation of WNV infection is fatal encephalitis (inflammation of the
brain) in humans and horses, as well as mortality in certain domestic and wild birds.
WNV has also been a significant cause of human illness in the United States in 2002
and 2003.
History
West Nile virus was first isolated from a febrile adult
woman in the West Nile District of Uganda in 1937. The
ecology was characterized in Egypt in the 1950s. The
virus became recognized as a cause of severe human
meningitis or encephalitis (inflammation of the spinal
cord and brain) in elderly patients during an outbreak
in Israel in 1957. Equine disease was first noted in
Egypt and France in the early 1960s. WNV first
appeared in North America in 1999, with encephalitis
reported in humans and horses.The subsequent spread in the United States is an
important milestone in the evolving history of this virus.
View enlarged map of
laboratory-positive
West Nile virus
infections during 2003
Geographic Distribution
West Nile virus has been described in Africa, Europe, the Middle East, west and
central Asia, Oceania (subtype Kunjin), and most recently, North America.
Outbreaks of WNV encephalitis in humans have occurred in Algeria in 1994, Romania
in 1996-1997, the Czech Republic in 1997, the Democratic Republic of the Congo in
1998, Russia in 1999, the United States in 1999-2003, and Israel in 2000.
Epizootics of disease in horses occurred in Morocco in 1996, Italy in 1998, the United
States in 1999-2001, and France in 2000, and in birds in Israel in 1997-2001 and in
the United States in 1999-2002.
In the U.S. since 1999, WNV human, bird, veterinary or mosquito activity have been
reported from all states except Hawaii, Alaska, and Oregon.
Human Case and Virus Distribution Information
• Current human case and epizootic distribution maps (on Statistics,
Surveillance, and Control page)
• Case human counts for 2003
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• Human case information and maps from 2002
• From 1999 through 2001, there were 149 cases of West Nile virus human
illness in the United States reported to CDC and confirmed, including 18
deaths.
West Nile Virus: What You Need To Know
What Is West Nile Virus?
West Nile virus (WNV) is a potentially serious illness. Experts believe WNV is
established as a seasonal epidemic in North America that flares up in the summer
and continues into the fall. This fact sheet contains important information that can
help you recognize and prevent West Nile virus.
What Can I Do to Prevent WNV?
The easiest and best way to avoid WNV is to prevent mosquito bites.
• When you are outdoors, use insect repellent containing an EPA-registered
active ingredient. Follow the directions on the package.
• Many mosquitoes are most active at dusk and dawn. Be sure to use insect
repellent and wear long sleeves and pants at these times or consider staying
indoors during these hours.
• Make sure you have good screens on your windows and doors to keep
mosquitoes out.
• Get rid of mosquito breeding sites by emptying standing water from flower
pots, buckets and barrels. Change the water in pet dishes and replace the
water in bird baths weekly. Drill holes in tire swings so water drains out. Keep
children's wading pools empty and on their sides when they aren't being
used.
What Are the Symptoms of WNV?
• 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 neurological effects may be permanent.
• Milder Symptoms in Some People. Up to 20 percent of the people who
become infected have symptoms such as fever, headache, and body aches,
nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the
chest, stomach and back. Symptoms can last for as short as a few days,
though even healthy people have become sick for several weeks.
• No Symptoms in Most People. Approximately 80 percent of people (about
4 out of 5) who are infected with WNV will not show any symptoms at all.
How Does West Nile Virus Spread?
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• Infected Mosquitoes. Most often, WNV is spread by the bite of an infected
mosquito. Mosquitoes become infected when they feed on infected birds.
Infected mosquitoes can then spread WNV to humans
and other animals when they bite.
• Transfusions, Transplants, and Mother-to-Child. In a
very small number of cases, WNV also has been spread
through blood transfusions, organ transplants,
breastfeeding and even during pregnancy from mother to
baby.
• Not through touching. WNV is not spread through
casual contact such as touching or kissing a person with the virus.
How Soon Do Infected People Get Sick?
People typically develop symptoms between 3 and 14 days after they are bitten by
the infected mosquito.
How Is WNV Infection Treated?
There is no specific treatment for WNV infection. In cases with milder symptoms,
people experience symptoms such as fever and aches that pass on their own,
although even healthy people have become sick for several weeks. In more severe
cases, people usually need to go to the hospital where they can receive supportive
treatment including intravenous fluids, help with breathing and nursing care.
What Should I Do if I Think I Have WNV?
Milder WNV illness improves on its own, and people do not necessarily need to seek
medical attention for this infection though they may choose to do so. If you develop
symptoms of severe WNV illness, such as unusually severe headaches or confusion,
seek medical attention immediately. Severe WNV illness usually requires
hospitalization. Pregnant women and nursing mothers are encouraged to talk to their
doctor if they develop symptoms that could be WNV.
What Is the Risk of Getting Sick from WNV?
People over 50 at higher risk to get severe illness. People over the age of 50
are more likely to develop serious symptoms of WNV if they do get sick and should
take special care to avoid mosquito bites.
Being outside means you're at risk. The more time you're outdoors, the more
time you could be bitten by an infected mosquito. Pay attention to avoiding mosquito
bites if you spend a lot of time outside, either working or playing.
Risk through medical procedures is very low. All donated blood is checked for
WNV before being used. The risk of getting WNV through blood transfusions and
organ transplants is very small, and should not prevent people who need surgery
from having it. If you have concerns, talk to your doctor.
Pregnancy and nursing do not increase risk of becoming infected with WNV.
The risk that WNV may present to a fetus or an infant infected through breastmilk is
still being evaluated. Talk with your care provider if you have concerns.
What Is the CDC Doing About WNV?
CDC is working with state and local health departments, the Food and Drug
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Administration and other government agencies, as well as private industry, to
prepare for and prevent new cases of WNV.
Some things CDC is doing include:
• Coordinating a nation-wide electronic database where states share
information about WNV
• Helping states develop and carry out improved mosquito prevention and
control programs
• Developing better, faster tests to detect and diagnose WNV
• Creating new education tools and programs for the media, the public, and
health professionals
• Opening new testing laboratories for WNV
• Working with partners on the development of vaccines
What Else Should I Know?
If you find a dead bird: Don't handle the body with your bare hands. Contact your
local health department for instructions on reporting and disposing of the body. They
may tell you to dispose fo the bird after they log your report.
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Links to State and Local Government West Nile
Virus Web Sites
Click on a state to link directly to their West Nile virus Web page.
See list below for additional city-level and main State Health Department Web sites.
Maps and boundary data are copyrighted by FOTW Flags Of The World *
• Expanded list of State and Local West Nile Virus Resources
Maintained by the National Pesticide Information Center (NPIC)
List of State and Local Health Department Web Sites, by
State
and City Health Department West Nile Virus Web Sites
• Alabama
• Alaska
• Arizona
• Arkansas
• California
o Los Angeles County Department of Health Services
• Colorado
• Connecticut
o West Nile Fever Fact Sheet
• Delaware
• District of Columbia
• Florida
• Georgia
o DeKalb County Board of Health
DeKalb County Mosquitoes and West Nile Home Page
• Hawaii
• Idaho
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• Illinois
• Indiana
• Iowa
• Kansas
• Kentucky
• Louisiana
• Maine
• Maryland
• Massachusetts
• Michigan
• Minnesota
• Mississippi
• Missouri
• Montana
• Nebraska
• Nevada
• New Hampshire
• New Jersey
o New Jersey Department of Agriculture West Nile Virus Information
o New Jersey West Nile Virus On-line Information Resources
• New Mexico
• New York
o Monroe County Department of Health
Monroe County West Nile Virus page
o New York City Department of Health
New York City Department of Health West Nile Virus
Information
o Westchester County Department of Health
Westchester County West Nile Virus Watch
• North Carolina
• North Dakota
• Ohio
• Oklahoma
• Oregon
• Pennsylvania
o Philadelphia Department of Public Health
Philadelphia West Nile Virus Page
• Rhode Island
• South Carolina
• South Dakota
• Tennessee
• Texas
o Harris County Public Health Services
• Utah
• Vermont
• Virginia
• Washington
• West Virginia
• Wisconsin
• Wyoming
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It's time to prepare for West Nile Virus.
West Nile Virus is spread by mosquitoes. Infection with the virus can cause severe
and sometimes fatal illness. There were over 4000 cases of West Nile disease in the
US during 2002, including 284 deaths. It is likely that all mainland states in the
United States will see West Nile virus activity in 2003.
To help you prepare for mosquito season, read the truth about some common West
Nile virus myths:
Five Common Myths about West Nile Virus
Myth #1: There's not much I can do about
West Nile virus.
Truth: There is a lot that you, personally, can
do to reduce your chance of West Nile virus
infection.
• Reduce the number of mosquito bites you
get. Make a habit of using insect repellent
with DEET when outdoors. Spray repellent
on exposed skin and clothing. Get the
details about safe repellent use.
• Prime mosquito-biting hours are usually
dusk to dawn. Pay special attention to
protection during these hours, or avoid
being outdoors.
• You can reduce the number of mosquitoes
around your home. Mosquitoes breed in standing water, so check your yard
once a week: get rid of containers that aren't being used, empty water from
flower pots, change water in bird baths and maintain clean gutters.
Avoid mosquito bites by applying insect
repellent when spending time outdoors. Use
repellent safely. Always read and follow
product instructions.
• Make sure window and door screens are in good condition. Have an older
neighbor or family member? See if they need help installing or repairing
screens.
Myth #2: Kids are at the most danger of getting sick from West Nile virus.
Truth: People over 50 are at the highest risk for developing severe West
Nile disease.
• Relatively few children have been reported with severe West Nile Virus
disease. By contrast, most of the deaths due to WNV during 2002 were
among people over 50 years old. Half of those deaths were among people
over 77 years old.
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• It is always a good idea for children to avoid mosquito bites, but it's also
important for adults - especially older adults - to take steps to avoid mosquito
bites. Click here for suggestions on how to avoid mosquito bites.
Myth #3: It's only people who are already in poor health who have to worry
about West Nile virus.
Truth: Healthy, active older adults who spend time working and exercising
outdoors have been affected by severe West Nile virus infection.
• Being over 50 is a risk factor for developing severe West Nile disease if
infected with the virus. There is a risk of getting mosquito bites while leading
an active life outdoors. This doesn't mean you have to stay inside - it does
mean that it's important to use repellent when you go outside.
Myth #4: Repellents containing DEET are not safe.
Truth: Repellents containing DEET are very safe when used according to
directions.
• Because DEET is so widely used, a great deal of testing has been done. When
manufacturers seek registration with the US Environmental Protection Agency
(EPA) for products such as DEET, laboratory testing regarding both short-
term and long-term health effects must be carried out.
• There are products with different strengths (percentage of DEET) available.
The longer the protection you need the higher percent of DEET needed.
• Repellent with DEET can be used for both adults and children, according to
directions
• Click here for much more information on using repellents safely.
Myth #5: As long as my area has a mosquito control program, I don't have
to worry about using repellent.
Truth: Mosquito control activities don't eliminate every mosquito, so
personal protection is still important.
• Public activities, such as using products to kill mosquito
larvae and adult mosquitoes, are one part of control.
Personal protection, such as using repellent, keeping
window screens in good condition, and control of
household breeding sites are other important steps.
• Collaboration between the community, the family and the
individual is needed to achieve the best prevention of West Nile virus
infection.
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West Nile Virus Transmission Cycle
• Horses infected with West Nile Virus (WNV) are not contagious.
• Horses can't spread it to other horses or people.
• Mosquitoes that have fed on infected birds spread WNV.
• A mosquito cannot bite an infected horse and spread the virus to another horse
or person.
• Horses are not known to spread West Nile Virus to people. Horses are
considered to be "dead-end" hosts for WNV because it appears that they do not
develop a sufficient viremia to transmit the virus from contact. Clinical signs are
usually not apparent until 3-14 days post infection and viremia. Regardless, it is
very important that veterinarians and other animal health workers take standard
recommended precautions for all contagious equine viral encephalitic agents
such as rabies and other viral encepaphalitis agents when dealing with horses
suffering from undiagnosed neurological diseases.
• Treatment consists of supportive measures, and there is no specific cure.
• WNV is not analogous to Foot and Mouth Disease (FMD)) and Exotic Newcastle
Disease (END). Both FMD and END are very contagious and spread with ease
and rapidity.
• There will be no quarantines nor regulatory movement restrictions placed on
WNV positive horses.
• Control of WNV in horses involves working with one's veterinary practitioner to
establish both effective mosquito control and vaccination programs.
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Fight The Bite!
Avoid Mosquito Bites to Avoid Infection
Fight The Bite!
Avoid Mosquito Bites to Avoid Infection
When dealing with West Nile virus, prevention is your best bet. Fighting mosquito
bites reduces your risk of getting this disease, along with others that mosquitoes can
carry. Take the commonsense steps below to reduce your risk:
When dealing with West Nile virus, prevention is your best bet. Fighting mosquito
bites reduces your risk of getting this disease, along with others that mosquitoes can
carry. Take the commonsense steps below to reduce your risk:
• avoid bites and illness;• avoid bites and illness;
• clean out the mosquitoes from the places where you work and play;• clean out the mosquitoes from the places where you work and play;
• help your community control the disease.• help your community control the disease.
Something to remember: The chance that any one person is going to become ill
from a single mosquito bite remains low. The risk of severe illness and death is
highest for people over 50 years old, although people of all ages can become ill.
Something to remember: The chance that any one person is going to become ill
from a single mosquito bite remains low. The risk of severe illness and death is
highest for people over 50 years old, although people of all ages can become ill.
Avoid Mosquito Bites
Use Insect Repellent
on exposed skin when you go outdoors. Use an EPA-registered
insect repellent such as those with DEET, picaridin or oil of
lemon eucalyptus. Even a short time being outdoors can be
long enough to get a mosquito bite. For details on when and
how to apply repellent, see Insect Repellent Use and Safety in
our Questions and Answers pages. See also Using Insect
Repellent Safely from the EPA.
Clothing Can Help Reduce Mosquito Bites
When weather permits, wear long-sleeves, long pants and
socks when outdoors. Mosquitoes may bite through thin
clothing, so spraying clothes with repellent containing
permethrin or another EPA-registered repellent will give
extra protection. Don't apply repellents containing
permethrin directly to skin. Do not spray repellent on the
skin under your clothing.Get double protection: wear long
sleeves during peak mosquito
biting hours, and spray repellent
directly onto your clothes.
Be Aware of Peak Mosquito Hours
The hours from dusk to dawn are peak biting times for many species of mosquitoes.
Take extra care to use repellent and protective clothing during evening and early
morning -- or consider avoiding outdoor activities during these times.
------------------------------------------------------------------------------------------------------------

Mosquito-Proof Your Home
Drain standing water
from around your
home
Drain Standing Water
Mosquitoes lay their eggs in
standing water.Limit the number
of places around your home for
mosquitoes to breed by getting
rid of items that hold water.
Need examples? Learn more on
the Prevention of West Nile Virus
Question and Answer page.
Install or Repair Screens
Some mosquitoes like to come indoors. Keep them outside by having well-fitting
screens on both windows and doors. Offer to help neighbors whose screens might
be in bad shape.
Help Your Community
Report Dead Birds to Local Authorities
Dead birds may be a sign that West Nile virus is circulating between birds and the
mosquitoes in an area. Over 130 species of birds are known to have been infected
with West Nile virus, though not all infected birds will die. It's important to
remember that birds die from many other causes besides West Nile virus.
By reporting dead birds to state and local health departments, you can play an
important role in monitoring West Nile virus. State and local agencies have different
policies for collecting and testing birds, so check the Links to State and Local
Government Sites page to find information about reporting dead birds in your area.
Click here for more info about reporting dead birds and dealing with bird carcasses.
Mosquito Control Programs
Check with local health authorities to see if there is an
organized mosquito control program in your area. If no
program exists, work with your local government officials to
establish a program. The American Mosquito Control Association
can provide advice, and their book Organization for Mosquito
Control is a useful reference. The final report from the Mosquito
Control Collaborative is also online.
More questions about mosquito control? A source for information about pesticides
------------------------------------------------------------------------------------------------------------

and repellents is the National Pesticide Information Center, which also operates a
toll-free information line: 1-800-858-7378 (check their Web site for hours).
Clean Up
Mosquito breeding sites can be anywhere. Neighborhood clean up days can be
organized by civic or youth organizations to pick up containers from vacant lots and
parks, and to encourage people to keep their yards free of standing water.
Mosquitoes don't care about fences, so it's important to control breeding sites
throughout the neighborhood.
Find out more about local prevention efforts
Find state and local West Nile virus information and contacts on the Links to State
and Local Government Sites page.
What You Need to Know about Mosquito Repellent
Why You Should Use Mosquito Repellent
Insect repellent helps reduce your exposure to mosquito bites that may carry West
Nile virus or other diseases, and allows you to continue to play, work, and enjoy the
outdoors with a lower risk of disease.
When You Should Use Mosquito Repellent
Use repellent when you go outdoors. You should use repellent even if you're only
going outside for a few minutes-it only takes one bite to get West Nile virus. Many of
the mosquitoes that carry the West Nile virus bite between dusk and dawn. If you're
outside during these hours pay special attention to using repellent.
Which Mosquito Repellents Work Best
A wide variety of insect repellent products are available. CDC recommends the use of
products containing active ingredients which have been registered with the U.S.
Environmental Protection Agency (EPA) for use as repellents applied to skin and
clothing.
When EPA registers a repellent, they evaluate the product for efficacy and potential
effects on human beings and the environment. EPA registration means that EPA does
not expect a product, when used according to the instructions label, to cause
unreasonable adverse effects to human health or the environment.
Of the active ingredients registered with the EPA, two have demonstrated a higher
degree of efficacy in the peer-reviewed, scientific literature.* Products containing
------------------------------------------------------------------------------------------------------------

these active ingredients typically provide longer-lasting protection than others:
• DEET (N,N-diethyl-m-toluamide)
• Picaridin (KBR 3023)
Oil of lemon eucalyptus [p-menthane 3,8-diol (PMD)], a plant based repellent, is also
registered with EPA. 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.
These recommendations are for domestic use in the United States. See CDC
Travelers’ Health website for specific recommendations concerning protection from
insects when traveling outside the United States.
In addition, certain products which contain permethrin are recommended for use on
clothing, shoes, bed nets, and camping gear, and are registered with EPA for this
use. Permethrin is highly effective as an insecticide and as a repellent. Permethrin-
treated clothing repels and kills ticks, mosquitoes, and other arthropods and retains
this effect after repeated laundering. The permethrin insecticide should be reapplied
following the label instructions. Some commercial products are available pretreated
with permethrin. Permethrin is not to be used directly on skin.
How Often You Should Re-apply Repellents
Follow the directions on the product you are using. Sweating or getting wet
may mean that you need to re-apply more frequently.
How the Percentage of Active Ingredient in a Product Relates
to Protection Time
In general, the more active ingredient (higher percentage) it has, the longer a
repellent will protect you from mosquitoes. For example, DEET products are available
in many formulations--something with 30% DEET will protect you longer than one
with 5% DEET. You cannot directly compare the percentage of one active ingredient
to another, however.
Use your common sense. Re-apply repellent if you start to get bitten and follow the
label instructions.
As a “rule of thumb”:
• For many hours outside (over 3-4 hours) and/or where biting is very
intense—look for a repellent containing more than 20% DEET. Products with
more than 50% DEET do not offer additional protection.
• For shorter periods of time, repellents containing less than 20% DEET, the
repellent currently available with 7% picaridin or one of the products
containing oil of lemon eucalyptus may provide adequate protection. There
are other products available, but they may not protect as long as those
named here.
------------------------------------------------------------------------------------------------------------

• Even if you’re going out for 10 minutes use a repellent —that’s long enough
to get bitten!
Hint: Applying permethrin to your clothing ahead of time will give you even greater
protection.
Remember—if you’re getting bitten, do something about it!
Choose a repellent that you will use consistently. Also, choose a product that
will provide sufficient protection for the amount of time that you will be spending
outdoors. Product labels often indicate the length of time that you can expect
protection from a product. If you are concerned about using insect repellent, consult
your health care provider for advice.
The National Pesticide Information Center (NPIC) can also provide information
through a toll-free number, 1-800-858-7378 or http://npic.orst.edu.
General Considerations for Using Repellents Safely
• Always follow the instructions on the product label.
• 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 bad reaction from an insect repellent,
stop using the repellent, wash the repellent off 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 to show the doctor.
Note that the label for products containing oil of lemon eucalyptus specifies that they
should not to be used on children under the age of three years.
Other than those listed above, EPA does not recommend any additional precautions
for using registered repellents on pregnant or lactating women, or on children.
For additional information regarding the use of repellent on children, please see
CDC’s Frequently Asked Questions about Repellent Use.
DEET-based repellents applied according to label instructions may be used along with
------------------------------------------------------------------------------------------------------------

a separate sunscreen. No data are available at this time regarding the use of other
active repellent ingredients in combination with a sunscreen.
See http://www.epa.gov/pesticides/factsheets/insectrp.htm for additional
information on using EPA-registered repellents.
In addition to wearing repellent, you can protect yourself and
your family by taking these precautions:
• Wear clothing with long pants and long sleeves while outdoors. Apply
permethrin or another EPA-registered repellent to clothing, as mosquitoes
may bite through thin fabric. (Remember: don't use permethrin on skin.)
• Use mosquito netting over infant carriers.
• Reduce the number of mosquitoes in your area by getting rid of containers
with standing water that provide breeding places for the mosquitoes.
Updated Information regarding Insect Repellents
Repellents are an important tool to assist people in protecting themselves
from mosquito-borne diseases.
A wide variety of insect repellent products are available. CDC recommends the use of
products containing active ingredients which have been registered with the U.S.
Environmental Protection Agency (EPA) for use as repellents applied to skin and
clothing. EPA registration of repellent active ingredients indicates the materials have
been reviewed and approved for efficacy and human safety when applied according
to the instructions on the label.
Of the active ingredients registered with the EPA, two have demonstrated a higher
degree of efficacy in the peer-reviewed, scientific literature *. Products containing
these active ingredients typically provide longer-lasting protection than others:
• DEET (N,N-diethyl-m-toluamide)
• Picaridin (KBR 3023)
Oil of lemon eucalyptus [p-menthane 3,8-diol (PMD)], a plant based repellent, is also
registered with EPA. 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.
These recommendations are for domestic use in the United States. See CDC
Travelers’ Health website for specific recommendations concerning protection from
insects when traveling outside the United States.
In addition, certain products which contain permethrin are recommended for use on
clothing, shoes, bed nets, and camping gear, and are registered with EPA for this
------------------------------------------------------------------------------------------------------------

use. Permethrin is highly effective as an insecticide and as a repellent. Permethrin-
treated clothing repels and kills ticks, mosquitoes, and other arthropods and retains
this effect after repeated laundering. The permethrin insecticide should be reapplied
following the label instructions. Some commercial products are available pretreated
with permethrin.
Length of protection from mosquito bites varies with the amount of active
ingredient, ambient temperature, amount of physical activity/perspiration, any
water exposure, abrasive removal, and other factors. For long duration protection
use a long lasting (micro-encapsulated) formula and re-apply as necessary,
according to label instructions.
EPA recommends the following precautions when using insect repellents:
• 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 bad reaction from an insect repellent,
stop using the repellent, wash the repellent off 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 to show the doctor.
Note that the label for products containing oil of lemon eucalyptus specifies that they
should not to be used on children under the age of three years. Other than those
listed above, EPA does not recommend any additional precautions for using
registered repellents on pregnant or lactating women, or on children. For additional
information regarding the use of repellent on children, please see CDC’s Frequently
Asked Questions about Repellent Use.
[http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm]
DEET-based repellents applied according to label instructions may be used along with
a separate sunscreen. No data are available at this time regarding the use of other
active repellent ingredients in combination with a sunscreen.
------------------------------------------------------------------------------------------------------------

Vertebrate Ecology
Transmission Cycle
West Nile (WN) virus is amplified during periods
of adult mosquito blood-feeding by continuous
transmission between mosquito vectors and bird
reservoir hosts. Infectious mosquitoes carry virus
particles in their salivary glands and infect
susceptible bird species during blood-meal
feeding. Competent bird reservoirs will sustain
an infectious viremia (virus circulating in the
bloodstream) for 1 to 4 days after exposure,
after which these hosts develop life-long
immunity. A sufficient number of vectors must feed on an infectious host to ensure
that some survive long enough to feed again on a susceptible reservoir host.
View enlarged image.
People, horses, and most other mammals are not known to develop infectious-level
viremias very often, and thus are probably "dead-end" or incidental-hosts.
Birds
West Nile virus has been detected in dead birds of at least 138 species. Although
birds, particularly crows and jays, infected with WN virus can die or become ill, most
infected birds do survive. Click here for more information on species of dead birds in
the U.S. in which West Nile virus has been detected.
There is no evidence that a person can get WN virus from handling live or dead
infected birds. Persons should avoid bare-handed contact when handling any dead
animals, and use gloves or double plastic bags to place the bird carcass in a garbage
bag or contact their local health department for guidance.
Dogs and Cats
West Nile virus does not appear to cause extensive illness in dogs or cats. There is a
single published report of WN virus isolated from a dog in southern Africa (Botswana)
in 1982. West Nile virus was isolated from a single dead cat in 1999. A serosurvey in
New York City of dogs in the 1999 epidemic area indicated that dogs are frequently
infected. Nonetheless, disease from WN virus infection in dogs has yet to be
documented.
There is no documented evidence of person-to-person or animal-to-person
transmission of WN virus. Because WN virus is transmitted by infectious mosquitoes,
dogs or cats could be exposed to the virus in the same way humans become
infected. Veterinarians should take normal infection control precautions when caring
for an animal suspected to have this or any viral infection. It is possible that dogs
and cats could become infected by eating dead infected animals such as birds, but
this is undocumented.
------------------------------------------------------------------------------------------------------------

There is no reason to destroy an animal just because it has been infected with WN
virus. Full recovery from the infection is likely. Treatment would be supportive and
consistent with standard veterinary practices for animals infected with a viral agent.
Horses
Cases of WN virus disease in horses have been documented, either by virus isolation
or by detection of WN virus-neutralizing antibodies in 1999, 2000, and 2001.
Approximately 40% of equine WN virus cases results in the death of the horse.
Horses most likely become infected with WN virus in the same way humans become
infected, by the bite of infectious mosquitoes.
In locations where WN virus is circulating, horses should be protected from mosquito
bites as much as possible. Horses vaccinated against eastern equine encephalitis
(EEE), western equine encephalitis (WEE), and Venezuelan equine encephalitis (VEE)
are NOT protected against WN virus infection. A West Nile virus vaccine for horses
was recently licensed, but its effectiveness is unknown. Horses infected by WN virus
develop a brief low-level viremia that is rarely, if ever, infectious to mosquitoes.
There is no reason to destroy a horse just because it has been infected with WN
virus. Data suggest that most horses recover from the infection. Treatment would be
supportive and consistent with standard veterinary practices for animals infected
with a viral agent.
Other Vertebrates
Through December 2001, CDC has also received a small number of reports of WN
virus infection in bats, a chipmunk, a skunk, a squirrel, and a domestic rabbit.
Entomology
Arthropod-borne viruses (termed "arboviruses") are viruses that are maintained in
nature through biological transmission between susceptible vertebrate hosts by
blood-feeding arthropods (mosquitoes, sand flies, ceratopogonids "no-see-ums", and
ticks). Vertebrates can become infected when an infected arthropod bites them to
take a blood meal. The term 'arbovirus' has no taxonomic significance.
The arboviral encephalitides are zoonotic, being maintained in complex life cycles
involving a nonhuman primary vertebrate host and a primary arthropod vector.
These cycles usually remain undetected until humans encroach on a natural focus, or
the virus escapes this focus via a secondary vector or vertebrate host as the result of
some ecologic change. Humans and domestic animals can develop clinical illness but
usually are incidental or "dead-end" hosts because they do not produce significant
viremia (circulating virus), and thus do not contribute to the transmission cycle.
------------------------------------------------------------------------------------------------------------

In the United States, West Nile virus is transmitted by infected mosquitoes, primarily
members of the Culex species.
Arboviral encephalitis can be prevented
in two major ways:
1. Personal protective measures to
reduce contact with mosquitoes
and
2. Public health measures to
reduce the population of infected
mosquitoes in the environment.
Personal protection measures include
reducing time outdoors, particularly in
early morning and evening hours,
wearing long pants and long sleeved shirts, and applying mosquito repellent to
exposed skin areas and clothing.
Image: Culex mosquito laying eggs.
(View enlarged image.)
Public health measures include elimination of larval habitats or spraying of
insecticides to kill juvenile (larvae) and adult mosquitoes. The combination of
mosquito control methods selected for use in a control program depends on the time
of year, the type of mosquitoes to be controlled, and the habitat structure. In
emergency situations, wide area aerial spraying is used to quickly reduce the number
of adult mosquitoes. In many states, aerial spraying may be available as a means to
control nuisance mosquitoes. Such resources can be redirected to areas of virus
activity when necessary.
Financing of aerial spraying costs during disease outbreaks is often provided by state
or local emergency funds. Federal funding of emergency spraying is rare and almost
always is associated with a natural disaster such as flood or hurricane.
Virology: Classification of West Nile Virus
1. Family: Flaviviridae
2. Genus: Flavivirus Japanese Encephalitis Antigenic Complex
3. Complex includes: Alfuy, Cacipacore, Japanese encephalitis, Koutango,
Kunjin, Murray Valley encephalitis, St. Louis encephalitis, Rocio, Stratford,
Usutu, West Nile, and Yaounde viruses.
4. Flaviviruses: share a common size (40-60nm), symmetry (enveloped,
icosahedral nucleocapsid), nucleic acid (positive-sense, single stranded RNA
approximately 10,000-11,000 bases), and appearance in the electron
------------------------------------------------------------------------------------------------------------

microscope. Therefore, images of West Nile virus are representative for this
group of viruses.
Public Health Confronts the Mosquito: Developing Sustainable State and
Local Mosquito Control Programs
Report by Association of State and Territorial Health Officials
See "What You Can Do About Mosquito Control"
Report Overview
State and Local Mosquito Control
Mosquito control is an important and basic public health function. The rapid spread of
West Nile virus across the U.S. in the last five years demonstrates the continuing
need for organized mosquito control activities. States and local communities are
challenged to develop and maintain these essential vector control programs,
especially in tight budgetary times and when emergency situations have quieted.
The Association of State and Territorial Health Officials’ Mosquito Control
Collaborative, a body comprised of state, local, and federal representatives from
public health, environmental, and agricultural agencies, as well as other
organizations closely involved with vector control and public health, has developed a
report titled Public Health Confronts the Mosquito Control: Developing Sustainable
State and Local Mosquito Control Programs. The report contains four sections
discussing the major components of successful state and local mosquito control
efforts:
• Planning Ahead
Understanding the structures and roles of the state, local and federal participants,
defining workforce and training requirements, identifying legal authorities and
funding alternatives, and developing strategies for evaluating programs are elements
that should be included in any successful planning effort. States, localities, and the
federal government all have active roles in mosquito control. The exact roles of each
will differ among the individual states and localities. Whatever structure is chosen, it
should be based on solid legal authority to act. The structure of the funding
mechanism for mosquito control activities also impacts the ultimate sustainability of
the program or activities.
• Involving Others
The foundation to any successful mosquito control action is involving key participants
early in the process. Governments should develop a strategy for involving others,
which includes identifying and engaging a wide variety of stakeholders. Governments
------------------------------------------------------------------------------------------------------------

should take care to identify the individuals, organizations, and agencies with a stake
in mosquito control decisions. A variety of mechanisms should be used to target
appropriate outreach to stakeholders. Special care should also be given to provide
decision makers with solid information upon which to base policy.
• Use the Best Science and Data
It is critical that science drives the assessment of local and state needs, strategies
selected, and design and monitoring of mosquito control programs. There are
numerous proven methodologies and practices that guide the best mosquito control
programs. All programs need to be based on an identified need that is matched with
local and state resources and technically sound strategies. Access to epidemiologic
capacity to conduct surveillance of mosquito-borne diseases in the human
population, and monitor disease and the distribution of relevant animal and insect
populations, is critical to begin any mosquito control activity. States and localities
must also determine their mosquito control needs. A scientific response to combat
nuisance mosquitoes may look very different from a program to combat mosquitoes
carrying disease.
• Informing the Public
Mosquito control programs need the support of an informed public. Many of the
successful strategies for control involve individuals, their families, and their
neighborhoods. The public also has concerns about the problems related to mosquito
populations and about insecticides and spraying. Development of a communications
plan that includes public education about preventing the breeding of mosquitoes,
personal protection guidance, and the activities and success of the agencies involved
is critical to the success of the program.
Conclusion
Mosquito control is a multi-discipline effort that can and should involve many
agencies and organizations at the local, state, and federal level. When programs are
started for a specific disease threat, there is often a temptation to abandon control
efforts once the threat has passed. As history demonstrates, the mighty mosquito
always returns and frequently with a previously unknown and unpredictable disease
threat. Public health has a responsibility and an opportunity to be part of a
comprehensive and thoughtful approach to continued mosquito control through
partnerships and teamwork at all levels of government.
More information about state and local mosquito control programs and a copy of
Public Health Confronts the Mosquito is available at
www.astho.org/?template=mosquito_control.html. The report also contains Planning
and Action checklists highlighting the major decision points and recommendations.
Source: Public Health Confronts the Mosquito: Developing Sustainable State and
Local Mosquito Control Programs. Association of State and Territorial Health Officials.
(June 2005). Available at www.astho.org/?template=mosquito_control.html.
What You Can Do About Mosquito Control
• Find out about your local mosquito control program
Contact them for information or questions about their mosquito control practices.
------------------------------------------------------------------------------------------------------------

• Support mosquito control activities
Report mosquito breeding sites untended pools, discarded tires, drainage ditches
with standing water.
• If your community doesn't have a mosquito control program
Contact your local government officials (blue pages of the phone book) or health
department. Information in the Public Health Confront the Mosquito (described
above) provides guidance about starting a program.
------------------------------------------------------------------------------------------------------------

Mosquitoes
Each summer, hordes of these insects descend on backyards, parks and campgrounds.
While most mosquitoes are merely nuisances, some can transmit serious diseases such
as encephalitis and malaria in humans and heartworm disease in dogs.
While the principles for west nile virus and mosquitoes are fairly common from state to
state and generally worldwide, it would be impossible to discuss the specifics for all areas
of the globe in a short volume such as this. So when possible I’ll relate to the west nile
virus and mosquito control with regard to the state I live in, Illinois. Keep in mind this in no
way denigrates the material in this book. All mosquitoes lay eggs in water, the virus is
transferred via birds. Most specifics come from the Center for Disease Control and State
Health Departments.
What kinds of mosquitoes are
common in Illinois?
Two different kinds of mosquitoes
plague Illinoisans. Floodwater
(temporary pool) mosquitoes deposit
their eggs singly in low-lying areas that
will be flooded later. Under normal
summer temperatures, large numbers of
biting mosquitoes will emerge about two
weeks after heavy rains and can be a
major nuisance problem for several
weeks. The most common of these in Illinois is the inland floodwater mosquito. A vicious
biter, this mosquito will commonly fly 10 or more miles from where they hatch, particularly
along prevailing winds. Floodwater mosquitoes have not been significant disease carriers
in Illinois.
Vector mosquitoes carry diseases and lay their eggs in stagnant ditches and sewage
treatment ponds or water in treeholes, old tires, clogged gutters, old tin cans and anything
else that will hold water. Eggs are laid on or just above the water surface, where they
usually hatch within two to three days. Two of the more common vector mosquitoes in
Illinois are the Culex, or house mosquito, and the tree-hole mosquito. Neither migrates
long distances.
Another disease-carrying mosquito is the Asian tiger mosquito, which arrived in the United
States in 1985 in old tires. An aggressive day-biting mosquito, it breeds in large numbers
in water-filled artificial containers.
Do all mosquitoes carry disease?
Floodwater mosquitoes are not major vectors of human disease in Illinois, but they do
transmit heartworm disease in dogs, as do Culex mosquitoes. The worms live and
reproduce in the heart and pulmonary vessels and can severely weaken or kill the dog.
------------------------------------------------------------------------------------------------------------

Although difficult to treat, the disease is easily prevented by medication prescribed by a
veterinarian.
In Illinois, the most common human illness carried by mosquitoes is encephalitis. This
inflammation of the brain is caused by viruses and the disease can range from mild to
severe. Severe symptoms include rapid onset of severe headaches, high fever and mental
disturbances, such as confusion, irritability, tremors, stupor and coma. Severe cases
sometimes end in death or with survivors suffering permanent physical and mental
disabilities.
Mosquitoes do not carry all types of encephalitis virus, but they do carry at least three that
can cause illness. The Culex mosquito, which bites from dusk to dawn, is a vector of St.
Louis encephalitis and West Nile virus; it becomes infected by feeding on birds that carry
these viruses. St. Louis encephalitis and West Nile virus affect mainly older adults. The
tree-hole mosquito, which bites during the day, is the main vector of California (LaCrosse)
encephalitis in Illinois. The virus infects chipmunks, squirrels and other small woodland
animals; in humans, it affects mainly children. The Asian tiger mosquito transmits dengue
fever in other parts of the world and could become involved in the California encephalitis
cycle in Illinois.
The last major nationwide epidemic of mosquito-borne encephalitis occurred in 1975. In
Illinois, 578 cases of St. Louis encephalitis, which resulted in 47 deaths, and 23 cases of
California encephalitis were identified during that year.
When was West Nile virus found in Illinois?
West Nile virus was first identified in September 2001 when laboratory tests confirmed its
presence in two dead crows found in the Chicago area. The following year, the state's first
human cases and deaths from West Nile disease were recorded and all but two of the
state's 102 counties eventually reported a West Nile positive, human, bird, mosquito or
horse. By the end of 2002, Illinois had counted more human cases (884) and deaths (66)
than any other state in the nation. In 2003, the number of human cases fell to 54 and only
one death, and West Nile activity was
reported in 77 counties.
What is the best way to reduce
populations of mosquitoes?
The first and best defense against these
pests and the illnesses they may carry i
to eliminate the places where they
breed. Here are a few suggestions:
s
• Remove or empty water in old
tires, tin cans, buckets, drums,
bottles or other places where
mosquitoes might breed. Be sure to check clogged gutters and flat roofs that may
have poor drainage. Make sure cisterns, cesspools, septic tanks, fire barrels, rain
barrels and trash containers are covered tightly with a lid or with 16-mesh screen.
------------------------------------------------------------------------------------------------------------

• Empty plastic wading pools at least once a week and store indoors when not in
use. Unused swimming pools should be covered or drained during the mosquito
season. (Note: If you choose to drain your pool, be sure the hydrostatic relief valve
is open in order to keep it from floating out of the ground if the water table rises.)
• Change the water in bird baths and plant pots or drip trays at least once each
week.
• Store boats covered or upside down, or remove rainwater weekly.
• Empty your pet's water bowl daily.
• Level the ground around your home so water can run off and not collect in low
spots. Fill in holes or depressions near your home that accumulate water.
• Fill in tree rot holes and hollow stumps that hold water.
• If you have an ornamental water garden, stock it with mosquito-eating fish (e.g.,
minnows, "mosquito fish," or goldfish). They eat mosquito larvae.
• Keep weeds and tall grass cut short; adult mosquitoes look for these shady places
to rest during the hot daylight hours.
• Use a flyswatter or household spray to kill mosquitoes, flies or other insects that
get into buildings. Spray shrubbery and high weeds to kill adult insects. (Check the
insecticide label to make the sure the spray will not damage flowers or ornamental
plants.)
• Small impoundments of water can be treated for mosquito larvae with "Bti," a
bacterial insecticide. Many hardware stores carry doughnut-shaped Bti briquets
(Mosquito Dunks R) for this purpose. Be sure to follow the insecticide label
directions exactly.
• Some mosquito control methods are not very effective. Bug zappers are not
effective in controlling biting mosquitoes. Various birds and bats will eat
mosquitoes, but there is little scientific evidence that this reduces mosquitoes
around homes.
• Community-wide mosquito abatement efforts can be quite effective if they are
conducted as part of an integrated pest management program. This includes
monitoring and draining or treating areas where mosquitoes breed — such as
street catch basins, occasionally flooded marshes, river backwater areas, swamps
and other low-lying areas.
How can people protect themselves from mosquito bites?
• Avoid places and times when mosquitoes bite. Generally, the peak biting periods
occur just before and after sunset and again just before dawn. Each species,
however, has its own peak period of biting. Tree-hole and Asian tiger mosquitoes,
for example, feed during daylight hours in or near shaded or wooded areas.
• Be sure door and window screens are tight-fitting and in good repair.
• Wear appropriate clothing. Long-sleeved tops and long pants made of tightly
woven materials keep mosquitoes away from the skin. Be sure, too, that your
clothing is light colored. Keep trouser legs tucked into boots or socks.
• Use mosquito netting when sleeping outdoors or in an unscreened structure and to
protect small babies any time.
• When it is necessary to be outdoors, apply insect repellent as indicated on the
repellent label. The more DEET a product contains, the longer the repellant can
protect against mosquito bites. However, concentrations higher than 50 percent do
not increase the length of protection. For most situations, 10 percent to 25 percent
DEET is adequate. Apply repellents to clothes whenever possible; apply sparingly
------------------------------------------------------------------------------------------------------------

to exposed skin if label permits. Consult a physician before using repellents on
young children.
Mosquitoes and Encephalitis
The Problem - Mosquito bites cause itching and irritation,
and scratching may result in infected sores. Mosquitoes also
transmit serious and sometimes fatal diseases to humans
and their pets.
Diseases - Encephalitis is an inflammation of the brain
that can be caused by viruses. The symptoms of encephalitis
can range from mild to severe. Severe symptoms include
rapid onset of severe headaches, high fever, and mental
disturbances such as confusion, irritability, tremors, stupor
and coma. Severe cases sometimes end in death or with
survivors suffering permanent loss of limb function, reduction
of intelligence and/or emotional instability.
Not all types of encephalitis viruses are carried by mosquitoes. However, mosquitoes carry
at least two types of encephalitis viruses that cause human disease in Illinois. La Crosse
(California) encephalitis is normally an infection of squirrels and chipmunks; in humans it
affects mainly children. St. Louis encephalitis is an infection of wild birds; in humans it
affects mainly older adults.
Mosquitoes can also infect dogs with heartworm. The worms live in the heart and can
severely weaken or kill the dog. Although difficult to treat, this disease is easily prevented by
medication that can be prescribed by your veterinarian.
Prevent Mosquitoes from Breeding Around
the Home
Mosquito larvae or "wrigglers" must live in still water for five
or more days to complete their growth before changing into
adult biting mosquitoes capable of transmitting disease.
Often, the number of mosquitoes in an area can be reduced
by removing sources of standing water. Hundreds of
mosquitoes can come from a single discarded tire.
• Get rid of old tires, tin cans, buckets, drums, bottles o
any water-holding containers.
r
• Fill in or drain any low places (puddles, ruts, etc.) in
the yard.
• Keep drains, ditches, and culverts free of weeds and
trash so water will drain properly.
• Keep roof gutters free of leaves and other debris.
• Cover trash containers to keep out rainwater.
------------------------------------------------------------------------------------------------------------

• Repair leaky pipes and outside faucets.
• Empty plastic wading pools at least once a week and store indoors when not in use.
Unused swimming pools should be drained and kept dry during the mosquito
season.
• Fill in tree rot holes and hollow stumps that hold water.
• Change the water in bird baths and plant pots or drip trays at least once each week.
• Keep grass cut short and shrubbery well trimmed around the house so adult
mosquitoes will not hide there.
Only a constant, complete program to control mosquitoes will reduce the numbers, the
nuisance and the danger of disease.
Protection from Mosquito Bites
Although many kinds of mosquitoes bite at dusk or at night, some kinds will bite during the
day. Almost all kinds will try to bite if you enter an area where they are resting, like high
grass.
• When possible, avoid places and times when mosquitoes bite.
• Wear light-colored protective clothing: Tightly woven materials that cover arms and
legs provide some protection from mosquito bites. Keep trouser legs tucked into
boots or socks, and collars buttoned.
• Have good screening: Make sure door and window screens fit tightly and all holes
are repaired.
• Use mosquito netting when sleeping outdoors or in an unscreened structure, and to
protect small babies any time.
• Small impoundments of water can be treated for mosquito larvae with "Bti," a
bacterial insecticide. Many hardware stores carry doughnut-shaped Bti briquets
(Mosquito Dunks R) for this purpose. Be sure to follow the insecticide label directions
exactly.
• When participating in outdoor activities where mosquitoes are biting, wear protective
clothing (shoes, socks, shirt and long pants). For additional protection from
mosquitoes, use an insect repellent. The more DEET a product contains, the longer
the repellant can protect against mosquito bites. However, concentrations higher
than 50 percent do not increase the length of protection. For most situations, 10
percent to 25 percent DEET is adequate. Apply repellents to clothes whenever
possible; apply sparingly to exposed skin if label permits. Consult a physician before
using repellents on young children.
• Spraying your backyard with an insecticidal fog or mist is effective only for a short
time. Mosquitoes will return when the effect of the spray has ended.
• Insect light electrocutors ("bug zappers") or sound devices do little to reduce biting
mosquitoes in an area.
• Installing bird or bat houses to attract these insect-eating animals has been
suggested as a method of mosquito control. However, there is little scientific
evidence that this significantly reduces the mosquito population around homes.
• Some communities conduct community-wide mosquito abatement programs.
Whenever possible, the primary effort of such programs should be identification of
mosquito-breeding sites, followed by removal or treatment of these sites with an
insecticide used for control of mosquito larvae.
------------------------------------------------------------------------------------------------------------

Questions and Answers about Mosquito
Prevention for People, Property and Pets
What kinds of diseases can be carried by mosquitoes?
Mosquito-borne disease is rare in Illinois. However, mosquitoes can
carry at least three encephalitis viruses that cause human disease.
La Crosse (California) encephalitis is normally an infection of squirrels
and chipmunks; in humans it affects mainly children. St. Louis
encephalitis is an infection of wild birds; in humans it affects mainly
older adults. In 2001, West Nile virus (WNV) was detected for the first
time in Illinois in birds, horses and mosquitoes. West Nile virus, like St. Louis encephalitis,
causes encephalitis primarily in older adults.
What is encephalitis?
Encephalitis is an inflammation of the brain that can be caused by arboviruses (viruses
carried by arthropods, such as mosquitoes and ticks) or by other types of viruses. In Illinois,
arboviruses are primarily transmitted to humans by the bites of infected mosquitoes. Most
individuals who are bitten by an infected mosquito will experience no symptoms of the
disease or will have only very mild symptoms. Approximately 1 percent to 2 percent will
develop recognizable symptoms. Some persons may have mild symptoms, such as a fever
and headache. Severe infection may cause rapid onset of severe headache, high fever,
muscle aches, stiffness in the back of the neck, problems with muscle coordination,
disorientation, convulsions and coma. Symptoms usually occur five to 15 days after the bite
of an infected mosquito. Not all viruses that cause encephalitis are carried by mosquitoes.
How can I help protect my family and myself from mosquitoes and the
diseases they may carry?
During the summer, mosquitoes can develop in any standing water that lasts more than
seven to 10 days. Consequently, you can begin protecting your family from mosquitoes by
reducing the amount of standing water available for mosquito breeding around your home:
• Dispose of discarded tires, cans, plastic containers, ceramic pots or other unused
similar water-holding containers that have accumulated on your property. Do not
------------------------------------------------------------------------------------------------------------

overlook containers that
have become overgrown
by vegetation.
• At least once per week,
empty standing water from
containers on your
property, such as tire
swings, or bird baths.
• Fill in tree rot holes and
hollow stumps that hold
water.
• Drill holes in the bottom of
recycling containers that
are left outdoors. Drainage
holes drilled in the sides of
containers allow sufficient
water to collect in which
mosquitoes may breed.
• Clean clogged roof gutters, particularly if the leaves from surrounding trees have a
tendency to plug up the drains. Flooded roof gutters are easily overlooked but can
produce hundreds of mosquitoes each season.
• Turn over plastic wading pools when not in use. A wading pool becomes a mosquito
producer if it is not used on a regular basis.
• Turn over wheelbarrows and do not allow water to stagnate in bird baths. Change
water in bird baths and wading pools on a weekly basis.
• Aerate ornamental pools or stock them with fish. Water gardens are fashionable but
become major mosquito producers if they are allowed to stagnate.
• Clean and chlorinate swimming pools that are not being used. A swimming pool that
is left untended by a family that goes on vacation for a month can produce enough
mosquitoes to result in neighborhood-wide complaints. Be aware that mosquitoes
may breed in the water that collects on swimming pool covers.
• Keep drains, ditches and culverts free of grass clippings, weeds and trash so water
will drain properly.
• Fill in low areas on your property to eliminate standing water. Ponds or streams
where fish are present or the water is disturbed by current or wave action do not
produce many mosquitoes.
• Report possible mosquito breeding sites to your local mosquito control agency if
one exists in your community.
Should we stay indoors?
It is not necessary to limit outdoor activities unless there is evidence of mosquito-borne
disease in your area. However, you can and should try to reduce the risk of being bitten by
mosquitoes.
• Minimize time spent outdoors between dusk and dawn when mosquitoes are most
active.
Northern house mosquito (Culex pipiens) 1
------------------------------------------------------------------------------------------------------------

• Be sure door and window screens are tight-fitting and in good repair.
• Wear shoes, socks, long pants and a long-sleeved shirt when outdoors for long
periods of time, or when mosquitoes are most active. Clothing should be light
colored and made of tightly woven materials to keep mosquitoes away from the
skin.
• Use mosquito netting when sleeping outdoors or in an unscreened structure and to
protect small babies when outdoors.
• When it is necessary to be outdoors, apply insect repellent as indicated on the
repellent label. The more DEET a product contains, the longer the repellant can
protect against mosquito bites. However, concentrations higher than 50 percent do
not increase the length of protection. For most situations, 10 percent to 25 percent
DEET is adequate. Apply repellents to clothes whenever possible; apply sparingly
to exposed skin if label permits. Consult a physician before using repellents on
young children.
• Insect light electrocutors ("bug zappers") or sound devices do little to reduce biting
mosquitoes in an area.
• Spraying your backyard with an insecticidal fog or mist is effective only for a short
time. Mosquitoes will return when the effect of the spray has ended.
• Installing bird or bat houses to attract these insect-eating animals has been
suggested as a method of mosquito control. However, there is little scientific
evidence that this significantly reduces the mosquito population around homes.
Can pets and livestock get WNV infection?
Horses can become infected with WNV if bitten by mosquitoes that carry the virus. There is
a published report of West Nile virus isolated from a dog in southern Africa (Botswana) in
1982. West Nile virus has been isolated from several dead cats in 1999 and 2000. A blood
of dogs and cats in the epidemic area showed a low infection rate.
What signs of infection should I look for in domestic animals?
West Nile virus and other mosquito-borne viruses can cause encephalitis in domestic
animals. Sick animals may have a fever, weakness, poor muscle coordination, muscle
spasms and signs of a neurological disease, such as change in temperament or seizures.
What should I do if I suspect my pet has WNV?
If your animal is sick, contact your veterinarian. The veterinarian will evaluate your animal,
provide treatment and forward samples for laboratory testing to rule out other possible
diseases. The Illinois Department of Agriculture can help veterinarians determine if WNV is
the cause once the illness is reported.
Can you get WNV directly from birds, game or domestic animals?
The risk to humans and domestic animals is from the bite of WNV-infected mosquitoes.
Although there is no evidence of human infection from handling infected live or dead
animals, the U.S. Centers for Disease Control and Prevention recommends that anyone
handling sick or dead animals avoid bare-handed contact. Hunters should use gloves when
cleaning game animals and persons disposing of dead birds should use a shovel, gloves or
------------------------------------------------------------------------------------------------------------

double plastic bags to place carcasses in a garbage can. After disposing of the carcass,
thoroughly wash your hands with soap and warm water. Veterinarians should use normal
veterinary infection control precautions when caring for a horse suspected to have this or
any other infection.
Is there a vaccine for pets and livestock for WNV?
A vaccine is available to protect horses from WNV infection; vaccines for other domestic
animals are not available currently.
How is WNV infection in domestic animals treated?
As in people, there are no specific treatments for WNV infection in domestic animals.
Treatment is primarily supportive to lessen the severity of the symptoms.
How can I protect pets and livestock from WNV infection?
You can reduce the risk of WNV infection in animals by minimizing their exposure to
infected mosquitoes.
Questions and Answers about
Spraying for Adult Mosquitoes
How are adult mosquitoes controlled?
Mosquito control agencies use truck-mounted fogging units to apply insecticides as an
ultra-low-volume (ULV) spray. ULV spray units dispense very fine aerosol droplets (fog)
that stay aloft and kill mosquitoes on contact. The amount of insecticide sprayed by ULV
units is small compared to the area treated, usually about 3 to 5 ounces per acre, which
minimizes exposure and risks to people and the
environment. Some communities have thermal foggers that
use an oil carrier that is heated to disperse the pesticide in a
dense smoke-like fog.
What agency conducts mosquito control in my town?
With a few exceptions, where mosquito control is conducted,
it is locally funded and carried out by village or city
governments. Some communities are part of a local
government agency called a mosquito abatement district that
receives local property taxes to conduct mosquito contr
operations.
ol
Why is the local government fogging for mosquitoes in my community?
------------------------------------------------------------------------------------------------------------

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