The 19th Century’s Silent Killer: Tuberculosis
Authors: Valentin Charlier, Sophie Vanwambeke
La miseria, 1886, painting by Cristóbal Rojas (© Public Domain)
What did Queen Louise d’Orléans, George Orwell, Frédéric Chopin, Franz Kafka, and Thérèse of Lisieux have in common?
They all died from tuberculosis, the same disease that claimed millions of lives across the world. For centuries, tuberculosis was one of humanity’s deadliest companions, likely the leading cause of death in human history.
In Belgium, tuberculosis was a major killer well into the 19th century, particularly as urbanization and industrialization reshaped living conditions. But were all Belgians affected equally? Let’s explore how this disease spread and how it was eventually brought under control.
What is tuberculosis?
History of Tuberculosis
Tuberculosis is one of humanity’s oldest diseases, with evidence of infection dating back to the Neolithic period and written descriptions in ancient civilizations such as Egypt, India, and Greece. Because it slowly wastes the body, it was historically known as phthisis or “consumption.” For centuries, its cause remained unknown and was often attributed to hereditary weakness or imbalances in bodily humors.
The disease became a major public health threat in early nineteenth-century Western Europe during the Industrial Revolution. It thrived in overcrowded and unsanitary urban environments marked by poor housing, inadequate sanitation, and malnutrition. Around 1850, tuberculosis was the leading cause of death in many industrialized countries, accounting for 15–20% of all deaths. In Belgium, infectious diseases caused approximately 40% of all deaths by the mid-nineteenth century, with tuberculosis claiming more lives than cholera, measles, and scarlet fever and remaining deadly well into the twentieth century.
Causes of death in Belgium from 1850 to 1980 by percentage of total deaths
A modern understanding of tuberculosis emerged in the late 19th century, when it was shown to be contagious and Robert Koch identified Mycobacterium tuberculosis as the causative agent in 1882. This discovery led to public hygiene measures and the isolation of patients in sanatoria, which played a key role in reducing transmission.
In the following decades improvements in living conditions, nutrition, sanitation, and public health, along with medical advances such as X-rays, diagnostic tests, vaccines, and antibiotics, transformed tuberculosis from a largely fatal disease into one that could often be cured. However, effective drug treatment became available only after 1947, and in Belgium vaccination efforts were limited by medical skepticism and the absence of systematic programs. The decline of tuberculosis has also been partly attributed to increased population resistance over time.
Despite the impact of antibiotics, the importance of addressing the social determinants of tuberculosis, including poverty, housing conditions, nutrition can not be ignored. More recently, risk factors include HIV, diabetes, substance abuse, and smoking.
From killing 1 in 5, to nearly disappearing
Let’s take a closer look at the evolution of tuberculosis through time in Belgium. The government started counting causes of death nationwide from in 1851 onwards. That first year, tuberculosis killed 17,730 people, meaning the disease accounted for nearly 20% of all deaths or 1 in 5 of all deaths (!). Tuberculosis mortality peaked at 19,478 deaths in 1865.
Industrialization played a big role. In Belgium in the 1840s, many people migrated to urban areas, fleeing rural poverty and seeking better opportunities. The cities became overcrowded, with poor housing, unsanitary living conditions and poor nutrition forming an ideal ground for the disease to spread.
Crude Death Rate from Tuberculosis per 10.000 inhabitants
The sharp drop in deaths in 1903 did not result from a specific event but was related to the introduction of the first International Classification of Disease in Belgium, which involved a change in the recording of deaths associated with pulmonary issues. The category “Phthisis and other chronic diseases” was too broad and led to an overestimation of deaths caused by tuberculosis.
Nevertheless, during the 20th century, the disease declined steadily and only flared up during the two World Wars. In 1978, the number of people killed by tuberculosis was only 296, almost 0%. Today, tuberculosis can still be found in Belgium although it generally occurs in people originating from countries where the disease is still prevalent.
A disease of industrial regions?
Between 1889 and 1950, tuberculosis mortality was higher in Flanders than in Wallonia. Two main factors help explain this difference:
- Socioeconomic conditions
Flanders remained impoverished until the 1960s, undergoing delayed industrialization following the collapse of the rural linen industry in the 19th century. The arrival of cheap grain from the New World led to widespread unemployment. In contrast, Wallonia experienced considerable prosperity due to the rise of coal and steel industries, positioning it as a major European industrial center until the early 20th century. However, this industrial boom came at a cost to workers’ health and was followed by socio-economic decline after the collapse of heavy industry [Buyst, 2009]. - Health infrastructure and habits
Wallonia developed stronger healthcare networks earlier on. In Flanders, lower breastfeeding rates and poor-quality water may have contributed to weaker immunity and higher vulnerability to infectious diseases [Eggerickx & Tabutin, 1994; Van Rossem et al., 2018].
Despite these differences, tuberculosis eventually declined across both regions as industrial living conditions, healthcare, and nutrition improved. By the mid-20th century, the era of tuberculosis as a major public health threat in Belgium was coming to a close.
On the maps above, we see the evolution of the number of people dying from tuberculosis through four chronological periods
(sum up everything we see: also the absence of tb deaths in certain periods and regions)
During periods X-X the high mortality by tuberculosis in the Walloon industrial basin is visible on the map, and it did concentrate more deaths from tuberculosis in the final years of our analysis – the tail end of tuberculosis as a major cause of death in Belgium.
In Belgium, as in other European countries at the time, before the causes, prevention, and treatment were fully understood, tuberculosis affected the population broadly. But our maps show that some areas were particularly badly affected, which can be related to the agricultural crisis as well as the urban transition related to the industrial revolution.
Tuberculosis and scientific innovation: Koch’s postulates
For centuries, people believed diseases like tuberculosis came from “bad air” (miasma) or divine punishment. The discovery of microbes and the development of germ theory revolutionized that understanding.
In 1882, Robert Koch identified Mycobacterium tuberculosis as the cause of tuberculosis. To prove this, he developed a set of principles known as Koch’s postulates, which laid the foundation for modern microbiology:
- Find it – The germ should always be found in people (or animals) who have the disease, but not in healthy ones.
- Isolate it – Take the germ out of the sick person’s body and grow it in a lab (so you have only that germ, nothing else).
- Test it – Give the germ to a healthy person or animal, and they should get the same disease.
- Prove it – Take the germ out of this newly sick person or animal, it should be the exact same germ you started with.
Although modern science has revealed exceptions (some microbes can’t be cultured or don’t always cause disease), Koch’s approach remains a cornerstone of scientific rigor in infectious disease research.
Conclusion
Tuberculosis was once the leading cause of death in Europe and a defining feature of 19th-century urban life. Its decline , driven by better living conditions, public health reform, and scientific discovery , marks one of humanity’s great public health successes.
Yet the story is far from over. Tuberculosis continues to thrive where poverty, overcrowding, and limited healthcare persist. Understanding its history reminds us how deeply health is shaped by social and economic conditions, and how progress against disease depends not only on medicine, but also on equity.
Further reading
Ineqkills research on the subject
Sources and Literature
Eggerickx & Tabutin, 1994;
Van Rossem et al., 2018]
WHO 2023
Buyst 2009
