Dengue fever ranks behind only malaria among diseases spread by insects as a threat to humans. The fight to eliminate the mosquitos that carry the disease has been slowed by environmental concerns and by political indifference. So, it is an emerging disease that is threatening larger sections of the world’s growing population, including parts of the United States. There is a timeline of the history of the disease and of efforts to eradicate it, and sidebars on the life cycle of a mosquito and ways climate change is aiding the spread of the disease.