Serological evidence of subclinical Usutu virus exposure among West Nile virus-seropositive individuals in Israel.
BACKGROUND Usutu virus (USUV) is a mosquito-borne orthoflavivirus closely related to West Nile virus (WNV), with confirmed circulation in mosquitoes and horses in Israel but no reported human exposure. OBJECTIVES To determine whether USUV circulates in humans in Israel and to assess its contribution to serological cr...