Tuberculosis (TB)

TB detection and diagnosis

On 20 January 2017, World Health Organization (WHO) convened a Technical Expert Consultation to assess the performance of the new Ultra assay compared with the Xpert MTB/RIF assay in a multi-centre diagnostic accuracy study coordinated by FIND in ten study sites in eight countries. The Technical Expert Group found that the Ultra assay is non-inferior to the Xpert MTB/RIF assay for the detection of Mycobacterium tuberculosis (MTB) and for the detection of rifampicin resistance. This means that the new Ultra cartridge is at least as good for the detection of MTB and rifampicin resistance as Xpert MTB/RIF.

In certain populations, the Ultra performs better for MTB detection especially for individuals whose specimens are frequently paucibacillary. The Ultra cartridge showed better performance for the detection of MTB in smear-negative culture-positive specimens, paediatric specimens, extra-pulmonary specimens (notably cerebrospinal fluid) and in testing smear-negative culture-positive specimens from HIV-positive individuals.

The current WHO recommendations for the use of Xpert MTB/RIF now also apply to the use of Ultra as the initial diagnostic test for all adults and children with signs and symptoms of TB and in the testing of selected extrapulmonary specimens (CSF, lymph nodes and tissue specimens).

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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