Health officials from Los Angeles, Orange, Riverside, San Bernardino, San Diego, gathered Tuesday in Garden Grove to announce that the region experiences a resurge of West Nile virus an to warn people to “take this threat seriously,” as Gerard Goedhart, district manager of the Orange County Vector Control District, said, quoted by the Los Angels Times.

The risk of human infection is nearly five times higher than in previous years. In 2004, Southern California experienced 710 human West Nile virus cases and 21 people died.

So far this year, 12 people have been infected in Los Angeles County, nine in Orange County and two in San Diego County and 566 dead birds samples and 316 mosquito samples tested positive for West Nile, according to the California Health Department. 70% of the victims have contracted the more serious neurological form of the disease, called West Nile neuroinvasive disease, officials said.

“We’re seeing a trend almost two times higher than we’ve seen in the past years, and every bit as high and in some cases higher than 2004,” Robert Cummings, director of scientific services for Orange County Vector Control, said.

As we are moving into the most dangerous period of the year for infections, officials fear an outbreak between August and October.

Officials announced a full scale campaign against West Nile that will begin in mid-August, when West Nile season reaches its high point.

Abandoned swimming pools and stagnant water are the perfect breeding ground for mosquitoes. Officials are trying to obtain access to many foreclosed pool properties and treat all the storm drains in order to cut down the mosquito population and to combat the potential spread of the virus. County agencies have increased the number or crews spraying storm drains, swimming pools and underground drains where mosquitoes can breed. They are also working overtime.

The West Nile virus can be spread through insects’ biting or blood transfusion. Its symptoms can have three different stages in humans. The first stage is represented by unnoticeable symptoms: people can be infected without being aware of it. The next level includes symptoms similar with those of flu. The final stage can lead to loss of consciousness. The West Nile virus can seldom lead to meningitis or death.

Officials warned that people need to protect themselves from mosquito bites. In order to avoid the contamination with the virus, people are advised by the authorities to avoid exposure at dusk and dawn, when mosquitoes are most active. Wear insect repellent containing permethrin or DEET on top of clothing and wear long sleeves and pants while outdoors. About 20 percent of the people who are exposed to West Nile virus end up with fever. A blood test can detect the presence of the virus. County agencies are also launching a region-wide radio campaign in a few weeks to warn about West Nile virus and explain how to prevent mosquito bites.

Officials warned that although this virus rarely causes death, it is extremely important for elderly people to pay more attention, as they are more prone to severe complications, as their immune system is weakened. Those with chronic medical affections and children are also advised to be more attentive.