The fatalities, reported by the Robert Koch Institute (RKI), have prompted an intensified response at Germany's busiest airport. All four infected workers were employed on the tarmac and are believed to have been bitten by a single mosquito that survived a flight from a malaria-endemic region of Africa before being unloaded with luggage or cargo.

Health authorities first detected the malaria cluster in early August, tracing it to a mosquito that arrived on a plane from sub-Saharan Africa, where malaria is endemic. At the time, five workers were reported to have been exposed; that figure has since been revised to four, with two now deceased. The remaining two are being treated in hospital and are said to be in stable condition.

"This is an extremely rare event in Germany," said RKI spokesperson Dr. Anja Weiss. "Malaria is not transmitted locally. The infection came from a single insect that survived the flight." The species of mosquito has been identified as an Anopheles gambiae, the primary malaria vector in Africa.

Frankfurt Airport operator Fraport has deployed mosquito traps across terminal areas and tarmac zones and is reviewing its aircraft disinsection protocols. "The safety of our employees is our highest priority," Fraport said in a statement. "We are working closely with federal health authorities to prevent any further cases."

The incidents belong to a rare but documented phenomenon known as "airport malaria" or "runway malaria," where infected mosquitoes are transported via aircraft and infect people at airports far from endemic zones. The World Health Organization records roughly a dozen such cases globally each year, but deaths remain exceptionally rare in Europe.

Investigations are underway to determine whether additional workers or passengers on the same flights may have been exposed. The RKI has urged airports across Germany to increase monitoring for stowaway insects, particularly on flights arriving from tropical regions.

The airline that operated the flight has not been named. Aviation industry groups have noted that disinsection procedures are already required by international health regulations, but critics argue that compliance and effectiveness vary widely between carriers and airports.

Malaria is preventable with antimalarial drugs and treatable if caught early, but delays in diagnosis in non-endemic countries can prove fatal. The two workers who died reportedly developed symptoms days after the exposure and were not immediately diagnosed with malaria, a disease rarely seen by German clinicians. The outbreak has renewed calls for better global coordination on mosquito control and for improved health screening of ground staff who handle aircraft arriving from tropical regions.