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The emergence of dengue/dengue hemorrhagic fever as a major public health problem has been most dramatic in the American region. In an effort to prevent urban yellow fever, which is also transmitted by
Aedes aegypti, the Pan American Health Organization organized a campaign that eradicated
Aedes aegypti from most Central and South American countries in the 1950s and 1960s. As a result, epidemic dengue occurred only sporadically in some Caribbean islands during this period. The
Aedes aegypti eradication program, which was officially discontinued in the United States in 1970, gradually eroded elsewhere, and this species began to re-infest countries from which it had been eradicated. In 1997, the geographic distribution of
Aedes aegypti is wider than its distribution before the eradication program.
There is a small, but significant, risk for dengue outbreaks in the continental United States. Two competent mosquito vectors,
Aedes aegypti and Aedes albopictus, are present and, under certain circumstances, each could transmit dengue viruses. This type of transmission has been detected three in the last 16 years in south Texas (1980, 1986, and 1995) and has been associated with dengue epidemics in northern Mexico. Moreover, travelers returning from tropical areas where dengue viruses are endemic introduce numerous viruses annually. From 1977 to 1994, a total of 2,248 suspected cases of imported dengue were reported in the United States. Although some specimens collected were not adequate for laboratory diagnosis, 481(21%) cases were confirmed as dengue.
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