The disease called tuberculosis, or TB, affects the lungs and sometimes other parts of the body. In the 18th and 19th centuries tuberculosis was the leading cause of death in Europe and North America. At that time the disease was commonly called consumption. People who had it were kept—sometimes for years—in special hospitals called sanitariums. Today tuberculosis is treatable. However, it remains a major cause of death in some countries of Africa, Asia, and Latin America.

Causes

Tuberculosis is caused by several types of rod-shaped bacteria. The kind of bacteria that causes most cases in humans is called Mycobacterium tuberculosis. This bacterium infects the respiratory system, especially the lungs. This form of the disease is called pulmonary tuberculosis. A less common form of tuberculosis is caused by a bacterium called Mycobacterium bovis. It affects the bones and joints. Humans get this kind of tuberculosis by drinking milk from an infected cow.

Symptoms

Most of the people infected with the bacteria that cause tuberculosis do not suffer from the disease. The body's immune system defends against the bacteria by surrounding them with protective cells. The bacteria and the surrounding cells create lumps called tubercles in the lungs. The infection usually heals without causing any symptoms.

Sometimes the infection does not heal and instead spreads into the bloodstream and through the body. This happens mostly in children. In other people the bacteria remain harmless for years before becoming active again in adulthood. This can happen when a person's immune system is weakened because of advanced age or another illness. These people become ill with pulmonary tuberculosis. Their symptoms include coughing, chest pain, difficulty breathing, fever, sweating, loss of energy, and weight loss. The person may cough up blood. If the tubercles spread throughout the lungs, the person may die from not being able to breathe properly.

The form of tuberculosis that spreads from cows to humans first attacks the lymph nodes. The nodes swell in the neck and then burst through the skin to create sores. The bacteria may spread to any part of the body, but usually they damage bones and joints. Eventually the disease causes deformities of the spine or other body parts.

Diagnosis and treatment

Doctors take a number of steps to find out whether a person has tuberculosis. They perform a special skin test to see if the person is infected with the bacteria that causes the disease. However, the test does not indicate whether the person has the active disease or not. If the skin test shows infection, the doctor can ask for a chest X-ray to see if there are tubercles in the lungs. The doctor may also use a microscope to look for bacteria in the person's sputum (the matter that the person coughs up).

If the person has tuberculosis, the doctor prescribes a medicine called an antibiotic. Some patients may be hospitalized so that the antibiotics can be given through the veins. If the medications are taken as directed, the person has a good chance of recovery.

Prevention

Tuberculosis spreads most easily in crowded places where living conditions are poor. Therefore, one important way to prevent the disease is maintaining good sanitation and keeping people generally healthy and well nourished. In some countries people are given a vaccine to protect them from tuberculosis.

The type of tuberculosis that is spread through cow's milk can be prevented by pasteurizing the milk. Pasteurization is a heat-treatment process that kills the disease-causing bacteria. This form of tuberculosis is rare in parts of the world where milk is pasteurized.