*This blog post first appeared in Dutch on the NL-Lab website on 31 March 2020*
The Netherlands are in lockdown to curb the covid-19 epidemic since prime minister Mark Rutte announced social distancing rules on 13 and 15 March. Since that time, various people have asked me, as a medical historian, ‘how we handled this kind of thing in the past’. By this they mean: how did people, both in the Netherlands and abroad, deal with epidemic respiratory infections in the past? The short answer would be: very different. The long answer could fill a book, but a blog post (or two) is written and read faster. This week part 1, on the history of our understanding of respiratory illnesses. Next week part 2, on treatments and management of respiratory illnesses.
We now understand respiratory infections as an infection of the mucous membranes of the airways, caused by pathogens such as bacteria and viruses. On the website of the Dutch National Institute of Public Health (RIVM), we read: “Infections of the upper respiratory tract, such as colds and sore throats, are usually caused by a virus and normally pass without treatment. Infections of the lower respiratory tract or for example pneumonia and bronchitis. These can be caused by both viruses and bacteria and can lead to severe illness. Pneumonia is an important cause of death in the Netherlands.”
Confusingly, respiratory infections which can present with very similar symptoms, such as the common cold, flu, and covid-19, are caused by completely different viruses, which do not belong to the same taxonomic and morphological families. Cold virus (Rhinovirus) is part if the Picornaviridae family; the four influenza viruses (A,B,C,D) are part of the Orthomyxoviridae family, and corona viruses such as are part of the Orthocoronavirinae family. Comparing covid-19 to ‘a flu’ hence is incorrect, not only clinically, but also taxonomically speaking.
Yet this is all very recent knowledge from a historical perspective. Although it has been known since antiquity that certain diseases are very contagious, and that their transmission can be stopped by isolating the ill from healthy people, that line of thought in general was not applied to respiratory infections or illnesses. The reason for that is that only in the late nineteenth century the role of viruses and bacteria in respiratory infections became clear, and that respiratory infections therefore can be contagious. Epidemic respiratory infections with flu-like symptoms have been described with some regularity since antiquity though. In Hypocrates’ Book of Epidemics, written around 410 BCE for example, we already find a description of a very contagious disease in the north of Greece, which sounds a lot like flu. Until the Middle Ages, throughout Europe a wide variety of epidemics is described. Nearly all of these epidemics, including those that appear to have been respiratory infections, were described as ‘plague’ or ‘pest’.
In Florence in 1357 an epidemic of ‘influenza’ was first documented. The word influenza literally means ‘inlfuence’ in Italian. From antiquity until late in the nineteenth century people thought that many contagious diseases were actually caused by the influence of celestial bodies, weather, or climates – a believe still reflected in contemporary language, think of ‘flu’, the ‘common cold’, or catching ‘a cold’. The influenza epidemic in Florence of 1375 was indeed most likely an ‘influenza di freddo’, a ‘cold influence’ or influenza epidemic. But until the eighteenth century, the word influenza, like plague, meant a (contagious) disease more generally. It appears that the term also did not spread throughout Europe until the eighteenth century. For example, Lord Chesterfield wrote in a letter to this son in 1767: ““a little fever that kills nobody but elderly people that is now called by a beautiful name: influenza”. 
In the Netherlands, the word influenza first appeared by the end of the eighteenth century, as a synonym for the common cold, but used metaphorically rather than medically. The Utrecht professor of philosophy and mathematics J.F. Hennert for example in 1785 published a pamphlet with the title Special Effects of the Influenza, and the Cures Against that Contagious Disease. It’s actually not a text on the symptoms and treatment of colds or flu, but a squib aimed a critic who tried to slander his work. Something similar is going on in The Lighter: Being an Elaborated Treatise on the Influenza, that is Public Cold, published in 1800 by army physician Pieter van Woensel. On closer inspection, it’s not about physical colds at all, but about the spreading of dangerous political ideology.
The word ‘griep’ did not appear in Dutch until around 1800, when the French armies brought their grippe, which is most likely etymologically related to the German grippen (‘to catch’). Before that time, respiratory afflictions in Dutch were described using a wide variety of terms, such as verkoudheid, longontsteking, pneumonia, peripneumonia, consumptie, zydewee, pleuris, tering or Phthisis. Lacking a microbiolological understanding of respiratory illnesses, the categories in which they were divided were also much more fluid. We should also be aware of the fact that such terms, even if they seem identical to modern words, had a different meaning for the people who used them in the eighteenth century. Understandings of illness are always simultaneously clinical and social, and separating those two dimensions is nearly impossible. Therefore, we cannot simply say that eighteenth-century consumption sufferers ‘actually’ had tuberculosis – after all, TBC did not exist in social, biological, and medical reality before 1882, the year in which the tuberculosis bacteria was first identified. Hence it is not useful either to assume that the ‘zydewee’ (‘side ache’) described by a seventeenth-century doctor was the same disease as modern pleurisy.
This of course does not mean that medical people did not think critically about the causes of various respiratory illnesses. According to the Amsterdam physician Steven Blankaart (1650-1704) for example, coughing in colds was caused either by ‘a salty and sharp substance excreted by the glands that cover the inside of the lungs’ or because of the fact that ‘the air sometimes contains more sour particles than other times, which are breathed in, sharpening the blood, and dismay the lung to coughing’. But how were respiratory illnesses treated before the late nineteenth century? More next week!
 A similar etymology is found in malaria: mal’aria literally means ‘bad air’ in Italian
 Lina 2008, p. 202.
 Johann Friedrich Hennert, Bijzondere Uitwerkzelen van de Influenza, En de Geneesmiddelen Tegen Die Besmettelijke Ziekte(Utrecht: A. van Paddenburg, Akademie drukker, 1785).
 Pieter Van Woensel, De Bij-Lichter, Zijnde Eene Uitgewerkte Verhandeling over de Influenza, Dat Is Publieke Verkoudheid(Amsterdam: In ’t Nieuwe Licht, 1800).
 E.g. Vanessa Harding, “Housing and Health in Early Modern London,” in Environment, Health and History, by Virginia Berridge and Martin Gorsky (Basingstoke: Palgrave Macmillan, 2012), 23–44, pp. 38.
 Steven Blankaart, De Kartesiaanse Academie Ofte, Institutie Der Medicyne (Amsterdam: Johannes ten Hoorn, 1683), p. 285. “een siltige en scherpe [stof] door de kliertjes die de longe-pijps rok van binnen bekleeden, uitsypert” (…) “de locht d’eene tijd meerder suure deeltjens by sich heeft als d’andere tijd, welk dan ingeademt wordende, het bloed scherper maakt, en de long tot hoesten ontstelt”.