Screening

Several clinical characteristics, conditions and comorbidities can indicate an increased risk for developing TB disease or suffering worse outcomes from the disease, or both. Individuals identified as having untreated fibrotic lesions on CXR and who are not diagnosed with TB disease are at increased risk of developing TB disease (34–37). These individuals are often identified through TB screening or clinical evaluation or during a clinical evaluation done for other reasons.

The production of the WHO consolidated guidelines on tuberculosis. Module 2: screening was coordinated and written by Cecily Miller, with support from Annabel Baddeley, Dennis Falzon and Matteo Zignol, under the overall direction of Tereza Kasaeva, Director of the World Health Organization (WHO) Global Tuberculosis Programme. The WHO Global Tuberculosis Programme gratefully acknowledges the contribution of all experts involved in producing these guidelines¹.

Tuberculosis (TB) is a leading cause of death from a single infectious agent, despite being largely curable and preventable. In 2019 an estimated 2.9 million of the 10 million people who fell ill with TB were not diagnosed or reported to the World Health Organization (WHO). The Political Declaration adopted by the United Nations General Assembly in September 2018 at the High-Level Meeting on the Fight Against Tuberculosis commits to, among other goals, diagnosing and treating 40 million people with TB by 2022.

The tables below contain modelled estimates of the performance and outcomes of the 10 screening algorithms described above, when applied to a population of 100,000 people being screened, across three different TB prevalence settings: 0.5%, 1% and 2%. 

1 – Screening with cough

2 – Parallel screening with cough and CXR

3 – Sequential positive serial screening with cough and CXR

4 – Sequential negative serial screening with cough and CXR

5 – Screening with any TB symptom

mWRDs are now also recommended for screening people living with HIV. (See 3.1.4 for a full description of their use in screening). A positive mWRD screen result in a person with HIV must be followed by further diagnostic evaluation to confirm or rule out TB.