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What is Disease?

Authored by Robert Hicks
Published on 4th April, 2024 18 min read

What is Disease?

Five centuries ago, an outbreak of contagion in Italy happened so suddenly and severely that it acquired the name that it has had ever since: influenza, referring to the cosmic influence that was thought to cause the disease. Today, although we attribute the disease to a specific virus that invades and reproduces within our bodies, it still carries the same name.

Somewhere between health and disease is an elastic, elusive category of illness. One can be ill because of some social or personal circumstance that induces fatigue, lassitude, lack of appetite or interest, or general discomfort. Etymologically, the relationship between illness and disease is ambiguous. The etymology of disease is dis-ease, or “ill at ease.” All of us manifest illness that combines physical and social circumstances. When one identifies oneself as ill, the causative circumstances may include shame, ostracism, self-doubt, or other phenomena wrapped in a riddle inside a cranial enigma called the brain. One may be recognised for personal resilience and self-sacrifice while carrying a disease or stigmatised―even rejected―by health professionals. One may find inspiration while physically suffering because the malady may furnish proof that God is paying personal attention.  

When a pandemic appears, when people see that symptoms familiar from other diseases have appeared with new viciousness, they recognise that something terribly new is happening. They respond in ways that accord with their bodily suffering, encompass community and family support, retain status, and maintain economic security. Sufferers may also seek realignment with God. A pandemic unravels a complex knot of entwined ingredients, including physical manifestations of infectious diseases, social circumstances that abet or inhibit contagion, and social identities and beliefs.  How one sees oneself as sick within a larger community, how one interacts with healers, and how the community takes actions to contain and eliminate disease are socially constructed ideas. As a concept, the definition of disease varies from person to person, culture to culture, era to era. For instance, the primary sources in Pandemics, Society, and Public Health, 1527–1925 illustrate how Londoners experienced the bubonic plague of 1665 and the influenza pandemic of 1918. What is conspicuous is the way in which these experiences differed according to people’s personal beliefs, the intervention of healers, and the response of the community and state.[1]

Sufferers’ beliefs about their bodies and the nature of the remedies that they seek demonstrate how they defined disease. Growing up in London conferred resistance to the symptoms of many diseases, and Londoners were no strangers to the bubonic plague. In 1665 the familiar plague symptoms appeared: fever, vomiting, expelling blood, delirium, and enlargement of lymph nodes resulting in buboes to the groin and armpits. This time, however, people perceived the disease as singular in its rapid and widespread devastation. By September, mortality had peaked. Yet by the summer of 1666, plague deaths had ebbed to a tiny number, ending the most pernicious plague visitation since the fourteenth century. By the time the plague ended, upwards of 100,000 Londoners―a fifth of the population―had died.[2]

Londoners did not understand the disease the same way that we do. Professional healers aimed not to cure diseases, but to restore bodily vitality holistically. They sought to achieve balance, driven by balancing four humours that, according to their system of knowledge, give life through a vital spirit: blood, phlegm, black bile, and yellow bile. People took medicines—whether home-prepared or purchased from apothecaries―to rebalance the body so it could expel disease. They also sought spiritual guidance and favour as a remedy for fear. Symptomatic people knew that isolation was required to reduce contagion. They were likewise aware that if they survived the mandated forty days of seclusion, they could consider themselves free of disease. They scrupulously cleaned homes, walls, and other surfaces with vinegar, and ended living with animals because authorities demanded their removal and the killing of pets and livestock. To prevent panic, human corpses were removed at night and buried secretly. Anxious about the absence of busy daily life, diarist Samuel Pepys remarked that “little noise [was] heard day or night but tolling of bells…till the nights…are grown too short to conceal the burials of those that died the day before”.[3]

King Charles II ordered his Privy Council to create a committee to come up with a response “to prevent spreading and increase of the Infection of the Plague”.[4] The Council asked London’s College of Physicians for advice. On 13 May 1665, the College published a pamphlet that advised “three great Remedies”: purging, bleeding, and vomiting.[5]  Medicines that induced these reactions were deemed the most effective in extinguishing or preventing infection. Yet these methods were dangerous without a physician’s supervision. The College asserted that in order “to open or keep soluble the Body, the Pills of Rufus, commonly called Pestilential-Pills, are the best and most proper to be used”.[6] Most of the recommendations are directed to the individual sufferer on the assumption that his or her experience of disease is unique, despite its familiar symptoms. The afflicted person who defines his or her own disease must also define the achievement of health. Only the sufferer or a household member has intimate knowledge of the afflicted body. In humoral theory, the balance of bodily essences differs for each person.

By the influenza pandemic of 1918, much had changed. Disease-causing entities were believed to exist, though these were envisaged as very small. Some had been identified and a few vaccines existed. In the closing months of the First World War, influenza ravaged the planet in a form that killed more people in a limited period than any previous disease, plague included. Londoners recognised flu symptoms from its previous outbreaks throughout 1889–90. The 1918 wave of flu, however, had a pernicious new effect: high mortality among healthy young adults. The global death toll is unknown, but it approached 100 million, between two and a half and five percent of the world’s population.

Londoners of 1665 understood that each sufferer’s humoral balance was unique, but those of 1918 shared a common definition of influenza, its sources and symptoms, and believed that specific remedies were applicable to all. In 1918, infected people appeared healthy at first, but soon developed headaches, body aches, fatigue, fever, and coughing that could be violent and bloody. In extreme cases, as alveoli in the lungs burst, victims gasped for air and became cyanotic as their bodies were starved of oxygen. Some went blind, blood trickling from their eyes or nose. Victims emitted a peculiar odour likened to “musty straw.” Collectively, these symptoms defined a new disease, a flu variant, consisting of familiar bodily responses combined with new phenomena associated with high mortality. Despite having different health histories, sufferers recognised that flu affected other bodies similarly and accepted common diagnoses and remedies.[7]

In their response to sufferers’ symptoms and requests for help, healers provided a specific definition of disease under the authority of a professional class. The pamphlet published by the College of Physicians in 1665 recommended three classes of professional healers―physicians, apothecaries, and chirurgeons (surgeons)―to be organised into plague response teams. These professionals were empowered to invade personal intimacy by employing and training watchers of houses under quarantine as well as examiners and searchers of people’s bodies. For the latter, the pamphlet advised inspecting a person’s body for

any Carbuncle, which is something like the Blain [blister], but more fiery and corrosive, easily eating deep into the flesh, and somethings [sic] having a black Crust upon it, but always compassed about with a very fiery red (or livid) flat and hard Tumour, about a finger-breadth more or less.[8]

The violation of personal intimacy has been a prerogative of community-recognised healers into the present, but amidst the panic of 1665 authorities assigned ordinary citizens the right to inspect bodies for symptoms. 

Some physicians publicised free services to the poor and provided recipes for medicines. In 1665 Roger Dixon published a broadsheet titled A Directory for the Poor, Against the Plague, and Infectious Diseases. Published for the common good.[9] Dixon hoped that his free advice would inspire Christian charity in others to prevent “a greater calamity [to] draw down a just Judgement upon themselves”.[10]  His “Cordial Anidote [sic] against the Plague” itemised several substances to be “bruised” and placed in a solution of “Maligo Wine” and boiled within a “Pipkin close covered”.[11] The required herbs included sage, rue, “Butter-bar root” (butterbur or Petasites hybridus), “Angelica roote,” “Zedoary” (white turmeric), saffron, and “Virginia Snake-root”. A sick, poor person would likely be unable to create this mixture, so Dixon recommended obtaining the ingredients at the “Herb shops and Drugsters”.[12]

To meet the challenge of creating this medicine, the sufferer had to patronise another healer: the apothecary. Daniel Defoe’s A Journal of the Plague Years, a fictional account of the 1665 epidemic, grounded in primary sources, observes,

[I]t is incredible and scarce to be imagined, how the posts of houses and corners of streets were plastered over with doctors’ bills and papers of ignorant fellows, quacking and tampering in physic, and inviting the people to come to them for remedies, which was generally set off with such flourishes as these, viz.: ‘Infallible preventive pills against the plague.’[13]

Healers defined diseases in print, but Christian charity, status, authority, and a bank account all figured as part of the definition.

Following the end of the First World War, pandemic flu cases declined, only to rise again as successive waves appeared in various cities. In London, cases emerged within the Ministry of Munitions, the government agency created in 1915 to coordinate the production of munitions, unencumbered by the British War Office, trades unions, or commercial businesses and their separate policies and practices. At the direction of Dr Mary M. Phillips, Medical Officer, managers of the Aircraft Production Department took steps to refresh precautions during the flu pandemic. Staff were to “flush the rooms with fresh air” and disinfect spaces, surfaces, and equipment “with Formalin Vapour”, including bathrooms, recreation areas, and writing spaces.[14] Supervisors were required to be strict about reporting the appearance of symptoms including “cough, catarrh, sore throat, or malaise” in afflicted staff.[15] Workers were statistics, part of daily or weekly tallies as a measure of the healthy workforce.  

In early 1919, Dr Phillips introduced a novel procedure: administering “Mandle’s Paint”.[16]  This substance, better known as Mandl’s Paint (named after its inventor, Agrawal Mandl), is still available today as a remedy for throat soreness. It contains iodine and potassium iodide and is made palatable with peppermint oil. Having been referred to her by a supervisor, Dr Phillips sent an ailing worker home “after having the throat disinfected with a solution of Iodine (Mandl’s Paint)”.[17] Thus, the supervisor inherited the jobs of watcher and searcher that had existed during the days of plague. Dr Phillips stressed, however, “that this treatment should only be administered by a fully qualified nurse who is thoroughly conversant with its use and application”.[18] The use of this substance was not to replace the usual remedies for influenza, which included “gargles of Potassium Permanganate and common salt, and Quinine” in combination with isolation and bed rest.[19] Mandating these remedies for all staff validated the healers who authored the narratives of disease and suffering.

Communities where contagion occurred shaped the definition of disease through public mandates and controls and the designation of medical authorities to contain and reduce outbreaks. Months after the wave of plague that struck in 1665 had peaked, the government of King Charles II published Rules and Orders to be observed by city officials with law enforcement authority.[20] Most of the orders seem familiar today: public gatherings being forbidden, daily market trade diminished to near zero, people had to apply and be examined for health certificates that permitted travel. Furthermore, symptomatic citizens who did not remove themselves to pest houses to recover or die were quarantined in their homes. These had red crosses painted on the doors and were under surveillance by watchers. The policy of quarantine was derived from the Bible, the ultimate civic authority. Official documents about managing the plague refer to seclusion for forty days, the original meaning of quarenteine (Anglo-Norman), which referred to the place where Jesus had fasted for that period.[21]

By 1919 the Ministry of Munitions operated as a government island with a few thousand employees at desk jobs, all monitored for signs of the flu through their own Health and Welfare Department. Proud of success in reducing flu cases, Dr Phillips thought that the government should set an example for the private sector in monitoring employee health and rapid response to flu cases. Quoting Winston Churchill, who was Minister of Munitions between July 1917 and January 1919, Phillips stated that much could be accomplished to improve health “if there were the will behind it”.[22]

Despite removing the sick from the workplace and lathering throats with Mandl’s Paint, however, documents from the Ministry of Munitions described widespread fear. Managers recognized that relocating workers to a new location meant overcrowding. “I fear that it will be impossible to keep up [our] good record”, Dr Phillips added.[23] Her report acknowledged that the new prophylactic measures constituted “a great factor in warding off the disease,” but that employee fear was palpable.[24] The report stated that in “one house alone, three members of the family, father, mother and brother, of one of our women staff have taken influenza and died in one week since she went home with Influenza―while in her own case the attack was slight.”[25] State-imposed controls were not disease-proof, and both the control measures and their results contributed to the definition of influenza as understood in 1919.

These brief summaries of Londoners’ responses to two pandemics illustrate how diseases accrue definition through the fears of the sufferers, the knowledge of healers who intervene to help recover health, and the actions of the community and state to control, limit, or extinguish the disease. Soon after the onset of a pandemic, all three actors define what symptoms and ideas constitute “being ill.” Ill people come under surveillance, whether by local people appointed as watchers and healers or supervisors in a government office. If the victim dies, the state logs a statistic that serves economic and political purposes. The ill person’s home or belongings may be appropriated and destroyed or cleansed and returned by state action. Sufferers adopt remedies sanctioned by authorities but also abstract some of their own, often guided by published recipes. In an emergency, a neighbour’s recommendation of a remedy may carry more weight than a doctor’s. If the state does not support unofficial remedies, it might punish sufferers for using them.

Healers may reject a sufferer who refuses to accept their definition of the disease and its symptoms. If death results, the sufferer’s corpse may receive disrespectful treatment (placed in a cart for a mass burial) and may not receive spiritual recognition. If the sufferer survives, then the state’s policies are vindicated, and God is thanked for a personal intervention. Being struck down by illness and recovering from it are attributed to God’s inscrutable favour, still true for many in the twenty-first century. The healer—physician, nurse, or apothecary―is the mediator among the state, community, and sufferer.

If we became more aware of how we socially construct diseases, when pandemics envelop the planet, we might temper the fear that impels us to seek a responsible party, whether it be a deity, foreigners, or germs. When our definitions imagine perpetrators, we get the “Spanish flu”, “German measles”, “Asiatic cholera”, and “Chinese Covid”. Thus, xenophobia, too, becomes part of the definition of disease.

[1] Roy Porter, “What is Disease?,” in The Cambridge History of Medicine, ed. Roy Porter (Cambridge: Cambridge University Press, 2006), 71–2, 91, 98; Kenneth F. Kiple, “The History of Disease,” in The Cambridge History of Medicine, ed. Roy Porter (Cambridge: Cambridge University Press, 2006), 22.

[2] Bubonic plague, Yersina pestis, is a bacterium that infects a kind of flea which locates itself within people if the usual host, the black rat, is scarce. See Jacalyn Duffin, History of Medicine (Toronto: University of Toronto Press, 2006), 141, 162.

[3] Samuel Pepys, diary entry for 4 September 1665, quoted in “Great Plague of 1665–1666: How did London Respond to it?,” The National Archives (UK), available at

[4] University College London (UCL), 0002/015/UCL0003410, Certain necessary Directions As well For the Cure of the Plague As for preventing Infection: Many easie Medicines of small Charge…Set down by the College of Physicians (London, 1665), available at

[5] Ibid., 20.

[6] Ibid., 21.

[7] Alfred W. Crosby, America’s Forgotten Pandemic: The Influenza of 1918 (Cambridge: Cambridge University Press, 1989), 215ff; John M. Barry, The Great Influenza: The Story of the Deadliest Pandemic in History (London: Penguin Books, 2009), 102–3, 396ff. Medical research to identify diseases had long involved the study of pathological anatomy. Yet by 1918 laboratories with microscopes and chemical analysis informed our understanding of disease. Nonetheless, by 1918 no vaccine existed either for the plague (the bacterium had been identified in 1894) or for influenza. The flu virus itself would not be identified until 1933.

[8] UCL, Certain necessary Directions As well For the Cure of the Plague As for preventing Infection: Many easie Medicines of small Charge…Set down by the College of Physicians, 5.

[9] Roger Dixon, A Directory for the Poor, Against the Plague, and Infectious Diseases. Published for the common good (16 June 1665), London, The National Archives (TNA), PRO 30/24/4/140, available at

[10] Ibid.

[11] Ibid.

[12] Ibid.

[13] Daniel Defoe, A Journal of the Plague Years (London, 1722). Fictional account based on actual events of the 1665 plague, available at Project Gutenberg,

[14] TNA, MUN 4/3702, "Aircraft Production Department Report," 13 March 1919, 1–2, available at

[15] Ibid., 2.

[16] Ibid.

[17] Ibid.

[18] TNA, MUN 4/3702, "Central Establishment Notice No. 91," 9 March 1919, available at

[19] TNA, MUN 4/3702, "Aircraft Production Department Report," 13 March 1919, 4, available at

[20] TNA, SP2/155 f102, Rules and Orders To be observed by all Justice of the Peace, Mayors, Bailiffs, and other Officers, for prevention of the spreading of the Infection of the Plague (1666), available at

[21] Duffin, History of Medicine, 14; See also “Great Plague of 1665–1666,” The National Archives, available at See also UCLA History Public History Initiative, “Living through the Great Plague of London,” available at

[22] TNA, MUN 4/3702, Typescript of memorandum from C.S.D. to Dr Collis, 21 February 1919, available at

[23] TNA, MUN 4/3702, "Aircraft Production Department Report," 13 March 1919, 4, available at

[24] Ibid.

[25] Ibid.

Authored by Robert Hicks

Robert Hicks

Robert D. Hicks directs the F.C. Wood Institute for the History of Medicine at The College of Physicians of Philadelphia, where he also holds the William Maul Measey Chair. Prior to this role, he was the director of the college’s Historical Medical Library and Mütter Museum.

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