Dengue fever had been eradicated after the 1950s from the Americas with pesticides and the elimination of sources of standing water. In the late 1980s, efforts to eradicate the carrier mosquito diminished while the Latin American population increased along with poverty and urbanization, and so dengue fever has erupted again.
After 1985, there was further concern about dengue fever in North America because a potential new carrier, the Asian tiger mosquito [Aedes albopictus], was been found in the USA. It can withstand cold and is a ravenous biter.
Any semi-permanent large congregation of people without adequate shelter in a climate where mosquitoes can breed increases the risk of dengue fever, such as large city slum inhabitants and people in refugee camps. Although dengue fever has been reported in some international travellers, in general there is a low risk of DHF in tourists returning to the developed world. Prevention is key, because there is no specific therapy for dengue fever.