The boom in case numbers is being blamed on unusually high temperatures throughout the state in March which in turn started an earlier beginning to the West Nile virus season than in other years. Human illnesses have been documented in six counties, led by Kern County with 22, and one each in San Joaquin, Merced, Stanislaus, Glenn and Mendocino counties, state health officials reported Friday. Eighteen of the cases were documented in the last week. According to westnile.ca.gov, the states West Nile Virus information web page, 355 dead birds have been reported statewide, as well as 4 horses, 5 squirrels and 22 sentinel chickens.

The California Department of Public Health warned earlier this month that the rising numbers "could indicate that the mosquito and vector control agencies may have another busy year battling West Nile virus-carrying mosquitoes." Dr. Mark Horton, director of the state's public health department, recently recommended that people take steps to avoid mosquito bites. "Even though the likelihood of serious illness from West Nile virus is low for most people, all Californians should take every precaution to reduce their risk of exposure," he said. West Nile virus, first detected in California five years ago, is transmitted to humans and animals through mosquito bites. Mosquitoes become infected when they feed on infected birds. People throughout California can assist with detection by reporting dead birds at westnile.ca.gov or at (877) 968-2473.