During the early part of the summer season, mosquitoes that transmit encephalitis restrict their feeding to birds. As the summer progresses, they start to feed on mammals. Therefore, disease transmission to humans usually occurs during mid to late-summer. In order to determine if the mosquitoes are infected with a virus that is harmful to humans, the Colorado Department of Public Health and Environment assists local health departments and others in using chickens as early warning devices to determine the presence of the virus. The chickens are placed in areas where problems have previously occurred.
Blood is drawn and tests conducted to diagnose encephalitis.
If the virus is detected, then controlling the mosquito population becomes necessary to prevent the transmission of the infection to humans. Mosquito control is conducted on a local basis through the local health departments, other agencies and contractors. Such programs emphasize elimination of larva and breeding areas. A natural larvacide, an insecticide that kills larva, not adult mosquitoes is used. In addition to mosquito fogging programs, residents can assist in controlling these pests by eliminating unnecessary standing water and exercising good water management in irrigation practices to ensure water runs off and doesn't collect.