In 1993, the World Health Organization (WHO) declared tuberculosis a global emergency. Tuberculosis (TB) is responsible for more deaths than any other infectious disease. Every year around 9 million people are infected with TB around the world, and 1.5 million people die from it.
TB is caused by an infection with a bacterium called Mycobacterium tuberculosis. It most commonly affects the lungs but can spread via blood from the lungs to any organ in the body. This means that TB can develop in the covering of the lungs (the pleura), lymph nodes, brain, skin, bones, urinary tract, sexual organs and the intestines.
TB is more common in areas of the world where poverty, malnutrition, poor general health and social disruption are present. It is also seen in people whose immunity is reduced, for example in people with HIV infection. TB is especially common in sub-Saharan Africa, where the proportion of people who are HIV-positive is exceptionally high.
In the UK, the number of TB cases is rising. People who are alcohol dependent, HIV-infected, have recently settled in the UK or who work in healthcare are at increased risk.
Today, treatment involves three or four different antituberculous drugs given in combination over six months for drug sensitive disease and over 20 months for multi-drug resistant (MDR) disease.
The MRC Clinical Trials Unit has recently participated in two multi-centre international clinical trials, REMoxTB and RIFAQUIN, which investigated the possibility of shortening treatment from 6 to 4 months. Another study, Study C, addressed the question whether giving a combined formulation of drugs is as effective as giving the drugs separately.
The evidence base for treating MDR-TB is very poor. The MRC CTU is currently conducting STREAM, a trial assessing a 9-month regimen previously studied in an uncontrolled investigation in Bangladesh. The control regimen is the standard treatment of up to 24 months duration which is currently recommended by WHO.