Investigations

If available, a tuberculin skin test should be done, as it may provide supportive evidence. A negative tuberculin test does not exclude TB. The tuberculin test is discussed in Section 4.5.

CXR is a common investigation in suspected PTB or miliary TB. The most consistent specific feature on CXR is nodal enlargement and this will be present in many children with PTB. Cavitation may be seen in older children and adolescents, who will often be sputum smear-positive. A normal CXR can be useful to exclude PTB or miliary TB in a child with suggestive symptoms, such as persistent fever, night sweats and failure to thrive.A single CXR at the time of presentation of illness has limited value.A child presenting with persistent cough should receive a course of broad-spectrum antibiotics, with a follow-up CXR at least one month later. As for clinical examination, marked abnormalities are occasionally found on CXR in a child who does not look acutely unwell. This is suggestive of PTB.

The usefulness of the tuberculin test and CXR are further reduced in malnourished or HIV-infected children (see Section 4.5). This is unfortunate as these are common conditions that the health worker often needs to differentiate from TB. To add to the confusion, both groups are at particular risk for TB disease.

Differential diagnosis of chronic respiratory symptoms

Other conditions that present with chronic respiratory symptoms include:

° pertussis (whooping cough) ° asthma

° HIV infection (see section 4.8) ° aspirated foreign body ° bronchiectasis ° cystic fibrosis ° cardiac disease

° severe gastro-oesophageal reflux ° severe cerebral palsy

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