Figure 1. DENV IgM ELISA titers, by serotype, for DENV PCR–positive serum samples from travelers returning to Germany or Italy, 2013–2016. A) DENV-1; B) DENV-2; C) DENV-3; D) DENV-4. Data lines indicate average titers; error bars indicate SDs. The antigens in this ELISA were Equad proteins (i.e., envelope protein from each DENV serotype with 4 amino acid changes T76R, Q77E, W101R, and L107R). In these examples, the highest endpoint titers corresponded to the DENV serotype identified by PCR analysis. DENV, dengue virus.