The risk of contracting West Nile virus in Los Angeles County is at a five-year high, according to vector control officials.
The number of mosquito samples testing positive for the virus in the county is three times the number at this point last year, according to Levy Sun, spokesman for the Greater L.A. County Vector Control District.
"It is shaping up to be a very active year, and we can expect people to be sick from West Nile virus," Sun says.
He adds that cases of the virus in dead birds and sentinel chickens are also up compared with last year.
"It's really hard to predict how many people, or where people will get sick," says Sun. "We just know that right now, throughout L.A. County, the risk is higher than usual."
Statewide, the number of mosquito samples testing positive for West Nile virus at this point in the year is almost double the five-year average.
Over the previous dozen years the number of cases in California has fluctuated significantly, from a high of 880 in 2005 to a low of 110 in 2010.
Last year, 783 people developed West Nile virus statewide; 53 died.
Most people who become infected with West Nile don't develop symptoms, according to the Centers for Disease Control and Prevention. About one in five people who are infected will develop a fever and other symptoms, including headaches, body aches, joint pains, vomiting, diarrhea or rash. Most people with this type of the disease will recover completely.
Less than 1 percent of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis. Recovery from the severe form of the disease takes several weeks or months. About 10 percent of people who develop neurologic infection due to West Nile will die.
Experts say the best way to avoid getting West Nile virus is to wear insect repellent and long clothes outdoors, especially during dawn and dusk, when mosquitoes are most likely to bite.