DNA study confirms Duke of Tuscany died of malaria, not poison

Modern DNA analysis of bone fragments from the Medici Chapels in Florence has proved that Francesco I de' Medici, Grand Duke of Tuscany, and his wife Bianca Cappello died of a severe form of malaria in 1587, overturning centuries‑old rumours of arsenic poisoning by Francesco’s brother, Fernando.

Scientists from the Universities of Pisa and Turin, together with researchers from Yale, sequenced the genetic material of Plasmodium parasites preserved in the ducal remains. The findings, published in the journal iScience, match contemporary court medical reports describing intermittent high fevers and confirm the historical diagnosis of malaria. The study also discredits a 2006 Florentine analysis that had suggested arsenic contamination, noting that the earlier samples could not be definitively linked to the duke.

The results exonerate Fernando de' Medici, who succeeded Francesco, and provide new insight into the evolution of the malaria parasite, showing an ancient variant of the disease that afflicted the Renaissance elite.