Dengue is the most common vector-borne viral disease in the world, causing an estimated 50-100 million infections and 25,000 deaths each year. Most cases occur in semitropical and tropical regions of the Americas, the Caribbean, Southeast Asia, Africa, and the Pacific. Historical epidemiologic and clinical reports describe the occurrence of dengue epidemics in larger U.S. cities, as far back as Colonial times. In 1780, a dengue-like outbreak was reported in Philadelphia, Pennsylvania, and in the 1820s, dengue outbreaks also occurred in Pensacola, Florida; Charleston, South Carolina; Savannah, Georgia; and New Orleans, Louisiana. The last major dengue outbreak, the ‘‘Galveston outbreak’’ of 1922, resulted in over 500,000 cases of dengue fever along the Gulf Coast.
The Ae. aegypti eradication program established by the Pan American Health Organization (PAHO) in the 1940s and 1950s to combat yellow fever was one of the most important factors in suppressing dengue in the Americas into the 1970s. Between 1948 and 1972, Ae. aegypti, was eradicated in 21 of the countries of the Hemisphere. Unfortunately this program could not be sustained as Ae. aegypti mosquitoes and the diseases they carried lost political importance, consequently, attention to the program diminished and so did funding. Resistance to DDT in Ae. aegypti became more widespread and programs to monitor for re-infestation went unfunded, ultimately resulting in the loss of hard won advances. By 1997, virtually all the countries of the Americas that had eradicated Ae. aegypti were reinfested, including the southern United States.
In the US, a few scattered outbreaks of locally transmitted disease have occurred over the past 20 years in Texas, Florida and Hawaii, but by far, most reported cases are diagnosed in travelers returning from Dengue endemic areas of the world. The potential for dengue to become established in the United States is increasing with the expansion of the ranges of its two main vectors: Ae. aegypti and Ae. albopictus. Recent dengue activity in the U.S. demonstrates that areas of the country where the vectors are well established are at risk of experiencing outbreaks. Changing demographics, increases in international travel to dengue endemic regions and changing climatic and ecological conditions that provide more suitable habitat for vectors all contribute to this increasing risk.
Dengue fever (DF) is caused by any of four closely related viruses, or serotypes: dengue 1-4. Infection with one serotype does not protect against the others, and sequential infections put people at greater risk for developing more severe forms of the disease, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). According to CDC, signs and symptoms of dengue include: fever, headaches, muscle, bone and joint pain and pain behind the eyes. Many people, especially children and teens, may experience no signs or symptoms during a first case of dengue fever. A vaccine has recently been become available, but is currently approved for use in only 11 countries.