West Nile virus: What you need to know about pesky mosquitos in the Coachella Valley

Nothing ruins a beautiful sunrise or sunset quite like finding your legs and arms covered with a bunch of itchy, red mosquito bites, and unfortunately, these pesky insects can carry viruses.

West Nile virus is the leading cause of mosquito-borne disease in the United States, according to the Centers for Disease Control and Prevention. The Coachella Valley had its first positive sample of the virus around 2011, said Tammy Gordon, spokesperson for the Coachella Valley Mosquito and Vector Control District, and it's been consistent ever since. So far this year, there have been 100 positive samples of West Nile virus, mainly concentrated in the east valley.

Here's what you need to know about the current West Nile virus situation in the Coachella Valley.

What is West Nile virus?

West Nile virus was first identified in 1937 in Uganda, and it was first discovered in the United States in New York in 1999. Since then, the virus has spread throughout the country.

The virus spreads when a female mosquito bites an infected bird. The mosquito then can become a carrier and transmit the virus to people.

Cases occur during mosquito season, which starts in the summer and continues through fall.

Where are the disease-carrying mosquitos in the valley?

Mosquitos with West Nile virus are fairly common in the valley, particularly in the Salton Sea area because that is where the flyway is for birds, Gordon said.

The district has detected at least 100 West Nile virus-positive samples (which is a collection of mosquitos) so far this year. Most have been concentrated in the areas of Mecca, Thermal, Oasis and North Shore, but they were also detected in La Quinta.

Gordon said the district has hundreds of traps set up each week throughout Coachella Valley cities and unincorporated areas. Mosquito control treatments are also taking place this week in Mecca.

"We're trying to interrupt that transmission. If we can get rid of those mosquitos and birds fly away, we shouldn't see any more detections," Gordon said. "It's just whether or not we can get that in time before those birds stick around to get more mosquitos sick."

There are 13 species of mosquitos in the Coachella Valley, but only three can transmit disease, Gordon said. Two species transmit West Nile virus, and another is an invasive species that's been found the past few years that can transmit Dengue, Chikungunya and Zika viruses.

"It's a bad lady," Gordon said. "She is so aggressive and so good at being invasive that she's spread from 2016, and she's now finding pockets of really good spots, which are backyards."

The district has been using a toxin produced by a bacteria to kill this species' mosquito larvae.

Additionally, there have been 53 samples that tested positive for St. Louis encephalitis virus, and 16 with both West Nile virus and St. Louis encephalitis this season. A person infected with St. Louis encephalitis typically does not experience symptoms, but those who do become ill may experience fever, headache, nausea, vomiting, and tiredness. There have been no human cases in the Coachella Valley thus far.

What are the symptoms of West Nile virus?

Most people (eight out of 10) infected with West Nile virus do not develop any symptoms. But for those who do, about one in five infected people develop a fever and other symptoms such as headache, body aches, joint pains, vomiting, diarrhea or rash.

About 1 out of 150 infected people will develop a severe illness that affects the central nervous system, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the protective membranes covering the brain and spinal cord). Symptoms of severe illness include high fever, headache, neck stiffness, near-unconsciousness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Severe illness can affect anyone, but people 60 years and older are at greater risk.

There are no vaccines to prevent or medications to treat West Nile virus in people. Anyone with symptoms should contact their health care provider.

Has anyone gotten sick in the Coachella Valley?

No one has gotten sick in the Coachella Valley thus far. In California, there have been 67 human cases in 16 counties as of Monday. The closest ones to Riverside County include Los Angeles (eight cases) and Orange counties (three cases).

How does this year compare to others?

So far, there have been fewer positive samples in the Coachella Valley compared to last. In 2021, 129 samples were positive. It's much less than the more than 500 positive samples seen in 2019 following severe flooding in the area, Gordon said.

"We had all this water right when it was about to start warming up, and mosquitos love water and they love warm weather, so it was just that perfect storm," she said.

The Coachella Valley experienced a few hot and humid days this summer, which could have been another perfect breeding opportunity for mosquitos.

How can I protect myself?

To protect against bites, the Coachella Valley Mosquito and Vector Control District encourages people ages 50 and older and those who are immunocompromised to take more caution, which includes wearing insect repellent and long sleeves and pants when outdoors, and staying indoors when mosquitos are most active at dawn and dusk.

Everyone can also do their part when it comes to cleaning up stagnant water. This includes:

• Check lawn drains for water and debris and clean drains regularly

• Drain water collected under potted plants, bird baths, tires and other water-holding containers

• Clean and scrub pet dishes and water features weekly

• Swimming pools, ponds and fountains require working pumps and regular maintenance

More information about mosquito viruses and preventing the spread in the Coachella Valley can be found at CVMosquito.org.

Ema Sasic covers entertainment and health in the Coachella Valley. Reach her at ema.sasic@desertsun.com or on Twitter @ema_sasic.

This article originally appeared on Palm Springs Desert Sun: West Nile virus: What you need to know about Coachella Valley situation, how to protect yourself