Genetic Variability, Virulence and Epidemiology of Dengue Virus in Africa

Dengue Fever is one of the neglected tropical diseases that results in case of approximately 100 million per year with over 5 billion individuals at risk of infection and re-infection. It is now one of the most prominent vector-borne diseases of humans in subtropical and tropical parts of the globe with four dengue virus strains (DEN-1, 2, 3 and 4) being reported based on their genomic variants. Transmission to humans is mainly through theinfective female Aedes mosquito bite which can be enhanced due to the climate of the tropic and subtropics.Thevirulence of DENV is function of its genetic variability andthe elevation many cytokines level and chemical mediators, which responsible for capillary leakage and shock. This situation enhances the progression of DF to DHF and DSS in the infected patients. TNF- α and cytokines (IL-1b, IL-6 and IL-8)that are secreted downstream of TNF- α as the inflammatory cascade, contribute to the disease severity. Marked IL-2 and interferon (IFN)-γ are then produced by T cells due to the immune activation that occurs during DENV-infections in the patients with DHF and DSS than the patients with DF. Genetic diversities in the DENV is important in the understanding of viral virulence and mechanisms of its pathogenicity. This will help in the control of the virus especially in vaccine development and preparedness towards any emerging or re-emergence of the virus.