International Dispersal of Dengue through Air Travel: Importation Risk for Europe

Abstract

BackgroundThe worldwide distribution of dengue is expanding, in part due to globalized traffic and trade. Aedes albopictus is a competent vector for dengue viruses (DENV) and is now established in numerous regions of Europe. Viremic travellers arriving in Europe from dengue-affected areas of the world can become catalysts of local outbreaks in Europe. Local dengue transmission in Europe is extremely rare, and the last outbreak occurred in 1927–28 in Greece. However, autochthonous transmission was reported from France in September 2010, and from Croatia between August and October 2010.MethodologyWe compiled data on areas affected by dengue in 2010 from web resources and surveillance reports, and collected national dengue importation data. We developed a hierarchical regression model to quantify the relationship between the number of reported dengue cases imported into Europe and the volume of airline travellers arriving from dengue-affected areas internationally.Principal FindingsIn 2010, over 5.8 million airline travellers entered Europe from dengue-affected areas worldwide, of which 703,396 arrived at 36 airports situated in areas where Ae. albopictus has been recorded. The adjusted incidence rate ratio for imported dengue into European countries was 1.09 (95% CI: 1.01–1.17) for every increase of 10,000 travellers; in August, September, and October the rate ratios were 1.70 (95%CI: 1.23–2.35), 1.46 (95%CI: 1.02–2.10), and 1.35 (95%CI: 1.01–1.81), respectively. Two Italian cities where the vector is present received over 50% of all travellers from dengue-affected areas, yet with the continuing vector expansion more cities will be implicated in the future. In fact, 38% more travellers arrived in 2013 into those parts of Europe where Ae. albopictus has recently been introduced, compared to 2010.ConclusionsThe highest risk of dengue importation in 2010 was restricted to three months and can be ranked according to arriving traveller volume from dengue-affected areas into cities where the vector is present. The presence of the vector is a necessary, but not sufficient, prerequisite for DENV onward transmission, which depends on a number of additional factors. However, our empirical model can provide spatio-temporal elements to public health interventions.

Prevalence and burden of dengue infection in Europe: A systematic review and meta‐analysis

“…Dengue prevalence may vary between neighboring countries, even between neighboring cities inside the same country despite the same climate suitability, population density, and the vector predominant. The obvious discrepancy between Germany and Poland, also France and Spain, could be attributed to socioeconomic factors and increased travel rate in Germany and France . In 2010, nearly 5.8 million airline travelers joined Europe from dengue‐affected areas worldwide.…”

Epidemiological Characteristics and Risk Factors of Dengue Infection in Korean Travelers

“…Previous studies in Europe, Australia, and Japan reported various dengue cases imported from endemic regions (111213). The study analyzed the relationship between the number of dengue cases imported into each region and the number of travelers arriving from dengue-affected areas, using national dengue importation data from web resources and surveillance reports.…”

“…The study analyzed the relationship between the number of dengue cases imported into each region and the number of travelers arriving from dengue-affected areas, using national dengue importation data from web resources and surveillance reports. The study in Europe reported that travelers arriving from dengue-endemic regions affect dengue importation into Europe and the risk of dengue importation was greatest in August, September, and October (11). For Japan, most of dengue cases were imported from Southeast Asia and the trend in dengue infection among Japanese travelers was associated with seasonal fluctuation of DF incidence in Southeast Asia (12).…”

Imported Chikungunya fever case in Greece in June 2014 and public health response

“…40 Clinicians should be aware of the CHIKV geographical distribution around the world, and especially the ongoing outbreaks, such as those in the Caribbean region and Central/South America, given the potential for the virus introduction through viremic patients in naïve countries where the competent vector is established. The same is true for potential Dengue 41,42 and Zika 5,43-45 virus introductions. Concurrent infection with more than one such pathogen should not be overlooked and has been recently described.…”