.png){kind=small}
.png){kind=small}
.png){kind=small}
.webp)
Why Is West Nile Virus Appearing in California?
West Nile virus (WNV) is the most common mosquito-borne disease in the continental United States, and cases are on the rise this year. California has reported an increase, including recent infections in Los Angeles County, but it’s not just a California issue.
Other states are also seeing more activity:
- Allegheny County, Pennsylvania recently reported its third human case.
- Massachusetts elevated risk levels in more than 40 communities after two new cases.
- Cook County, Illinois confirmed its first West Nile death of the season.
This trend shows that West Nile virus is a national health concern, not limited to one region.
What Is West Nile Virus?
West Nile virus is primarily spread through the bite of an infected mosquito. Most people infected will never develop symptoms, but about 1 in 5 experience mild illness and 1 in 150 develop severe illness affecting the brain and nervous system.
Mild symptoms can include:
- Fever, headache, or body aches
- Fatigue and weakness
- Vomiting, diarrhea, or rash
Severe symptoms can include:
- High fever and stiff neck
- Confusion, tremors, or seizures
- Paralysis, coma, or even death
Why Cases Are Increasing
Several factors may explain why West Nile virus is appearing more often in California and across the U.S.:
- Warmer weather and climate shifts → Longer mosquito seasons (summer into fall).
- Urban environments → Standing water in gutters, yards, and neglected pools provides breeding sites.
- Bird populations → Mosquitoes pick up the virus from infected birds before passing it to humans.
- Travel and mobility → People moving between regions where the virus is active can spread risk.
Each year, the number of human cases typically peaks in late August through early September, which matches the current rise in reports【CDC】.
Who Is Most at Risk?
Anyone can get West Nile virus, but severe illness is more likely in:
- Adults over 60
- People with chronic conditions (diabetes, high blood pressure, kidney disease, cancer)
- Immunocompromised individuals
How to Protect Yourself
There is no vaccine or specific treatment for West Nile virus, which means prevention is key:
- Use EPA-registered insect repellent when outdoors.
- Eliminate standing water around your home (buckets, birdbaths, clogged gutters).
- Wear long sleeves and pants during dawn and dusk, when mosquitoes are most active.
- Keep screens in good repair on windows and doors.
If you experience symptoms like high fever, severe headache, or neurological changes, seek medical care immediately.
Frequently Asked Questions
Can you get West Nile virus more than once?
Most people develop lifelong immunity after infection, but those with weak immune systems may not.
Is there a treatment for West Nile?
No specific medicine exists. Supportive care—fluids, rest, and pain relievers—can help mild cases. Severe cases may require hospitalization.
When is mosquito season in California?
Mosquito season typically runs June through October, peaking in late summer.
The Bottom Line
West Nile virus is appearing in California, but it’s part of a larger national trend this year, with cases reported from the West Coast to the Midwest to the East Coast. While most infections are mild, severe cases can be life-threatening.
The best protection is prevention: avoid mosquito bites, reduce standing water, and talk to your healthcare provider if you develop concerning symptoms.
Concerned about unexplained fever, fatigue, or neurological symptoms? Request an appointment with a BASS Medical Group provider
.webp)
.webp)
