FINS
Questions and answers about MOSQUITOES and
WEST NILE VIRUS AND ENCEPHALITIS
The attractiveness of different persons to the same or different
species of mosquitoes varies substantially. In general, adults are
more likely to be bitten than children, although adults may become
less attractive to mosquitoes as they age. Men are bitten more readily
than women. Larger persons tend to attract more mosquitoes, perhaps
because of their greater relative heat or carbon dioxide output.
What is West Nile Encephalitis?
"Encephalitis" means an inflammation of the brain and can be caused
by bacteria and viruses, including viruses transmitted by mosquitoes.
West Nile encephalitis is an infection of the brain caused by West
Nile Virus (WNV), a virus commonly found in Africa, West Asia, and the
Middle East. It is closely related to St. Louis Encephalitis virus,
also found in the United States.
How is it passed from mosquitoes to people?
Mosquitoes become infected when they feed on virus infected birds.
The West Nile Virus may circulate only a few days in a bird. After an
incubation period of 10-14 days, infected mosquitoes can transmit West
Nile virus to humans or other animals. Disease symptoms do not develop
in everyone that is bitten by an infected mosquito. Records from last
summer's disease outbreak in New York City showed that elderly and
physically weak people were more likely to develop symptoms.
How long has West Nile virus been in the United States?
It is not known how long the virus has been in the U.S., but
Centers for Disease Control and Prevention (CDC) scientists first
detected it in the eastern U.S. during the summer of 1999.
How do people get West Nile Encephalitis?
Transmission comes through the bite of a mosquito (primarily the
Culex species) that is infected with the West Nile Virus. The
virus is located in the mosquito's salivary glands. The virus
cannot be transmitted from person to person. You cannot get
the disease from birds.
Are we at risk on Fire Island?
Culex is a fresh water species of mosquito. West Nile Encephalitis
and Eastern Equine Encephalitis (EEE) are most prevalent in fresh
water mosquitoes. There are very few of these at Fire Island National
Seashore. Also, culex mosquitoes are a "backyard" mosquito. According
to Dominick Ninivaggi of Suffolk County Vector Control "The mosquito
species that carries West Nile doesn't fly much further than a few
hundred feet from its water source."
The vast majority of mosquitoes you encounter are salt marsh
mosquitoes. Salt marsh mosquitoes can carry encephalitis, but it is
rare. The National Park Service has captured and tested hundreds of
thousands of mosquitoes at Fire Island since 1982 and none has ever
been found to be carrying encephalitis.
Is there a vaccine against West Nile Virus?
There is no vaccine for the West Nile Virus at this time.
Is a woman's pregnancy at risk if she gets West Nile encephalitis?
There is no documented evidence that an infection caused by the
West Nile virus present additional risk to the non-born child of a
pregnant woman.
What precautions is the National Park Service taking to prevent an
outbreak of West Nile Encephalitis in its park units in 2000?
All National Park Service areas are working in cooperation with
their federal and local mosquito management and health agencies. At
Fire Island National Seashore, the National Park Service, in
cooperation with the Centers for Disease Control, Suffolk County
Vector Control, and New York State and Suffolk County health
departments, is carrying out active site specific monitoring and
surveillance programs at Fire Island. The surveillance activities will
make possible early detection of the virus if it returns in 2000.
Samples of live mosquitoes are routinely checked at state laboratories
for the presence of West Nile Virus. Positive mosquito samples will be
used to trigger activities designed to decrease mosquito populations
and the habitat in which they multiply. This may include pesticide
spraying.
Does the National Park Service actively manage mosquitoes in its
park units?
Yes, under certain circumstances, native species such as mosquitoes
are managed to decrease populations such as when a public health
emergency has been declared. The localized application of larvicides
and adulticides for the management of native mosquitoes is allowed but
must be approved by the Director of the National Park Service in
Washington. The 2000 National Park Service Management Policies states
that pests may be controlled "to manage a human health hazard when
advised to do so by the Centers for Disease Control or to otherwise
protect against a significant threat to human safety." The Centers for
Disease Control and the U.S. Public Health Service have not indicated
that there is a significant threat human safety on Fire Island.
Do you have to wait for an "emergency" to do something?
Until there is a health risk declared by the CDC, the application
of pesticides may be a greater health threat to the public than the
mosquitoes. We do take numerous other steps to help prevent the spread
of disease before there is a health emergency.
What are the benefits of mosquitoes?
Benefits are in the eye of the beholder. Everything in nature
occupies an important place. From most public stand points mosquitoes
don't have much use. However, mosquitoes pollinate flowers, and
provide an important food source for a wide range of creatures such as
fish, turtles, frogs, birds, and bats. It is also important to
remember that pesticides kill almost all insects and many other
organisms they contact. This includes butterflies, mites, ladybugs,
and other insects that pollinate flowers, remove detritus from the
ecosystem, digest feces, and all the other important functions we
depend upon insects to perform in the environment.
What can park visitors or park employees do to increase their
awareness and prevent becoming infected with the West Nile virus?
Mosquito activities increase at dawn and dusk. Be aware of
mosquitoes if you're out during these times.
Help eliminate temporary mosquito habitat and stagnant fresh water
(flowerpots and buckets, stopped-up rain gutters, discarded cans,
etc.)
Learn about mosquitoes. Avoid going into heavy mosquito areas at dusk.
Do not wear cologne or perfume, smells that may attract mosquitoes.
Long-sleeved shirts, long pants, a hat, and gloves can provide
increased protection from mosquitoes.
The use of an insect repellent on clothes or sparingly on exposed skin
can decrease encounters with mosquitoes. A repellent with 20% to 30%
DEET (N,N-diethyl-meta-toluamide) as the active ingredient works the
best.
Where can I get more information on West Nile Virus and other
mosquito borne diseases?
Check on the web at http://www.cdc/ncidod/dvbid/arbor/ or call your
local public health office.