http://dailynews.yahoo.com/h/nm/20010613/hl/westnile_1.html
Scientists Analyze 1999 West Nile Outbreak
NEW YORK (Reuters Health) - Scientists have published
their analysis of the first North American outbreak of West Nile virus (news -
web sites), a disease that has spread rapidly since its 1999 debut in New York
City.
It has spread so rapidly, in fact, that US physicians
along the entire eastern seaboard who see patients with inflammation of the brain
and the surrounding membranes should consider West Nile virus as a possible cause,
according to Dr. Denis Nash of the New York City Department of Health and
colleagues. Older patients and those with muscle weakness are particularly
likely to have the infection, they add.
As a result of the outbreak, 59 patients were hospitalized
and seven later died from the infection, the researchers note in the June 14th
issue of The New England Journal of Medicine (news - web sites).
There is no treatment for West Nile infection in humans,
which can spread to the brain (a condition known as encephalitis) or the tissues
surrounding the brain (a condition known as meningitis). Efforts are under way to develop a vaccine
against the disease, but are not expected to bear fruit for years.
The risk of being infected with West Nile virus by a bite
from an infected mosquito is less than 1%, according to the Centers for Disease
Control and Prevention (news - web sites) (CDC) in Atlanta, Georgia. Fatality
from the disease is 3% to 15% in infected people, with the greatest risk of
death in the elderly.
Birds are the main carriers of the infection, which is
spread by mosquitoes. Humans are only believed to catch the disease from mosquitoes,
and are not thought to be able to catch it from other infected animals or from
one another.
“Sensitive, specific and early diagnosis of West Nile
virus infection is crucial for the implementation of appropriate public health
measures to limit or prevent outbreaks of disease,” Dr. Kenneth L. Tyler of the University of
Colorado Health Science Center in Denver writes in an accompanying editorial.
“It seems that West Nile is surviving in North America,”
Tyler told Reuters Health. “We will see additional human cases of infection and
encephalitis for the foreseeable future.”
Tyler stresses that physicians should be alert to the
possibility of the disease.
“Unexpected deaths in bird or horse populations are likely
to be sentinel events that precede the infection of humans,” he explains.
He also notes that a person’s age plays an important role
in risk, with people older than 50 years 20 times more likely to develop meningitis
or encephalitis from West Nile infection.
In May, New York City Mayor Rudolph W. Giuliani unveiled
the city’s comprehensive West Nile virus prevention and control plan for 2001.
According to a statement from the city, the plan focuses
on prevention and emphasizes destroying mosquito larvae; eliminating sites
where mosquitoes breed; surveillance of mosquitoes, birds, mammals and humans
for infection; and public education.
“In less than 2 years, New York City has developed a
state-of-the-art program to protect the city from West Nile virus and other mosquito-borne
diseases,” Giuliani told attendees at a press conference in May. “Since the
first appearance of West Nile virus here in 1999, the Department of Health has
worked closely with federal, state and city agencies to effectively monitor and
control this disease.
“This year, the city will continue and even enhance the
preventive work it carried out last year and will again emphasize the
importance of breeding site reduction and treating areas of standing water with
larvicides,” he continued.
“As the weather gets warmer and the mosquito season gets
under way, I am asking all New Yorkers to eliminate potential mosquito breeding
sites around their homes and businesses. Unclogging roof gutters; emptying
unused swimming pools; discarding old tires, buckets and other containers that
hold water; and changing bird baths at least once a week will significantly
help the city’s efforts,” Giuliani concluded.
SOURCE: The New England Journal of Medicine
2001;344:1807-1814, 1858-
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