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

We estimate that the 2017 Zika outbreak in Cuba was similar in size to outbreaks from other Caribbean islands that peaked the year prior (Fig. 2) . These analyses utilize . CC-BY-NC 4.0 International license is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It . https://doi.org/10.1101/496901 doi: bioRxiv preprint the relationships between local-and travel-associated Zika data from non-Cuba countries, in combination with travel volumes and travel associated cases from Cuba. Other studies have used similar approaches to estimate the number of people infected with influenza A/H1N1 virus (Fraser et al., 2009) and the number of Middle East Respiratory Syndrome cases (Cauchemez et al., 2014) . However, there are important limitations to such approaches that may influence our ability to estimate the size of the Zika outbreak in Cuba. First, accurate travel data are necessary to calculate travel incidence rates of Zika cases. This is challenging for Cuba, as travel policies from the United States have repeatedly changed during the past few years (Robles, 2016) . To minimize this issue, we included air travel from both scheduled commercial flights from the International Air Transportation Association (IATA, 2018) and chartered flights from the U.S. Department of Transportation (US DOT, 2018). Additionally, we also obtained travel-associated Zika virus case data from Europe, where the travel policies to Cuba to the best of our knowledge have not recently changed.