Travel-associated Dengue illnesses among Wisconsin residents, 2002-2008

Dengue infections in humans can result in self-limited illness or conditions that can be severe and life-threatening. Persons traveling to many tropical regions are at risk for dengue infection. This report retrospectively summarizes travel-associated dengue cases occurring among Wisconsin residents from 2002 through 2008.

We used a surveillance case definition based on the Centers for Disease Control and Prevention (CDC) 1996 dengue illness case definition. Detection of dengue-specific IgM antibody in serum specimens was used for laboratory confirmation of dengue. Clinical and travel histories, mosquito exposure, and repellent use were obtained from patients by interview using arbovirus-specific data collection forms.

During 2002-2008, 32 travel-associated dengue illnesses were reported among Wisconsin residents; none met the case criteria of dengue hemorrhagic fever or dengue shock syndrome. Fever (100%), headache (90%), and myalgia (87%) were the most frequently reported signs and symptoms. Nine (28%) patients were hospitalized; no deaths occurred. Onsets in 25 (81%) of 31 patients with reported travel histories occurred after return to Wisconsin. Eighteen (56%) of the 32 patients were female; median age was 35.5 years (range 12 to 68 years). Patients most frequently reported travel to Mexico/Central America (45%) or the Caribbean Islands (39%). Cases occurred during all months. Reported mosquito exposure was high among patients (85%), but consistent repellent use was low (6%).

Dengue illnesses occur in travelers to dengue-endemic tropical areas. Travelers to these areas must take precautions to prevent mosquito bites. Clinicians should consider dengue in travelers who develop febrile illnesses with headache or myalgia within 2 weeks of their return. Arboviral diseases, including dengue, are reportable in Wisconsin.