Advances in Dengue Vaccine: A Review Study

Abstract

Dengue virus (DENV) is a vector-borne viral disease that cause more human morbidity and mortality worldwide than any other arthropod-borne virus. It is estimated that 3.97 billion people living in 128 countries are at risk of dengue, 400 million infections annually, and 96 million asymptomatic cases occurring every year [1-4]. Four closely related dengue serotypes cause the disease: DENV-1 to -4. Serotype specific differences in clinical manifestations have been reported. In a cross-sectional study, Balmaseda et al. [5] reported that among hospitalized children in Nicaragua over 3 years period DENV-2 was associated with more shock and internal hemorrhage while DENV-1 was associated with increased vascular permeability. Furthermore, DENV-1 was associated with more hospitalized primary dengue cases and more primary DENV infection with severe manifestations. Others reported that DENV-2 and DENV-3 may cause more severe diseases than the other serotypes and that DENV-4 is associated with milder illness [6-12]. Certain genotypes within particular serotypes are associated with epidemics of dengue hemorrhagic fever (DHF) vs. classic dengue [11,13]. Aedes aegypt mosquitoes are the primary vectors of DENV throughout the tropics [14]. DENV infection is categorized as asymptomatic infection, subclinical infection, undifferentiated fever, dengue fever, DHF with or without dengue shock syndrome (DSS) and other severe forms of dengue. DHF is characterized by fever, bleeding diathesis, and a tendency to develop a potentially fatal shock syndrome. Clinical manifestations of dengue infection range from mild dengue fever to severe plasma leakage with hemorrhagic manifestations. Thrombocytopenia is an important finding in patients with dengue. A study reported that platelet count of dengue patients can be normal or abnormally high or low. This should be used for future diagnosis [15-17]. Management of dengue patient is to have good fluid replacement therapy until recovery of platelet. Multiple factors have been suggested to contribute to severe dengue such as secondary infections, age, viral load and infecting serotype and genotype [6-8]. Dengue infection is spreading at an alarming rate around the globe and statistics shows that the disease has increased dramatically since 1980, with epidemics occurring in both eastern and western Africa [18,19]. The WHO statistics indicates that 2.4% of the global burden of dengue hemorrhagic fever is in Africa and one-fifth of the populations are at risk [17].