WHO Policies on Tuberculosis Diagnostics

WHO Rapid Implementation of the Xpert MTB/RIF Diagnostic Test, 2011

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STAG/WHO endorses negative policy recommendations on commercial serological tests for TB diagnosis, 2010

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WHO roadmap for Xpert MTB/RIF for rapid diagnosis of TB and MDR-TB, 2010

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WHO Framework for Implementing New Tuberculosis Diagnosis, 2010

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WHO policy statement: Same-day diagnosis of tuberculosis by microscopy, 2010

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WHO policy statement: Fluorescent light emitting diode (LED) microscopy for diagnosis of tuberculosis, 2010

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WHO policy statement: Non-commercial culture and drug-susceptibility testing methods for screening of patients at risk of multidrug-resistant tuberculosis, 2010

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WHO Policy on Liquid Media for Culture and DST, 2007

WHO recommends, as a step-wise approach:
  • 1. The use of liquid medium for culture and DST in middle- and low-income countries.
  • 2. The rapid species identification to address the needs for culture and drug susceptibility testing (DST). Taking into consideration that liquid systems will be implemented in a phased manner, integrated into a country specific comprehensive plan for laboratory capacity strengthening and addressing the following key issues:
    • 1. Appropriate biosafety level;
    • 2. detailed customer plan describing guarantees and commitments of the manufacturer;
    • 3. appropriate training of staff;
    • 4. maintenance of infrastructure and equipment in laboratories;
    • 5. quick transportation of samples from the peripheral to the culture laboratory;
    • 6. rapid communication of results.
Link to full-text: http://www.who.int/tb/dots/laboratory/policy/en/index3.html

WHO Policy on Definition of a New Sputum Smear-Positive TB Case, 2007

The revised definition of a new sputum smear-positive pulmonary TB case is based on the presence of at least one acid fast bacilli (AFB+) in at least one sputum sample in countries with a well functioning external quality assurance (EQA) system.

Link to full-text: http://www.who.int/tb/dots/laboratory/policy/en/index1.html

WHO Policy on Reduction of Number of Smears for the Diagnosis of Pulmonary TB, 2007

WHO recommends the number of specimens to be examined for screening of TB cases can be reduced from three to two, in places where a well-functioning external quality assurance (EQA) system exists, where the workload is very high and human resources are limited.

Link to full-text: http://www.who.int/tb/dots/laboratory/policy/en/index2.html

WHO Policy on Molecular Line Probe Assays for Rapid Screening of Patients at Risk of Multidrug-Resistant Tuberculosis, 2008

The use of line probe assays is recommended by WHO, with the following guiding principles:
  • Adoption of line probe assays for rapid detection of multidrug-resistant tuberculosis (MDR-TB) should be decided by Ministries of Health within the context of country plans for appropriate management of MDR-TB patients, including the development of country-specific screening algorithms and timely access to quality-assured second-line anti-TB drugs.
  • Line probe assay performance characteristics have been adequately validated in direct testing of sputum smear-positive specimens and on isolates of Mycobacterium tuberculosis complex grown from smear-negative and smear-positive specimens. Direct use of line probe assays on smear-negative clinical specimens is not recommended.
  • The use of commercial line probe assays, rather than in-house assays, is recommended to ensure reliability and reproducibility of results, as in-house assays have not been adequately validated or used outside limited research settings. Any new or generic line probe assays should be subject to adequate validation, that is, published laboratory validation studies, adequate data to allow systematic review and meta-analysis (including assessment of data quality), and results from field demonstration projects documenting feasibility and consistent performance equal to conventional methods and commercial line probe assays.
  • Adoption of line probe assays does not eliminate the need for conventional culture and drug-susceptibility testing (DST) capability; culture remains necessary for definitive diagnosis of TB in smear-negative patients, while conventional DST is required to diagnose extensively drug-resistant TB (XDR-TB). However, the demand for conventional culture and DST capacity may change, based on the local epidemiological situation and the use of line probe assays in country-specific screening algorithms.
  • As current line probe assays only detect resistance to rifampicin and/or isoniazid, countries with documented or suspected cases of XDR-TB should establish or expand conventional culture and DST capacity for quality-assured susceptibility testing of second-line drugs, based on current WHO policy guidance.
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STAG-TB endorses LED microscopy, same-day smear diagnosis, and selected non-commercial rapid culture methods

Link to full-text: http://www.who.int/tb/advisory_bodies/stag_tb_report_2009.pdf