An Imported Case of Dengue/Zika Coinfection — Sichuan Province, China, 2026

<abstract abstract-type="Summary"> <sec> <b>What is already known about this topic?</b> Dengue virus (DENV) and Zika virus (ZIKV), primarily transmitted by <i>Aedes aegypti</i> and <i>Aedes albopictus</i>, belong to the Flaviviridae family. Their clinical presentations overlap considerably, including acute fever, nausea, rash, joint pain, and myalgia, making differential diagnosis challenging. </sec><sec> <b>What is added by this report?</b> Because DENV and ZIKV share a common mosquito vector, their co-circulation increases the likelihood of dengue–Zika coinfection in both human and mosquito populations. This study documents the first laboratory-confirmed case of dengue/Zika coinfection in China. The patient presented with a fever on the day of entry. </sec><sec> <b>What are the implications for public health practice?</b> This study provides a comprehensive epidemiological and phylogenetic analysis of a dengue/Zika coinfection case imported from Malaysia. Climate change and frequent cross-border travel are heightening the risk of imported mosquito-borne infectious diseases in China. International port cities must therefore strengthen surveillance and diagnostic testing for imported mosquito-borne diseases. For suspected febrile cases, clinicians should consider arbovirus coinfection based on travel history to prevent serious public health risks arising from missed diagnoses. </sec>