Tuberculosis (TB)

Guideline Development Group meeting “Molecular assays intended as initial tests for the diagnosis of pulmonary and extrapulmonary TB in adults and children. Policy Update”, 3-6 December, 2019, Geneva, Switzerland

Tuberculosis (TB) causes 10 million cases and 1.5 million deaths annually and it is estimated that 3 million cases go undiagnosed each year[1]. WHO-endorsed rapid TB diagnostics and drug susceptibility testing (DST) should be available to all persons with signs and symptoms of TB to meet the targets of the End TB Strategy.

The development of the Xpert® MTB/RIF assay (Cepheid, Sunnyvale, USA) was a major step forward for improving the diagnosis of TB and rifampicin resistance (RR) detection globally. In 2011, WHO endorsed the use of Xpert MTB/RIF for diagnosis of TB and detection of RR, and recommended that it be used as the initial diagnostic test in individuals living with HIV and/or suspected of having drug-resistant TB. The Xpert® MTB/RIF Ultra assay (Ultra) has been developed by Cepheid as the next-generation assay to overcome these limitations, which uses the same GeneXpert® platform as Xpert MTB/RIF. Furthermore, new molecular assay Molbio TrueNat MTB/Rif was developed in India, which potentially may be used at the same health system level as Xpert MTB/RIF, and be used as an initial test for TB.

WHO will convene a Guideline Development Group (GDG) to meet 3-6 December 2019 in accordance with the WHO processes and procedures for guideline development, to assess the available evidence on the use of Xpert® MTB/RIF, Ultra and Molbio TrueNat MTB/Rif for the diagnosis of active TB (pulmonary and extra-pulmonary) and rifampicin-resistance in adults, adolescents and children with signs and symptoms of TB, as well as people being screened for TB which will be later disseminated as the updated WHO guidelines.

Key topics

Early TB detection

Too many people have undetected TB for too long; late detection of TB increases their risk of transmitting the disease to others, having poor health outcomes, or that they and their family will suffer distress and economic hardship. Progress in controlling TB and mitigating its consequences can be expedited through early diagnosis and treatment.

Diagnostics and laboratory strengthening

A high-quality laboratory system that uses modern diagnostics is a prerequisite for the early, rapid and accurate detection of TB and drug resistance. WHO has established a structured, systematic process to rapidly review the evidence base for new TB diagnostics, ensuring that new tools meet the required performance standards.

Active case finding/systematic screening

Systematic screening for active TB is defined as the systematic identification of people with suspected active TB, in a predetermined target group, using tests, examinations or other procedures that can be applied rapidly.

Contact investigation

Tuberculosis contacts are people who have close contact with patients with infectious TB. As they are at high risk for infection (and in line with the End TB strategy), TB contacts should be investigated systematically and actively for TB infection and disease.

Outbreak management and air travel

The transmission of airborne infections between people in confined spaces such as aircraft cabins is of particular concern to health officials and the general public.

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