Dengue fever is particularly widespread in the tropics and subtropics. Africa, South America and Southeast Asia are particularly affected. But as a result of climate change, there are also more infections in our latitudes.
Worldwide, 50 to 100 million infections are reported every year, and the trend is rising. Studies on prevalence assume that there are significantly more cases.
The dengue virus is transmitted by mosquitoes of the genus Aedes, which are also responsible for spreading yellow fever and Zika viruses. In contrast to the malaria mosquito, they are predominantly diurnal.
In most cases, an infection with the dengue virus is asymptomatic or is accompanied by mild symptoms at best. However, the so-called dengue haemorrhagic fever (DHF) is feared, which can develop especially in secondary infections. It leads to internal bleeding and can be lethal if left untreated.
So far, a vaccine has only been available for residents of endemic areas who have already had an initial infection. It is not intended for tropical travellers from Europe. This gap in travel medicine is now closed by Qdenga® from the Japanese pharmaceutical company Takeda. It contains attenuated dengue viruses and covers four different serotypes.
In the registration trials, the new vaccine provided reliable protection against fever and hospitalisation as a result of the infection. Fever progression was reduced by 80% and hospitalisation by 90% compared to placebo.
It is well tolerated. The most common side effects were pain and redness at the injection site, headaches, muscle aches and a general feeling of illness. The symptoms usually disappear after a few days and were less frequent after the second injection than after the first.
As with all live vaccines, caution is advised if you have a weakened immune system. Immunosuppressive drugs or an HIV infection are contraindications. Similarly, vaccination is not recommended for pregnant and breastfeeding women.
The new vaccination against dengue completes the range of preventive travel medicine. It is approved from the age of four and offers comprehensive protection. In addition, preventive measures such as long clothing, repellents and impregnated mosquito nets remain indispensable. GPs should always point this out to their clients with an affinity for travel.