Tuberculosis occupies a singular place among large-scale epidemics. Certainly, the number of cases of tuberculosis is very gradually decreasing around the world, and the rate of mortality fell 45% between 1990 and 2013. But in 2013, 9 million people developed tuberculosis and 1.5 million died from it. More than 95% of cases of tuberculosis and deaths come from countries with low or moderate income.
However, the infectious agent, the tuberculosis bacterium (Mycobacterium tuberculosis) that causes the illness, was identified in 1882 along with its mode of transmission -airborne, though person-to-person contact with infected people- and an effective treatment is available for free worldwide, which is atypical for such a large-scale epidemics.
This paradoxical situation is explained by the very high prevalence of the infection, as it's estimated that a third of all people are infected with tuberculosis bacteria, even if only 5% of people will actually develop the disease at some point in their life, sometimes years after contact with a contagious person.
Children under 5 and people infected with HIV are particularly vulnerable populations, with a 5 to 30 times elevated risk of developing the disease. Tuberculosis diagnosis is difficult and often comes late, when people are the most contagious, allowing the epidemic to continue. Moreover, children under five and people infected with HIV frequently have a disseminated form of the disease, which is more serious and very difficult to diagnosis with standard methods. New technology allowing for rapid diagnosis is being developed and represents an important advance. Treatment, which consists of a combination of four medications over six months, is often difficult to administer in its entirety, which leads to the development of treatment-resisted tuberculosis. In 2013, 480,000 people developed multidrug-resistant tuberculosis, for which diagnosis and treatment is more difficult, and 9% of them developed extensively drug-resistant tuberculosis (which resists all standard treatment), for which the vital prognosis is very grim.
Tuberculosis and HIV
Tuberculosis and HIV mutually accelerate their progression. People living with HIV have a much higher risk than others of developing the active disease. In 2013, an estimated 1.1 million new cases of tuberculosis were reported in people living with HIV, 78% of them living in Sub-Saharan Africa.
Preventative treatment for tuberculosis has demonstrated the possibility of limiting the epidemic, but it is still little used. Mortality related to tuberculosis is also elevated in people living with HIV: around 360,000 people died in 2013 of tuberculosis associated with HIV, which makes it the No. 1 cause of mortality in people infected with HIV.
Access to preventative treatment and diagnosis for tuberculosis in people infected with HIV and children under five remains one of the major challenges in countries with limited resources. Solthis is leading projects in operations research to evaluate the performance and cost/efficiency for different tuberculosis testing strategies for people living with HIV, particularly in Niger and Guinea. Solthis is also working to develop access to preventative treatment for adults and children in Guinea.