Two dead crows in Northern California have raised alarms about West Nile virus returning for the season. Found in Newark and San Jose, these birds were part of routine tracking efforts that often spot the virus before it affects people.

The disease isn’t new to California—it’s been circulating for years, mostly between birds and mosquitoes. Humans and horses rarely catch it, but when they do, it’s usually from an infected mosquito bite. Experts say we’re just accidental hosts, not part of the virus’s main cycle.

Why do dead birds matter? They’re often the first warning sign. Mosquitoes spread the virus by feeding on sick birds, then biting humans or animals. So far, tests on thousands of mosquito pools show no infections, but that could change as temperatures rise.

Weather plays a big role in how fast the virus spreads. Heavy rains followed by heat create perfect mosquito breeding grounds. Even a few warm days can speed up the process, making mosquitoes infectious quicker than expected.

The bugs responsible are Culex mosquitoes, active at night and drawn to stagnant water. Officials suggest simple steps to stay safe: dump out standing water, cover up at dusk, and use repellent when needed. Prevention is key as summer kicks off.


# **Dead Crows in Northern California Signal Return of West Nile Virus**

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## **A Familiar Threat Resurfaces**
Two dead crows—one in **Newark** and another in **San Jose**—have set off alarms in Northern California, signaling the seasonal return of **West Nile virus**. These birds were part of routine surveillance programs that monitor the virus before it reaches human populations.

While the disease has circulated in California for years, it primarily thrives in a **bird-mosquito cycle**, with humans and horses as rare, accidental hosts. Most infections occur when an **infected mosquito** bites an unsuspecting person.

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## **Why Dead Birds Are a Critical Warning**
Dead birds serve as the **early red flag** in tracking West Nile virus. Mosquitoes contract the virus by feeding on infected birds before spreading it to humans or other animals. Though tests on **thousands of mosquito pools** have come back negative so far, rising temperatures could accelerate transmission.

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## **How Weather Fuels the Spread**
Heavy rains followed by **sweltering heat** create ideal conditions for mosquitoes to breed. Even a few days of warmth can **speed up the process**, making mosquitoes infectious faster than anticipated. The primary culprits? **Culex mosquitoes**, which are most active at night and drawn to stagnant water.

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## **Simple Steps to Stay Protected**
Officials urge residents to take preventive measures as summer approaches:
- **Eliminate standing water** (buckets, plant saucers, clogged gutters)
- **Cover up at dusk** when mosquitoes are most active
- **Use EPA-approved repellent** when spending time outdoors

With vigilance, the risk of West Nile virus can be **minimized before it escalates**.



Early signs of West Nile in Bay Area birds

Why Dead Birds Are a Critical Warning

Simple Steps to Stay Protected

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