The first human case of West Nile virus this year was reported in Merced County.
The patient, who is under 18, is recovering, said Allan Inman, director of the Merced County Mosquito Abatement District. The person has a travel history, but lives in Merced County, therefore, it counts as a county case, he said.
"This case offers unique challenges to the district based on the urban setting of this case," he said.
The latest infection had been a probable case for about two weeks, but officials got confirmation this week, Inman said.
Six human cases have been reported in the state this year, according to the California Department of Public Health. The cases are from Merced, Stanislaus, Fresno, Bakersfield and Los Angeles counties.
Ten birds have tested positive for the virus in Atwater, Inman said. No birds have tested positive in Merced, but the human case was reported in an urban area of the city of Merced, he said.
"We have been concentrating all of our efforts in Atwater," Inman said. Officials have sprayed Atwater by air and are doing ground treatments at least twice a week, he said.
The last time officials saw a high West Nile activity in Atwater was in 2005.
The virus started to spread early this year, but every year is different, Inman said.
"The only thing you can predict about mosquitoes is their unpredictability," he said.
Inman said people should take precautions to prevent becoming infected because the virus might start to spread throughout the county as it enters a critical stage.
"We need people to be vigilant," he said.
Richard Rios, program manager with the Merced County Department of Public Health, said the human case wasn't unexpected, but it's important to remind residents that the virus is once again circulating in the county. "The risk for humans is real," he said. "It's very important that people from midsummer to late fall take the preventive steps to protect themselves."
A large majority of people who become infected will not have any pronounced symptoms, Rios said. A small percentage will experience mild flulike symptoms and then recover.
A smaller percentage will experience fevers, fatigue, headaches and meningitis among other symptoms, he said, and those are the cases that can result in hospitalizations and even death.
Local health providers are asked to consider West Nile virus for patients with those or similar symptoms.
For preventive measures, people are advised to apply mosquito repellant and to wear light-colored clothing to avoid attracting mosquitoes. They should wear long-sleeved shirts and pants, and avoid being out during the first two hours after dusk and before dawn because that's when mosquitoes are most active.
Residents are asked to report any standing water on their properties to the abatement district.
Last year, a 2-year-old horse with the West Nile virus died in Delhi.
In 2010, the only person who became infected with the virus in Merced County died.
In 2009, four human cases were reported and one resulted in a fatality.
Rios said officials urge local horse owners to consult their veterinarians about getting vaccinations for their animals.
The public can report dead birds to the California Department of Public Health at http://westnile.ca.gov/report_wnv.php or by calling (877) 968-2473.
For more information on how individuals and families can protect themselves, contact Inman at (209) 722-1527.
Reporter Yesenia Amaro can be reached at (209) 385-2482 or email@example.com.