Al-Razi and how he told smallpox from measles

A child has a high fever and a rash is about to appear. Is it smallpox or measles? Today a doctor settles the question with a laboratory test. Eleven hundred years ago, only a careful eye could tell the difference. One such eye belonged to Abu Bakr Muhammad ibn Zakariya al-Razi (al-Razi), whose short treatise on smallpox and measles was translated into many languages and read for centuries.

From Rai to Baghdad

In 1848, the 19th-century British physician William Alexander Greenhill (W. A. Greenhill) translated the treatise from Arabic into English and also collected details of al-Razi’s life. According to him, al-Razi was a native of the Iranian city of Rai and was called “Razi” after it. He was probably born in the middle of the ninth century, but the year of his birth is not known.

Citing older biographers, Greenhill writes that al-Razi began studying medicine at a fairly advanced age. He was first a physician at the hospital in his home city of Rai and later at the hospital in Baghdad. His fame was such that pupils came to him from distant lands. Sami Hamarneh, a medical historian at the Smithsonian Institution in the United States, has described him as the greatest clinician in Arabic medicine.

The date of his death is disputed. Greenhill gives 923 or, more probably, 932, while Hamarneh writes about 925.

Two diseases, one treatise

Smallpox is called “jadari” in Arabic and measles “hasbah”. According to Greenhill, the date of writing of the treatise is not known, but it was written after al-Razi’s two major books, “al-Mansuri” and “al-Hawi”, as it refers to them. “Al-Hawi” contains scattered notes on the two diseases, which al-Razi later arranged into this treatise.

The treatise has 14 chapters. In the first, al-Razi explains why smallpox occurs and why almost no one escapes it. He does not claim to have been the first to see the disease. Instead, he cites the books of the Greek physician Galen, which mention smallpox. Greenhill also writes that the earliest acknowledged writer to mention these diseases was a physician named Ahrun, extracts from whose book were preserved by al-Razi himself. Al-Razi’s achievement was not the first mention but a clear, orderly and detailed account of both diseases.

The difference in symptoms

The third chapter is the most important. It describes the symptoms that appear before the rash. In Greenhill’s translation, al-Razi writes that smallpox is preceded by continued fever, pain in the back, itching of the nose and terrors in sleep. In his words, the most characteristic of these is fever with back pain. Others include redness of the face, redness of the eyes, heaviness of the body, sore throat, cough and hoarseness.

He then gives the main difference. Restlessness, nausea and anxiety are more frequent in measles, while back pain is more peculiar to smallpox. In the extracts from “al-Hawi”, he also writes that the measles rash is less raised than the smallpox rash, and that smallpox is more harmful to the eye, especially when the pustules are small and crowded together. He also records that smallpox mostly attacks children.

Observation beyond books

The greatest strength of al-Razi’s writing is that he does not merely repeat old books but records what he has seen himself. In Greenhill’s translation, one of his sentences begins: “In the hospital I have found that…”. Elsewhere he writes that he established by examination that the danger of smallpox can be estimated from difficulty of breathing and hoarseness.

Greenhill has also recorded some of his sayings, which remain the principles of a good physician today. For example: when a cure can be had through regimen and diet, avoid medicine, and when a simple medicine is enough, do not use a compound one. Another saying means that knowledge written in books is far inferior to the practical experience of a wise and thoughtful physician.

It should also be remembered that al-Razi prescribed treatments according to the medical theories of his time, many of which are no longer accepted as correct. His real contribution is his method of recognising disease, not his prescriptions.

A thousand-year journey

According to Greenhill, the treatise was first translated from Arabic into Syriac and then into Greek, and reached Europe first through this Greek translation. The first Latin translation made directly from Arabic was published in 1747, and the Arabic text was first printed in 1766. An Arabic manuscript of it is preserved at Leiden University in the Netherlands. Greenhill’s own English translation was published in London in 1848.

When a doctor in a Quetta hospital today examines a child with fever and a rash, asking about each symptom, when the fever began, where the pain is and what the spots look like, he is doing the same thing al-Razi did in the hospitals of Rai and Baghdad: looking closely at similar diseases and telling them apart. In medicine this is called diagnosis, and every correct treatment begins with it.