Dengue is the most important mosquito-borne viral infection of humans. Although outbreaks of disease which are now recognized as clinically consistent with dengue have been reported for centuries, it was not until half a century ago that laboratory identification of dengue viruses as the etiological agent of febrile illness was achieved. This debilitating and sometimes fatal disease is widely distributed in >125 countries in tropical and subtropical zones of the world. Asia, South America and the Pacific Islands are hyper-epidemic regions while currently there is less prevalence in Europe, North America and Australia. The estimated global incidence ranges between 200 and 400 million clinical cases per year. While some areas of past epidemics are now considered to be under control, recent decades have witnessed an epidemic rise in dengue worldwide. Major factors facilitating expansion include climate change and increase in urbanization and international travel. Concurrently, the non-availability of an efficacious antiviral drug or vaccine and a lack of effective vector control strategies collectively make dengue a serious public health concern. Thus, it is of paramount importance to analyze the history of the spread of infection and to gain a deeper understanding of patterns of transmission in order to anticipate epidemiological trends more accurately, thereby enabling better preparedness for future outbreaks.