Abstract
This chapter discusses the evolution and history of dengue viruses, emphasizing those aspects that help explain the emergence of severe and fatal dengue disease as a global public health problem in the waning years of the 20th century and the beginning of the 21st century. The discovery of dengue virus, its mosquito vectors and transmission, the emergence of dengue haemorrhagic fever, and the factors responsible for the global resurgence of dengue are described.