Dengue serotypes and genotypes circulating in recent years in the Caribbean and imported to Europe

Introduction Dengue viruses (DENV) are the most widespread arthropod-borne viruses endemic in the tropics and transmitted to humans through the bites of Aedes mosquitoes. Travelers can act as vectors to introduce DENV to uninfected areas or regions. Travelers can also serve as sentinels for ongoing outbreaks and dominating serotypes and genotypes in the source countries. We set out to describe the importation of dengue virus from the Caribbean via travelers to Europe. Methods From 2011 to 2014, we collected samples from viraemic travelers returning from the Caribbean with confirmed dengue to 11 TropNet clinics in Europe that are participating in the DengueTools project. Sequences of the Envelope gene were used to identify serotype and genotype. Results The main countries of importation were Barbados, Cuba, Dominican Republic, Guadeloupe, Haiti, Martinique, Netherlands Antilles and Puerto Rico. All 4 DENV serotypes were identified. DENV 1 strains were grouped within genotype V creating a new clade. All DENV 2 sequences clustered within a clade in the American/Asian genotype which was recently also identified in other Caribbean and Brazilian strains. DENV 3 strains were grouped within genotype III. All DENV 4 strains were phylogenetically grouped within a modern Caribbean basin clade in genotype II. Conclusions Travelers provides unique insights into the global picture of circulating DENV strains. This study from the Caribbean region led to the identification of novel clades. Moreover, we were be able to detect dengue strains circulating in Cuba from 2011 to 2013, although officially no dengue was reported during that time period. Travelers serve as sentinels to provide timely information about current distribution of dengue serotypes and genotypes associated or not with outbreaks and track the spread of DENV strains in areas with scarce epidemiological information.