The District's aggressive campaign against mosquito larvae is intended to minimize the need to use public health pesticides targeting adult mosquitoes. If West Nile virus is detected in the community, the District's initial response will be to intensify its efforts to reduce mosquito breeding sites and increase its levels of larviciding in those areas in which West Nile virus has been found. Reducing the population of adult mosquitoes with public health pesticides (adulticides) that are registered by the US Environmental Protection Agency (US EPA) will be done if necessary to prevent human illness or to suppress a heavy nuisance infestation of mosquitoes. The decision to use adult mosquito control application either by truck-mounted, handheld, or aircraft application equipment will be based on surveillance information or the documentation of West Nile virus activity at a level that indicates a threat to human health. Adulticing will be concentrated in areas most at risk for disease occurrence and will be conducted by certified and licensed applicators.