Mycobacterium tuberculosis causes tuberculosis, or TB. This is an infection primarily of the lungs, but it can affect other areas of the body as well. The bacteria can spread throughout the bloodstream and lymphatic system to reach distant organs like the liver, intestines and kidneys. It can also infect organs that are near the lungs.
Miliary Tuberculosis
Miliary tuberculosis is also called disseminated tuberculosis because it disseminates or spreads throughout the body. The term "miliary" is used because pathologists in the 19th century thought the lesions it caused resembled millet seeds, according to Dr. Mario Raviglione, director of the StopTB Department at the World Health Organization in "Harrison's Principles of Internal Medicine." The bacteria spread throughout the bloodstream. Symptoms depend upon what part of the body is affected by the disease. People usually experience weight loss, night sweats, weakness, decreased appetite and fever.
TB Meningitis
Meningitis is the inflammation of the meninges, or the membrane that covers the brain. In TB meningitis, bacteria infect this membrane. This disease is more common among people who have an impaired immune system and the elderly. Symptoms include headache, fever and drowsiness. Without treatment, people will become less mentally alert and may even go into a coma. Some may develop a lesion in the brain called a tuberculoma. Others can have a stroke if a clot interferes with blood flow to a vessel of the brain, explains Dr. Edward Nardell, associate professor of Harvard Medical School in "The Merck Manual for Health Professionals."
Pericardial TB
The pericardium is a two-layer membrane that surrounds the heart. Pericardial TB is also called tuberculous pericarditis, which refers to the inflammation of the pericardium. Bacteria either directly infect this membrane or infect it after a nearby lymph node ruptures, releasing the bacteria inside. This disease usually affects the elderly and HIV patients. Dr. Raviglione writes in "Harrison's Principles of Internal Medicine," that there is a high mortality rate, as much as 40 percent. Normally, there is a small amount of fluid between the two layers of the membrane. The infection can cause a buildup of fluid that can press down on the heart. People may experience pain, fever and difficulty breathing.
Skeletal TB
Most people with skeletal TB have an impaired immune system, or have emigrated from a country with many cases of tuberculosis. Approximately 50 percent of skeletal TB infections affect the spine, according to Dr. David Hellmann, chairman of the Department of Medicine at Johns Hopkins Bayview Medical Center in "Current Medical Diagnosis & Treatment." When people have a TB infection in their lungs, the bacteria reach the spine by traveling through the bloodstream. Symptoms may not manifest until years later. This is called Pott's disease and the symptoms may include back pain and weakness in the legs.
References
- "Current Medical Diagnosis & Treatment 2010"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2010
- "Harrison's Principles of Internal Medicine"; Anthony Fauci, M.D., Dennis Kasper, M.D., Dan Longo, M.D. et al.; 2008
- The Merck Manual for Health Professionals: Tuberculosis (TB)
