Two Frankfurt Airport workers have died of malaria after a rare outbreak led to six employees contracting the serious infection spread by mosquitoes.

It is believed the mosquitoes arrived at Germany's busiest airport on a plane, according to German public health officials, triggering an outbreak which was first detected in July.

A spokesperson for airport operator Fraport told the BBC an employee had died as a result of the infection, while public health officials said later on Wednesday that two of the affected individuals had died.

Traps have been installed at the airport, and captured mosquitoes will be analysed in a laboratory to determine their species and origin.

"We have provided comprehensive information to all employees and encourage them to consult a doctor if they experience any symptoms," the Fraport spokesperson told the BBC.

The outbreak is being investigated by the Frankfurt Public Health Department.

The BBC understands that six male airport workers in different roles and areas of the airport were infected, and officials are analysing blood samples to determine whether they were infected by one mosquito or six different mosquitoes.

Later on Wednesday, public health officials in Frankfurt sent a letter to media outlets which said two of the affected individuals had died.

"For the population of Frankfurt, the risk is considered very, very low. The disease is not transmissible from person to person but is always transmitted by mosquitoes," the letter added.

It said laboratory tests to determine the source of the infections were not expected to be available for several weeks.

It was reported in July that the outbreak involved four infected workers.

The Robert Koch Institute - a German federal government agency and research institute for disease control and public health - previously said the four employees fell ill between 4 and 6 July and the mosquitoes were brought in by plane.

The institute said malaria in Germany almost exclusively affects long-haul travellers who were infected in malaria-endemic areas, and that malaria transmitted within a German airport is rare.

"The lack of a travel history can lead to a delayed diagnosis. A delayed diagnosis increases the risk of a severe course of the diseases," the institute said in its epidemiological bulletin.

The last case of airport malaria was in 2023, also at Frankfurt Airport, it added.

Malaria is a disease spread by certain types of mosquitoes that bite humans and is most common in tropical countries, according to the World Health Organisation (WHO).

The infection, which is preventable and curable, is caused by a parasite and does not spread from person to person. However, symptoms can range from mild to life-threatening.