Operational Handbooks

In children with signs and symptoms of PTB in settings with a pre-test probability of 5% or higher (prevalence of confirmed TB of 5% or above in this specific population), repeat testing with Xpert MTB/RIF or Ultra may be considered after an initial negative Xpert MTB/RIF or Ultra test if the clinician has a high index of suspicion that the child has TB, using any of the recommended specimen types.

The urine lateral flow lipoarabinomannan (LF-LAM) assay is an immunocapture assay based on the detection of the mycobacterial lipoarabinomannan antigen in urine. For specific populations, LF-LAM may be used together with other approved TB diagnostics tests and affords a distinct advantage as a point-of-care test. Although the assay lacks sensitivity, it can be used as a fast bedside rule-in test for people living with HIV, especially in urgent cases where a rapid TB diagnosis is critical for the person’s survival.

Depending on the availability, resources and capacity, appropriate specimens from suspected sites of involvement should be collected for rapid testing using mWRDs or culture, and histopathological examination should be done for children with EPTB whenever possible. WHO recommends that NTPs replace microscopy as the initial diagnostic test for TB with mWRDs, which can be used on various respiratory and non-respiratory specimens (Table 4.4) (76).

WHO-recommended clinical samples for the diagnosis of PTB in children and adolescents using Xpert MTB/RIF or Ultra include sputum (expectorated or induced), gastric or nasopharyngeal aspirates, and stool. Other mWRDs using respiratory samples have only been validated on sputum samples. Each of these specimen types has distinct advantages and disadvantages (Table 4.1). Annex 3 summarizes the types of respiratory and non-respiratory specimens.

Although there are no findings on clinical examination that can confirm TB, some clinical signs are highly suggestive. In addition, a variety of nonspecific signs should raise clinical suspicion and prompt an evaluation for TB disease. The following clinical features can alert care providers that the child may have TB (6, 72):

TB may present in atypical ways, such as acute severe pneumonia (more common in children aged under 2 years and children living with HIV) or fixed airway wheezing (more common in young children aged under 5 years) (72).

Signs of severe pneumonia include:

In most cases, children with TB disease develop chronic unremitting symptoms that persist for more than 2 weeks without sustained improvement or resolution following treatment for alternative diagnoses (e.g. antibiotics for pneumonia, antimalarials for fever, nutritional rehabilitation for failure to thrive or malnutrition). The most common clinical presentation of PTB in children is persistent cough and poor weight gain.

PTB refers to any bacteriologically confirmed or clinically diagnosed case of TB involving the lung parenchyma or tracheobronchial tree. Tuberculous mediastinal and/or hilar intrathoracic lymphadenopathy is also classified as PTB, following an expert consultation convened by WHO in September 2021.¹⁵ Miliary TB is classified as PTB because there are lesions in the lungs. Tuberculous pleural effusion without radiographic abnormalities in the lungs constitutes EPTB. A person with both PTB and EPTB should be classified as having PTB (71).

Diagnostic evaluation is the step in the care cascade after screening. Children and adolescents who screen positive during contact investigation or at health facility-based screening, and those who present to a health care facility with signs and symptoms of TB and who are identified as having presumptive TB must be evaluated further for TB disease.