Two West Nile cases are the first in Riverside County this year.

Two human cases of West Nile virus – the first in Riverside County this year – were confirmed by Riverside University Health System – Public Health this week, serving as a reminder that residents should take steps to protect against mosquitoes, which transmit the disease.

One of the affected residents, from western Riverside County, has required hospitalization. The other individual, from the San Gorgonio Pass area, is recovering at home. There are no indications that the two cases are related.

The virus is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds. Health officials emphasized that the overall risk of serious illness to humans is low.

Most individuals who are infected with the virus will not experience any illness. About one in five infected people develop a fever with symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash.

Most people with a fever due to West Nile virus recover completely, but fatigue and weakness can last for weeks or months.  Elderly individuals and those with compromised immune systems are at greater risk for serious illness.

“While West Nile is rarely life-threatening, it can occasionally be serious,” said Dr. Geoffrey Leung, public health officer for Riverside County. “Unlike common respiratory viruses, which are easily transmitted, the West Nile virus can only be spread by mosquito bites, and there are steps to take to reduce your risk of being bitten.”

Here are some ways to protect yourself:

  • Avoid spending time outside when mosquitoes are most active, especially at dawn and dusk, and wear pants, long sleeves, and other protective clothing outdoors.
  • Apply EPA-registered insect repellent that contains DEET, following the instructions on the product label. If you are using sunscreen, apply sunscreen first, then repellent.
  • Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes.
  • Eliminate all sources of standing water, such as old tires, buckets, flowerpots, and toys that can support mosquito breeding. Empty and scrub the water sources. Some mosquitoes can even breed in the amount of water in a bottle cap.
  • Anyone who becomes ill after mosquito exposure should contact their healthcare provider.

Riverside County’s Disease Control office can be reached at 951.358.5107. Information about mosquito abatement is available online at



Image Sources

  • Blood test for West Nile: Shutterstock