Dengue is a
mosquito-borne disease associated with significant morbidity and mortality in
tropical and subtropical regions, where the dengue viruses(DENV) circulate. An
estimated 390million infections occur annually in more than 100 countries with
about one third of infections resulting in apparent disease. Infection
with any of the four DENV serotypes can cause a broad spectrum of disease, most
often an acute febrile illness typically lasting for 3-7days accompanied by
headache, myalgia and a maculopapular rash (dengue fever,DF). Laboratory
findings in DF include leukopenia, thrombocytopenia, and elevated serum
transaminases. Progression to more severe dengue disease (previously known as
dengue haemorrhagic fever(DHF) and dengue shock syndrome(DSS) occurs in a
subset of individuals and is characterised by the occurrence of vascular
permeability resulting in plasma leakage; multifactorial haemostatic
abnormalities including marked thrombocytopenia; and a bleeding diathesis.
There is evidence that DENV-specific humoral and cell
mediated immune responses may contribute to enhancement of disease severity, as
well as to protection. The recent unexpected failure of a live-attenuated
dengue candidate vaccine, designed to induce protective anti-DENV neutralising
antibody against all four DENV serotypes, highlights the need to better
understand the role of B and T cell responses in protection as well as
pathogenesis of DENV infection.