Lake County Public Health & Vector Control District:  Joint Statement on West Nile Virus Activity


Lake County has recently observed a concerning uptick in West Nile Virus (WNV) activity. We wish to address and consolidate the current information and provide guidance on how residents can protect themselves from this mosquito-borne disease.

Jonathan Portney, Health Services Director of Lake County, "Public health is a collective endeavor, and our recent challenges with the West Nile Virus underscore its significance. I urge all Lake County residents to take proactive measures against mosquito bites and to be vigilant in eliminating potential breeding grounds. We're deeply saddened by the loss in our community and are steadfast in our efforts to control and reduce the spread of the virus. Together, we can create a safer environment for everyone."

Jamesina Scott, Ph.D., District Manager and Research Director of the Lake County Vector Control District highlights that West Nile Virus infection can range from mild, even symptomfree infections, to deadly forms of the disease. Mild forms of the infection often go undetected. Less than 1% of cases result in severe illness and these are the most likely to be diagnosed. People over age 50 and diabetics are at risk for the more severe forms of the disease.

The first human case reported this year in Lake County became ill during the third week of July. The second probable case that remains under investigation became ill in mid-August. Both individuals experienced the “neuroinvasive” form of the infection, which can produce symptoms ranging from a form of meningitis to more severe and potentially permanent effects on the nervous system.

 Key Highlights:

  • Lake County has reported four confirmed human cases of WNV this year, including one unfortunate fatality. Director or Nursing Philip Wegner “the fourth case was outof-state community member, did not contract in Lake County.
  • Earlier this year, WNV activity was detected in seven mosquito samples and one dead bird in the county.
  • The Lake County Vector Control District (LCVCD) and Lake County Public Health continue to work closely together in monitoring and controlling WNV.

West Nile Virus Overview:

  • West Nile Virus is transmitted primarily by the mosquito Culex tarsalis (western encephalitis mosquito)
  • While many WNV infections can be symptom-free or mild, severe cases can result in encephalitis or meningitis, with potentially permanent effects on the nervous system. •
  • Individuals over the age of 50 and those with conditions like diabetes are at a higher risk for severe forms of the disease.


Residents play a critical role in reducing the spread of WNV. Here are ways to stay protected:

  • Avoid Mosquito Bites: The most effective way to prevent WNV is to prevent mosquito bites. Use repellents containing DEET, Picaridin, IR3535, or Oil of Lemon Eucalyptus, and wear long-sleeved clothing, especially during dawn and dusk when mosquitoes are most active.
  • Eliminate Standing Water: Remove any stagnant water around your property. Mosquitoes need water for breeding. For larger water sources, like unmaintained swimming pools, the LCVCD provides free mosquito-eating fish.
  • Report Concerns: Residents should report dead birds, especially crows, ravens, and scrub-jays, as they can be indicators of WNV activity. Report them to the state's toll-free hotline at 1-877-968-2473 (1-877-WNV-BIRD) or online. Additionally, neglected swimming pools or large standing water areas can be reported to the LCVCD for intervention.

West Nile Virus (WNV) can manifest in different forms in infected individuals. The majority of people infected with WNV will have no symptoms, but some will experience symptoms ranging from mild to severe. Most Common Symptoms:

  • Most people (about 80%) won't show any signs of being infected.
  • Some may feel like they have the flu: fever, tiredness, headache, body aches, and sometimes a rash.

Serious Symptoms (less common but more severe):

  • High fever •
  • Intense headache
  • Stiff neck
  • Confusion or dizziness
  • Muscle weakness or paralysis
  • Shaking or tremors

Remember: Those over 50 or with certain medical conditions (like diabetes or high blood pressure) may be more at risk for severe symptoms

Jamesina Scott, Ph.D., District Manager and Research Director of LCVCD emphasizes the reason we are providing the community with this information "We find West Nile virus every year in Lake County. Our goal is to 'flatten the mosquito curve' to reduce the risk of people being infected with West Nile virus." Since 2004, 14 individuals in Lake County have been diagnosed with West Nile virus, with the last reported human case prior to this year being in 2018.

Resources and Contacts: For more information on WNV and prevention measures:

For issues concerning biting mosquitoes, neglected pools, or yellow jacket nests, or to request mosquitofish for standing water, contact the Lake County Vector Control District at (707) 263- 4770 or submit a request online.

So far this year, West Nile virus activity has been detected in seven mosquito samples and one dead bird in Lake County. Statewide, 24 California counties have detected WNV this year, mainly in mosquitoes.

Lake County Public Health and the Lake County Vector Control District appreciate the community's diligence and urge all residents to remain cautious and proactive during this time.