West Nile virus entered the United States in 1999 and is now considered a seasonal epidemic that starts in the summer and continues into the fall. First isolated in Uganda in 1937, the virus can cause severe human meningitis or encephalitis in 1% of those infected.  In2007 the U.S. Centers for Disease Control reported 124 fatalities. The rapid spread of West Nile virus has put local and state mosquito surveillance programs on the front line of public health and disease preparedness. In this episode, MicrobeWorld Video interviews Dr. Jorge Arias, an expert in vector-borne diseases of the Americas. Arias currently serves as the Environmental Health Supervisor of the Fairfax County Health Department in Northern Virginia. In this role, he is responsible for directing the Disease-Carrying Insects Program which focuses on West Nile virus and Lyme disease. For more information about West Nile Virus, please visit: *U.S. Centers for Disease Control and Prevention - http://www.cdc.gov/ncidod/dvbid/westnile/index.htm*National Pesticide Information Center - http://npic.orst.edu/wnv/*Fairfax County Health Department - http://www.fairfaxcounty.gov/hd/westnile/ This episode was filmed at the Marian Koshland Science Museum, the Fairfax County Health Department, Huntley Meadows Park in Fairfax, Va., and the National Zoo in Washington, D.C.