West Nile Virus Activity Widespread Despite Autumn Season

Unusual weather and rain in October fueling increased virus activity in Los Angeles County communities

11/13/15

Los Angeles County, Calif. – Late autumn may not seem like a time mosquitoes are active, but in Southern California, when there is frequently warm weather, they are still public health threats. The Greater Los Angeles County Vector Control District (GLACVCD) urges residents to take the necessary precautions against mosquito bites, since the risk for human infection is higher now, compared to last year.

“Due to the unusually high temperatures and the intermittent rain events we experienced in October, we are observing higher than normal West Nile virus activity,” said Susanne Kluh, Director of Scientific-Technical Services at GLACVCD.

Percentage of Mosquito Samples Tested in October That Were WNV-Positive

October 2015
42%
October 2014
16%

In October 2015, 42% of mosquito samples tested positive for West Nile virus (WNV) – compared to only 16% positive mosquito samples during the same period last year. Another key indicator of  continued virus transmission are the District’s sentinel chicken flocks, the majority of which have tested positive for WNV indicating widespread virus activity in area mosquitoes.

Additionally, in the past two weeks, vector control reported virus activity for the first time this year in the cities of Diamond Bar, Gardena, Paramount and Santa Clarita. To date, the Los Angeles County Department of Public Health have confirmed 168 human infections, 14 of which have been fatal. Officials expect more cases to be reported in the coming weeks, and urge residents to protect themselves from bites through the end of the year.

A complete list of WNV activity to date can be found at www.GLACVCD.org and at www.publichealth.lacounty.gov.

GLACVCD recommends residents dump and drain stagnant water from containers to remove any potential mosquito breeding sources. Everyone should use mosquito repellents where mosquitoes are present. Effective repellents contain EPA-registered active ingredients such as DEET, Picaridin, oil of lemon eucalyptus, or IR3535.

What is West Nile Virus?

West Nile virus is transmitted to people and animals through the bite of an infected mosquito. There is no cure for West Nile virus. One in five persons infected with West Nile virus will exhibit symptoms. Symptoms usually occur between five and 15 days, and can include fever, headache, body aches, nausea, or a skin rash. These symptoms can last for several weeks to months. One in 150 people infected with the virus will require hospitalization. Severe symptoms include high fever, muscle weakness, neck stiffness, coma, paralysis, and possibly death.

Residents experiencing mosquito problems or wish to report dirty, green pools can contact the Greater Los Angeles County Vector Control District at (562) 944-9656 or visit www.ReportMosquitoes.org.

Due to the unusually high temperatures and the intermittent rain events we experienced in October, we are observing higher than normal West Nile virus activity.

Susanne Kluh, Director of Scientific-Technical Services