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The original item was published from 8/22/2019 9:14:00 AM to 8/22/2019 9:15:23 AM.


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Posted on: August 22, 2019

[ARCHIVED] West Nile Virus detected in Lafayette


Lafayette has received confirmation that a mosquito monitoring trap at Waneka Lake has tested positive for West Nile virus (WNV). The pool collected consisted of 65 Culex tarsalis and was one of six pools of that species submitted for testing in the Boulder County Sentinel Zone 3. 

The Vector Index (VI) of the positive zone was 0.27.  VI is a measure of transmission risk based on infection rate and abundance of local mosquito populations.  Based on CDC studies, a VI of 0.75 is considered to be of high risk of WNV transmission to humans and may result in recommendations of additional control measures by Public Health.  While we are currently below that measure, these positive mosquito pools reinforce that West Nile virus continues to be a threat to all Boulder County communities and residents should take personal protective measures such as wearing repellent, limiting outdoor activities during the hours when WNV mosquito species are most active (dusk and dawn), and removing standing water from properties.

The Lafayette Parks Department contracts with Vector Disease Control International (VDCI) to conduct surveillance of adult mosquito populations and to provide limited adult mosquito control when predetermined disease and annoyance thresholds have been surpassed. One primary focus of our integrated mosquito management program is larval control and reducing the populations of mosquito larvae in the water before they become biting adults through the use of cultural, biological, and least-toxic chemical procedures that are environmentally compatible and economically feasible.

VDCI will continue performing larval stage control, adult mosquito surveillance, and adult mosquito control as necessary. To report mosquito problems or concerns please call VDCI at 888-774-2161 or visit

For information on how to protect your loved ones and property, please visit  

During mosquito season, please remember the 4Ds!

1. Use DEET-enhanced insect repellent

2. DRESS in long sleeves and pants.

3. Avoid the outdoors from DUSK to DAWN

4. DRAIN standing water outside your home

View the Boulder County Mosquito Monitoring Map at

Additional Info from Boulder Cty Public Health...
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