CDC Works For You 24/7 Protecting People - Working to Protect Against the Dangers of Dengue - Dengue, a painful and sometimes deadly viral disease transmitted by mosquitoes, threatens more than 3.5 billion people worldwide. Dengue is endemic in at least 100 countries in Southeast Asia, the Pacific Islands, the Caribbean, Central America, South America, and parts of Africa. As many as 100 million people become infected yearly, and nearly 500,000, mostly children, develop the potentially deadly dengue hemorrhagic fever.