Tuberculosis, a resilient disease
According to the World Health Organisation, more than 10 million people contract tuberculosis every year, and 1.5 million die from the disease.
There are different forms of tuberculosis: some affect the viscera, the kidneys, the meninges, etc. But the pulmonary form is largely dominant and is highly contagious, unlike forms outside the lungs.
What are the symptoms of tuberculosis?
The tuberculosis germ is a bacterium: Koch's bacillus, or Mycobacterium tuberculosis. It most often enters the lungs to reach the alveoli, the little grape-like sacs at the end of the bronchial tree. This is where respiratory exchanges take place. The bacillus will multiply inside the defence cells of the alveoli (alveolar macrophages), then gradually attack the lung tissue. The result may be chest pains, a persistent cough, with or without chronic exhaustion, loss of weight and appetite, or sputum containing blood.
A highly contagious disease
In countries where pulmonary tuberculosis is widespread, it is a highly contagious disease that spreads through the airways: sneezing, coughing and spitting release tubercle bacilli into the surrounding air.
In France, contagiousness is much lower than in countries with a tuberculosis epidemic. An infected person infects less than one other person.
In around 90% of cases, infected people do not develop symptoms and are not contagious - the disease is said to be latent.
However, in 5% to 10% of cases, the disease reawakens over time, with patients showing symptoms and becoming contagious. Anyone with a weakened immune system (due to HIV, malnutrition or diabetes, for example) is at greater risk of infection.
In 80% of cases, tuberculosis affects the lungs, and in more than half of cases it occurs outside the lungs.
The WHO estimates that a quarter of the world's population has a latent infection.
Tuberculosis: the history of an epidemic
Over the centuries, population movements have played a major role in the spread of the disease around the world.
Described in ancient times by Hippocrates, tuberculosis was first known as phthisis, which means "wasting away" in Greek. But we now know that it has been around for tens of thousands of years, as confirmed by Roland Brosch, director of mycobacteriology research at the Institut Pasteur: "We can estimate that the first tuberculosis bacilli appeared 50,000 or 70,000 years ago in East Africa. They were then transmitted with the migration of humans from Africa to other continents".
Tuberculosis: a historical social scourge
During the 19th century, tuberculosis caused thousands of deaths across Europe and became a social scourge. Known as the white plague because of the pallor of the patients, the disease was accompanied by lung pains, sweating and severe weight loss. Without a cure, tuberculosis was a death sentence.
But at the end of the 19th century, the discovery of the tubercle bacillus was the first sign of hope: "in 1882, a German doctor, Robert Koch, was able to demonstrate that the disease was caused by bacteria that he named mycobacterium tuberculosis", explains Roland Brosch. A discovery that "made it clear that we were no longer dealing with a hereditary problem (...), but with a contagious and infectious disease. We were therefore able to take measures to prevent contagion".
The importance of socio-economic conditions is clear to see. To combat insalubrity, the public authorities appointed health visitors. These nurses played the role of social workers before their time, showing people the way to better health. Honoured with the symbol of the double cross, tuberculosis became an international battle. The incidence of the disease slowly declined. But there was still no cure. The only known treatment was pure air, and the sanatoria designed to care for tuberculosis patients were showing their limitations.
BCG vaccine and antibiotics: effective weapons against tuberculosis
It wasn't until 1921 that the first vaccine was developed. Albert Calmette and Camille Guérin created BCG at the Pasteur Institute in Lille. "It was an oral vaccination, so live cultures of the bacteria were given to children. And after this vaccine, there was a clear drop in the incidence of tuberculosis and in the number of cases of tuberculosis in France".
In the 1940s, the discovery of antibiotics revolutionised the way the disease was treated. It dramatically improved patients' vital prognosis. Antibiotics acted as a therapeutic bulwark, warding off tuberculosis. In the northern hemisphere, the epidemic was thought to be under control. But with the AIDS epidemic weakening the immune system, Koch's bacillus re-emerged in the early 1990s in forms that were resistant to treatment.
Although the incidence of the disease has now stabilised in UK, it is still being closely monitored by the authorities.
Tuberculosis, an invincible disease?
BCG vaccination has not been compulsory in France since 2007. But it is still strongly recommended for at-risk populations. These recommendations are not always followed. Some regions are becoming reservoirs for the epidemic.
Existing antibiotic treatment is highly effective, curing the vast majority of patients within six months. But in some cases, recovery is more complicated. Resistant forms of the disease can develop, particularly to rifampicin.
Multi-resistant tuberculosis
For several years now, there has been an increase in the number of patients suffering from multi-resistant tuberculosis in UK. Most of these patients come from Eastern Europe, particularly Georgia, and know that they can benefit from very rigorous monitoring in UK.
Over 4,300 new cases of tuberculosis are reported in UK every year. Many cases of tuberculosis are resistant to the antibiotics traditionally used. Fortunately, other molecules are effective, such as clofazymine or amykacin.
There are tuberculosis centres in every département where people can be tested and treated free of charge. Today, a third of the world's population is infected, and 22 countries alone account for 80% of global cases.
A cocktail combining several antibiotics with bedaquiline has produced excellent results according to several studies (80% cure rate) for multi-resistant tuberculosis. But it has one major obstacle: its cost...
Since 2020, a combination of tablets has been recommended for 9 months: bedaquiline and linezolid, with two other treatments (levoflaxine or moxifloxacin, and cycloserine or clofazimine). The therapeutic arsenal against tuberculosis is expanding.