First human case of West Nile Virus reported in LA County

A mosquito sits on a human's arm. Los Angeles County Department of Public Health/Facebook

Earlier this month, the Los Angeles County Department of Public Health identified the first case of human West Nile Virus in Los Angeles County in 2017.

The case was reported in the San Gabriel Valley region of Los Angeles County.

An elderly resident was hospitalized in late-March and West Nile was confirmed as the cause by the Department of Public Health in June.  According to officials, the patient has since recovered.

“West Nile is a serious illness spread by mosquitoes in Los Angeles County,” said Jeffrey Gunzenhauser, Interim Health Officer for Los Angeles County in a statement. “There is currently no vaccine or treatment for West Nile virus. Elderly persons and other people with weak immune systems are at highest risk of developing severe illness.”

So far in 2017, two human cases, 25 dead bird cases and 157 mosquito samples were found to have West Nile Virus throughout the state of California.

The first case of human West Nile Virus in California was reported in Kings County in late-April.

West Nile Virus is a leading cause of severe infections of the nervous system of adults 50 years and older in Los Angeles County, which can cause meningitis, encephalitis and paralysis.  It is spread to humans through the bite of an infected mosquito.

Those infected with the West Nile Virus may develop mild symptoms that include fever, headache, nausea, body aches and a mild skin rash.

This year, warmer temperatures and standing water is bringing mosquitoes out earlier in the year.

With standing water remaining in buckets, containers and household items, the Greater Los Angeles Vector Control District is encouraging residents to “tip and toss” the water and its container.

“The biggest issue that we’re seeing is all the tiny amounts of water sitting in people’s yards in containers that can include recyclables and tires and household containers,” said Levy Sun, spokesperson for Greater Los Angeles County Vector Control District.  “Get rid of the water in those containers and then toss out those containers.”

The vector control agency also encourages residents to empty out rain barrels, used to capture rain water, on a weekly basis.

“These can become mosquito farms in people’s backyards,” Sun said.  “If anyone has a rain barrel, please empty it out in completion each week and do what we call ‘the barrel roll’ and empty out every drop of water.”

The same rules are true for residents who have troughs for livestock or horses on their properties.

“West Nile virus is a big deal, especially for horse owners, so make sure troughs get cleaned out once a week,” Sun said.

If residents believe they have a mosquito problem, they are welcome to contact the Greater Los Angeles Vector Control District at 562-944-965 and report infestations at

They also can report stagnant swimming pools to the Public Health Environmental Health Bureau at 626-430-5200 and report dead birds by calling 877-968-2473 or online at

Tips from the Los Angeles County Department of Public Health to decrease the risk of infection:

  • Avoid mosquito-infested areas at dawn and dusk.
  • Wear long-sleeved shirts and long pants when you are outdoors, particularly at these times and when in areas where more mosquitoes are present.
  • Use repellents containing DEET, picaridin, or oil of lemon eucalyptus. These are effective defenses against mosquitoes when used as labeled.
  • Check your window screens for holes.
  • Dump stagnant water. Do not allow water to collect and stagnate in old tires, flowerpots, swimming pools, birdbaths, pet bowls, or other containers. These are prime breeding grounds for mosquitoes.
  • Clean and chlorinate swimming pools; drain water from pool covers.
  • Stock garden ponds with goldfish or other mosquito- eating fish. These eat mosquito eggs and larvae.

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