Information on West
Nile Virus changes rapidly. Here is some basic
information accurate at the end of 2002 followed by
links to further resources that may have been
updated more recently.
did it first occur? What is the current range
It first appeared in New York City in the summer of
1999. The first outbreak was centered in Queens,
NY, but also detected in other locations within a
75-mile radius of New York City (in NY, NJ and
By the end of 2002
it had been reported in all but 6 states - Alaska,
Arizona Hawaii , Nevada, Oregon and Utah. Plus five
and human mortality
As of Dec 19, 2002 - Center for Disease control
reported 3,852 human cases with 232 fatalities from
39 states and Washington D.C.
days after being bitten by an infected
infected show no symptoms
West Nile Fever
Fever, headaches, body aches, swollen lymph glands
and in some a body rash.
West Nile Virus
About 1 infected person in 150 becomes seriously
ill with central nervous system infection
(encephalitis &/or meningitis) - severe
headache, weakness, high fever, neck stiffness,
disorientation, tremors, convulsions, paralysis and
More than 140 bird species reported with West Nile
doves, grackles, gulls, herons, kingfishers,
pelicans, sparrows, swans, turkeys, warblers,
woodpeckers and wrens.
- Natural immunity
protects some individuals
- Past fall
significant impact on raptors, will this lead to an
increase in rodent populations?
- Spread to the
winter tropics range where mosquitoes are active
in other species
- 14,000 horses reported infected in the past
- Other mammals
including reindeer, squirrel, wolf, cat, dog,
mountain goat and sheep, black bears
- Harbor seal at
the New Jersey State Aquarium died of the
- In zoos -
penguins, seals, emus and flamingos
- Florida alligator
farms lost 200 + alligators from the
is it spread?
- WNV is transferred via the bite of several
species of mosquito. It is typically spread back
and forth - mosquito to bird - bird to mosquito -
mosquito to another bird.
- Occasionally the
virus does spread from mosquito to mammal, such as
humans or horses.
- Raptors can
acquire the virus by eating infected
- Some birds can
apparently spread the virus in their droppings.
- There's also
evidence that some birds can pass the virus
directly to their chicks while they're still inside
- West Nile virus
can be transmitted directly from adult mosquitoes
to their eggs, so that newly hatched aquatic larvae
are born infected.
- The virus can
persevere through the winter, even in many Northern
states. Winter host unknown, allows the disease to
spread year round and earlier each year.
- 36 mosquito
species carry the virus.
- Handling of
infected birds with cuts
- Mother to unborn
potential breeding areas for mosquitoes
- wear long sleeve
shirts and pants as well as mosquito
- A horse vaccine has been available in some areas
for about a year and is proving to be very
- The horse vaccine
was tested on birds and proved not to be
- In November,
veterinarians at the Los Angeles and San Diego zoos
injected condors an experimental vaccine to try to
confer immunity before the spring egg-laying
season. Results look positive so far.
- Human vaccine may
be available for testing in mid to late
Wildlife Health Center
for Disease Control
Birding Association also published
an informative article 2002.