Miliary tuberculosis. X-ray of the chest of a patient with miliary tuberculosis (TB). Affected areas of the lungs (black) are shown by grainy white patches. TB is caused by the bacterium Mycobacterium tuberculosis, which is spread by coughing and sneezing. The bacteria create primary tubercles, nodular lesions of dead tissue and bacteria, when inhaled into the lungs. Miliary TB is the spread of the disease, via the blood and lymph, to other organs. Tubercles are found throughout the body, including in the brain. Miliary TB is often hard to detect and if left untreated is fatal. Treatment is with long-term antibiotics.