The origin of contagious diseases has been commonly deemed obscure …” — W. Blackburne, 18031

Anne de Bourgh, the heiress of Rosings Park in Pride and Prejudice, might have had scarlet fever when she was a teenager. If so, what caused it? Dr. Buchan described two forms of scarlet fever: a simple variety, which seldom required medical treatment, and a malignant form that could be very dangerous. The perceived cause of this often deadly disease was not known, possibly because there was much confusion at the time regarding the nature of scarlet fever. (Was it one disease, or two …or three?) Fortunately for us, several Regency doctors speculated about the cause of this illness.

A Specific Contagion Caused by a Poison

William Withering (1741-1799), an English doctor, botanist, chemist, and discoverer of digitalis (Wikimedia Commons [PD-1923])

William Withering (1741-1799), an English doctor, botanist, and chemist. He discovered digitalis. (Wikimedia Commons [PD-1923])

Dr. William Withering, writing in 1793, believed a specific contagion caused scarlet fever.2 After treating numerous patients who had either simple or malignant scarlet fever, he became convinced the two conditions were one and the same disease and were caused by the same agent. Specifically, he believed scarlet fever was caused by a poison that acted as a sedative on the nervous system. The poison acted first on the pituitary gland and then spread to the esophagus, stomach, larynx and lungs.3

Other well-known physicians believed likewise. One Dr. Morton, cited by Dr. Withering, said the cause was a poison “defiling the animal spirits, whose malignity does not only overwhelm the spirits in its first attack, but breaks down the mass of blood by agitation.”4 Another expert, Dr. Philip, believed its “exciting cause” was a specific contagion, but the factors that predisposed an individual to catch scarlet fever were unknown.5

Something Acrid, Caustic and Putrefactive

A physician named Navier believed scarlet fever was caused by “something acrid, caustic and putrefactive, like that of the measles.”6 Furthermore, he believed this same “something” also caused the sweating sickness and dysentery. He noted the similarity between scarlet fever in humans and the distemper among cattle, concluding that the human disease arose from cattle and passed into humans. In fact, he believed scarlet fever was connected with smallpox.

Wind and Weather, Among Other Things

A View at Hampstead with Stormy Weather by John Constable (Wikimedia Commons [PD-1923])

A View at Hampstead with Stormy Weather by John Constable, c. 1830 (Wikimedia Commons )

Dr. James Hamilton believed the epidemic form of scarlet fever was much affected by the season of the year, the weather (whether kind or inclement), the air temperature, and possibly other unknown aspects of the atmosphere. Of course, an individual’s natural constitution and overall health were important factors in his susceptibility to the contagion, as were lodging, ventilation and general cleanliness.7 Dr. Hamilton seemed to be much affected by the words of a doctor from Ispwich, for he cited the man’s letter (addressed to Mr. Urban, the editor of The Gentleman’s Magazine) in its entirety. According to this letter writer, the predisposing cause was whatever generated a quantity of acrid bile in the primæ viæ (a Latin term that Google translates as “first roads” and which I take to mean the stomach and intestines). The proximate cause of scarlet fever, in this writer’s opinion, was the quick transition from heat to cold and vice versa caused by swings and roundabouts in the winds.8


Animalcules in the teeth, from a 1744 book on dentistry (Wellcome Library, image # L0002253, CC BY 4.0)

Animalcules in the teeth, from a 1744 book on dentistry (Wellcome Library, London, image # L0002253, CC BY 4.0)

The most interesting speculation was given by the physician Plenciz.9 Writing in 1780, he attributed the effects of scarlet fever to “animated seminal particles” or animalcules, which he believed were capable of multiplying their kind. [emphasis mine] He imagined the animalcules could be carried by winds for long distances or might lie dormant for a long time in the body. He was not certain how the miasma generated by the animalcules exerted their effects—possibly by some mode of fermentation that was not yet understood—but he had no doubt of the disease being contagious, nearly equal to that of smallpox and measles.

Today we know that scarlet fever is not caused by a poison or something acrid or wind and weather. It results from a bacterial infection—specifically an infection by a group A streptococcus (GAS) bacterium, most frequently the bacterium streptococcus pyogenes. It is truly remarkable that Dr. Plenciz, an 18th-century physician, should consider animalcules responsible for the contagion of scarlet fever. He was more than one hundred years ahead of his time: the connection between scarlet fever and streptococcus bacteria was not established until the early 1900s.


1Blackburne, W. Facts and Observations concerning the Prevention and Cure of Scarlet Fever, with some Remarks on the Origin of Acute Contagions in general. [book review] In: London Medical and Physical Journal, vol. X, June-December, 1803, p. 461 (PDF p. 490).
2Withering, William. An Account of the Scarlet Fever and Sore Throat; or Scarlatina Anginosa: Particularly as It Appeared at Birmingham in the Year 1778, 2nd ed. (London: G.G. & J. Robinson, 1793), p. 11 (PDF p. 16).
3Ibid., p. 62 (PDF p. 67).
4Ibid., p. 59 (PDF p. 64).
5Philip, A. P. Wilson. A Treatise on Febrile Diseases, including The Various Species of Fever, and All Diseases Attended with Fever. (London: Thomas Underwood, 1813), p. 469 (PDF p. 490).
6Withering, p. 60 (PDF p. 65).
7Hamilton, James. Observations on the Utility and Administration of Purgative Medicines in Several Diseases. (Edinburgh: Archibald Constable and Company, 1819), pp. 50-51 (PDF pp. 89-90).
8Ibid., pp. 65-66 (PDF pp. 104-105).
9Plenciz, Marci Antonii. Tractatus de Scarlatina. (Vindobonæ: Joann, Thomæ nob. de Trattnern, 1780).