Health officials say mosquitoes are spreading the West Nile Virus through L.A. County at an alarming rate.
So far this year 117 people in California have been infected with West Nile Virus. The vast majority of those cases, 74, are in Los Angeles County.
But Vector Control officials say they fear the actual number of cases is considerably higher.
"You work backwards through the statistics and you come up with over a thousand cases of West Nile Virus that are out there," said Kenn Fujioka, San Gabriel Valley Mosquito and Vector Control.
Fujioka fears those cases are going unreported. Most people infected with West Nile show no symptoms, but 20 percent end up with severe headaches, crippling fatigue and fevers.
"It takes three weeks to several months to recover," said Fujioka. "The most severe form is encephalitis. You'll be incoherent, you'll be immobile and you'll require hospitalization."
Mosquitoes pick up the West Nile Virus when they bite infected birds. The virus is then spread to people when those mosquitoes bite humans.
L.A. County has posted warning signs throughout the area, including at the L.A. County Arboretum and Botanic Garden, which tested positive for West Nile.
The Mosquito and Vector Control District says last year was worse than normal for West Nile, and unless more people start maintaining their pools and cleaning up standing water from their yards, they don't see the numbers improving.
"We're concerned because we're on track to equal last year's rate," said Fujioka.