Dengue fever among ill-returned travellers and concurrent infection by two dengue virus serotypes.

ABSTRACT

A sudden increase in dengue virus (DENV)-infected returned travellers was observed at the outpatient department of Tropical Medicine, Academic Medical Center, Amsterdam, The Netherlands. A descriptive observational study was conducted to analyse the epidemiology, clinical manifestations and laboratory features of imported DENV-infected patients. From September 2008 to June 2009, a total of 45 ill-returned travellers suspected for dengue were prospectively and four ill-returned travellers retrospectively were included. The majority (32 out of 49, 65%) of patients returned after a visit to the Dutch Antilles or Suriname. DENV-1, DENV-2 and DENV-3 were found in 27 viraemic patients. We identified four patients with a concurrent DENV infection with DENV-1 and DENV-2 serotypes and described their clinical and laboratory features. The clinical signs and symptoms in DENV-infected patients were mild and variable. Leukopenia and thrombocytopenia were observed between three to six days after the onset of illness. The majority of the patients had elevated serum transaminases levels between 7 to 10 days after the onset of illness. Within the first six months of 2009, ~10% were diagnosed with dengue infection. DENV infection at our hospital is not a rare imported viral disease. Increased international travel with changing epidemiology and increasing frequency of dengue in the sub-tropics will induce imported DENV infections in Western countries, including The Netherlands.