Phased Response to Mosquito Surveillance

The following recommendations are intended to guide mosquito control programs and may include other applicable community procedures.  All actions are subject to change due to organizational priorities, weather or other unforeseen circumstances.



Probability of
human outbreak

Public Health

Recommended response



No evidence of  Mosquito or viral activity

Control Measures

  • Contact community partners
  • Secure necessary control resources to enable emergency response



Normal mosquito
activity with little or no evidence of viral activity

Control Measures

  • Source reduction through physical and environmental measures
  • Biological – mosquito fish
  • Larvicides (surface oils, biorational bacterial products and insect growth regulators)


Moderate Virus detected inmosquito samples Control Measures

  • Larvicing of breeding sites around infected trap sites
  • Consider Ground-based ULV adulticide application around positive trap location, with continued mosquito surveillance



Virus detected in multiple mosquito

samples from different times and locations and confirmed human cases

Control Measures

  • Ground-based ULV adulticide application of area around confirmed human case(s) after mosquito trapping confirms the presence of disease
  • Ground-based ULV adulticide application of positive mosquito sites and expanded areas around sites
  • Consider  aerial treatment(s)


Outbreak in


Multiple human

cases confirmed and detection of increased or continued viral mosquito activity

Control Measures

  • Ground-based ULV adulticide application in areas of clustered human cases
  • Recommend aerial adulticide applications in targeted zones

These guidelines were adapted from the Center for Disease Control report “Epidemic/Epizootic West Nile Virus in the United States: Guideline for Surveillance, Prevention and Control, 2003”




Revised: 06/01/13