West Nile Alert
This Year, Experts Expect The Perennial Virus To Break New Ground
May 7th, 2004
By Ken McGrath : eCureMe Staff Writer
May 6th, 2004 : Physician Reviewed
Like a microscopic immigrant, the West Nile virus arrived in New York City in
1999 and public health officials expect it to complete its all American
journey this summer by arriving in California. The West Coast is expected to
be the next "hot spot" for the disease, but doctors and scientists
are still urging people across the country to exercise caution, even as
researchers are getting closer to a vaccine.
Cross Country
For the last several years, typically starting in late July and continuing
through early autumn, a wave of West Nile diagnoses and deaths has captured
the public’s attention. Carried in the bloodstream of infected birds
and spread to humans through contact with mosquitoes that have fed on
infected birds, each year the epicenter of the outbreak has fallen farther
west. In 2003, over 9,800 cases were diagnosed throughout 46 of the lower
48 states. 262 cases were fatal. However, 2,863 of the diagnoses were made
in Colorado alone. In 2002 the state had only reported 14 cases.
The fear among experts is that the disease may cross the Rockies this year,
and California’s experience in 2004 could be similar to
Colorado’s in 2003. Speaking about the virus’ apparent Westward
migration, Dr. Grant L. Campbell, head of the branch of the Centers for
Disease Control (CDC) that tracks West Nile, told reporters, "California
should light up this year - but it all depends on climate and mosquito
control and luck." Some experts have noted that California may be in a
better position to deal with the disease when it arrives: the state has
had plenty of advanced warning and maintains a strong mosquito monitoring
program. However alert though, it’s sure that the Golden State will
be facing the virus in one way or another: already this season three birds
in the state have tested positive.
Relative Danger
Though the disease may be unfamiliar to Californians, it’s by no
means new. West Nile was identified in Uganda, in 1937, and has since
spread through much of Asia, Africa and Europe. Compared to other
diseases that have spread around the globe, West Nile has a relatively
low impact on humans.
Even in areas where the disease exists in the mosquito population, less
than 1% of the bugs carry it. About 20% of people bitten by infected
mosquitoes will experience the most common symptoms; headaches, body aches
and fever. Most who are bitten won’t notice any signs of the
infection before it passes. The real risk of West Nile infection is the
possibility it will develop into a case of encephalitis. Encephalitis
occurs when, as a reaction to infection, the brain becomes inflamed.
Once a patient falls ill with West Nile encephalitis, there’s little
doctors can do other than try to alleviate discomfort and assist breathing.
In extreme cases, the inflammation can cause death. Even so, most whose
infections do lead to encephalitis, less than 1% of those initially bitten
by a West Nile mosquito (though the rate is higher for older adults)
will recover.
As always, prevention is the best medicine. To avoid contact with the
disease in the first place, experts recommend that in the coming summer
months, Americans should make sure they wear insect repellant that
contains DEET when they venture outside. It’s also helpful to wear
long sleeves and pants outdoors, instead of shorts and t-shirts,
in order to give the bugs less to feed on. Staying inside during dusk
and dawn, prime mosquito feeding hours, can’t hurt either. To keep
the number of mosquitoes to a minimum, people are urged to remove any
standing water from their property. Mosquitoes frequently lay their eggs
in standing water, and old tires, neglected garbage cans, large puddles,
dog dishes and birdbaths can mean more mosquitoes and more disease.
The Future of West Nile
In the not too distant future, preventing West Nile may be as simple as
getting a shot. A number of drug companies and government agencies are
planning to test vaccines in the next few years. As soon as this summer,
dozens of hospitals across North America will be participating in a
study that injects antibodies from patients who have fought off the
disease into those who are infected, hopefully killing off the virus.
Other researchers are using weakened forms of Yellow Fever virus and Dengue
Fever virus as the basis for a vaccine. A recent study conducted by
Hawaii Biotech, Inc. used a protein similar to the West Nile virus to
inoculate animals, and found that 100% of the tested subjects developed a
resistance to the disease.
Still, it’s likely to be a matter of years before a vaccine can be
fully approved and tested by the FDA. In the mean time, West Nile’s
cross continental spread may be good news, at least in the short term.
Though scientists don’t know exactly why, when West Nile hits an area
particularly hard one season, it tends to abate the next. Ohio, which has
already reported the first human case of the disease this year, reported
108 cases in 2003 - down from 441 in 2002.
Until epidemiologists can get a handle on this season’s toll,
however, West Nile is likely to keep the scientific community, and the
public, guessing.
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