Surge in Dengue Virus Infections Reported Globally

The incidence of dengue virus infections has seen a significant rise worldwide, raising concerns among health officials. Dengue fever, a viral infection transmitted primarily by the Aedes aegypti mosquito, is now recognized as the most prevalent mosquito-borne viral disease across the globe.

This virus predominantly affects tropical and subtropical regions, especially in areas of Africa, South America, and parts of Southeast Asia. The Aedes aegypti mosquito, along with its counterpart Aedes albopictus, plays a crucial role in the transmission of dengue, particularly in urban environments. According to the Robert Koch Institute (RKI), the geographical spread of these mosquito species has doubled in the past decade.

In Germany, however, the virus has not established a significant presence. Most reported cases are linked to travelers returning from endemic regions. The number of dengue cases in Germany had already been on the rise before the COVID-19 pandemic, with reported cases jumping from 613 in 2018 to 1,176 in 2019, and further increasing to 1,646 in 2024 as per the latest epidemiological bulletin from RKI.

Questions have arisen regarding the potential for dengue viruses to spread within Germany. The adaptability of the Aedes mosquito is a factor contributing to its increasing prevalence, with reports confirming its presence in 26 European countries, including Germany. Notably, there have been observations of these mosquitoes overwintering in regions of Baden-Württemberg. Given the current population levels of these mosquitoes, there is a theoretical risk of localized outbreaks.

Despite these concerns, the RKI maintains that the reported cases in Germany are mainly linked to international travel. While the Aedes mosquito can reproduce in Germany, environmental conditions early in the year typically inhibit mosquito activity. Historically, the majority of dengue cases in Germany occur during summer months, when mosquito activity peaks, yet reported cases remain lower compared to other times of the year.

The Federal Environment Agency also suggests that transmission of the virus is most likely in areas where a high population of mosquitoes coincides with infected individuals. So far, such cases have only been documented in Southern Europe, particularly in countries like France and Croatia.

Analysis from the RKI indicates that the increase in dengue cases is not primarily due to higher travel volumes but rather a surge in virus activity within endemic regions.