Updated

A 4-year-old girl in northern Italy died on Sunday of cerebral malaria, raising fears that the deadly blood disease is back in a region that has been free of it for decades.

Sofia Zago, of Brescia, was rushed to the hospital on Saturday with a high fever and died sometime between Sunday and Monday, Reuters reported. Her death has puzzled Italian doctors, who are trying to pinpoint exactly how she contracted the disease in a malaria-free country.

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

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Luigi Gradoni, an infectious disease researcher at the state health institute, said though it’s unclear how Zago contracted malaria, residents nearby shouldn’t worry because the disease can’t be transmitted from person to person.

Health officials are investigating several theories. Zago didn’t travel to any countries where malaria is common, but had recently visited Bibione, an Adriatic resort near Venice, for vacation. Anopheles mosquitoes, that carry the disease, can live in suitcases that are taken on planes.

Zago, who had diabetes, was also recently hospitalized and could have been exposed to malaria from two girls who were recovering from the disease in a separate room. The girls had contracted malaria in Africa, according to Reuters.

Officials said Zago’s hospital room will be fumigated as a precaution.

Italy was declared malaria-free in 1970 after marshes with the disease-carrying mosquitoes were drained in the country. Others have worried an unusually hot and humid August have brought back the mosquitoes in the region.