Six Santa Ana residents have been infected, as well as one each in Costa Mesa, Orange and Laguna Niguel. The district has found 105 dead birds carrying the virus in north county cities.
Orange County officials are calling this an intense year for transmission of the virus. So far, 80 percent of the mosquitoes collected in Orange County this year have tested positive for West Nile virus. Last year, only about 10 percent tested positive.
Ninety percent of dead birds turned into Orange County Vector Control tested positive for West Nile.
"We've seen that pattern before. We know August and September are our worst two months," said Robert Cummings, an ecologist with the Orange County Vector Control District.
West Nile Virus is spread from humans through the bite of an infected mosquito; mosquitoes can become infected by biting a bird that carries the virus. Most mosquitoes do not carry the virus and most people bitten by a mosquito are not exposed to the virus. The virus is not spread through person-to-person contact, or directly from birds to humans.
In most cases, people who are infected with West Nile virus never become sick, or have only very mild symptoms that include fever, headache, nausea, body aches, and a mild skin rash. Symptoms of WNV could appear within three to 12 days after infection.
"We really don't know the key factors that kick this off every year," Cummings said.
Authorities say it could be a combination of factors from mosquitoes breeding in standing water, backyards, gutters, and even neglected swimming pools.
Vector Control is offering residents with "green pools" mosquito-eating fight. The city of Santa Ana has also done a number of things to try to fight the problem.
Santa Ana spokesperson Tanya Lyon says the city "drained underground water, cleared brush, cleared debris, did everything we could."
Officials are asking residents to do their part.
Decrease risk of infection:
- Avoid mosquito-infested areas at dawn and dusk.
- Wear long-sleeved shirts and long pants whenever you are outdoors.
- Repellants containing DEET, picaridin, or oil of eucalyptus, when used as labeled, are effective defenses against mosquitoes.
- Check your window screens for holes.
- Do not allow water to collect and stagnate in old tires, flowerpots, swimming pools, birdbaths, pet bowls, or other containers. These are prime breeding grounds for mosquitoes.
- Clean and chlorinate swimming pools; drain water from pool covers.
- Stock garden ponds with goldfish or other mosquito-eating fish. These eat mosquito eggs and larvae.
- Empty and wash birdbaths and wading pools weekly.
Authorities are warning people of the possible dangers. So far this year, two people in California have died due to the West Nile virus.
"This year, even one mosquito bite may be all it takes to change a life forever," said Jared Dever with the Orange County Vector Control District.