Clinical features

Tuberculosis can present in children in

many ways. Serious forms like tuberculous meningitis, miliary tuberculosis etc. often affect young children less than 5 years of age. In routine office practice, tuberculosis should be suspected in the following situations:

• Cough of more than 3 weeks duration _ without sneezing, running nose or wheeze.
• Low grade fever of more than 2 weeks duration with no response to first line antibiotics.
• Lymphadenopathy: which may be generalised,
  but most commonly involving cervical lymphnodes. The lymphadenopathy is usually soft to firm and there may be matting. other causes of lymphadenopathy like pharyngitis, scalp infection, Dilantin therapy must be ruled out. Axillary lymphnodes may be enlarged following BCG vaccination itself and trivial injuries to the lower limbs may result in inguinal adenopathy.
• Hepatosplenomegaly, where other infections and noninfections possibilities have been ruled out.
• Any child who has positive history of contact with tuberculosis with any combination of the aforementioned clinical features.
• Any child with malnutrition, particularly Grade III and IV* (I.A.P.** classification) with any of the afore mentioned constellations.

Investigations:

A CBC may reveal information such as lymphocytosis in tuberculosis. However, it may be nonspecific. Other investigations for tuberculosis are:

1. E.S.R. : this is usually raised

2. Mantoux test _ In India, we must use only I tuberculin unit of Purified Protein Derivative. A positive reaction is defined as induration more 10mm, which usually occurs 48.72 hours after the administration of test.

The mantoux test is a skin test for detecting tuberculous infection and is based on delayed hypersensitivity. It should be administered whenever a child's disease process is suspected to be tuberculous. It should be given as I.T.U of PPD (Purified Protein Derivative) on the flexor aspect of the forearm. The left forearm is the chosen spot, by convention. The tuberculin should be given intradermally. One should ensure that the injection raises a wheal. The test is read 48,72 hours after the injection. A positive reaction is induration and not erythema. It should have a diameter of greater than 10 mm, to merit the designation of positivity. The Mantoux test is invaluable in tuberculous detection, in the under-five age group, beyond which its relevance may diminish.

Several conditions may lead to false negativity of this test. They are (a) faulty tuberculin product, (b) faulty techniage, (c) age < 6 months, (d) Immunosuppression, (e) incubation period of tuberculous and (f) severe forms of tuberculous.

Few conditions may cause false positivity. There are (a) recent vaccination with BCG, (b) Atypical mycobacterial infections.

3. X-ray chest - This investigation may reveal changes such as collapse, collapse with consolidation (so called segmental lesion), bronchopneumonia (which may mimic miliary mottling), lobar pneumonia, miliary mottling (the infiltrations involve the entire lung fields unlike in bronchopneumonia), pericardial effusion (very rare).

4. Gastric aspirate for AFB: This test is very useful in children who don't bring out the sputum like adults. It is done by aspirating the gastric contents early in the morning on empty stomach for 3 consecutive days.

5. Analysis of various aspirates: Such as pleural, peritoneal and pericardial fluid aspirates may be useful. These aspirates are subject to chemical as well as bacteriological tests.

Flow chart for office practice of Tuberculosis

6. Miscellaneous tests - these include CT scan for Neurotuberculosis. Fine needle aspiration cytology (FNAC) and excision biopsy for lymphadenopathy. Skin biopsy for cutaneous tuberculosis etc.

7. Newer tests - include there are PCR, ELISA etc. These may not be feasible in most of the instances.