California health officials are advising the public to be vigilant against West Nile virus (WNV) as the number of human cases increase significantly. Dr. Ron Chapman, director of the California Department of Public Health (CDPH) and state health officer said, “Last week, 52 new human cases were reported to CDPH. We expect to see more people become infected as this is the time of year when the risk of infection is the highest.”

West Nile virus
Culex quinquefasciatus mosquito/CDC

California has seen 181 human cases of WNV from 22 counties, including eight fatalities so far in 2014. Orange County has seen the most cases with 61.

This is a significant increase compared to the 101 cases reported by this time last year.

In addition, Chapman says, “The proportion of mosquitoes infected with West Nile virus is at the highest level ever detected in California.”

As of September 2, a total of 44 states and the District of Columbia have reported West Nile virus infections in people, birds, or mosquitoes. Overall, 399 cases (this does not include the newest 52 cases from California) of West Nile virus disease in people have been reported to CDC. Of these, 214 (54%) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 185 (46%) were classified as non-neuroinvasive disease. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page