Aug. 12, 2004
King County taking steps to reduce potential West Nile virus impact
Residents reminded to minimize mosquito habitat at home
2004 Archived News
Alonzo Plough, Public Health - Seattle & King County director, and Pam
Bissonnette, King County Department of Natural Resources and Parks
director, today outlined the current status of West Nile virus in the
region and detailed the county's mosquito control efforts to minimize
the impact of West Nile virus when it arrives in King County.
"We
are fortunate to not yet have cases of West Nile virus in King County,"
said Plough, "but people must be vigilant in removing mosquito breeding
habitat in their yards by tipping out anything that can hold standing
water."
"We're
doing our part at Natural Resources and Parks by monitoring our
stormwater facilities, and larviciding those where the health risk is
greatest," said Bissonnette. "While stormwater ponds are essential for
protecting health and property from flooding and polluted runoff, they
can occasionally provide habitat for mosquitoes. When such ponds are
located near concentrations of people at risk and where mosquito larvae
are present, our staff are applying an environmentally friendly
larvicide to reduce the threat."
Nearly
500 cases have been reported to the Centers for Disease Control so far
this year, with 10 deaths nationwide. Plough said that while anyone can
become infected with West Nile virus and become ill, people over the
age of 50 are most at risk for serious illness. In 2003, almost 10,000
people were confirmed with West Nile virus, and more than 250 people
died. Most people become infected with West Nile virus in the later
summer and early autumn months.
Bissonnette
said that through July, DNRP staff had made roughly 350 stormwater
facility site visits and treated approximately 75 facilities. The
larvicides used are Bti and Bs, which are naturally occurring
bacterium. They are applied in areas of the ponds or drainage
structures where the mosquito larvae live. When the larvicide is
ingested, it produces a toxin that crystallizes in the larval gut,
resulting in death. It is not harmful to other species.
State
law requires permits for larviciding in any body of water that is not
fully contained, such as a lined fountain or ornamental pond. The
Department of Natural Resources and Parks has found that many of their
stormwater ponds do not have larvae in them, either because the ponds
are dry or because they have enough water to provide habitat for fish,
frogs, and other mosquito predators.
To
lessen the number of mosquitoes near people's homes, residents are
urged to reduce artificial habitat by removing or tipping out any
source of standing water. If larger bodies of water on private property
do appear to be a source of mosquitoes, homeowners may consult a Pest
Control Operator who is licensed and can obtain permits to apply
larvicide in water.
"We
will never be able to eliminate all mosquitoes so people should protect
themselves when mosquitoes are biting by wearing clothing that covers
up bare skin," Plough said. Insect repellents containing the chemical
N,N-diethyl-meta-toluamide (DEET) are known to be safe and effective
for adults and children, but is important to read and follow the
instructions on the label carefully. It is also recommended that all
door and window screens be free of rips or tears.
West
Nile virus is primarily a bird disease, and crows are especially
susceptible. Mosquitoes become infected by feeding on an infected bird
and can pass the virus to humans, horses, or other animals when they
bite. As part of surveillance activities, Public Health – Seattle &
King County is tracking bird deaths in the County. Residents may assist
by calling to report dead birds.
Horses
are at high risk for West Nile virus. Horse owners are urged to contact
their veterinarian about a vaccine for West Nile virus. Other domestic
pets, such as cats and dogs, are very unlikely to become ill from West
Nile virus.
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