Smallpox and medical knowledge in the Lewis and Clark expedition

A new post in the smallpox and American otherness series.

At the time of organising the expedition, which aimed to explore the interior of the continent from west of the Mississippi as far as the Pacific coast of what is now British Columbia, Jefferson told Lewis to take with him “some matter of the kine-pox”, adding: “inform those of them with whom you may be, of it’s efficacy as a preservative from the small pox; and instruct & encourage them in the use of it”.[1] Vaccination programmes are part of a broader presence of medical interests in the expedition, which unfolds both in terms of gathering detailed information on the populations encountered, and in the use of practical medical knowledge as a means of gaining credit and prestige, and establishing diplomatic relations.[2]

The use of medical preparations and practices in diplomacy was certainly not an invention of the expedition: in North America, for example, there were cases of vaccinations by a delegation from Shawnee and Delaware in Washington in 1802, and material sent to the Five Nations in Canada by Jenner himself.[3] The circulation of knowledge in the field of medicine and public health between the eighteenth and nineteenth centuries was – at various levels and latitudes – part of the cultural and administrative apparatus of European colonial expansion around the world.[4]

The doctors Benjamin Rush (1745-1813), Benjamin Smith Barton (1766-1815) and Caspar Wistar (1760-1818) from Philadelphia collaborated in the preparation of the expedition, contributing to a list of questions on the subject of “Physical History and Medicine” that Lewis took with him as an outline for the collection of information. Rush, already in contact with Jefferson and a signatory to the Declaration of Independence, was also, in 1797, the author of the inoculation against smallpox of the Miami chief Little Turtle, the first documented inoculation of a Native American.[5] Rush’s role was central: as Jefferson’s privileged correspondent for the organisation of the expedition and for questions of health and medicine, he was asked to draw up the instructions for observation entrusted to Lewis,[6] guidelines for maintaining the health of the expedition’s participants,[7] and for the purchase of supplies. It is also known that Lewis received some rudimentary medical training from Rush in Philadelphia in the spring of 1803.[8]

The list of questions the expedition will have to try to answer with each new group encountered includes questions on longevity and diet, food preservation, sexual, marital and educational customs, as well as the most severe and widespread diseases, the treatments adopted and their effectiveness:

What are their acute diseases?

Is rheumatism, Pluricy, or bilious fivers known among them? & does the latter ever terminate in a vomiting of black matter? What are their chronic diseases – are palsy, apoplexy, Epilepsy, Madness, the goiture (or Swelled Neck) and the Venereal disease known among them?

What is their mode of treating the Small pox particularly?

Have they any other disease amongst them, and what are they? What are their remidies for their different diseases?[9]

The equipment included medical supplies that Lewis requested both to treat the expedition members should the need arise (as it did on several occasions, with various accidents, ailments and illnesses, including the death of one of the men during the first months of the journey), and, as mentioned above, to adopt the provision of treatment to the native peoples as a factor in increasing the credibility of the expedition members and helping to establish good relations.[10] However, the smallpox vaccine material was reported to have lost its effectiveness prematurely, as Lewis wrote in 1803,[11] and a considerable part of the medicinal supplies was lost in May 1805 in the Yellowstone River (in present-day Montana) when a boat capsized, along with some books, papers and other articles.[12]

There were no doctors or scientists in the body of the expedition.[13] The result is a sporadic recording of medical observations, conducted without the methodicalness and systematicity suggested by the guiding questions put to Lewis.[14] Similarly, the administration of remedies is conducted intuitively rather than on the basis of in-depth diagnoses. The frequent use of laudanum and opium, for example, in many cases brings easy relief by temporarily alleviating the immediate symptoms of various pathological conditions without affecting the causes, which remain misunderstood.[15]

Comments are made above all on venereal diseases and ocular diseases – among the symptoms for which remedies are most often administered, rheumatism, scrofula, fevers and ulcers that cannot be traced back to a particular disease, and paralysis are also frequently noted. The subject of venereal diseases is particularly insidious from a diplomatic point of view, and from the point of view of medical knowledge, the origin of syphilis has been the subject of heated debate ever since it first appeared in Europe at the end of the 15th century, a debate that has not been exhausted by more recent historical epidemiology. European observers of the first epidemic that broke out three years after the first voyages of Christopher Columbus and Antonio de Torres, including Oviedo and Las Casas, identified its origin in the West Indies or Hispaniola.[16]

The Journals recorded cases of syphilis among the expedition members, attributing the origin of the contagion to the Mandan women encountered by the expedition in the winter of 1804 and early 1805, and again at the Chinook people on the Pacific coast in the winter of 1805.[17] On the Pacific coast the fur trade had already spread, by the beginning of the nineteenth century, sexually transmitted diseases unknown until a few decades earlier, and not recorded in the accounts of those who had visited the same territories in the 1890s.[18] Lewis noted various practices and remedies of the Manda nation that considered worthy of future investigation and verification, and credit was also given to the decoctions that the Chippeway people used to treat syphilis and gonorrhoea.[19] At the Shoshone in what is now western Montana, Lewis attempted to learn about the presence and remedies used for venereal disease without success, and while he acknowledged the exogenous nature of smallpox, he believed gonorrhoea and syphilis to be originating in America.


[1] Jefferson to Meriwether Lewis, June 20, 1803, in The Papers of Thomas Jefferson, general editor B. O. Oberg, Princeton, Princeton University Press 2013, vol. XL – 4 March to 10 July 1803, pp. 176-182, see p. 179.

[2] Forms of medical diplomacy characterised the stays of American delegations on the Atlantic coast and in Europe: D. Pearson, Medical Diplomacy and the American Indian: Thomas Jefferson, the Lewis and Clark Expedition, and the Subsequent Effects on American Indian Health and Public Policy, ‘Wicazo Sa Review’, 19, 1, 2004 (American Indian Encounters with Lewis and Clark), pp. 105-130, see pp. 108-109 for vaccination of a delegation from Shawnee and Delaware to Washington in 1802, pp. 112-115 for disease and mortality within the delegations from Arikara, Omaha, Otoe, Missouria, Pani, Kanza, Osage, Sacsand Foxe, Kickapoo, Potawatomie and Miami sent by Lewsi and Clark to St. Louis and Washington between 1804 and 1806. For cases of transatlantic contagion and inoculation: A. T. Vaughan, Transatlantic Encounters: American Indians in Britain, 1500-1776, Cambridge, Cambridge University Press 2006, pp. 181, 197, 250-251.

[3] Pearson, Medical Diplomacy, p. 108; D. R. Hopkins, The Greatest Killer: Smallpox in History, Chicago and London, University of Chicago Press 2002, p. 270.

[4] D. Arnold, Colonizing the Body: State Medicine and Epidemic Disease in Nineteenth-Century India, Berkeley, University of California Press 1993; M. Few, Circulating Smallpox Knowledge: Guatemalan Doctors, Mayan Indians and Designing Spain’s Smallpox Vaccination Expedition, 1780-1803, ‘The British Journal for the History of Science’, 43, 4, 2010, pp. 519-537; M. Few, All of Humanity: Mesoamerican and Colonial Medicine in Enlightenment Guatemala, Tucson, AZ, University of Arizona Press 2015; M. Vaughan, Slavery, smallpox and revolution: 1792 in Ile de France (Mauritius), ‘Social History of Medicine’, 13, 2000, pp. 411-428.

[5] Pearson, Medical Diplomacy, p. 106; B. Waterhouse, A prospect, part II, pp. 37-38 (quoting an article in the European Magazine of April 1802).

[6] Jefferson to Rush, Washington, February 28, 1803, in The Papers of Thomas Jefferson, general editor B. O. Oberg, Princeton, Princeton University Press 2012, vol. XXXIX – 13 November 1802 to 3 March 1803, pp. 598-600.

[7] D. Jackson, ed., Letters of the Lewis and Clark Expedition with Related Documents, 1783-1854, 2nd ed., Urbana, University of Illinois Press, 1978, 2 vols., I, pp. 54-55.

[8] P. R. Cutright, Contributions of Philadelphia to Lewis and Clark History, Philadelphia, Lewis and Clark Trail Heritage Foundation, 2001, pp. 1-19.

[9] Lewis and Clark, Original Journals, VII, Appendix XXXII – Ethnological Information Desired, pp. 283-287, cit. p. 283, in the same volume see also Appendix XV – Lewis to Jefferson, Philadelphia, May 29, 1803, pp. 224-225, see p. 224 for the role of Rush, Barton and Wister, Appendix XVI – Lewis Invites Clark to Join Him, Washington, June 19, 1803, pp. 226-230, see p. 229; Jefferson instructions to Lewis, p. 249; O. Larsell, Excerpts from Medical Aspects of the Lewis and Clark Expedition (1804-1806) (1947), Wilderness and Environmental Medicine, 14, 2003, pp. 265-271, see p. 265.

[10] Lewis and Clark, Original Journals, VII, Appendix XVII – Documents Relating to the Equipment of the Expedition, May-June, 1803, pp. 231-246, p. 236 for the medical equipment required by Lewis, see also p. 244 for the expenses incurred by the Surveyor of Public Supplies, see also Larsell, Excerpts, p. 266. T. P. Lowry, Venereal Disease and the Lewis and Clark Expedition. With a foreword by Edwin C. Bearss, Lincoln and London: University of Nebraska Press 2004, pp. 35-45.

[11] “I would thank you to forward me some of the Vaxcine matter, as I have reason to believe from several experiments made with what I have, that it has lost it’s virtue”, Lewis and Clark, Original Journals, VII, Appendix XXXIV – Lewis to Jefferson, Cincinnati, October 3, 1803, pp. 274-279, cit. p. 278.

[12] Here and below the reference edition of the journals adopted is: The Journals of the Lewis and Clark Expedition, edited by G. E. Moulton, digitised edition in Journals of the Lewis & Clark Expedition, section, ad vocem. This edition is a development of the 13-volume edition edited by Moulton, Lincoln University of Nebraska Press 1983-2001. The electronic edition includes accounts by all members of the expedition and expanded apparatus. Henceforth this edition will be abbreviated as Journals, followed by the date and surname(s) of the authors of the entries of interest, in this case: May 14, 1805, Lewis, Clark, Gass, Whitehouse. The transcriptions respect the capital letters, spellings and linguistic peculiarities of this edition of the manuscripts.

[13] Lowry, Venereal Disease, 32 for a reconstruction of Lewis’s probable medical knowledge.

[14] It should be noted that processes and methods of collecting information are generally not dealt with in journals. This is true for the processes of translation and interpretation and the collection of oral testimonies, as well as for the medical-anatomical observation, which is captured through oblique references, as well as all the notations referring to the sexual behaviour and practices of the peoples encountered and of the members of the expedition, diluted by euphemistic periphrases as well as by the diachronically connoted lexical uses of late eighteenth- and early nineteenth-century English.

[15] Pearson, Medical Diplomacy; Lowry, Venereal Disease, 42-43 insists on the success of the expedition from a medical point of view, given the knowledge of the time.

[16] D. Hayden, Pox: Genius, Madness, and the Mysteries of Syphilis, New York, Basic Books 2003, pp. 3-21; Lowry, Venereal Disease, also for a discussion of sexual behaviour during the expedition; D. L. Hutchinson, Disease and Discrimination: Poverty and Pestilence in Colonial Atlantic America, Gainesville, University Press of Florida 2016, pp. 28-33.

[17] Larsell, Excerpts, 267; Lowry, Venereal Disease, 63.

[18] Larsell, Excerpts, 269; Lowry, Venereal Disease, 24 states that syphilis was in all probability unknown to the populations along the course of the Missouri until 1766 and that the evidence available to date does not make it incontrovertibly clear whether the men of the expedition brought it with them, see also 29 for Jonathan Carver’s testimony among the Sioux. See also Journals, November 21, 1805, Clark, for venereal diseases among the Clatsops (Clap-sott) in Oregon, January 27, 1806, Lewis, Clark for the Chippewa.

[19] Larsell, Excerpts, 267, 269.

This post is adapted from: Giulia Iannuzzi, “in the raging time of the small pox”: Il vaiolo e la documentazione dell’alterità americana tra fine Settecento e primo Ottocento, Diciottesimo Secolo, 6 (2021): 67-82, doi: 10.36253/ds-12544; ISSN: 2531-4165. This article is available in full green open access:

Cite this article as: Giulia Iannuzzi, "Smallpox and medical knowledge in the Lewis and Clark expedition," in Geographies of Time, 01/10/2022,

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