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c. late 9th-early 10th century CEPeer-reviewed · 2 sourcesWell documented

Al-Razi Distinguishes Smallpox From Measles

A Baghdad physician's clinical descriptions become medical classics for centuries

On the timeline · around c. late 9th-early 10th century CE · The Abbasid Caliphate and the Islamic Golden AgeThe Abbasid Caliphate and the Islamic Golden AgeAl-Razi Distinguishes Smallpox From Measles800 CE825 CE850 CE875 CE900 CE925 CE950 CE975 CE1000

Quick facts

Physician
Abu Bakr Muhammad ibn Zakariya al-Razi (Rhazes)
Base of practice
Baghdad and Rayy, Persia
Key work
Treatise distinguishing smallpox from measles
Later recognition
WHO called the account original and accurate (1970)

What happened

Abu Bakr Muhammad ibn Zakariya al-Razi, known in the Latin West as Rhazes, trained in Baghdad after an earlier career as a musician and money-changer and became one of the most respected physicians of the medieval Islamic world, eventually serving as court physician and directing hospitals in Baghdad and his home city of Rayy in Persia. Al-Razi wrote the first clinical account that clearly distinguished smallpox from measles as separate diseases, based on direct observation of patients rather than received authority, and he proposed that survivors of smallpox gained lasting immunity. His ten-part medical textbook, known as al-Mansuri, remained in use for teaching medicine in Europe for centuries after his death.

Why it matters

Al-Razi's insistence on clinical observation over inherited theory, and his willingness to test remedies before trusting them, anticipated methods central to modern evidence-based medicine. The World Health Organization recognized his ninth-century writing on smallpox and measles as an original and accurate description centuries ahead of comparable European work.

How we know

Al-Razi's biography and his smallpox and measles treatise are documented by the University of Alabama at Birmingham's Reynolds-Finley Historical Library, which holds a 1388 CE Hebrew translation of his medical textbook, and corroborated by a peer-reviewed history of medicine article in PubMed Central.

Sources

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