The remainder had reasonable evidence of an alternative disease: one dengue fever by IgM ELISA; one hepatitis A (versus dengue) by IgM ELISA for both hepatitis A and dengue; one hemolytic uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP) by clinical laboratory profile; and one rat bite fever bacteremia in a patient who reared laboratory rats. This evidence concerns the gene CD40LG and thrombotic thrombocytopenic purpura.