CD40LG and dengue disease: All serum specimens from suspected dengue cases were tested as previously described.12,13 Briefly, specimens collected within 4 days of illness onset were tested by DENV-type specific, multiplex reverse transcriptase-polymerase chain reaction (RT-PCR),14 and specimens collected 6 days or more after illness onset were tested by anti-DENV immunoglobulin M (IgM) antibody by capture enzyme-linked immunosorbent assay (MAC ELISA).15 From 2005 to 2006, specimens collected 5 days after illness onset were tested only by RT-PCR.