LAKEPORT, Calif. – Officials on Thursday confirmed Lake County's first West Nile Virus detection of the year.

Public health and vector control officials said the virus was found in a sample of 50 Culex tarsalis – Western encephalitis mosquitoes – collected Wednesday near Upper Lake.

Thirteen human cases of West Nile Virus infection have been reported in five California counties this summer, serving as a reminder that taking precautions is important to preventing this sometimes serious and even deadly infection. No cases have been reported in Lake County thus far.

The best way to stay healthy during West Nile Virus season is to prevent exposure to mosquito bites. West Nile Virus appears throughout most of California, so if you plan to be outside, use a mosquito repellent.

“When properly used, mosquito repellents that have been registered with the U.S. Environmental Protection Agency are safe and effective,” said Lake County Health Officer Dr. Karen Tait. “People should not rely on products that have not been scientifically tested.”

“Statewide there has been nearly five times the West Nile Virus activity that we had in 2011 at this time,” said Dr. Jamesina Scott, district manager and research director for the Lake County Vector Control District. “Both mosquitoes and West Nile Virus multiply faster when it’s hot, and the recent high temperatures have increased both mosquito and virus activity.”

Scott said the district is working hard to reduce the risk of mosquito bites and West Nile Virus to Lake County residents and visitors, but there is one area where they still need the public’s help – finding backyard sources like neglected swimming pools or ornamental ponds.

“Just one neglected swimming pool can produce thousands of mosquitoes per day, and cause problems for an entire neighborhood,” Scott said. “Fortunately, mosquitoes are easy to control in these habitats once we know where they are.”

Residents can request service, get mosquitofish, or report neglected swimming pools to the district at 707-263-4770 or www.lcvcd.org .

Officials emphasized that people need to drain standing water sources around their homes that may breed mosquitoes and they need to protect themselves with long sleeves or an effective repellent during dawn and dusk when mosquitoes are most active.

West Nile Virus is transmitted by mosquitoes to a variety of animals and to humans. Mosquito and Vector Control agencies usually detect the virus in mosquitoes, birds and sometimes tree squirrels before human cases appear.

To report a dead bird or squirrel, call 1-877-WNV-BIRD (1-877-968-2473) or visit the California Department of Public Health’s West Nile Virus website at www.westnile.ca.gov .

So far in 2012, the majority of West Nile Virus activity detected through testing of dead birds, mosquito pools, and “sentinel” chickens has occurred in the southern portion of the state, but has appeared as close to Lake County as Contra Costa, Sutter, Glenn and Sacramento counties.

Most people who become infected with West Nile Virus do not show symptoms and will recover uneventfully. Health officials said up to 20 percent of people will develop fever, headache, and other nonspecific symptoms that may last several weeks.

Approximately one in 150 people will develop severe illness known as neuroinvasive disease, health officials reported. People over age 50 and diabetics appear to be at most risk for the more severe forms of disease. There is no vaccine for humans.

A vaccine is available for horses and is strongly recommended because West Nile Virus also can cause serious infections in horses.

For additional information on West Nile Virus, visit http://www.westnile.ca.gov , http://www.cdc.gov/ncidod/dvbid/westnile/wnv_factsheet.htm and http://www.cdc.gov/ncidod/dvbid/westnile/RepellentUpdates.htm .