Travel Volume to the United States from Countries and U.S. Territories with Local Zika Virus Transmission

Abstract

Introduction: Air, land, and sea transportation can facilitate rapid spread of infectious diseases. In May 2015 the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil. As of March 8, 2016, the U.S. Centers for Disease Control and Prevention (CDC) had issued travel notices for 33 countries and 3 U.S. territories with local Zika virus transmission.Methods: Using data from five separate datasets from 2014 and 2015, we estimated the annual number of passenger journeys by air and land border crossings to the United States from the 33 countries and 3 U.S. territories listed in the CDC’s Zika travel notices as of March 8, 2016. We also estimated the annual number of passenger journeys originating in and returning to the United States (primarily on cruises) with visits to seaports in areas with local Zika virus transmission. Because of the adverse pregnancy and birth outcomes that have been associated with Zika virus disease, the number of passenger journeys completed by women of childbearing age and pregnant women was also estimated.Results: An estimated 216.3 million passenger journeys by air, land, and sea are made annually to the United States from areas with local Zika virus transmission (as of March 8). The destination states with the largest numbers of arrivals were Texas (by land) and Florida (by air and sea). An estimated 51.7 million passenger journeys were made by women of childbearing age and an estimated 2.3 million were made by pregnant women.Conclusion: Travel volume analyses provide important information that can be used to effectively target public health interventions as well as direct public health resources and efforts at local, regional, and country-specific levels.

Infant outcomes among women with Zika virus infection during pregnancy: results of a large prenatal Zika screening program

“…For example, most travelers to Texas originated in Northern Mexico and traveled by land, while those originating from the Caribbean islands were more likely to travel by air or sea to states such as Florida and New York; these states have relatively higher numbers of travelassociated Zika infections. 26 For the same reason, we did not screen for travel to elevations <2000 m above sea level, due to the impracticality in a large screening process where most of our patients travel by land to arrive in Texas. In 2016, Zika virus outbreaks described in Mexico were primarily localized to the Southern half of the country, thus travel history within specific regions of Mexico may be an important addition to our Zika screening in the future.…”

Multiple introductions of Zika virus into the United States revealed through genomic epidemiology

“…The data were obtained from the International Air Transportation Association, which collects data on an estimated 90% of all passenger trips worldwide. Nelson et al 26 previously reported flight data from 33 countries with ZIKV transmission entering major United States airports during October 2014 through September 2015, which we used to assess the potential for ZIKV introductions outside of Florida.…”

“…Therefore, the combination of international travelers, mosquito ecology, and human population density near Miami likely make it one of the few places in the continental United States most at risk for Ae. aegypti-borne virus outbreaks 20,24,26 . Relative Ae.…”

Projecting the end of the Zika virus epidemic in Latin America: a modelling analysis

“…This may seem surprising as flight data are cited as a source of emerging infections, such as ZIKV. 44 But cars and public transportation are used for most journeys; and the movement of people impacts the spatial spread of vector-borne diseases. 38,45 Perhaps for highly transmissible infectious diseases movements facilitated by flights are sufficient for predicting introduction of a pathogen in a new population, but this analysis suggests that triggering of a ZIKV outbreak may require more frequent exposure than air travel.…”