Tuberculosis in Children
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Direct answer
A child with fever or cough beyond two weeks, weight loss or failure to gain, especially with a household tuberculosis contact, has paediatric tuberculosis until excluded — the Ghon focus with its draining lymph node (the primary complex) is the hallmark, and lymphohaematogenous spread produces miliary disease, tuberculous meningitis and spinal TB. Diagnosis is paucibacillary and stitched together: tuberculin testing (induration 10 mm or more, only 5 mm in HIV or severe malnutrition), chest X-ray, and CBNAAT (Xpert MTB/RIF) on gastric aspirate, induced sputum or stool per the National Tuberculosis Elimination Programme. Treatment is the daily weight-band regimen 2HRZE then 4HRE, and contacts under six years receive preventive therapy once disease is excluded.
What you must remember
- The primary complex: a subpleural Ghon focus plus enlarged hilar or mediastinal nodes; most infections self-heal, but progression risk is highest under five years, in malnutrition and in HIV.
- Tuberculin test: 1 TU of RT-23 intradermally on the volar forearm, transverse induration read at 48–72 hours; 10 mm or more is positive, 5 mm suffices in HIV or severe malnutrition, and a BCG scar does not explain 10 mm or more.
- False-negative mantoux: severe malnutrition, measles, disseminated tuberculosis, immunosuppression, early infection — a negative test never excludes TB in a sick child.
- CBNAAT detects Mycobacterium tuberculosis and rifampicin resistance in about two hours, and the NTEP endorses it on gastric aspirate, induced sputum and stool in children.
- Triggers for work-up: fever or cough over two weeks, unexplained weight loss or failure to thrive, a compatible chest X-ray — household contact history raises pre-test probability sharply.
- NTEP treatment of a new case: daily isoniazid, rifampicin, pyrazinamide and ethambutol for two months, then isoniazid, rifampicin and ethambutol for four, dispensed by weight-band boxes with pyridoxine; tuberculous meningitis gets longer therapy plus corticosteroids.
- Preventive therapy: contacts under six years and HIV-infected child contacts, after active disease is excluded, receive isoniazid for six months or a shorter rifampicin-based regimen.
- BCG protects mainly against miliary and meningeal disease — not reliably against pulmonary tuberculosis — and every severely malnourished child failing nutritional treatment deserves a TB evaluation.
Working through a contact
A four-year-old, weight flat for three months, night fevers for three weeks, lives with a sputum-positive father now on treatment. Examination and weight-plotting come first; the mantoux reads 14 mm; chest X-ray shows right hilar fullness; a gastric aspirate (or stool, in many NTEP settings) sent for CBNAAT reports detected, rifampicin not detected. He is registered and started on the weight-band daily regimen — HRZE for two months, HRE for four — with pyridoxine and monthly weights; the expected response is fever settling within weeks and the curve turning up by two months. His two-year-old sibling, asymptomatic with a normal film, is not treated for disease: after exclusion, preventive therapy begins. Two prescriptions from one household — treatment and prevention — are the pairing the exam tests. Had rifampicin resistance been detected, the child would move to the drug-resistant pathway, which is the point of ordering CBNAAT rather than relying on smear.
Where students slip
The greatest confusion is infection versus disease: a positive mantoux in a well, growing child with a normal chest X-ray is infection (or BCG), and full treatment is not given — preventive therapy is a consideration for contacts and the immunocompromised. Second, the cut-offs get swapped and the "BCG causes positivity" excuse is stretched to big reactions. Third, abandoning microbiology because "children are paucibacillary" — the programme explicitly pushes CBNAAT samples in children. Fourth, forgetting the contact under six: "what do you do for the 3-year-old sibling" answers "screen, exclude disease, give preventive therapy". And fifth, calling every failure-to-thrive case tuberculosis without looking hard at nutrition — both drive each other in India; the answer is to investigate, not to choose one dogma.
Frequently asked questions
What size of mantoux induration is positive in a child?
Ten millimetres or more of transverse induration at 48–72 hours; five millimetres or more is positive in HIV infection or severe malnutrition, and a BCG scar does not account for reactions of 10 mm or more.
Which samples are used for CBNAAT in young children?
Gastric aspirates obtained early morning, induced sputum, and — increasingly under the NTEP — stool, which avoids intubation and returns rifampicin-resistance results in about two hours.
What is the NTEP regimen for new paediatric tuberculosis?
Daily isoniazid, rifampicin, pyrazinamide and ethambutol for two months, then isoniazid, rifampicin and ethambutol for four months, in weight-band boxes with pyridoxine.
What care does a child contact under six years receive?
Screening for active disease with examination and chest X-ray, then preventive therapy with isoniazid or a rifampicin-based short regimen once disease is excluded.
Why can a mantoux be negative in advanced tuberculosis?
Severe malnutrition, disseminated disease, measles and immunosuppression depress cell-mediated immunity — anergy makes the test unhelpful in exactly the sickest children.
What does BCG protect against?
Chiefly the disseminated forms — miliary tuberculosis and tuberculous meningitis of early childhood — rather than pulmonary disease, which is why BCG status never overrides a compatible picture.