TB remains a major infectious disease worldwide, with more than 10 million cases, resulting in 1.4 million deaths each year. The synergy with the AIDS epidemic and the emergence of strains of Mycobacterium tuberculosis (Koch's bacillus) multiresistant to antibiotics and chemotherapeutic agents contribute to aggravating the impact of this disease, considered by the World Health Organization (WHO) as a global health emergency. Despite the enormous health and social issues surrounding TB, there is some progress to note. Indeed, the WHO estimates that between 2000 and 2019, 63 million lives were saved thanks to the diagnosis and treatment of this disease, but the future of this promising assessment may be impacted by the COVID-19 pandemic, which causes many disruptions to screening and treatment centers.
Epidemiology
On average, 10 million people develop an active form of the disease each year (10 million in 2019, according to the World Health Organization - WHO). And TB is one of the top 10 causes of death worldwide. In 2019, 1.4 million people died, 208,000 of whom were also infected with HIV. More than 95% of TB deaths occur in developing countries, but TB remains a major public health problem in many industrialized countries, especially when it comes to multidrug-resistant forms, which are particularly difficult and long (2 years) to treat.
Globally, a quarter of the world's population is infected with Mycobacterium tuberculosis, and 30 countries alone account for 87% of global cases. Globally, there were an estimated 206,030 cases of multidrug-resistant TB in 2019, 10% more than in 2018.
Transmission
Tuberculosis is a contagious disease, caused by the Koch's bacillus (strains of the Mycobacterium tuberculosis complex). This infectious agent is transmitted by air, via droplets containing bacteria, and expectorated by the cough of patients. Inhaling a small number of contaminated droplets is enough to infect an individual. An untreated TB person can infect an average of 5 to 15 people each year. Precarious health and social conditions are often associated with the spread of the disease.
The disease
The active development of the disease among people infected with Koch's bacillus depends on many factors (genetic, immunological, nutritional, and social). It is estimated that 5-15% of infected people will develop TB with symptoms during their lifetime. The bacillus can remain in the body in a 'dormant' state for years. Immunocompromised people have a higher risk of developing active TB. The HIV virus and Koch's bacillus form a dangerous combination, as system deficiencies caused by HIV infection help TB progression. If left untreated, TB is fatal in almost all people with AIDS.
Treatment
In the 40s, there were no drugs to cure tuberculosis. Today, a combination of antibiotics and chemotherapy is used to treat tuberculosis patients, but treatment must be followed for at least 6 months (and up to two years in the case of multidrug-resistant strains). Incomplete or poorly followed treatment is often responsible for the development of antibiotic-resistant TB, which is then transmitted in the community. When treatable, these cases of drug-resistant TB are 100 times more expensive to treat than TB cases that can be treated with standard regimens.
Vaccine
B.C.G. (Bacille de Calmette et Guérin) is the only vaccine currently licensed to vaccinate against tuberculosis. Nevertheless, this vaccine, which celebrates its 100th anniversary in 2021, is a partially effective vaccine: although it is very useful for preventing severe forms of the disease in young children (almost 90% effective in the case of tuberculous meningitis), it provides little protection against cases of pulmonary tuberculosis in adolescents and adults. It, therefore, does not prevent the transmission of the disease and stop the global epidemic.
At the Institut Pasteur
Several teams of microbiologists, immunologists, and geneticists are developing research programs to understand the host-bacillus interaction (including genomic tools), study the genetic evolution of the bacillus, improve the diagnosis of the disease, and find new anti-tuberculosis drugs and improved vaccines.
Faithful to its teaching mission, the Institut Pasteur offers a course "Tuberculosis – biology of microorganisms", and a MOOC, based on international experts. This course is intended for physicians, veterinarians, directors of clinical mycobacteriology laboratories, pharmacists, and researchers who wish to acquire current knowledge about tuberculosis and the practice of molecular methods of diagnosis and medical susceptibility testing, new drugs and treatment regimens as well as molecular and traditional epidemiology. Created in Shanghai in 2008, it has since been taught in Paris, Tunis, and Yaoundé. The next session of the course will take place in 2023.
Latest WHO Reports
TANZANIA, Tanzania (AP) — Senior United Nations officials, health industry leaders, and activists on Monday called for the world to invest more in developing new vaccines and fighting a resurgence of tuberculosis, fuelled by the impact of COVID-19 and armed conflict, including in Ukraine and Sudan.
Monday's event aims to set the stage for the annual meeting of the UN General Assembly in September, which will hold a meeting on tuberculosis.
The latter is the most common deadly infectious disease today, killing approximately 4400 people every day worldwide, including 700 children," said Dr. Lucica Ditiu, Executive Director of the Stop TB Partnership.
UN Under-Secretary-General Amina Mohammed said international efforts to combat the disease have saved 74 million lives since 2000. However, more than 10.5 million people contracted the disease and about 6.1 million died in 2021, and it is now the leading cause of death among people living with HIV.
The TB epidemic is fuelled by a multitude of factors, including poverty, malnutrition, and HIV, and disproportionately affects the most vulnerable in all countries, she said.
According to her, $22 billion is needed to provide all people diagnosed with TB with access to quality treatment by 2027, as well as access to health and social benefits so that they do not suffer financial hardship. It also says an additional $5 billion a year is needed for research.
"We can develop safe and effective vaccines and one-stop shops for quality testing and care," she said.
The Director-General of the United Nations World Health Organization (WHO), Tedros Adhanom Ghebreyesus, said in a video address to the meeting that COVID-19 "has turned our world upside down" for three years and that in addition to the millions of deaths attributed to it, it has deprived millions of people of essential health services.
"Conflicts in Europe, Africa, and the Middle East have made these essential services even more difficult for people living with TB to access," he said. These challenges were a setback in the fight against TB, wiping out some of the important gains we had made over the past 20 years in expanding access to prevention, testing, and treatment. »
Ukraine has the highest estimated number of people with TB in the European Region, at 34 000. It is also home to a high number of people with drug-resistant TB, Dr. Ditiu said.
Ghebreyesus argued that the September meeting must be a turning point in reviving the fight against the disease. This is why WHO "has proposed to establish a TB Vaccine Acceleration Council to facilitate the development, licensing, and use of new vaccines."