U.S. Officials Urge Steps Against West Nile
Virus
Science - Reuters
U.S. Officials Urge Steps Against West Nile
Virus
Fri May 24, 3:03 PM ET
By Sue Schwendener
CHICAGO (Reuters) - U.S. health officials in the Midwest are urging
residents to take steps to control possible record numbers of
disease-carrying mosquitoes after heavy spring rains left ample
breeding grounds, including flooded fields, gutters and empty
containers.
"People tend to think that all mosquitoes come from swamps, but
they can breed and hatch in any standing water," said Michael
Sinsko, senior medical entomologist at Indiana State Department of
Health.
Health experts noted that a larger population of the blood-sucking
insects could hasten the spread of the West Nile virus, responsible
for the deaths of 18 people and 187 horses in the United States over
the past three years.
Mosquitoes also carry other deadly diseases, including strains of
encephalitis, an inflammation of the brain. The Centers for Disease
Control receives between 150 and 3,000 cases of mosquito-borne
encephalitis in humans per year, according to its Web site
http://www.cdc.gov.
There is no vaccine available to immunize against these encephalitis
strains or West Nile virus, but the U.S. Department of Agriculture
conditionally approved a vaccine for horses last August.
The elderly, very young and those with compromised immune systems are
most at risk of developing mosquito-borne encephalitis and West Nile
virus. For most, inflections are mild, with symptoms including fever,
headache and body aches.
But among those who do develop severe illnesses, fatalities range from
three to 30 percent, with the highest death rate among the
elderly.
CLEANING UP BREEDING GROUNDS
"The (mosquito) species that are the primary vectors of West Nile
virus breed mainly in containers and in septic effluent," Sinsko
said. "We need to motivate people to clean out watering troughs,
old tires, anything that can be a potential mosquito breeding
ground."
He also advised people to wear long sleeves and pants and to cover
exposed skin with insect repellents containing diethyl-meta-toluamide
when spending time outdoors.
Mosquitoes transmit the virus by biting infected birds, then biting
people or horses. There is a one or two-week lag before any illness
develops. No evidence exists that the disease can be passed from horse
to humans or from horse to horse, but the CDC said the virus has been
shown to infect cats, domestic rabbits, squirrels, chipmunks and
bats.
West Nile virus, which has been known for hundreds of years in the
Middle East and Africa, which first appeared in the United States in
1999 in New York City and Long Island.
On Wednesday, New Jersey health officials reported five dead crows had
tested positive for the virus, but no cases have yet shown up in the
Midwest this year.
"We haven't had any West Nile cases yet this year,"
said Sinsko. "There are lots of mosquitoes developing, but the
cool, wet weather has held them in the larval and pupa
stages."
"It's a cycle of birds being bitten by infected mosquitoes and
birds infecting more mosquitoes," said Howard Cundiff, director
of consumer protection at the Indiana State health department.
"The major concern is late in the summer and early fall, because
it's had a chance to amplify over the summer."
Veterinarians at Indiana's Purdue University have also been
vaccinating horses against West Nile virus since last fall.
"We're trying to educate people all over the Midwest that it's
important to get your horse vaccinated," Amanda Spencer, a Purdue
large animal veterinarian, said in a statement from the university.
"We're stressing that if horses do come down with the disease,
there is no specific treatment."
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