International travelers and genomics uncover a ‘hidden’ Zika outbreak

Nathan D. Grubaugh; Sharada Saraf; Karthik Gangavarapu; Alexander Watts; Amanda L. Tan; Rachel J. Oidtman; Jason T. Ladner; Glenn Oliveira; Nathaniel L. Matteson; Moritz U.G. Kraemer; Chantal B.F. Vogels; Aaron Hentoff; Deepit Bhatia; Danielle Stanek; Blake Scott; Vanessa Landis; Ian Stryker; Marshall R. Cone; Edgar W. Kopp; Andrew C. Cannons; Lea Heberlein-Larson; Stephen White; Leah D. Gillis; Michael J. Ricciardi; Jaclyn Kwal; Paola K. Lichtenberger; Diogo M. Magnani; David I. Watkins; Gustavo Palacios; Davidson H. Hamer; Lauren M. Gardner; T. Alex Perkins; Guy Baele; Kamran Khan; Andrea Morrison; Sharon Isern; Scott F. Michael; Kristian G. Andersen

Weekly cumulative travel-associated Zika and dengue case numbers were collected from 2014-2018, and are publically available from the FL DOH (FL DOH, 2018). The cases reported on the FL DOH database include those that were confirmed by both PCR and serological assays, and within and without symptoms onset dates (note that many of the pregnant women that were serologically positive for Zika virus were asymptomatic). A travel history was also recorded for most patients. For this study, we only included PCR positive cases with a known date for the onset of symptoms and who only traveled to one international location within the 2 weeks prior to symptoms onset so we could more accurately sort the temporal and spatial distribution of travel-associated cases. We also excluded cases with sexual or congenital exposure. We aggregated the data by month of symptoms onset and by location of likely exposure (i.e. travel origin). Of the travel-associated Zika cases diagnosed in Florida (n = 1,333), 49% were visiting friends and relatives, 17% were refugees or immigrants, 17% were traveling for tourism, 3% were traveling for business, and 14% were traveling for unknown or other reasons. Of the travelassociated dengue virus cases where the questionnaire was given (only started for dengue in 2016, n = 88), 67% were visiting friends and relatives, 25% were traveling for tourism, and 8% were traveling for other reasons.