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How Ramazzini, an Epidemiology Frontier From Northern Italy, and Leibniz Experimented with Contagion and Disease

Painting detail credits: 最美太湖水 by 商亚东

In the face of the COVID19 virus, I decided to describe an interesting piece of history of epidemiology. It is a beautiful story of how Gottfried Wilhelm Leibniz (1646-1716), a German polymath, and Bernardino Ramazzini (1633-1714) collaborated and encouraged each other to develop early conceptions and experiments of epidemiology. Ramazzini lived and worked in Northern Italy where the COVID19 has now spread with devastating measures. It is thus important to see and pay tribute to a local frontier without whom the science of epidemiology would certainly not be where it is now. It also shows how European collaboration of learning has advanced the knowledge in very important ways.

In the medical field, Ramazzini was one of Leibniz’s most important correspondents. They have met in Modena in the Winter of 1689 and for Ramazzini it was one of the most important events of his life because until then the 57 year-old professor of medicine had essentially no recognition outside Northern Italy. After their meeting, Leibniz has encouraged Ramazzini to intensify his work in medicine as well as in the scientific and technical fields and to publish his achievements. Leibniz’s encouragement paid off when in 1690 Ramazzini published his first epidemiological work. After their meeting, Ramazzini published a considerable number of works at short intervals that made a name for him in epidemiology and occupational medicine. Leibniz enthusiastically encouraged the promotion of Ramazzini‘s writings and thus made a major contribution to his success.

By the end of the 17th century, the use of thermometers, barometers and hygrometers made it possible to relate diseases to the prevailing weather. Mortality rates, morbidity and population development were also quantified for the first time. Prevention increasingly became the main goal of medical practice. The causes of diseases were sought and found in various circumstances, like the weather, the occupation, and the external living conditions. In addition to general preventive measures, doctors paid particular attention to the causes and circumstances of epidemics. Ramazzini followed Thomas Sydenham who coined the concept of the “Constitutio,” and was the first to publish Constitutiones epidemicae every year.

Ramazzini continued these efforts and published the Constitutiones epidemicae from 1690 to 1694. Ramazzini described in these works all epidemic diseases that occurred in the Emilia-Romagna region in the respective year. It contains precise information about symptoms, the course of the disease, the treatment used and the assessment of its effectiveness. Ramazzini also analyzed the weather of the respective years in which the diseases developed. He even took into account the futility of crops such as wheat or wine and the health of farm animals. He observed which population group was affected by the respective epidemic the most and in what way, and tried to explain why.

Between 1690 and 1694, malaria and typhoid epidemics occurred in the Emilia-Romagna region. The extreme humidity of 1690 led to a malaria epidemic, which mainly affected the rural population. Ramazzini described the course of this epidemic with reference to the individual seasons. He also discussed the side effects such as grain rust and animal diseases. In contrast, the following year 1691 was dry and hot. This time malaria mainly affected the poorer urban population, while the rural population was largely untouched. In the years 1692 to 1694, despite very different weather conditions, typhoid diseases were in the foreground. Ramazzini took the view that the transmission of these contagious diseases took place by air and that the south wind brought the plague from Africa to Italy.

Like many important physicians of the time, Ramazzini agreed with the Iatrochemists, so the diagnostic and therapeutic teaching of their school is reflected in his works. His Constitutiones epidemicae were very successful and groundbreaking in the field of epidemiology. A reprint of the Constitutiones appeared in the annex to the Miscellanea curiosa of 1691. His second Constitutiones also appeared in this magazine. These reprints made Ramazzini known primarily in Germany. Since Leibniz considered Ramazzini’s epidemiological work to be particularly important, he repeatedly recommended that other physicians should write such works for other areas and periods. These efforts were often successful, so that in the following years various Constitutiones were drawn up in several places in Europe.

In his De constitutione anni 1690 ac de rurali epidemia Ramazzini described the tragedy of the Emilia-Romagna. Its economic decline due to the climatic and epidemic situation in the previous two years was exacerbated by the danger of war: “Add to this the progress of war. I am afraid that the Duke of Mantua will reach our neighboring Gauls. Then we’ll be bordering in three areas.“ Ramazzini described difficulties in supplying the German troops stationed near Modena on March 30, 1692. He also suspected a connection between the emergencies and epidemics of recent years on the one hand and phenomena such as the malformation and mortality of pigs on the other hand.

Leibniz emphatically emphasized the importance and necessity of collecting medical statistics in Germany as well. The Leopoldina should support such projects and collect surveys from all parts of the empire. On November 2, 1691 Leibniz thanked Johann Georg Volckamer for sending him the reprint of Ramazzini’s De constitutione anni 1690 and voiced the hope that Volckamer would be able to do something similar in Germany: “I owe you so much that you have included my advice, or rather my wish, in your celebrated Ephemerides. I hope that it will bear fruits for the Republic because of your authority and encouragement.“

In addition to performing general physical barometer experiments, Ramazzini attempted to relate the barometer readings to human health. Ramazzini recalls that during his stay in Modena Leibniz had suggested measuring the temperatures in the wells: “I’d wish, as you have urged, to perform some experiments on the temperatures of these wells at different depths.“ When a new well was drilled in October 1690, Ramazzini carried out temperature and air pressure measurements. He devoted a detailed study to the water supply of Modena. He published the results in the work De fontium Mutinensium admiranda scaturigine tractatus physico- hydrostaticus, 1691. He described the surface and geological structure of the soil, the level and movement of the groundwater, the installation of artesian wells and measures to prevent contamination. The work also contains records of soil temperatures at various depths up to 80 feet. They were the first such measurements in Europe. The Modena fountains were an inexhaustible source of pure water that was also suitable for medical applications. Researching the origin and productivity of these sources was also one of Ramazzini’s goals.

Ramazzini’s teaching assignment for theoretical medicine at that time also included the field of occupational medicine. While exploring the Emilia-Romagna water sources, Ramazzini also examined the working conditions of the workers in the wells. He even descended into the wells himself, not only to rely on the information of third parties, the knowledge gained from these investigations was reflected in the most famous and significant work by Ramazzini De morbis arti cum diatriba, published almost a decade later.


1. Source: Leibniz, G. W., 1931- , Sämtliche Schriften und Briefe, Berlin: Akademie Verlag. III Reihe, V Band: XLIX- LV.

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