Tropical infections in travellers: ITM looks back on summer holidays

Each year, the Institute of Tropical Medicine's (ITM) travel clinic sees around 24,000 travellers before or after their trips. Now that the summer holidays are over, the clinical laboratory has taken stock. All viral infections have been identified in returning travellers. There is, as yet, no local transmission of the viruses causing these diseases in Belgium.

• Malaria remains the most common diagnosis.

• Dengue is the most notable riser, reaching a record number of cases in 2024

• The high number of chikungunya cases in 2025 is linked to an outbreak in Réunion.

• Zika and West Nile fever remain rare.

"Dengue has been on the rise in recent years. Globally, we are talking about 100 to 400 million infections a year. It is therefore not surprising that we also see an increase in infections among travellers," says Dr Marjan Van Esbroeck, medical microbiologist and head of ITM's clinical laboratory. "For travellers, malaria remains the greatest threat, due to its severity and the importance of prompt treatment. But when malaria is ruled out, in the case of a sudden high fever after a stay in the (sub)tropics, dengue should be the first consideration."

"Good preparation can help prevent health problems," says Dr Ula Maniewski-Kelner, infectiologist and Head of Travel Advice at ITM. "With our Wanda app, anyone can easily check which vaccinations, medications and precautions are needed for each destination. This way, travellers can significantly reduce their risk."