TB affects children differently to adults. It is very difficult, for example, for a child to transmit TB to another child, and an adult is almost always the source of infection. TB may also manifest not only in the lungs of children, but also even more dangerously, in other parts of the body such as the brain. TB can also be difficult to diagnose in a child because they find it difficult to cough up sputum.
If your child is under five and has been in close contact with someone who is diagnosed as having TB, the child will probably be put onto isoniazid preventative therapy (IPT). IPT is a precaution taken to ensure that any latent TB that may have infected the child is eliminated.