West Nile Virus in California

2002:  First found in CA in 2002 – LA County woman contracted WNV although no evidence of WNV was found in birds, mosquitoes, or sentinel chickens in CA.

2003:  First identified in June from mosquitoes in Imperial County.  WNV First identified in the San Gabriel Valley in September in a crow collected from the city of Arcadia.

2004: First crow collected February 24 from city of San Gabriel.  Mild winter, late spring rains followed by high temperatures spiked early season WNV transmission.  830 human WNV infections and 28 deaths were reported in California in 2004.     

2005: Unusually high rains caused concern for California.  Early reports of birds and mosquitoes infected with West Nile virus  occurred throughout Northern and Southern California.  935 human infections and 19 deaths were reported in California in 2005.  

2006:  A milder year across California.  292 human infections and 7 deaths were attributed to WNV.

2007: Increased WNV activity and predictions of epidemic transmission levels prompt Governor Schwarzenegger to issue WNV State of Emergency in CA on August 2.  380 human infections and 21 deaths were recorded by the end of the year.

2008: WNV re-emerges as significant public health concern in Southern California.  445 WNV Cases and 15 deaths in California in 2008.

2009 & 2010: WNV is endemic and continues to be widespread and transmitted to residents throughout the State every year.     

Updates for California can be found at: http://westnile.ca.gov

© San Gabriel Valley Mosquito & Vector Control District.
1145 N. Azusa Canyon Road - West Covina, CA 91790 - 626.814.9466