The victim, listed as being from central Contra Costa County, first became ill in Mid-July but was not diagnosed until two weeks later. Farley said the woman is recovering from the potentially fatal virus.
West Nile Virus is transmitted through the bite of an infected mosquito. Farley said that 80 percent of the time the person bitten suffers no ill effects. The other 20 percent suffer "West Nile Fever," which can include high fever, chills, headache, fatigue and vomiting.
In rare cases, fewer than 1 percent of those who develop West Nile Fever will have a much more severe reaction.
"It develops into a central nervous system disease, like meningitis or encephalitis," Farley stated.
Those affected will experience confusion, dizziness, loss of motor control and other neurological effects. Those most at risk of developing the more serious version of West Nile tend to be older or have a pre-existing condition of hypertension.
There is no vaccine or medicine for West Nile. Farley said the main treatment is "supportive care," taking medication to keep fevers down, staying hydrated and similar courses of action. In the extreme cases, hospitalization is required.
The number of cases of West Nile are down so far this season. The California West Nile Virus Web site said so far this year there are only five human cases of the virus in California, whereas last year at this time there were 28 in the state.
Officials with the health department as well as the County Mosquito and Vector Control District are continuing to monitor the situation and request that any dead birds found be reported to a special hotline at (877) 968-2473.