In conclusion, our study revealed a high specificity but low sensitivity of the Euroimmun ZIKV IgM-ELISA in an endemic region for both dengue and Zika, as well as a high specificity of the Euroimmun ZIKV IgG-ELISA in DENV primary infections contrasting with low specificity in DENV secondary infections. The gene discussed is CD40LG; the disease is infection.