A new rapid test that can diagnose TB meningitis within two
hours has been developed in SA and is currently undergoing validation to enter
the global market.
Finding a sensitive, rapid test for TB meningitis has been
elusive, but now one has been developed through a collaboration between the
University of Cape Town (UCT) and Antrum Biotech.
“Detection under the microscope only works 5% of the time. Smear microscopy is
a very poor test. Another existing test for TB meningitis involves growing the
bug in the lab in a culture, and there are problems with that too,” says
Professor Keertan Dheda, the director of the Centre for Lung Infection and
Immunity at UCT.
This culture-based test has a sensitivity of only 60% to 70%, and it can take
four to eight weeks to give a result. “By then most people would have died, or
they would have developed severe disabilities due to the disease,” says Dheda.
The GeneXpert DNA detection test for TB is widely used in
South Africa, but studies show that it is not sensitive enough to detect TB
meningitis, but the test has limited sensitivity. “Although it is rapid in
getting the answer on the same day, the problem is that it detects TB meningitis
in only 50-60% of cases; we have a major unmet need for a more sensitive test,”
“Preliminary results from our studies show a vast improvement in sensitivity
when compared to GeneXpert,” he says.
Two percent of TB cases, which are caused by mycobacterium tuberculosis,
develop into an infection of the membranes around the central nervous system
(meninges). This TB meningitis can cause death or disability, especially in
children, but is easily treatable if diagnosed early.
Funding from the BioFISA II programme has allowed researchers to develop the
test further, and it is now undergoing a series of validation studies in
southern African populations to pin down its sensitivity more accurately. This
will include comparative sensitivity to GeneXpert.
Antrum Biotech and its partners plan continue with validation studies even
after the test goes on sale soon.
“There will be even larger studies and studies by different groups of people in
different parts of the world to confirm the results that we found in Southern
Africa,” Dheda says.