Placer County health officials announced Monday that a Roseville resident has tested positive for West Nile virus, making it the first human case of the illness in the county this year. The resident became ill earlier this month and later tested positive for West Nile virus after a hospital visit. The patient lives in an area of Roseville where the virus has been detected in mosquito sampling. The Placer Mosquito and Vector Control District has done mosquito sprayings and fogging in the area, and continues to monitor this area and others in the county for the presence of West Nile virus in mosquitoes. The patient, who has now recovered from the illness, regularly engages in outdoor activities and has no travel history to indicate the disease was contracted elsewhere. So far this year, there have been 27 other counties in California where the disease has been detected and 26 other human cases. In 2009, there were no human cases reported in Placer County. In 2008, there were six. “We’ve seen this same pattern for several years in California,” said Dr. Mark Starr, Placer County Director of Community Health and Clinics. “The disease first shows up in the southern part of the state and then is detected in Placer County in the latter part of the summer. Because West Nile infections are preventable, we strongly urge residents and visitors alike to take some simple precautions to avoid mosquito bites that can transmit the disease.” While few who become infected with West Nile become sick, the disease can cause serious illness and death. About 20 percent of those infected with WNV may experience mild to moderate flu-like symptoms, called West Nile fever, which may be prolonged. About one in 150 people will become very ill. People over 50 and people with suppressed or compromised immune systems are more likely to become seriously ill. West Nile virus is rare, but people with symptoms, including high fever, severe headache and stiff neck, should contact their health care provider immediately.