West Nile virus found in Spokane County mosquitoes

West Nile virus has been found in Spokane County mosquitoes, prompting warnings for residents to take precautions.

No cases of the virus have been detected in people, birds or horses.

The virus is spread through bites from infected mosquitoes. Fewer than 1 percent of people who get the virus develop a severe illness. Those most at risk are older people and those with weakened immune systems.

There is no human vaccine for the virus. Symptoms of an infection develop within two weeks and include headache, fever, neck discomfort, muscle and joint aches, swollen lymph nodes and a rash.

There is a vaccine for horses. If horses become infected, the mortality rate is about 1 in 3.

Last year, the Spokane Regional Health District confirmed eight people in the county had the virus. In 2016, three people were infected.

Health officials warned that continued warm temperatures and standing water create a good breeding ground for mosquitoes. Smoke from wildfires that has settled across the region does not affect mosquitoes.