Medici brothers' deaths confirmed as malaria, not arsenic poisoning

Modern DNA analysis of 16th‑century tissue samples shows that Grand Duke Francesco I de Medici (died 1587, age 46) was infected with the malaria parasites Plasmodium falciparum and Plasmodium malariae, while his brother Cardinal Giovanni de Medici (died 1562, age 19) carried only P. falciparum. The study, reported by LiveScience and led by researchers including Valentina Giuffra of the University of Pisa, concludes that malaria, a disease common in swamp‑y‑filled Tuscany, caused the brothers’ deaths. “Nun können wir mit wissenschaftlicher Gewissheit sagen, dass Malaria und nicht eine Vergiftung Großherzog Francesco de Medici das Leben gekostet hat,” the med‑historian said. The findings overturn centuries‑old speculation of arsenic poisoning and provide a rare glimpse into the evolution of malaria strains in early modern Europe.

The discovery also highlights the value of historic DNA work for modern science, offering insights into ancient pathogen lineages that can inform current understanding of malaria’s genetic diversity.