Leon M. LedermanScience Education Center
Fermilab Flora & Fauna Virtual Exhibit

West Nile Virus

Prairie Resources -  Exhibit Home

What is West Nile virus?
West Nile virus is a mosquito-borne virus that may affect birds, humans, horses and other mammals. The birds most affected in this area are crows and blue jays.

How is West Nile virus transmitted?
Mosquitoes, which have bitten infected birds, may become carriers. Then the disease can be transmitted to humans by the bite of the mosquito.

How prevalent is West Nile virus in the Chicagoland area?
Cases, none in humans, have been reported in six counties in our area since 2001. Less than 1 percent of mosquitoes in this area are infected. If an infected mosquito bites a human, less than 1 percent will become seriously ill.

What are the symptoms of West Nile virus in humans?
When people become infected, they are quite often asymptomatic. However, some individuals exhibit mild flu-like symptoms. In rare cases a person may develop West Nile virus encephalitis. This could be fatal especially in the frail or elderly.

Do all types of mosquitoes carry West Nile virus?
Although all mosquitoes probably have the ability to carry the virus, the Culex spp. is the main carrier in this area. It breeds in stagnant water, appears in late summer and flies from dusk to dawn.

What precautions can you take to avoid mosquito bites?
When outside after dusk, wear long sleeves and long pants and spray exposed skin with a repellent containing DEET. Contact a physician for recommended concentration and see repellent's label for instructions.

Can the West Nile virus be prevented?
There is no West Nile virus vaccine and no known treatment! You can take steps to reduce the mosquito population. Mosquito reduction practices include:

Should you report the discovery of a dead bird?
The DuPage and Kane county health departments are no longer collecting dead crows and blue jays for testing. To dispose of a dead bird, handle it using gloves or a plastic bag and double bag the bird before placing it in the trash.