"Time Line for 1937 – Discovered in Uganda in the . Mistaken at first for 1951 – Israeli scientists determine the conditions for transmission from the perspective of mosquitoes. Temperature vrs. 1973 – Biggest outbreak in history in South Africa – 3,000 people sick. Hot and dry conditions followed by heavy rains 1999 – West Nile Virus first introduced in USA. Hottest, driest summer on record. 2010 – West Nile virus now an endemic infectious disease of and people. Yearly outbreaks common. All dependent on hot, dry weather, followed by a rain event"