2.3 Disseminated or miliary tuberculosis

Miliary TB is a generalised massive infection characterized by diffusion of bacteria throughout the body. The disease may manifest as a miliary pattern or very small nodulary elements (“millet seeds”) in the lungs. It can occur immediately after primary infection or during reactivation of a latent site; it is thought to occur during haematological spread10.

The classic acute form is mostly found in children, young adults and HIV patients. The presentation can be either abrupt or insidious, marked by a progressive deterioration of the patient’s physical condition. The clinical picture is often completed within one to two weeks and is characterized by a profoundly altered physical condition, marked wasting, headaches and constant high fever. Discrete dyspnoea and coughing suggest a pulmonary focus; however, lungs can often be clear on auscultation. A moderate hepatosplenomegaly is occasionally found. Certain forms of miliary TB evolve in a subacute fashion over several months.

Given this non-specific clinical picture, typhoid fever and septicaemia should be considered in a differential diagnosis.

Diagnosis of miliary TB is confirmed by chest X-ray (Chapter 3, Section 3.7). When feasible, fundoscopy would reveal choroidal tubercles. Generally, sputum smear examination is negative. When there is no possibility of obtaining chest X-rays, the lack of response to broad-spectrum antibiotics is an argument in favour of miliary TB.

In children, the risk of meningeal involvement is high (60-70%)11,12. Lumbar puncture should be routinely performed if miliary TB is suspected.

The tuberculin skin test is more likely to be falsely negative than in any other form of TB.

Miliary TB is a medical emergency.