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

Outbreaks of Ae. aegypti-borne viruses, including Zika virus, require conducive conditions to support sustained transmission and opportunities for virus introductions. As air travel is the main source of long-distance virus dispersion Nunes et al., 2014; Semenza et al., 2014) , we analyzed air travel patterns to determine if Cuba had fewer opportunities for virus introductions early during the epidemic, potentially delaying the outbreak (Fig. 4A ). Using monthly airline passenger arrivals coming from all 48 countries and territories in the Americas known to have local Zika virus transmission from 2014-2017, we did not detect any large deviations in air traffic to Cuba when Zika virus was being introduced elsewhere in the Caribbean (starting in mid-2015; Fig. 4A ) (Faria et al., 2017; Metsky et al., 2017) . Moreover, air travel volumes were higher into Cuba than neighboring islands with large outbreaks in 2016, including Puerto Rico and Jamaica (Fig. 4A) . These findings suggest that changes in air travel did not play a role in delaying the outbreak in Cuba.