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
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
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.