Network of Care

South Central
Public Health District
1020 Washington St N
Twin Falls ID 83301-3156
(208) 737-5900


West Nile Virus Information


Most human infections of West Nile virus are mild or have no symptoms. approximately 20 percent of those infected develop West Nile fever, a generally mild fever that lasts from 3 to 6 days and begins from 3 to 14 days after infection. Symptoms often include fever and headache, muscle aches, tiredness, nausea and vomiting, eye pain, skin rash, and enlarged lymph nodes.

Less than one percent of people infected develop the serious neurological disease called West Nile encephalitis. Blood tests to confirm the disease are available through commercial laboratories. Those over age 50 are more susceptible to serious complications from the virus.

The Idaho State Laboratory will limit their testing to more severe forms of the disease including encephalitis or hospitalized cases. People with mild fevers and flu-like symptoms are encouraged to consult their physician to discuss the necessity of testing.

Surveillance Measures

The Twin Falls County Pest Abatement District traps mosquitoes to test for virus through the county during the summer. Trapped mosquitoes are separated by species using a microscope. Some species are more prone to carry diseases than others and they try to focus their work more on them. Trapping of mosquitoes also allows them to monitor the effectiveness of their treatments and find additional areas in need of treatment.


The Idaho Department of Fish and Game will continue collecting dead birds that may have died from West Nile virus. Idaho tests dead magpies, crows, jays, and raptors, such as red tail hawks. West Nile virus has a high mortality rate among these birds. all dead birds to be tested and calls concerning dead birds should go directly to the local Fish and Game office in Jerome at 324-4359.

Prevention Measures

Insect proof your home and reduce standing water on your property that might provide breeding habitat for mosquitoes. Other tips include:

  • Cover up exposed skin when outdoors. Wear long sleeves, light-colored, and loose-fitting clothes.

  • apply insect repellent containing DEET to exposed skin and clothing. Follow instructions on the product label, especially for children.

  • avoid mosquitoes when they are most active at dawn and dusk.

  • Empty birdbaths and clean decorative ponds every three to six days. It is also important to eliminate mosquito-breeding areas such as clogged rain gutters, old tires, and other items that contain standing water.


2007 TV Spots

A Swarm of Mosquitos.

For More West Nile Virus Information