Mosquito-Borne Diseases (Encephalitis)

Mosquito-borne viruses that cause illness in humans and domestic animals are known as "arboviruses". There is a potential risk to humans and domestic animals in Washoe County from arboviruses, which can cause mild to serious illness. An arboviral-caused encephalitis (brain inflammation) can develop which may result in long-term disability including partial paralysis and memory loss or death.

The Vector-Borne Disease Prevention Program (VBDPP) staff conducts tests to detect the presence of the arboviruses that cause West Nile Virus, St. Louis Encephalitis, and Western Equine Encephalitis. Doing this type of surveillance is an important initial step in the prevention of these diseases since the virus usually shows up in wild and domestic animals before the first human cases appear.

The VBDPP staff conducts various types of testing to identify the presence of all three viruses. They include:

  • Sentinel chicken flocks - Five flocks of chickens are maintained, bled, and tested throughout the mosquito season for these arboviruses.
  • Mosquito pools - Adult mosquitos are trapped, batched in pools of 50, and tested for the arboviruses mentioned.

If any of these tests turn up positive, the VBDPP staff will respond rapidly to isolate and eliminate the virus by increasing mosquito control in the area where it has been identified.

West Nile Virus brochure.
CDC - Arboviral Encephalitis