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

Based on the occurrence of travel-associated Zika cases reported by the FL-DOH and the ECDC, we found that Zika virus transmission in Cuba was the most intense between June-December of 2017 (Fig. 5A) . We then used this time period to assess where local mosquito-borne Zika virus transmission could have been introduced from Cuba using global air travel data from Cuba and previously estimated world-wide Ae. aegypti suitability (Kraemer et al., 2015) (Fig. 5B) . Out of a total of ~4 million air travelers departing Cuba between June and December of 2017, we found 18 countries and US states that received >20,000 travelers, with >100,000 arriving in Florida, Canada, Mexico, and Spain (Fig. 5B) . Based on environmental suitability for Ae. aegypti of the 18 areas with >20,000 travelers from Cuba, we estimated that Florida, Mexico, Panama, Venezuela, and Colombia were most at risk of Zika virus having been introduced from Cuba during June-December, 2017 (Fig. 5B) . Indeed, four local Zika cases were reported in Florida during 2017 linked to their partners having recently returned from Cuba (FL DOH, 2017a . Despite these findings, however, beyond a few cases, no Zika outbreaks were reported in these 18 regions in 2017, perhaps due to existing herd immunity (Netto et al., 2017; Zambrana et al., 2018) . These The copyright holder for this preprint (which was not peer-reviewed) is the author/funder.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 results show the global connectedness of Cuba, and with Zika cases associated with travel to Cuba still ongoing as of October, 2018 (Fig. 1) , continued surveillance is required to detect potential further spread.