Miliary tuberculosis is a potentially life-threatening type of tuberculosis that occurs when millions of Mycobacterium tuberculosis bacteria travel through the bloodstream and spread throughout the body.
Tuberculosis (TB) is a contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. TB most commonly affects the lungs (pulmonary TB), but it can spread to many organs through the blood.
Miliary TB is so named because the infection causes tiny spots to form typically in the lungs but also in other organs. The spots are the size of a millet, which is the small round seed in bird food.
Miliary TB may affect one organ or several organs or occur throughout the body. It most often affects the lungs and bone marrow but may affect any organ, including the tissues that cover the brain and spinal cord (meninges) and the two-layered membrane around the heart (pericardium).
Miliary TB occurs most often in the following:
Children under 4 years old
People with a weakened immune system (especially those with HIV infection)
Older adults
Symptoms of Miliary TB
Symptoms of miliary TB can be vague. They include weight loss, fever, chills, weakness, general discomfort, and difficulty breathing.
Infection of the bone marrow may cause severe anemia or other blood abnormalities, suggesting leukemia.
If bacteria are intermittently released into the bloodstream from an unrecognized infection, people may have a fever that comes and goes and may gradually lose weight.
Diagnosis of Miliary TB
Examination and culture of a sample from the infected area
Nucleic acid amplification tests
Imaging tests
Diagnosis of miliary TB is similar to the diagnosis of pulmonary TB.
Samples of infected tissues and fluids may be examined under a microscope and/or sent to a laboratory to be grown (cultured) and tested. Samples may be:
Blood
Cerebrospinal fluid, obtained by spinal tap (lumbar puncture)
Urine
Fluid or tissue from the space between the two layers of the membrane that surrounds the lungs (pleura)
Fluid or tissue from the space between the two layers of the membrane that surrounds the heart (pericardium)
Joint fluid
Bone biopsy samples or bone marrow
Lymph nodes
Mycobacterium tuberculosis can sometimes be identified by doing nucleic acid amplification tests (NAATs) on certain types of samples. NAATs look for an organism's unique genetic material, its DNA or RNA (which are nucleic acids). NAATs use a process that increases the amount of the bacteria's DNA or RNA so that it can be more easily identified.
The tuberculin skin test or blood tests to detect TB (interferon-gamma release assay) are done.
A chest x-ray shows the thousands of small spots in the lungs. Other imaging tests are done depending on which areas of the body are affected. They may include computed tomography (CT) scans, ultrasounds, and magnetic resonance imaging (MRI) scans.
Treatment of Miliary TB
Antibiotics
Sometimes steroids (sometimes called corticosteroids or glucocorticoids)
Sometimes surgery
Generally, treatment of miliary TB is similar to the treatment of pulmonary TB.
Antibiotics are given for 6 to 9 months, unless the meninges are affected. Then antibiotics are given for 9 to 12 months.
Tuberculosis bacteria can easily develop resistance to antibiotics, particularly when people do not take the antibiotics regularly or for as long as they are supposed to.
Steroids may be given if the pericardium or meninges are affected.
Surgery is needed for some complications of miliary TB. For examples, doctors drain infected fluid from the membranes around the lungs or remove infected portions of intestine.
Miliary TB can rapidly progress to lung injury and cause acute respiratory failure or acute respiratory distress syndrome (ARDS) in untreated people who have a weakened immune system. Many organs can stop functioning properly, which increases the risk of death.
