A four-year-old Italian girl’s death from cerebral malaria in Northern Italy has baffled doctors as the region has been free of the disease for decades, the BBC reported on Tuesday.

Sofia Zago died on Sunday night after she was taken to hospital with a high fever a day earlier. Doctors said it was mysterious case as Italy has been free of the Anopheles mosquito that carries cerebral malaria – the deadliest form of the blood disease – since the 1950s.

Zago had never travelled outside the country. She had been on a holiday with her parents near Venice. When she was diagnosed, she was in the Trentino region, in the foothills of the Alps.

“It’s the first time in my 30-year career that I’ve seen a case of malaria originating in Trentino,” Dr Claudio Paternoster, an infectious diseases specialist at Trento’s Santa Chiara Hospital, told the BBC.

The theories

Investigators are looking into whether Zago might have caught malaria from one of two children treated for it at the Trento hospital after August 15, local daily Corriere della Sera reported. Sofia was in the hospital to be treated for diabetes. However, health officials said she was not in the same ward and did not have a blood transfusion.

Investigators are also looking into whether high temperatures in August may have caused malaria to reach Italy. The child could have also been infected by a mosquito arriving from abroad in luggage on a flight.

Manslaughter probe

State prosecutors in Trento are opening a manslaughter inquiry, according to the Corriere della Sera report. They will assess whether procedures were followed in the hospital’s paediatrics ward.