1^st isolated in 1937 in Uganda

Member of Japanese Encephalitis Group which includes, JE, SLE, Murray Valley E, and Kunjin.

Apparent evolution of a new WN virus variant associated with human encephalitis, as seen in Africa, India, Europe, Asia, and North America.

Current strain in U.S. most closely related to virus circulating in Israel in 1997-2000. Israel and US are the only countries with illness and death in humans and animals caused by this strain.