Adult mosquitoes can be controlled through the ground or air application of adulticides, although the plan includes cautions on the aerial application of pesticides. The plan calls for a four-step response by local health units, depending on whether the virus is present in the area. The first step applies to areas where there is no historical evidence of the virus. In these areas, local health units are encouraged to conduct basic educational efforts and passive human and bird surveillance programs. Passive surveillance involves the health units tracking reports they receive, for example under the state law that requires physicians to report all cases of encephalitis.
Active surveillance involves the health unit taking steps to encourage reporting.
The second step is when there is historical, but no current, evidence of the virus in or near the area. Local health units in such areas are urged to expand their educational efforts. They are also encouraged to undertake programs to reduce the breeding grounds of mosquitoes, begin surveillance of larval and adult mosquitoes, and control larvae. The third step occurs when there is current evidence of the presence of the virus in individual locations. Under these circumstances, local health units are advised to begin active surveillance of humans and birds.