The World Health Organization (WHO) has coined the term 'expanded dengue syndrome' (EDS) which incorporates a wide spectrum of unusual manifestations during dengue viral infection (DVI). These atypical manifestations were previously seen as unusual complications. The severity of EDS ranges from mild self-limiting illnesses to various fatal intricacies. In recent years, with the geographical spread of dengue and more involvement of adults, there have been increasing reports of EDS. These atypical and unusual organopathies include intricacies of major organs, such as the liver, kidney, heart, lungs, and nervous system, and could be explained as complications of severe profound shock or associated with underlying host conditions or co-infections. Existing evidence indicates that EDS is associated with high mortality, morbidity, prolonged hospital stays, and healthcare expenditure.

However, the long-term sequelae of EDS are currently not known. The involvement of various organs is being increasingly reported in dengue hemorrhagic fever (DHF) or severe dengue, while EDS can also occur during dengue fever (DF) without any evidence of plasma leakage. Currently, EDS is a new entity incorporated into WHO guidelines on the management of dengue infection. The majority of healthcare professionals are not familiar with the identification and management of these complications. Since dengue outbreaks have been repeatedly reported in various regions across the globe, many countries have reported these atypical complications in the form of case reports and small case series. However, a wide research gap has been noted on the epidemiology and potential challenges related to the EDS. Moreover, the disparate findings across various regions have made it quite difficult to draw a firm conclusion on this topic. In this context, large-scale studies are direly needed to fill the research gap and guide the health authorities to revise the management guidelines, keeping the identification and management algorithms of EDS in view.

This Special Issue encourages papers focused on describing the epidemiological aspects, clinical outcomes, and challenges related to EDS during the course of DVI. Knowledge about EDS will help to establish the diagnosis and prompt the appropriate treatment for dengue with unusual manifestations. Clinicians must be mindful of these unusual features so that they can suspect dengue early, especially during ongoing epidemics. Detailed knowledge and greater insights on this topic would have a positive impact on the early diagnosis, management, and outcome of EDS among dengue patients. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Studies evaluating the prevalence, pathogenesis, risk factors, and outcomes of expanded dengue syndrome
• Qualitative and quantitative synthesis studies of available evidence on EDS to draw a firm conclusion (systematic reviews and meta-analyses)
• Challenges faced by healthcare professionals in the management of EDS among dengue patients
• Awareness of EDS among healthcare professionals
• Studies assessing the health policies and guidelines on the management of EDS
• Studies estimating the barriers and challenges during the diagnosis and management of EDS