West Nile Virus Activity Moving Quickly
Colorado - After a slow start, West Nile Virus (WNV)
activity has increased sharply across Colorado since the beginning of
the month. Since August 1st, 30 mosquito pools throughout the state
have tested positive for the virus, compared to only 7 positive pools
the entire season prior to August.
Human cases and positive laboratory reports are also
increasing statewide. The first case in Colorado of the more serious
form of the disease, encephalitis (inflammation of the brain), was
reported on August 15. Prior to this, all cases had been the more mild
form. Three additional encephalitis cases are being investigated.
“One feature of WNV is that outbreaks develop rapidly
and progress very quickly,” said Heath Harmon, a Boulder County Public
Health (BCPH) epidemiologist. “Although the recent increase in
activity is happening about four weeks later than in the previous two
seasons, the potential for significant activity and increased risk to
the public is high.”
Experts from Colorado Department of Public Health and
Environment (CDPHE) estimate that most areas of the state will
probably see high levels of activity for at least the next 4-6 weeks.
So far this summer, 21 cases have been confirmed in Colorado,
including 3 in Weld County and 2 in Jefferson County.
As of August 13th, no human, animal, or mosquito
specimens have tested positive for the virus in Boulder County. Across
the state, 14 birds, 8 horses, and 37 mosquito pools have been
confirmed as positive for WNV. As of August 16th, the virus has caused
eight deaths nationally, with the greatest number of cases occurring
in California. Despite the low levels of activity present in Boulder
County, and given that WNV activity is likely to be at its highest
levels through the end of August, residents should not let their guard
down.
“Now, more than ever, it is important to take precautions to protect
yourself and your loved ones,” said Chana Goussetis, a BCPH health
educator. That is, remember and practice all 4 Ds:
The DEET alternatives listed below have been shown
to have the same efficacy as a low concentration of DEET, lasting
about 90 minutes. Please follow the manufacturer's instructions
provided on the product label.
-
Bite Blocker (key ingredient: soybean oil).
-
Picaridin, found in Cutter Advanced. This product
has not yet been approved for children under three. Picaridin,
also known as KBR 3023, has been available for many years in Asia,
Australia, and Europe. It was recently approved for use in
mosquito sprays by the EPA and has been included in the list of
repellent recommendations by the Centers for Disease Control
(CDC).
-
Oil of lemon eucalyptus, found in Repel Lemon
Eucalyptus, OFF! Botanicals & Fight Bite Plant-Based Insect
Repellent. These products should not be used on children under
three. Repel is 30% eucalyptus oil. Pure eucalyptus oil should
never be applied to skin.
The very hot, dry spell through much of July which
followed closely on the heels of a very wet June led to significant
hatches of mosquitoes during the first half of July. As the hot dry
weather continued, Culex mosquitoes, which are attracted to warm
stagnant water, continued to thrive. Areas with large-scale flood and
crop irrigation continued to produce significant numbers of mosquitoes
as we moved into the second half of August.
Mosquito populations continue to be monitored and
controlled in both the larval and adult stages.
Heavy irrigation in many areas has kept a large number
of sites wet and actively producing mosquito larvae, despite the
record high temperatures and extended dry conditions in July. Due to
high numbers of adult mosquitoes in many traps, particularly during
the first half of July and a significant number of calls from
residents, above-average adult mosquito control operations have been
necessary in many locations.
In 2004 there were 14 cases of WNV in Boulder County
and 291 cases in Colorado. There were four deaths from the virus in
the state - none in Boulder County. Nationwide, there were 2,470 cases
of WNV with 88 deaths.
For more information about West Nile virus, mosquito activity in
Boulder County, or steps to take to protect yourself and loved ones:
Information about WNV activity throughout the state is
posted on the
Colorado Department of Public Health and Environment website.
National WNV activity information can be found at the
Centers for Disease Control website.
To report a dead bird or mosquito nuisance in your area, call BCPH
Environmental Health Division: 303-441-1564.
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