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5 human cases of West Nile virus reported; first in LA County for 2013

A mosquito sits on a stick April 9, 2009 in Martinez, California.
Justin Sullivan/Getty Images
A mosquito sits on a stick April 9, 2009 in Martinez, California.

Five people have been infected with the West Nile virus, the first confirmed human cases in Los Angeles County for 2013, local health officials said Thursday.

Two of the patients were admitted to hospitals with serious symptoms of the disease, which was affecting their brains and spinal cords.

The other three discovered the infection by accident when they received routine screenings prior to donating blood. 

"They didn't know they'd had any disease, which is not uncommon, because about 85 percent of those that get West Nile from a mosquito bite don't know they've had any problem at all," said Dr. Jonathan Fielding, director of the L.A. County Department of Public Health. All five patients were recovering.

Humans and animals contract the West Nile virus through the bite of an infected mosquito, but the risk of serious illness is low for most people. Fewer than 1 percent of those with West Nile disease develop a serious neurologic illness such as encephalitis or meningitis, according to the California Department of Public Health.

Fielding pointed out that there is no specific treatment for West Nile. People older than 50 are more likely to get sick and develop complications, and new data suggest that people with diabetes or hypertension are also at greater risk, according to the state health department.

CDPH reported another human case on Thursday. An elderly resident in Glenn County was hospitalized but is now recovering.

So far this year, West Nile virus has been detected in 31 California counties.

In the past decade in California, the highest number of human cases reported in a single year was 880, and that was in 2005, according to data from the CDPH and partner agencies.

"This is just the very beginning of the season," said Fielding. "Last year we had the second highest number that we've ever had [for L.A. County], so it's really hard to tell what we're going to have this year. The pattern in other places as well has not been, you know — you can't predict from one year to the next."

The state health department offered some helpful tips to reduce your chances of being bitten by mosquitoes that may carry the West Nile virus. Just remember the "Three D's" —

  • DEET: Use insect repellant that contains DEET, picaradin, oil of lemon eucalyptus or IR3535. State health officials say DEET is safe to use on infants and children 2 months of age and older.
  • Dawn and Dusk: This is when mosquitoes bite. Wear proper clothing and repellant if you're planning to be outside at these times, and make sure your windows and doors have screens.
  • Drain: Watch out for standing water and get rid of it if you can, because this is where mosquitoes lay their eggs. Sources include flower pots, old car tires, rain gutters, pet bowls and, yes, swimming pools. State health officials recommend contacting your local mosquito and vector control agency if you know of a swimming pool that is not being maintained properly.