West Nile Virus Off To Slow Start This Summer

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West Nile Laying Low, So Far

Officials predict more infections as summer heats up

HealthDay

Friday, July 14, 2006

FRIDAY, July 14 (HealthDay News) -- The West Nile virus season is off

to a slow start this year, U.S. health officials say, but that

doesn't portend a worry-free summer.

" Just because we're having a late start doesn't mean you can infer

it's going to be an easy season, " said Daigle, a spokesman for

the U.S. Centers for Disease Control and Prevention. " Mosquito-borne

arboviral diseases are very difficult to predict. "

" We really don't know what the year will be like, but we know it's

about to start, " added Dawn Wesson, an associate professor of

tropical medicine at the Tulane School of Public Health and Tropical

Medicine in New Orleans.

So far, the virus has been detected in birds, animals or mosquitoes

in 28 states. At the same time last year, 48 states plus the District

of Columbia reported activity. The year before that, it was 47

states, the District of Columbia and Puerto Rico, Daigle said.

Ten people have tested positive for the virus so far this year, one

each in California, Colorado, Iowa, Mississippi, Missouri and South

Dakota, and two each in Nebraska and Texas. Seven of the cases

involved meningitis or encephalitis, which can result from the bite

of an infected mosquito.

Seven blood donors have also tested positive for the virus -- two in

Colorado and one each in Iowa, Kentucky, Oklahoma, South Dakota and

Texas. Blood donations are now routinely screened for the pathogen,

and infected blood is discarded.

July, August and September are considered peak mosquito-bite months,

and health officials expect to see more activity during this period.

Since it's introduction to North America in the New York City area in

1999, West Nile virus has spread across the continent and is now

found in every contiguous state. In 2005 alone, there were 3,000

human cases and 119 deaths linked to infection, up from 2,539 cases

and 100 deaths in 2004, according to the CDC.

West Nile virus is normally passed from an infected mosquito to a

bird, and then from the bird to other mosquitoes. The mosquitoes then

pass the virus on to humans.

The majority of people -- about 80 percent -- who become infected

with West Nile virus have no symptoms at all. Up to 20 percent may

experience flu-like symptoms such as fever, headache and body aches

or even nausea and vomiting. Only about one in 150 people will suffer

severe illness, resulting in meningitis or encephalitis. People aged

50 and older are at higher risk for developing severe complications

if infected.

While it's not impossible to predict the geographical course of the

disease this year, officials say that once a state has reported

infections, it's likely they will occur again.

In past years, Daigle said, " areas that had unusually hot or dry

summers tended to see more activity but there are exceptions. "

" A lot of people are watching the Gulf Coast after the storms last

year, " he added. " There may be more debris that will give mosquitoes

more sites to breed in. "

" We're poised to see human case here in Louisiana, " Wesson

said. " Upwards of 40 percent of mosquitoes tested have been positive,

and the time of year is about right. "

While human infections have been limited so far, it's never too soon

to take precautions.

Health officials recommend removing any standing water where

mosquitoes are likely to breed. People should also wear insect

repellant and long-sleeved clothing whenever outside.

" It just takes one infected mosquito bite to transmit WNV, " Daigle

said. " Even if you aren't noticing a large number of mosquitoes, it's

still worth it to use repellent. It only takes a few seconds to apply

repellent. "

Last year, in addition to the standard DEET-containing products, the

CDC also endorsed mosquito-repellent products containing oil of lemon

eucalyptus and Picaridin. Products containing permethrin can be used

on fabrics such as clothes and tents, officials said.

HealthDay

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