CD24-positive malignant and benign tumors are treated by administration of a naturally occurring or modified oncolytic Zika virus. Diseases associated with abnormal T cell activation or T cell-mediated autoimmunity, wherein CD24 expression is increased, are also expected to be treated by administration of a naturally occurring or modified oncolytic Zika virus. Also contemplated are compounds and methods for treating and/or preventing Zika virus infection in a subject.