New weapons needed to tackle growing threat of tuberculosis
28 March 2011
Leading experts from 12 countries discussed the growing threat from tuberculosis at a conference at the Institute of Tropical Medicine (ITM) in Antwerp this month.
Held to mark World TB Day, the conference addressed the need to develop new tools to prevent, treat and diagnose the disease.
Tuberculosis (TB) kills almost two million people each year, mostly in developing countries. It is an airborne infectious disease: people whose lungs are infected with the TB bacillus can infect others when coughing or sneezing.
When Robert Koch in 1882 announced his discovery of Mycobacterium tuberculosis (the tubercle bacillus that causes tuberculosis), the disease was raging through Europe and the Americas, causing the death of millions. Thanks to the progress of medicine, TB became preventable (with vaccines and hygiene) and curable (with drugs).
But the cure (taking several antibiotics for several months), is not easy on the patient, and many drop out. This leads to resistant bacilli, that are no longer sensitive to the antibiotics used. In this way, tuberculosis has re-emerged as one of the leading killers in the world.
The appearance of multi-drug-resistant strains — and even extensively drug-resistant strains, that are resistant to the most effective anti-TB drugs — has made the disease more difficult and more costly to treat than it was fifty years ago. In some isolated cases the bacilli even were found to be resistant against all available antibiotics.
What is more, TB and AIDS are aggravating each other. If you are infected with the one, you are more sensitive to the other. Approximately one-third of AIDS deaths today are caused by tuberculosis.
Resistant TB, HIV-associated TB, and weak health systems together raise concerns of a TB epidemic with restricted treatment options. To prevent TB from becoming a scourge again, it is vital that the TB control is managed properly.
One of those urgently needed tools is a simple, rapid, and affordable test to detect drug resistance in Mycobacterium tuberculosis, especially in low-resource countries where the incidence of tuberculosis is high.
In most low-income countries, diagnostic laboratories are unable to perform drug susceptibility testing on the TB bacillus, due to the high cost of the automated and molecular techniques, and the technological expertise required. This is where donors come in. But if funding stops, for instance because of the current economic crisis, the situation soon can turn dramatic.
Researchers at the Institute of Tropical Medicine began more than 10 years ago to investigate less expensive alternative non-commercial methods, accessible to low-income countries, to detect drug resistance “We focused on two new methods based on visual colorimetric detection”, say Juan Carlos Palomino and Anandi Martin, who also organise the conference. Their “CRI” and “NRA” tests (colorimetric redox-indicator, and nitrate reductase assay), giving results as good as commercial methods, now are recommended by the World Health Organisation for low-income countries.