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9 August 2003

Contact: Joe Malinowski, Consumer Protection Program Coordinator or Heath M. Harmon, MPH, Communicable Disease Control Program Coordinator

Mosquito Spraying to Help Combat West Nile Virus


Boulder County Public Health officials recommended aerial spraying for adult mosquitoes in Longmont and Louisville in order to reduce the risk of West Nile virus (WNV) infections among the cities' residents.

"Several areas of concentrated WNV activity within these communities have prompted these recommendations," noted Heath Harmon, Communicable Disease Control Coordinator for Boulder County Public Health (BCPH).  

"The majority of WNV infections identified in Boulder County so far this summer have come from these two cities," said Harmon. "Because we already know that adult mosquitoes are transmitting the virus in these areas, we are recommending spraying to knock down the adult mosquito populations." 

Officials from the cities of Longmont and Louisville, Colorado Mosquito Control, Boulder County Public Health, and the Colorado Department of Public Health and Environment talked at length on Friday to assess the need for spraying.  

The decision to recommend spraying was based on several factors, according to Joe Malinowksi, Consumer Protection Coordinator for Boulder County Public Health. "Aerial spraying for adult mosquitoes usually only makes up a small percentage of mosquito control efforts," said Malinowski. "However, based on the high level of mosquito activity and human illness within these communities, killing the adult mosquitoes would help reduce the risk of additional human illness due to WNV."  

All of the pesticide application will be performed by Colorado Mosquito Control (CMC) beginning early next week based on the following daily schedule, weather permitting:

  • Monday - Louisville: north of South Boulder Road, west of Via Appia, and west of McCaslin Blvd. Unincorporated Boulder County: Bari -Don, Fairview Estates, Fairview Acres, Long's View, Grandview Estates, Spanish Hills, Paragon Estates, and Apollo Estates. Longmont: west of Main Street and north of 9th Avenue.
  • Tuesday - Longmont, west of Main Street and south of 9th Avenue.
  • Wednesday - Longmont all incorporated areas east of Main Street.

The application will occur between dusk and dawn, with the majority of spraying done between
8:30 p.m. and midnight. According to Colorado Mosquito Control, if weather conditions reduce spraying effectiveness, the schedule will be delayed one day. Representatives from CMC and Boulder County Public Health will work together to monitor the adult mosquito population before spraying, and then at least every other day after spraying, to determine the effectiveness of the pesticide application. 

Smaller-scale applications have been made routinely over the past several years to control adult mosquito populations; however, this marks the first time an application of pesticide will cover an entire municipality. "We have contracted with Colorado Mosquito Control since 1995," said Malinowski. "In the past when adult mosquito activity was high, they applied pesticides in unincorporated regions of the county."

 Despite the increased control efforts, public health officials still urge residents to take necessary individual precautions to protect themselves. "A mosquito control program cannot eliminate all of the risk; it is only one component of West Nile virus protection," said Harmon. "For optimal protection against infection, all residents must be vigilant about taking precautions to reduce their exposures to mosquitoes."  

Precautionary measures to reduce the risk of West Nile virus infection include:

  • Reduce or eliminate outdoor activity between dusk and dawn because mosquito activity is especially high during that period.
  • Wear long sleeves and long pants while in areas where mosquito activity is high.
  • Wear insect repellent that contains the active ingredient known as DEET.
  • Eliminate areas of standing water around your house where mosquitoes are likely to live and breed.

For more information about West Nile virus, mosquito prevention, and mosquito control efforts for Boulder County, visit www.bouldercountymosquito.net or call the Boulder County Public Health Hotline at 303-441-1460.