Six airport employees have been diagnosed with malaria tropica, the most severe form of the disease, since July. Four of those infected were hospitalised and are reportedly no longer in danger.
The first employee fell ill and died in early July, but malaria was only identified after his death. A second airport worker died after contracting the disease in August, raising concerns over the unusual cluster of cases at one of Europe’s busiest aviation hubs.
What has made the outbreak particularly unusual is that none of the affected employees had recently travelled to countries where malaria is endemic.
Germany’s Robert Koch Institute, the country’s public health agency, therefore believes so-called “airport malaria” is the most likely explanation.
Airport malaria can occur when an infected Anopheles mosquito is inadvertently transported from a malaria-endemic region on an aircraft or in baggage. If the mosquito survives the journey and subsequently bites people at or near an airport, it can potentially transmit the parasite.
Health authorities have ruled out direct person-to-person transmission between the affected employees.
Investigators have now stepped up surveillance at Frankfurt Airport, deploying mosquito traps and monitoring equipment in an effort to determine how the infections occurred.
Blood samples from affected workers are being analysed alongside insects captured around the airport. The Institute of Tropical Medicine in Antwerp is also assisting with efforts to identify the malaria parasite and determine whether a particular mosquito species could be responsible for the outbreak.
Despite the deaths and the investigation underway, Frankfurt’s health authority has sought to reassure travellers and residents that the risk to passengers and the wider public remains very low.
Authorities have, however, advised airport employees and doctors in the surrounding area to remain vigilant, particularly when patients develop symptoms that could indicate malaria without having a history of travel to a malaria-endemic country.
Possible symptoms include unexplained fever, chills, headaches and nausea. Early recognition is considered particularly important because malaria tropica can progress rapidly and become life-threatening.
The unusual cluster has also highlighted a diagnostic challenge in Germany, where malaria is relatively uncommon compared with regions where the disease is endemic.
Doctors may be less likely to suspect malaria when a patient has not recently travelled abroad, potentially delaying diagnosis and treatment.
Airport malaria itself is exceptionally rare in Europe. Germany’s previous known case was reported in the vicinity of Frankfurt Airport in 2023.
The latest outbreak has prompted renewed attention to the potential for disease-carrying insects to travel internationally through modern air transport.
For investigators, the priority now is to determine how the infected mosquitoes may have entered the airport environment, whether they were transported on a particular aircraft or in baggage, and whether any additional infections have occurred.
While authorities maintain that the risk to the public is minimal, the deaths of two workers have underscored the potentially serious consequences of an imported malaria case going undetected, particularly when the disease is not initially suspected.