The Los Angeles County Department of Public Health has identified the first human case of Saint Louis encephalitis in Los Angeles County since 1997, in an elderly San Fernando Valley man.

The patient became ill in late August.

This is the first SLEV case in the state this year. Environmental monitoring for SLEV in Los Angeles County began in early spring, and to-date one mosquito sample from Playa Vista has tested positive for the virus.

“Since Saint Louis encephalitis is transmitted to people through the bite of an infected mosquito, the best way to prevent getting infected is to prevent mosquito bites,” said Muntu Davis, MD, MPH, Los Angeles County Health Officer.

“Residents should protect themselves by using EPA-registered repellent to keep mosquitoes from biting you, and checking for items that collect standing water in their homes or yards where mosquitoes can breed to tip out the water,” Davis said.

Saint Louis encephalitis virus is similar to West Nile virus and can affect the nervous system and result in infections of the brain, paralysis and cause death.

While all county residents are at risk for Saint Louis encephalitis, the majority of people infected with Saint Louis encephalitis virus have no or mild symptoms.

People over 50 years of age or individuals with lowered immune systems are at greater risk of experiencing severe symptoms when infected.

Symptoms of severe disease include fever, headache, stiff neck, confusion and decreased alertness.

There is no vaccine to prevent Saint Louis encephalitis, and only supportive treatment is available. Anyone with symptoms should contact their healthcare provider.

Decrease your risk of infection
PROTECT YOURSELF: Mosquito repellents can keep mosquitoes from biting you. EPA-registered repellents containing DEET, picaridin, IR3535, and oil of lemon eucalyptus are the longest lasting and most effective. Take precautions particularly at dawn and dusk when mosquitoes that spread West Nile and Saint Louis encephalitis are most active.

MOSQUITO PROOF YOUR HOME: Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

STOP MOSQUITOES FROM BREEDING: Mosquitoes lay eggs even in small amounts of standing water including standing water in flowerpot saucers, old car tires, rain gutters, rain barrels and pet bowls. Check such items each week and cover, clean or clear them out.

POOLS AND SPAS: Clean and maintain swimming pools, spas. Drain water from pool covers.

STOCK MOSQUITOFISH: Stock garden ponds or artificial lakes with mosquitofish or other mosquito-eating fish. Please contact your local Vector Control District to place service requests, report mosquito problems, request mosquitofish and report neglected pools or standing water where mosquitoes breed.

More information and resources can be found at:
* Los Angeles County Department of Public Health

* California Department of Public Health

* Centers for Disease Control and Prevention: https://www.cdc.gov/sle/

* Information about mosquito control and how to find your local vector control district: http://www.socalmosquito.org.

Where to call with questions about mosquitoes:
* Greater Los Angeles County Vector Control District: (562)944-9656
* Los Angeles County West Vector Control District: (310) 915-7370
* San Gabriel Valley Mosquito and Vector Control District: (626) 814-9466
* Antelope Valley Mosquito and Vector Control District: (661) 942-2917
* Compton Creek Mosquito Abatement District: (310) 933-5321
* Pasadena City Health Department: (626) 744-6004
* City of Long Beach Vector Control Program: (562) 570-4132.