Tuberculosis is one of the deadliest infectious diseases. A quarter of the world’s population is infected.
Last updated on 07 October 2026
Tuberculosis is an infectious disease caused by bacteria belonging to the “Mycobacterium tuberculosis complex” (a family of genetically related bacteria), mainly Mycobacterium tuberculosis in humans. The genus Mycobacterium is probably very ancient, but the tuberculosis complex is much more recent. Research in evolutionary genomics suggests that the ancestors of tubercle bacilli were already circulating in Africa among ancient hominins, whereas the M. tuberculosis complex may have emerged in Africa around 70,000 years ago, before spreading with human migrations and expanding considerably as populations became denser, particularly from the Neolithic period onwards. These dates nevertheless remain debated, depending on the molecular clock models and ancient DNA calibrations used.¹
Archaeological remains, including bone lesions consistent with the disease and traces of DNA from the M. tuberculosis complex identified in ancient human remains, attest to the longstanding presence of tuberculosis in many regions of the world, particularly in Africa, Eurasia and the Americas. Ancient medical texts also describe a chronic, often fatal disease consistent with pulmonary tuberculosis, then known as phthisis and later as consumption. In the Middle Ages, certain forms of tuberculosis affecting the cervical lymph nodes were known as the king’s evil or scrofula.
It was much later that René Laennec (1781–1826) helped to characterise pulmonary tuberculosis by linking clinical signs, auscultation findings and the pathological lesions observed in patients with phthisis. At that time, the disease was a major scourge in Europe, where it was a leading cause of death. However, its infectious nature had not yet been clearly established. The transmissibility of tuberculosis was demonstrated experimentally in 1865 by Jean-Antoine Villemin, and the bacillus responsible for the disease was subsequently identified in 1882 by Robert Koch, hence its name, “Koch’s bacillus”. Throughout the 20th century, tuberculosis remained a common and deadly disease worldwide, although its incidence and mortality gradually declined in many industrialised countries thanks to improvements in hygiene, vaccination, screening and antibiotic treatments.²
The first biomedical means of prevention and treatment emerged in the 20th century: the BCG vaccine, first administered to a human in 1921, marked a major milestone in tuberculosis prevention, while the first anti-tuberculosis antibiotics, particularly streptomycin in the 1940s, ushered in the era of curative treatment. Throughout the 20th century, particularly in industrialised countries where incidence was declining, tuberculosis became increasingly concentrated among the most disadvantaged or vulnerable populations, confirming its close association with social conditions, overcrowding, malnutrition and access to healthcare.²
The first complete genome sequence of Mycobacterium tuberculosis, obtained from the H37Rv reference strain, was published in 1998. This breakthrough profoundly renewed understanding of the biology of the tubercle bacillus and paved the way for comparative genomic analyses, which subsequently helped to trace the evolutionary history of the Mycobacterium tuberculosis complex more accurately.³
The bacterium primarily responsible for human tuberculosis, Mycobacterium tuberculosis, is an acid-fast bacillus belonging to the Mycobacteriaceae family. Its cell envelope, which is particularly rich in lipids and mycolic acids, contributes to its low permeability and relative resistance to many chemicals and antibiotics. M. tuberculosis is the main cause of tuberculosis in humans, but other species within the Mycobacterium tuberculosis complex, such as M. bovis or M. africanum, can also cause the disease. The genetic diversity of this complex has been shaped by its evolutionary history, human migration, population growth, urbanisation and, more recently, selection pressures associated with anti-tuberculosis treatments.¹
It is currently estimated that around a quarter of the world’s population has been exposed to tuberculosis bacteria. In most of these people, infection does not result in active disease and is not contagious. Only a minority of infected people develop tuberculosis disease during their lifetime, with the risk being particularly high in the first two years following infection and in people with immunosuppression or other vulnerability factors.⁴
In 2024, 10.7 million new cases of tuberculosis were recorded worldwide, 11% of which occurred in children, representing an average incidence rate of 131 per 100,000 population.⁵ As observed in France, the distribution of the disease is uneven across the globe.
The World Health Organization (WHO) categorises countries according to the rate of new cases recorded each year: most Western European countries belong to the lowest-incidence group (< 10 per 100,000 population in 2024). The highest-incidence group (≥ 500 new cases per 100,000 population in 2024) comprises Lesotho, Kiribati, Papua New Guinea and the Philippines. These four countries alone account for 8.8% of new tuberculosis cases worldwide. Overall, two-thirds of the cases reported in 2024 were concentrated in eight countries: India, Indonesia, the Philippines, China, Pakistan, Nigeria, the Democratic Republic of the Congo and Bangladesh.⁵
Although around nine out of 10 cases are cured following specific antibiotic treatment, the disease’s mortality rate reaches almost 50% without treatment. In 2024, tuberculosis once again became the leading infectious cause of death worldwide, ahead of COVID-19 and HIV/AIDS: it caused 1.23 million deaths worldwide, representing a mortality rate of 11.5%.⁵
Tuberculosis remains relatively uncommon in France, which is among the countries with a low incidence of tuberculosis. In 2024, 4,491 cases of tuberculosis disease were reported, representing 6.6 cases per 100,000 population. This figure is slightly lower than in 2023. Reported mortality remains low: 30 tuberculosis-related deaths were reported in 2023, representing approximately 0.6% of reported cases.⁶
However, the average incidence reported in France conceals substantial geographical and social disparities: Santé publique France highlights that French Guiana, Mayotte and Île-de-France remain the most affected areas, with notification rates significantly higher than those in other regions. In French Guiana, for example, 74 cases were reported in 2024, corresponding to the highest notification rate in France, at 25.4 cases per 100,000 population.
This uneven distribution partly reflects the influence of social determinants and living conditions. Tuberculosis disproportionately affects people experiencing severe socioeconomic hardship, particularly people experiencing homelessness, those living in overcrowded or insecure housing, and people in prison. It is also more common among people born outside France, particularly when they come from countries where tuberculosis incidence remains high or have recently arrived in the country. Santé publique France therefore estimates an incidence of around 32 cases per 100,000 among people born outside France, around 64 per 100,000 among people experiencing homelessness, and 46 per 100,000 among people in prison. People living with HIV or with other causes of immunosuppression also constitute a group at increased risk of developing tuberculosis disease.⁶
Tuberculosis is transmitted through the inhalation of respiratory droplets containing M. tuberculosis, released when a person with pulmonary tuberculosis coughs, sneezes, speaks or sings. M. tuberculosis is transmitted through the respiratory route by individuals who have developed a pulmonary form of the disease.⁷ The bacterium is present in droplets of bronchial secretions released when the individual coughs, sneezes or sings. The bacillus can survive for several hours in the open air. People with latent (or dormant) infection and those with an isolated extrapulmonary form are not contagious.⁷
Inhaling infectious droplets does not necessarily lead to active disease: most people will eliminate the bacterium or harbour it without developing symptoms (latent infection). Only a minority (5 to 10% of infected people) develop active tuberculosis during their lifetime.⁸
Several factors have been identified as risk factors for pathogen transmission and disease development:⁸
In most cases, primary infection goes unnoticed because symptoms are mild, non-specific and transient, or even absent. In other cases, the pulmonary form of the disease may develop following infection or reactivation of the latent bacterium: it manifests as a gradual deterioration in general health, with weight loss, a moderate fever, night sweats and an increasingly frequent cough producing little sputum.⁹
Without treatment, pulmonary foci of infection progress, become necrotic and promote the formation of cavities in the lungs, where the bacterium proliferates. This phase is characterised by the onset of purulent sputum and haemoptysis: it is highly contagious and, when inadequately managed, can lead to the emergence of resistant strains.⁹
Pulmonary involvement accounts for around 80% of cases. The remaining cases are extrapulmonary forms.¹⁰
Lymph node tuberculosis accounts for between one-third and two-thirds of all extrapulmonary forms. It mainly affects the cervical lymph nodes, where it forms a reddish mass beneath the skin.¹⁰
Tuberculous pleurisy is the second most common extrapulmonary manifestation. It causes sudden symptoms: fever, chest pain, cough and pleural effusion.¹⁰ Other extrapulmonary forms are less common: central nervous system involvement (meningitis, tuberculomas), pericardial, osteoarticular, gastrointestinal, urogenital and laryngeal forms.¹⁰
Finally, miliary tuberculosis is a severe, disseminated form of the disease resulting from the spread of the bacterium through the bloodstream or lymphatic system to other organs: its symptoms are more severe than those of pulmonary tuberculosis, with involvement of other organs (liver, kidney, spleen, meninges…). A chest X-ray shows tiny infectious nodules throughout the lung tissue.¹⁰
A foetus can develop congenital tuberculosis through maternal transmission before birth, but these cases are extremely rare. Paediatric forms are more likely to occur after birth, following close contact with a person who is ill.⁷,⁹
In young children, particularly those under two years of age, infection more often results in severe pulmonary or extrapulmonary tuberculosis.⁷,⁹
Since 2001, the UN has been involved in the international coordination of tuberculosis control. In 2014, it launched the End Tuberculosis strategy, aiming to reduce tuberculosis incidence by 80% and associated mortality by 90% by 2030.
This led to favourable trends: the WHO African Region recorded a 28% reduction in incidence and a 46% reduction in the number of deaths associated with the disease, while Europe recorded an even greater decline, with reductions of 39% and 49%, respectively, over 10 years. However, the COVID-19 pandemic slowed this progress.
Meanwhile, multidrug-resistant and extensively drug-resistant strains have been proliferating for around 15 years, encouraged by the prolonged duration and complexity of antibiotic treatments, further undermining the prospect of eradication. In 2023, the UN therefore reaffirmed its commitments while setting new targets: 100% coverage with recommended rapid diagnostic tests and access to quality treatment for 90% of infected people. The commitment to investment, particularly in the development of new vaccines, was also reaffirmed.⁵
USAID and the Global Fund to Fight AIDS, Tuberculosis and Malaria are two major sources of international funding for tuberculosis control, helping to maintain screening, diagnosis and community organisation services in low- and middle- income countries with a high prevalence of the disease. Recent budget cuts affecting these organisations in 2025 pose a serious threat to maintaining the successes achieved so far and sustaining current progress.⁵
Tuberculosis screening aims to identify and treat people with tuberculosis as early as possible to improve their prognosis and reduce the risk of transmission.⁶ It also aims to identify people with latent infection so that they can be offered treatment to prevent reactivation.⁹
In France, the screening strategy is based on two complementary approaches tailored to risk factors:⁹
The screening strategy relies on a chest X-ray in adults and adolescents. In children under 12 years of age, an immunological test is preferred initially, using:⁹
When the chest X-ray shows suspicious abnormalities, bacteriological testing is performed using the patient’s sputum or, sometimes, bronchial aspirates or bronchoalveolar lavage samples: the diagnosis is confirmed by microscopic examination and culture of the sample, which also enables testing for possible antibiotic resistance. Rapid molecular tests (rapid PCR (polymerase chain reaction)-based molecular biology tests) can confirm the presence of the bacterium and its susceptibility to the main anti-tuberculosis antibiotics in less than two hours.⁹
The mechanisms that enable Mycobacterium tuberculosis to persist in the body and reactivate have not been fully identified. Scientists are seeking to develop methods that are simple, inexpensive, easier to implement than the tests currently used and suitable for use outside centralised facilities, whether to diagnose the disease or characterise antibiotic resistance. This challenge is particularly acute in low- and middle- income countries, which face both high incidence and difficult access to healthcare. For example, a recent experimental approach suggests that it may be possible to distinguish infected patients from control subjects by identifying bacillus-specific metabolites in exhaled breath.
Implementation research is needed to enable screening as early as possible, both to treat those affected and to interrupt chains of transmission at an early stage. Public health research projects are also needed to develop screening and follow-up strategies in areas affected by conflict, migration and tuberculosis. Two projects are currently underway: one focuses on Ukrainian refugees and their effective access to HIV and TB care in host countries (the MIGRASSOC project led by Daniel Kashnitsky), and the other focuses on internally displaced people in Burkina Faso (the TB-PDI-Sit project led by Anca Vasiliu and Nongodo Firmin Kabore).
Treatment of active tuberculosis relies on a combination of antibiotics for at least six months.⁸ The duration of treatment is tailored to the clinical presentation of the infection, the susceptibility of the strain and the patient’s clinical and immune status.⁸
In France, treatment is most often started during a hospital stay in isolation lasting around two weeks, to allow the patient’s bacterial load and infectiousness to decrease.¹¹ However, treatment of forms without respiratory involvement or a risk of transmission can be started on an outpatient basis. Tuberculosis affecting the nervous system and meninges requires a longer treatment duration of nine to 12 months, often combined with immunomodulatory treatment.
Poor or partial adherence to treatment encourages the emergence of resistant strains, which can in turn be transmitted in the same way as susceptible strains.⁸
Since the early 1990s, the emergence of antibiotic-resistant strains of M. tuberculosis has complicated the management of the disease, as they respond less well to treatment and increase the risk of death. Tuberculosis is described as multidrug-resistant (MDR-TB) when the strain is not susceptible to the two most potent first-line drugs (isoniazid and rifampicin) or is resistant to rifampicin (MDR/RR-TB), and as extensively drug-resistant (XDR-TB) when it is also resistant to other second-line drugs (fluoroquinolone, bedaquiline, linezolid).⁵
Although the number of diagnoses of multidrug-resistant or extensively drug-resistant strains reached alarming levels in the mid-2010s, it has declined since then: in 2024, MDR-TB and XDR-TB accounted, respectively, for 3.2% of new cases tested and 16% of cases among those who had previously been treated for tuberculosis.⁵
However, these figures are thought to be underestimated because antibiotic susceptibility testing is not systematically performed at diagnosis. Four countries account for the largest number of people with MDR-TB: India (32% of all cases worldwide), China (7.1%), the Philippines (7.1%) and the Russian Federation (6.7%).⁵ In Eastern European countries (particularly Belarus, Ukraine and Russia), up to one in two treated patients is estimated to have a multidrug-resistant form.⁵ Furthermore, an extensively drug-resistant clone (W148) is currently of great concern because it has a high capacity for transmission, allowing it to spread more easily than other strains.¹
The development of new antibiotics that are more potent, active against resistant strains and better tolerated, alongside therapeutic regimens that shorten treatment as much as possible while maintaining efficacy, is needed to cure more people, limit the emergence of antibiotic resistance, reduce the spread of the bacterium and limit the risk of epidemics.⁵
Basic research is essential for this purpose: it enables researchers to describe interactions between the bacterium and its host, the processes it uses to evade the host’s immune defences, and the host’s immune and pathophysiological responses and biological reactions during these events, which may help identify new therapeutic approaches to tuberculosis. The rise of multidrug-resistant and extensively drug-resistant strains hampers efforts to curb infection worldwide, as there is a constant risk that the tubercle bacillus will develop a new resistance mechanism against any new drug.⁵ Any new antibiotic may exert selection pressure that favours the emergence of new resistance mechanisms.⁵ It is therefore necessary to strengthen understanding of the links between genetic variations in M. tuberculosis and resistance to anti-tuberculosis drugs: mutations affecting the antibiotic’s target, impaired activation of certain anti-tuberculosis drugs, enzymatic inactivation of the drug, or changes in the permeability of the bacterial envelope (efflux pump).¹¹
The issue of bacterial persistence is equally important: understanding how the bacterium survives in a latent state and thus becomes insensitive to antibiotics, and the mechanisms that allow certain populations of M. tuberculosis to survive in specific metabolic states and thereby become tolerant to antibiotics in the absence of resistance genes, would help shorten treatment duration and reduce the risk of relapse.¹¹
Several approaches are being investigated to overcome these challenges:
Combined with conventional antibiotic therapy, these different approaches will be more effective and faster-acting, with a lower risk of resistance developing.
Since the mid-2010s, preventive treatment for latent tuberculosis has been offered to asymptomatic people at risk of developing active disease or infecting close contacts (household contacts, immunocompromised people…). Their care relies on the same drugs as those used against active tuberculosis, but generally involves fewer drugs in combination and a shorter overall treatment duration: broadly speaking, the standard regimen consists of dual antibiotic therapy for three months or monotherapy for four to six months.
Furthermore, BCG vaccination is no longer offered across the population in France because it is not sufficiently effective to fully interrupt transmission and completely prevent the risk of pulmonary forms. It is only offered to children growing up in an environment where there is a risk of infection, to prevent them from developing a severe form of the disease.⁵,⁹
The only vaccine currently available is BCG, administered intradermally, but it is only partially effective against pulmonary forms in adults and does not provide sufficient protection to counter infection at the population level. Vaccine research is therefore very important. This requires a deeper understanding of the immune processes triggered during infection and their correlates of protection. The selection of bacterial antigens capable of eliciting the most specific, potent and lasting immune response must also be optimised.
Research is now turning towards innovative candidate vaccines capable of preventing both primary infection and reactivation of latent infection. Conventional vaccine approaches are limited by insufficient stimulation of immunity, particularly cellular immunity. mRNA vaccine technology is being studied extensively because, by inducing host cells to produce the antigenic protein, it could elicit a different and more effective immune response. Furthermore, certain routes of administration may be more effective than the intradermal route used for BCG: intranasal mucosal administration could provide more effective and lasting local immunity in the respiratory mucosa, which is the bacterium’s main entry point.
ANRS Emerging infectious diseases is a major contributor to the funding and structuring of French tuberculosis research. The agency has undertaken disease control activities benefiting the most endemic countries and the most vulnerable populations, and has enabled significant advances in the treatment of tuberculosis–HIV co-infection and multidrug-resistant tuberculosis. It also facilitates national and international researcher networks to encourage collaboration between basic, clinical and translational research teams.
Since 2023, ANRS MIE has been working with the WHO Global Tuberculosis Programme under a scientific and technical cooperation agreement: it supports research projects aimed at producing scientific evidence in low- and middle- income countries to advance public health policies.
Alongside this, the agency has been facilitating the French scientific community since 2023 through a coordinated action on Tuberculosis organised around three cross-cutting, multidisciplinary themes: tuberculosis in mothers and children, tuberculosis and immunosuppression, and new therapeutic and vaccine strategies.
Preclinical research conducted within this framework has notably shown that intranasal delivery of antibiotics encapsulated in nanoparticles can be more effective than oral administration. On the clinical side, in 2024, ANRS MIE partnered with the South African Medical Research Council (SAMRC) through a joint call for proposals to encourage collaborations between the two countries on epidemiology, pathogenesis and the development of diagnostic tools and therapeutic strategies. Among the selected projects, some aim to develop mRNA vaccine strategies, individualised screening and treatment approaches, or to optimise the interpretation of diagnostic imaging using artificial intelligence.
In low- and middle- income countries where people live in close proximity to livestock and wildlife, an animal mycobacterium — Mycobacterium bovis — can cross the species barrier from herds to humans or monkeys. It is important to understand the determinants of mycobacterial circulation in this context through a global approach (One Health). The TTHALESS project, established in the eastern Democratic Republic of the Congo, aims to determine the prevalence and genetic characteristics of susceptible and resistant mycobacteria in the population and in wild and domestic animals. It will identify factors that favour this transmission and help establish a prevention and surveillance strategy tailored to the area’s specific characteristics.
In France, the number of diagnosed cases is known and monitored by Santé publique France, but the data collected are not comprehensive enough to describe patients’ care pathways precisely: the nature and tolerability of prescribed medicines, rates of recovery or relapse following treatment, and the risk of pulmonary sequelae… To better characterise this population, the French TB cohort was established by ANRS MIE in early 2026 for a period of 24 months. It aims to study the sociodemographic, clinical and bacteriological characteristics of people affected by TB, associated comorbidities and changes in their health status during treatment. The objective is to enrol 2,000 adults receiving treatment for active tuberculosis. The findings will guide future public health policies at the national level.¹²
The coordinated action on Tuberculosis devotes one of its areas of work to infected, vulnerable and immunocompromised people who are living with HIV or have other forms of immunosuppression, such as those associated with anti-TNF treatments, transplants or dialysis. These people are at increased risk of developing tuberculosis, and the simultaneous presence of tuberculosis and HIV worsens the prognosis of both conditions. It is therefore important to identify more effective therapeutic strategies for this population. DATURA is a phase III clinical study initiated by ANRS MIE in March 2022 to compare the effectiveness of an intensified tuberculosis treatment regimen in immunocompromised people with HIV against standard treatment. The study was conducted in six countries in Africa and South-East Asia, and its results could help improve prognosis through a therapeutic approach tailored to immunocompromised people.
Furthermore, since February 2021, ANRS MIE has been leading the INTENSE-TBM project, which aims to improve the care of people with tuberculous meningitis. This randomised clinical study compares several treatment approaches to determine whether certain medicines combined with anti-tuberculosis antibiotics (such as steroids or anticoagulants) could reduce mortality and the neurological sequelae of the disease compared with conventional treatment. The study involves participants from four sub-Saharan African countries, and its results are expected in the next few years.
To mark the anniversary of the discovery, on 24 March 1882, of the bacillus responsible for tuberculosis by Dr Robert Koch.
24 March 2026