Infectious Disease
1553 CE, Italy — Giovanni Filippo Ingrassia's written account in Sicily, describing rossalia
Scarlet fever, the infectious illness historically characterized by its vivid rash and association with severe throat inflammation, swept through European and American populations in recurring epidemic waves from at least the 16th century onward, causing significant mortality particularly among children. Early physicians struggled to distinguish it from other rash-producing fevers and debated for centuries whether it represented a unique disease or a variation of more familiar conditions such as measles or erysipelas. The gradual unraveling of its bacterial origins in the late 19th and early 20th centuries marked one of the great triumphs of the emerging science of microbiology.
Historical Narrative
The earliest convincingly documented descriptions of what came to be called scarlet fever appeared in European medical literature during the 16th century, though historians of medicine have debated whether earlier references in ancient and medieval texts might refer to the same condition. The Italian physician Giovanni Filippo Ingrassia provided what many historians regard as the first clear written account of a disease he called rossalia or rosania in 1553, distinguishing it from measles on the basis of the distinctive character of its rash and the clinical course he observed in Sicilian patients. This description long went unacknowledged, and scarlet fever's formal entry into European medical consciousness was largely credited to Thomas Sydenham and Thomas Willis in 17th-century England, where epidemics had become conspicuous enough to demand systematic attention.
Sydenham, writing in the latter half of the 17th century, described what he called scarlatina anginosa with characteristic precision, noting the brilliant red discoloration of the skin and its distinction from other febrile rash illnesses. Willis had earlier described similar cases, and the two physicians together helped establish scarlet fever as a recognizable clinical entity in English medical literature. Despite this progress, physicians of their era understood the disease through miasmatic and constitutional frameworks, attributing epidemics to corrupted air, environmental conditions, or individual susceptibility rooted in bodily constitution rather than to any contagious agent.
Throughout the 18th century, scarlet fever continued to cause devastating epidemics in Europe and the American colonies, and medical writers debated vigorously whether the disease was contagious at all. Some physicians, influenced by the miasmatic tradition, attributed epidemic outbreaks to atmospheric or seasonal conditions that simultaneously rendered populations vulnerable. Others, observing the pattern of spread within households and communities, argued that person-to-person transmission was undeniable. William Withering, the English physician best known for his work with digitalis, contributed careful observations on scarlet fever epidemics, and various practitioners proposed treatments ranging from cold bathing and bark preparations to bloodletting and emetics, all grounded in humoral or constitutional reasoning.
The 19th century transformed the understanding of infectious disease broadly, and scarlet fever's history was reshaped by this transformation. The germ theory of disease, advanced by Louis Pasteur and Robert Koch, prompted investigators to search for specific microbial agents responsible for epidemic illnesses. American physicians George and Gladys Dick conducted experiments in the early 1920s that identified a specific strain of Streptococcus bacteria as the causative agent of scarlet fever, a finding that resolved decades of speculation and conflicting laboratory evidence. The Dicks also developed a skin test that bore their name, the Dick test, designed to determine susceptibility to the disease, and produced a toxin and antitoxin they hoped would serve preventive and therapeutic roles.
Before the bacteriological era, the most significant therapeutic development in scarlet fever's history was largely accidental. Physicians in the 18th and 19th centuries had observed that individuals who survived epidemic scarlet fever appeared to gain lasting protection against subsequent attacks, an observation that contributed to broader thinking about immunity and the variability of individual susceptibility. This recognition that past illness conferred protection became one of the conceptual building blocks that informed the development of immunological science in the late 19th century.
Key Historical Figures
Historical narrative only — this page describes how Scarlet fever was understood historically. It is not medical advice and does not describe current diagnosis or treatment. Sourced from verified medical history references (NIH, Encyclopaedia Britannica, and standard medical history texts). See our medical disclaimer.