So far this year, there are 21 human cases, but no deaths have been attributed to the virus.
Conditions now are similar to those in 2004 when the West Nile epidemic killed 21 people in Southern California.
"The West Nile virus situation in Southern California is dangerous. It is a very dangerous situation that is evolving in Southern California at this time. We are all threatened by this," said Gerard Goedhart from the OC Vector Control District.
Some tips to prevent West Nile virus:
- Insect repellent
- Wear long sleeves at dusk and dawn
- Keep windows screened
- Eliminate mosquito breeding sites, standing water
While many human West Nile victims never show symptoms, one in 150 will develop serious illness that can lead to death.
"Typically you obviously have fever, headaches, body aches, fatigue, and a possible rash. We are heading into part of the season where we typically would expect more human cases," said Dr. Hildy Meyers, OC Health Care Agency.