We describe two cases of West Nile (WN) encephalitis in a married couple in
Tel Aviv, Israel, in 1999. Reverse transcription-polymerase chain reaction
performed on a brain specimen from the husband detected a WN viral strain
nearly identical to avian strains recovered in Israel in 1998 (99.9% genomi
c sequence homology) and in New York in 1999 (99.8%). This result supports
the hypothesis that the 1999 WN virus epidemic in the United States origina
ted from the introduction of a strain that had been circulating in Israel.