West Nile spreads in Butte

Butte County authorities reported five new cases in the last nine days of illness caused by the West Nile virus, bringing the county's total of victims this year to 19 - nearly a sixth of California's total.

The new cases involved three Chico residents and one from Oroville, the county Public Health Department said Friday. One of the patients contracted the most severe form of the viral illness, which includes neurological symptoms. The others suffered from fevers.

Although the mosquito-borne microbe generally takes a heavier toll on seniors and the ill, the health department said four of the newest victims were younger than 65.

Twenty-three California counties have reported West Nile-related sicknesses this year, with 117 humans affected.

Only a fraction of those who contract the virus from mosquito bites shows the effects. According to the Centers for the Disease Control and Prevention, nearly 85 percent of those infected do not show symptoms.

Another 10 to 15 percent of those with the virus show moderate effects, including fever and body aches. Less than 1 percent of cases lead to life-threatening conditions.