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Press Releases

For Immediate Release  • July 17, 2013
Staff Contact: Rigo Leal, Public Information Officer, 303-651-8840

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Fight the Bite


Citywide Mosquito Spraying Rescheduled for Friday, July 19

A second application is planned for Monday, July 22


July 17, 2013 - In order to honor the city’s promise of providing a 48-hour notification before spraying for West Nile mosquitoes, the planned citywide emergency spraying has been rescheduled to Friday, July 19, at 9 pm weather permitting. A second citywide application is scheduled for Monday, July 22 at 9 pm, weather permitting.

Early forecasts predict cooler temperatures and a chance of rain for Friday and could delay any spraying by one day.

After receiving results from mosquito pool trapping in Longmont, officials from Boulder County Public Health (BCPH), the City of Longmont, and the Colorado Department of Public Health and Environment reached a decision to implement emergency spraying for the city. To date, there have been 14 of 33 mosquito pools that have tested positive for West Nile Virus (WNV) in Boulder County. There have been 92 pools that have tested positive statewide. There has been one confirmed human case of WNV in Delta County.

All of the pesticide application will be performed by Colorado Mosquito Control (CMC) using truck-mounted sprayers. The entire spraying operation begins at approximately 9 pm and will take approximately 4 hours to cover every street in the entire city, weather permitting.

Eleven CMC trucks will be spraying the City streets.  Additional spraying will be conducted to create a one-mile buffer zone area adjacent to the City in unincorporated Boulder County at the expense of Boulder County; ongoing discussions to spray a buffer area adjacent to Weld County  is being requested, but no decision has been made.

Based upon CMC's mileage estimate, the City is anticipating 380 miles of City streets to be sprayed at the cost of $62.75/linear miles for a grand total of $23,845.00, or less depending on mileage for Friday night’s operation.

CMC will apply a pesticide called AquaLuer 20 20, a permethrin based adulticide. The spraying process will produce a very fine mist that will be released from trucks into the air, killing mosquitoes on contact.  Most of the spraying will be conducted when adult mosquito activity levels are at their highest between 9 p.m. and 2 a.m.

Permethrin can and has been used previously for public health mosquito control programs posing little risk to humans and animals, as long as it is applied appropriately.  A similar mixture was used to spray the City in prior years.  It is estimated that this process was 75% – 80% effective after the first application.

Although permethrin poses minimal threat to humans and animals, some common sense steps can help reduce any unnecessary exposures:

The Vector Index, a calculation that helps indicate the risk of human WNV infection, from July 9 mosquito pool testing in Longmont yielded an index of 1.32. The index from the July 16 trapping was 1.18. When an index threshold of 0.75 is reached in a given area, county health officials recommend that leaders in affected municipalities implement emergency spraying.

“Mosquito activity so far this year indicates that there is heightened risk for transmission of West Nile virus,” said Jeffery Zayach, BCPH director. “We are fortunate that we had numerous planning discussions with city leaders well in advance of the WNV season and, like surrounding counties, are prepared to make formal recommendations for a spray option in order to protect our residents.”

WNV is a disease that can be transmitted to humans by mosquitoes. While most infections are mild, the more serious infections can cause encephalitis (inflammation of the brain) and/or meningitis (inflammation of the brain's lining), loss of vision, paralysis, coma, tremors, convulsions and in some cases, death.

“Based on data since WNV arrived in Colorado, we have learned that there is a four to six week window period in which spraying is most effective to reduce the human risk of infection,” said Lane Drager, BCPH Consumer Protection program coordinator.

There is no treatment, cure, or vaccination for WNV; health care providers can only treat the symptoms to help patients feel better and possibly recover more quickly. The only treatment available is prevention.

Public health officials remind residents that, as we enjoy these warm temperatures with outdoor activities, particularly at dusk and dawn, it is important that everyone take action to protect themselves by following ALL of the four Ds. The 4 D’s are:

For more information about WNV, please visit the BCPH website at To ask specific questions, call the Colorado Health Education Line for the public at 1-877-462-2911 (available in Spanish and English).

If people suspect they have WNV symptoms, BCPH urges them to consult with their primary care physicians.

For information about West Nile virus, please visit Boulder County web site at or call Boulder County Public Health Hotline at 303-441-1460 or visit