5.2 Characteristics of tuberculosis in children

Children have a high risk of TB infection. In endemic areas, children are likely to be exposed to TB in their household or community. A careful contact history is extremely important in children with signs and symptoms suggestive of TB. In children with diagnosed TB, an effort should be made to detect the source case and any other undiagnosed cases in the household. The younger the child, the more likely it is that a contact can be identified. Equally, all TB cases, especially children or adults who are smear-positive, should be asked about close contact with children (Chapter 16).

Children have a high risk of progression to active TB disease and of developing severe forms: 90% of young children, who develop TB, do so within 12 months of infection2. Children < 3 years and children with immune suppression (e.g. HIV, malnutrition, post-measles) are particularly vulnerable. TB screening with prompt treatment or prophylaxis is especially critical in these children.

Most cases are pulmonary TB (PTB), but smear positivity is rare because children generally have low bacillary loads. Furthermore, sputum samples can be difficult to obtain from children. As a result, smear-positive TB represents only an estimated 10% of all TB observed in the 0 to 14 age group.

Extrapulmonary TB (EPTB) is common in children. The site of EPTB disease is age related. Miliary and meningeal TB is more frequently seen in young children. TB lymphadenitis and osteoarticular TB are more common in older children.

BCG administered at birth offers partial protection against severe forms in young children. It offers little if any protection against pulmonary TB. A history of BCG vaccination does not exclude the possibility of TB in a child with suggestive signs and symptoms.