Most people infected with Jamestown Canyon virus do not become ill, or experience only mild illness. In rare cases, infections can become serious. The Health Department does not recommend avoiding the outdoors but urges precautions. Use appropriate repellant, wear protective clothing, and avoid areas with mosquito activity, when possible.

A resident in their 70s became ill in early July, according to the Lake County Health Department, although the sex, location or condition of the person was not provided.