This study aimed to evaluate the accuracy of an easier-to-use multiplex lateral flow immunoassay (DPP Fever Panel II Assay) that can detect IgM antibodies and specific antigens of common tropical diseases in Asia (Scrub typhus, Murine typhus, Leptospirosis, Melioidosis, Dengue fever, Chikungunya, and Zika virus). The gene discussed is CD40LG; the disease is leptospirosis.