A vaccine formulated from pieces of two viruses protects mice against the West Nile virus. Scientists will next try the hybrid vaccine in monkeys and then, if that works, test it in people.
West Nile virus was first identified in Uganda in 1937 and was later found elsewhere in Africa and in Asia and Europe. It surfaced in New York in 1999 and has spread to other states. The infection can go unnoticed in people, but it sometimes causes flu-like symptoms. It also can trigger encephalitis, or brain inflammation, which can be deadly in elderly people.