Nothing to sneeze at: TB crisis much worse than we think
People are getting the wrong meds for the drug-resistant strain, a researcher warns
SA’s multidrug-resistant TB (MDR-TB) cases are much worse than thought, according to a study just published in prestigious journal Lancet Infectious Diseases.
Multidrug-resistant TB (MDR-TB) usually takes two years to cure. Only about 40% of patients are cured and medicine can cause deafness, according to the national Department of Health and the South African National Aids Council (Sanac).
The study argues that the World Health Organisation-approved tests used in SA to diagnose TB are missing a particular strain of TB that is resistant to two antibiotics. The tests detect the TB but misdiagnose it as responsive to most TB medicines.
This means patients will be incorrectly treated with ineffective drugs, remain infectious, spread the disease and then succumb to the disease.
Dr Emmanuel André, author and researcher from Belgian institution Katholieke Universiteit Leuven (KU Leuven), told Times Select the outbreak of a specific drug-resistant TB that was misdiagnosed was much worse than thought. He feared that unless something was done it would get worse.
He used highly specialised testing and looked at TB samples from four provinces for a drug-resistant strain that commercial tests incorrectly show as treatable with common TB antibiotics.
Samples from four provinces were tested, and the strain was found in Gauteng, Mpumalanga and North West.
André said: “The [ordinary] tests used are not missing TB, but are misclassifying them as TB ‘sensitive’ to Rifampicin [an antibiotic that treats TB]. Patients, therefore, are not offered the correct treatment, remain infectious longer and experience adverse outcome [death].”
The study showed that “the current strategies are insufficient to control the spread of multidrug-resistant tuberculosis in SA”.
New tests were needed, or the drug-resistant strain would continue to spread in the country and to neighbouring countries, he said.
“With the current tools and strategies, the problem will only extend further. I am personally concerned about the risk of adverse evolution of this outbreak if nothing is done.”
The press release on the study, issued by the KU Leuven, said the same: “A substantial number of MDR-tuberculosis cases harbouring the specific mutation in the gene in South Africa are missed by current diagnostic strategies, resulting in ineffective first-line treatment, continued amplification of drug resistance and concurrent silent spread.”
Before the study was published, SA authorities and the World Health Organisation (WHO) were told about these findings, André said.
But a prominent local researcher said the tests done across the country showed that this type of TB was rare.
Professor Nazir Ismail from the National Institute of Communicable Diseases (NICD), who spent two years researching how bad MDR-TB was across SA, said he disagreed with the findings.
“I don’t think it reflects the general situation in South Africa. We have analysed the occurrence of this mutation from the TB drug-resistance survey conducted in South Africa, which was done at the same time as their research.”
He said his study found only one out of 1,535 (<0.1%) TB patients had this unusual mutation that didn’t respond to medication, but couldn’t be detected by ordinary tests.
But Ismail said doing repeated tests across the country had completely different results.
“Thus we have not been able to verify these findings using larger numbers from more diverse geographical regions. The implications are that the ‘outbreak’ referred to is in all likelihood very localised and has not become generalised in later years based on available information.”
He said they would collaborate with the investigators if they investigated those reported findings further.
Ismail added that although TB diagnostic tests were not 100%, 95% of all drug-resistant TB cases were correctly detected.
He cautioned there was no need for panic.
According to his studies, about 8,000 of the 400,000 TB cases are multidrug-resistant and correctly diagnosed.
The NICD also disagreed with André’s findings. They said it took place over four years, meaning the cases couldn’t be considered an outbreak (which happens in a short period of time).
The NICD did a much bigger study of TB prevalence in more places across the whole country at the same time and hardly found any of this drug-resistant TB, it said.
The NICD release said its study “would have detected an outbreak if it existed”.
But André is adamant current tests are missing the problem and that multidrug-resistant TB is going to spread through SA.