Research has showed that CLEC5A interacts with dengue virion directly, and is responsible for dengue virus (DV)-induced DAP12 phosphorylation. Data suggests that CLEC5A is a potential therapeutic target for dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). This project will study the genes of CLEC5A, Mannose receptor, DC-SIGN, NALP, decoy receptor 3 (DcR3), Toll-like receptors(TLRs), and (Nod)-like receptors (NLRs) for both DF and DHF groups. In addition, serum level of decoy receptor 3 (DcR3) will be tested. The study will collect the blood samples from 350 healthy persons and 350 persons infected with dengue fever.