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In October 2010, 28 missionaries from Nebraska and Georgia spent 7 to 11 days in Haiti, residing in a house with no screens or air conditioning. After several became ill with dengue on returning home, public health officials conducted an investigation to characterize the outbreak and identify risk factors.
Eighteen of the 28 missionaries reported illness during or within 14 days of travel; 23 provided at least one serum sample, and 25 completed questionnaires. Infection was confirmed by isolation of dengue virus (DENV) or by a fourfold or greater rise in anti–DENV IgG antibody in paired specimens.
Seven of the 18 ill travelers had acute DENV infection, 9 had no DENV infection, and 2 had indeterminate test results or did not provide serum specimen. Among the seven with acute DENV infection, all had fever, chills, myalgia, eye pain, and arthralgia, and five had rash; five (including all 4 with serologic evidence of previous flavivirus exposure) were hospitalized. None met WHO criteria for severe dengue. The implicated virus most closely resembled a dengue-1 virus isolated in the Dominican Republic and Puerto Rico in 2007.
Although 22 of 25 respondents had received pretravel advice from a healthcare provider, less than a third were aware of potential dengue exposure in Haiti; few reported correct insect-repellent use. Only two of the seven DENV-infected individuals recalled having mosquito bites. Knowledge and mosquito-avoidance practices were not significantly different between cases and noncases.
Sharp TM et al. A cluster of dengue cases in American missionaries returning from Haiti, 2010. Am J Trop Med Hyg 2012 Jan; 86:16.
Comment
This cluster shows a remarkably high attack rate during short-term travel, as well as disappointingly poor knowledge and use of mosquito-avoidance practices. Most patients with dengue do not require hospitalization; the high proportion of hospitalizations in these patients (5/7) may reflect concern about other tropical diseases, such as falciparum malaria, or worrisome clinical findings. Four of the five hospitalized patients had evidence of previous flavivirus exposure — a potential risk factor for more-severe DENV infection.