DNA in Francesco I de' Medici's remains reveals malaria as cause of death

Researchers from the Universities of Pisa and Yale have identified DNA from malaria parasites in the remains of Francesco I de' Medici, the Grand Duke of Tuscany. The study, published in the journal Science, found genetic traces of Plasmodium falciparum and Plasmodium malariae in three rib fragments.

This genetic evidence supports a diagnosis made by court physicians in 1587, when Francesco died following days of intermittent fever. His wife, Bianca Cappello, died shortly after with similar symptoms while staying at the Medici villa in Poggio a Caiano, an area where malaria was endemic.

The findings provide a natural explanation for the deaths, addressing long-standing historical suspicions of poisoning. For centuries, rumors suggested that Francesco’s brother, Cardinal Ferdinando de' Medici, may have orchestrated an assassination to secure his succession to the grand duchy.