German health authorities in Hesse widened their investigation on Saturday into the deaths of two Frankfurt Airport workers from malaria, examining whether infected mosquitoes arrived on aircraft from tropical regions. The Robert Koch Institute confirmed both victims had no recent travel history.

The two employees died after contracting Plasmodium falciparum, the deadliest malaria parasite, in cases doctors described as airport malaria. Neither had travelled to an endemic country, pointing investigators toward mosquitoes transported in aircraft cabins or cargo holds arriving from Africa or Asia.

Fraport, the operator of Frankfurt Airport, said it was cooperating with the Hesse state health ministry and had begun mosquito surveillance and disinsection checks on aircraft and terminal areas. The Robert Koch Institute urged clinicians in the Rhine-Main region to consider malaria in feverish patients even without travel history.

Airport malaria remains rare but has been documented near major European hubs, including previous clusters at Charles de Gaulle in Paris and Brussels. Researchers at the RKI said climate change and rising air traffic increased the risk of tropical vectors surviving in temperate Europe.

Dr. Susanne Herold, an infectious disease specialist at University Hospital Giessen, said early diagnosis was decisive. "Falciparum malaria can become fatal within days if untreated, and physicians must not rule it out simply because a patient has never left Germany," she said.