One out of 150 people who are bitten by an infected mosquito get severely ill, the vector control district said. People who catch the virus either do not become sick or experience mild symptoms, including fever, headache, nausea and body aches, though it could be fatal for people with weak immune systems, such as the elderly. Heintz said the virus first appeared in Los Angeles County in 2003 and had a banner year in 2004 with 331 human cases and 14 deaths. Last year, the county saw 47 cases and no deaths. “West Nile virus is now endemic,” said Jan Heidt, a vector control district board member and former Santa Clarita councilwoman. “It’s always going to be with us. … You’re just going to have to take precautions.” That includes using insect repellents containing DEET, and ensuring pools and ponds don’t become breeding grounds for mosquitoes, Heidt said. [email protected] (661)257-5253160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! SANTA CLARITA – The discovery of West Nile virus-infected mosquitoes in the city has spurred county vector control agents to post warning signs and treat area ponds, officials said Wednesday. Mosquito samples carrying the virus were discovered along the South Fork of the Santa Clara River, between the bike path and San Fernando Road, according to city officials and the Greater Los Angeles County Vector Control District. The district plans to post warning signs along the river from Via Princessa to Lyons Avenue and will monitor for stagnant ponds by helicopter, though there were no immediate plans for more drastic measures such as aerial spraying. “We’re confident with their approach,” city spokeswoman Gail Ortiz said. AD Quality Auto 360p 720p 1080p Top articles1/5READ MORE11 theater productions to see in Southern California this week, Dec. 27-Jan. 2The sample – along with those taken from Northridge and Chatsworth – tested positive May 17 by the state Department of Health Services and the arbovirus diagnostic laboratory at the University of California, Davis, the vector control district said. It’s an earlier appearance compared with last year, when the virus first showed up in July in area mosquito samples. Still, there have been no cases of the virus in humans, birds or horses so far in the county. Vector control district spokeswoman Stephanie Heintz declined to speculate if the timing indicates a strong showing for the virus this year, though the alternating wet and warm weather of the past two months has encouraged mosquito development. “It is helpful that we discovered the mosquito pool early in the season because now we can be prepared,” she said. “It is a new disease here. We’re still learning about it.” The virus, which can lead to complications such as encephalitis (inflammation of the brain) and meningitis, is transmitted by mosquitoes. Humans cannot catch the disease from other animals or each other.