CD40LG and dengue disease: Fourteen individuals with a second illness that was positive solely by MAC ELISA ≤ 90 days after a previous laboratory-confirmed episode of dengue were excluded from further analysis because anti-DENV IgM antibody can in some cases be detected up to 90 days after illness onset.18 Also excluded from further analysis were two individuals with DENV-1 and -4 detected in a single specimen in 2010, and one individual with DENV-2 detected by RT-PCR during independent illness episodes 16 months apart because virus could not be isolated from the specimen collected during the first illness.