Abstract
Tuberculosis (TB) is an urgent public health problem, but many people do not have access to critical diagnostic tools.
In 2016, the World Health Organization (WHO) noted that the TB epidemic was larger than previously estimated, with 10.4 million new cases of TB in 2015, the increase driven primarily by improved case notification from the private sector in India. However the TB incidence rate and the number of deaths from TB continue to fall globally.1,11-13 In 2015, an estimated 1.4 million people died from this largely curable disease with a further 400 000 deaths from TB reported among people living with HIV.1 The Global tuberculosis report (2015) noted that TB now ranks above HIV as a leading cause of death worldwide.11
Access to accurate TB diagnostics and drug susceptibility tests enable TB programmes to identify TB cases and select appropriate treatment. WHO estimates that almost 40% of all TB cases in 2015 were either not diagnosed or cases not reported to national tuberculosis programmes. The Global tuberculosis report (2016) noted: “If everyone with TB had a timely diagnosis and high-quality treatment, the case fatality rate would be low in all countries”.1 Recognizing the critical importance of drug susceptibility testing, the WHO End TB Strategy includes universal drug susceptibility testing as a key component of its first pillar: integrated, patient-centred TB care and prevention. Several of the molecular tests currently in development also o er genotypic drug susceptibility testing, either integrated into the diagnostic test or as a reflex assay for TB-positive samples.
Improvements in the diagnosis of multidrug-resistant tuberculosis (MDR TB) are associated with greater implementation of molecular tests, in particular, line probe assays and the Cepheid Inc. GeneXpert® MTB/RIF assay (hereina er Xpert® MTB/RIF). However, an estimated 75% of all MDR TB cases are still not identified and reported.1
Robust and accurate molecular technologies would have the greatest impact on improving diagnosis if they were made available at microscopy centres, where most people with signs and symptoms of TB seek a diagnosis.14 Although candidate products are described in this landscape report, to date, no molecular test has been su iciently assessed to demonstrate the potential to do this.
The WHO treatment guidelines for drug-resistant TB were updated in 2016.15 They note that rifampicin-resistant TB cases, with or without resistance to isoniazid should be treated with MDR TB regimens, with the recommendation that a shorter regimen (9–12 months) be used for cases that are not resistant to second-line drugs. Furthermore, WHO issued interim guidance on the use of bedaquiline in 2013 and the use of delamanid in 2014;16,17 and policy guidance on the use of delamanid for the treatment of MDR TB in children (aged 6–17 years).18
