Reintroduction of dengue fever into the continental United States. I. Dengue surveillance in Texas, 1980.

Two surveillance systems were initiated in Texas in 1980 to detect cases of dengue fever. Physicians throughout the state were requested to report cases of dengue (passive surveillance), and 27 out-patient facilities serving geographically and ethnically high risk populations were asked to report cases of dengue-like illness weekly (active surveillance). Additionally, two clinics participating in active surveillance submitted acute-phase blood specimens weekly for dengue virus isolation. Sixty-three cases of illness due to dengue type 1 infection (dates of onset 2 August-10 November) were documented by virus isolation or serologic testing; 52 of them (83%) occurred n countries adjacent to the Texas-Mexico border. Fifty-six patients (89%) were Hispanic; 46 (73%) were females. Twenty-seven patients (43%) had not traveled outside the U.S. before becoming ill. Since no clinically apparent outbreak of dengue was ever recognized by public health officials in Texas in 1980, the active surveillance system in other Gulf Coast states should be considered when the risk of introduction of dengue is considered high.