Dengue Facts Dengue fever is a mosquito-borne disease caused by four dengue virus serotypes. Half of the world’s population lives in areas where dengue is endemic and the disease has become a public health priority in many countries of Latin America and Asia. Of the estimated 390 million people infected annually, 500,000 develop dengue hemorrhagic fever (DHF), a severe form of the disease. DHF is a leading cause of hospitalization, straining medical resources during outbreaks and having a heavy economic and societal impact. Many factors have contributed to the re-emergence and growth in dengue fever including urbanization and increased travel which facilitate the dissemination of dengue viruses and the circulation of the disease. The World Health Organization (WHO) has set a target to reduce dengue mortality by 50% and morbidity by 25% by the year 2020.