Dengue viruses - an overview

Abstract

Dengue viruses (DENVs) cause the most common arthropod-borne viral disease in man with 50-100 million infections per year. Because of the lack of a vaccine and antiviral drugs, the sole measure of control is limiting the Aedes mosquito vectors. DENV infection can be asymptomatic or a self-limited, acute febrile disease ranging in severity. The classical form of dengue fever (DF) is characterized by high fever, headache, stomach ache, rash, myalgia, and arthralgia. Severe dengue, dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS) are accompanied by thrombocytopenia, vascular leakage, and hypotension. DSS, which can be fatal, is characterized by systemic shock. Despite intensive research, the underlying mechanisms causing severe dengue is still not well understood partly due to the lack of appropriate animal models of infection and disease. However, even though it is clear that both viral and host factors play important roles in the course of infection, a fundamental knowledge gap still remains to be filled regarding host cell tropism, crucial host immune response mechanisms, and viral markers for virulence.

Keywords: arbovirus; dengue fever; dengue hemorrhagic fever; dengue shock syndrome; dengue virus; flavivirus; vector-borne virus.

Fig. 1

Dark-gray shading indicates countries/areas at risk of DENV transmission, 2008. The contour lines indicate the potential geographical limits of the northern and southern hemispheres for year-round survival of Ae. aegypti, the principal mosquito vector of DENVs. Reprinted by permission from WHO, Dengue: guidelines for diagnosis, treatment, prevention and control – New edition (2009), ^© 2009 (6).

Fig. 2

The complex interplay of risk factors for severe dengue disease can be illustrated as a triangular interplay dominated by the three main risk factors: host factors, preexisting DENV-specific antibodies mediating antibody-dependent enhancement (ADE), and intrinsic virus features influencing strain virulence. The exact contribution of each risk factor may vary from case to case.