Tropical diseases like dengue fever sound as if they belong in faraway places. But in the past several years, some have begun showing up in the continental U.S. Now in Key West, FL, public health officials are combating a scourge they thought they'd eradicated seven decades ago. Until recently, a locally contracted case of dengue fever had not been seen in Florida since 1934. That suddenly changed in 2009, when doctors in Key West began seeing it in people who had not traveled outside the area. There were 27 cases that year. Last year, 66 people in Key West contracted dengue. "Typical dengue fever is a severe, flu-like illness," says Mark Whiteside, medical director at the Monroe County Health Department in Key West. While dengue is debilitating, he says it's rarely fatal. "It might last a week or two. You might wish you were dead, but almost everybody gets over it."