Twelve years of dengue surveillance in Belgian travellers and significant increases in the number of cases in 2010 and 2013.

During 12 years of surveillance in Belgium, dengue virus (DENV) infection was diagnosed in 676 of 7771 (8.7%) returning travellers by the use of ELISA, RT-PCR, and/or antigen detection. Men and women were equally infected. The mean age of the patients was 36.78 years (range, 3-77 years). Most of the infections occurred after a stay in Asia (55.9%), followed by the Americas (31.8%), Africa (7.2%), Oceania (1.0%), and Europe (0.4%). The number of patients coming from Africa increased as of 2009, to reach a proportion of 17% in 2011. The most prevalent serotype was DENV-1, followed by DENV-2, DENV-3, and DENV-4. Two remarkable increases in dengue incidence were noticed in 2010 and 2013.