State Health Department Warns Colorado Residents and
Visitors to Take Precautions Against West Nile Virus
DENVER--Surveillance systems monitoring West Nile virus
activity are
showing Culex mosquito populations are at or above the
counts observed
at the same time in 2003, when Colorado experienced a large
West Nile
virus outbreak. With three human cases confirmed in the
state so far
this season, state health officials are warning residents
that it is
important to immediately begin taking precautions to avoid
mosquito
bites.
"Based on the surveillance data from around the state,
the indicators
are suggesting that we're heading into a high-risk year, so
it's
important for people to take precautions against this
preventable
disease now," emphasized John Pape, an epidemiologist who
specializes in
animal-related diseases at the Colorado Department of Public
Health and
Environment.
Mosquito trapping shows populations of Culex mosquitoes,
which transmit
West Nile virus, are extremely high for this time of year
and rising
rapidly. Mosquitoes infected with the West Nile virus have
been found in
nine counties (Boulder, El Paso, Jefferson, Larimer, Logan,
Mesa, Otero,
Prowers and Weld). Twenty-six mosquito pools have tested
positive so
far, with 18 of those detected since July 1. A mosquito pool
is a group
of up to 50 mosquitoes tested together.
"Usually we don't pick up the first positive mosquitoes
until around
this time of year," said Pape, "but then the virus moves
quickly. Due to
the large numbers of mosquitoes out there now, we expect the
infection
rates, and therefore the human risk, to rise rapidly over
the next
several weeks."
The state has confirmed three human cases in individuals
from Boulder,
Cheyenne and Logan counties. However, four to five weeks
generally pass
between the time a person is bitten by an infected mosquito
and the date
the case is reported to the health department. This is due
to the one-
to two-week incubation period before the onset of symptoms
and delays
inherent with seeing a physician, getting test results and
reporting the
case. Thus, people being infected today may not be counted
until
sometime in early August.
According to case data from the previous four years, it
appears
approximately 85 percent of people are infected during a
period from
July 1 through the second week of August. Infected
mosquitoes continue
to feed through September and early October, depending on
the weather,
but fewer than 10 percent of human cases are contracted
after Labor
Day.
"July and August are the months posing the highest risk of
infection,"
Pape explained. "People should be extra diligent during this
time and
use whatever methods available to avoid mosquito bites,
especially
during the period from an hour before sunset through about
midnight,
when Culex mosquitoes are most actively feeding."
"We are entering the peak of the transmission season, even
though only
a few human cases have been reported," Pape noted.
Pape reminded Colorado residents and visitors to observe the
"Four Ds"
to protect against West Nile virus:
- Dawn/dusk-Be sure to use protection or avoid being
outside
during these times of the day, when mosquitoes are most
active.
- Dress-Wear loose fitting, lightweight long sleeves
and pants
when you're outside. For extra protection, spray thin
clothing with
insect repellent.
- DEET- Whenever you're outdoors, use an insect
repellent with
DEET (N, N-diethylm-toluamide) or another repellent
approved by the
Centers for Disease Control and Prevention, such as
products containing
picaridin and lemon of eucalyptus oil. DEET products
generally provide the longest protection times. Other
repellents do work but must be
applied more frequently. Follow the label directions,
and use products
with lower concentrations of DEET on children. Higher
concentrations
don't protect better; they just provide longer
protection.
- Drain-Get rid of standing water in your backyard and
neighborhood. Drain any standing water in old tires,
flowerpots and
clogged rain gutters. These are mosquito-breeding sites.
Change the
water in birdbaths at least weekly.
Since the West Nile virus was first detected in Colorado
in August
2002, there have been 3,706 human cases and 76 deaths,
although the
total number of identified cases represents only a small
proportion of
people who actually were infected and became ill during this
time. The
state's worst year was 2003, with 2,947 confirmed human
cases of the
disease and 63 deaths.
Pape advised anyone who finds a dead bird to call the
Colorado Health
Emergency Line for the Public (CoHELP) at 1-877-462-2911.
Emergency line
staff members are available to respond to hotline calls from
7 a.m. to
11 p.m. on Mondays through Fridays and from 9:30 a.m. to 8
p.m. on
Saturdays and Sundays. In addition to taking reports of dead
birds,
staff members can answer most questions about West Nile
virus. The Rocky
Mountain Poison and Drug Control Center operates the hotline
under
contract with the Department of Public Health and
Environment's
Emergency Preparedness and Response Program.
Additional information about West Nile virus is available
online at
www.FightTheBiteColorado.com.
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