LOS ANGELES, July 22 (Xinhua) -- West Nile virus has surged in parts of California, killing one woman and infecting 27 other people, health officials said on Sunday.

    One elderly woman has died from complications of the disease, making her the first death in the state from the virus this year, according to health officials.

    Officials attributed the surge to unusually high temperatures throughout the state in March.

    High temperatures triggered an earlier start to the West Nile virus season than in other years, officials said.

    Of the 27 cases, 18 incidents were recorded just last week. By this time last year, only five had been reported.

    Dead birds or other animals in 36 of California's 58 counties, including Los Angeles, Orange, Riverside and San Bernardino counties, have tested positive for West Nile virus, according to the state website tracking the disease, westnile.ca.gov.

    The California Department of Public Health warned earlier this month that the rising numbers "could indicate that the mosquito and vector control agencies may have another busy year battling West Nile virus-carrying mosquitoes."

    Dr. Mark Horton, director of the state's public health department, recommended that people take steps to avoid mosquito bites.

    "Even though the likelihood of serious illness from West Nile virus is low for most people, all Californians should take every precaution to reduce their risk of exposure," he said.

    About 80 percent of people infected with West Nile virus will be asymptomatic, while almost all of the remaining 20 percent will develop relatively mild symptoms, which can include fever, headache, body aches, swollen lymph glands or a rash on the chest, stomach and back.

    Less than 1 percent will become seriously ill, with those older than 50 particularly vulnerable. Recent data also indicate that people with diabetes or hypertension are at greatest risk.

    Severe symptoms can include disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. The neurological effects can be permanent.

    In 2006, 292 human infections, including seven deaths, were reported statewide.