The Los Angeles County Department of Public Health on Thursday confirmed that two people were infected by West Nile virus in July, the county's first cases of the year.
A woman in her 60s from the San Fernando Valley was hospitalized in mid-July and continues to recover at a hospital, according to a department statement.
The second case involved a man in his 20s, a blood donor who was infected in late July but showed no symptoms. He lives in southern L.A. County and is healthy.
Healthcare officials urged residents to remove of pools of stagnant water and use an insect repellent containing DEET when they're in mosquito-prone areas.
"All residents should take the proper precautions to avoid and protect against mosquitoes, as that is the primary way the disease is transmitted," said Jonathan Fielding, director of the Los Angeles County Department of Public Health. "Mosquitoes obtain the virus by feeding on infected wild birds."
In 2013, 165 human cases of West Nile virus were reported in L.A. County, one of the highest counts documented since 2004.
Most infected people don't seek medical care because they have mild or no symptoms. Therefore, the Los Angeles County Department of Public Health said, the total number of West Nile virus infections is much higher than what is reported.
Of cases in which patients showed symptoms in 2013 and were reported, 122 required hospitalization and nine cases were fatal, the department said.
As of Tuesday, West Nile virus infections have been detected in 48 mosquito pools, 10 dead birds and 14 chickens in the county.
"This is not a virus to take lightly," said Truc Dever, general manager for the Greater Los Angeles County Vector Control District. "Residents should report dead birds and also report sources of standing water to their local vector control agencies."
Dead birds can be reported online or by calling (877) 968-2473. Stagnant swimming pools should be reported to the Public Health Environmental Health Bureau at (626) 430-5200 or to a local vector control agency.