Our study revealed that IgG and IgM antibodies to JEV, WNV, and TBEV were frequently detected in dengue‐confirmed patients with identified DENV serotypes, suggesting that these anti‐JEV/WNV/TBEV serological positives likely reflect cross‐reactivity or limited specificity of the assays rather than true co‐infections or prior exposures to JEV, WNV, or TBEV. Here, CD40LG is linked to coinfection.