Dengue virus is an under-recognised causative agent of acute encephalitis syndrome (AES): Results from a four year AES surveillance study of Japanese encephalitis in selected states of IndiaDengue virus is an under-recognised causative.

•Dengue virus is one of the three most common agents identified in AES.•Existing surveillance for acute encephalitis syndrome (AES) does not include routine testing for dengue.•Dengue accounts for 5% of AES cases in India especially in the absence of laboratory evidence for other pathogens tested.•Testing for dengue in AES cases must be included in routine surveillance.