This summer has seen one of the largest outbreaks of West Nile Virus since the mosquito-borne illness first appeared in North America in 1999, officials from the Centers for Disease Control said Wednesday.

A dead crow with the virus was found last month in the Santa Monica-Brentwood area. It was the Earlier this month, ﻿infected crows were found in , and

According to the California West Nile Virus website, there have been 54 infected birds found in Los Angeles County. Four of the 34 statewide human cases of illness linked to the virus were also reported here, with two of them happening this week. "This is a reminder that West Nile virus continues to be a problem here in Los Angeles County," said Susanne Kluh, director of scientific-technical services for the Greater Los Angeles County Vector Control District, in a written statement. "We can anticipate more activity as the season progresses."

See West Nile Virus numbers for all of California on the state's website. Across the country, there are 1,118 reported illnesses. A normal year sees only 300 such cases by mid-August, according to the Washington Post. Half of the illnesses reported this year are in Texas.

The Center for Disease Control reports that WNV is most often spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite.

West Nile virus symptoms may include headache, fever, body aches, vomiting, nausea, swollen lymph glands, and skin rash on the chest, stomach and back.

Approximately 80 percent of people who become infected with West Nile virus will not show any symptoms, although some 20 percent will develop West Nile fever. Of those, less than 1 percent may develop a more severe form of illness with symptoms such as high fever, headache, neck stiffness, disorientation, coma, paralysis and in extreme cases death. While there is no cure for West Nile virus, it is preventable. Residents can help reduce the threat by eliminating unnecessary standing water in discarded tires, buckets, kiddie pools and stock backyard ponds or other permanent water features with mosquito fish.