Tuberculosis is a disease caused by a bacterium named Mycobacterium Tuberculosis which mostly affects the lungs but can also affect the live, lymph nodes, bones and kidneys.Tuberculosis occurs in those who are homeless, in those who are in prison and in those who live in crowded and unsanitary conditions. Immigrants from developing countries might also be affected by this disease.The disease spreads from human to human while breathing. If the affected person coughs or sneezes he will spread in the air droplets of saliva which contain the TB bacterium. The infection can not be taken so easily but those who live in the same place with the infected person are at risk of catching the disease.In most of the cases if the bacteria gets into the lungs the immune system will stop it from dividing and so the bacteria will remain in an inactive state inside the lungs. Many people are in this situation and they are just fine as long as their immune system is working properly. These people have no symptoms and they can be discovered as carriers of the disease only by a special skin test.The symptoms of TB will appear in 10% of those who have an inactive germ inside their lungs. These symptoms are common with the flu symptoms and most of the people will not even suspect tuberculosis and have a shock when they hear the diagnosis. Besides the classical symptoms of fever, night sweats and fatigue the patient might cough with blood and might loose weight in a shot while.The skin test is not enough to declare a man ill. A chest x-ray needs to be done along with laboratory tests for sputum. Also the fact that one has been living or got in close contact with an infected person might count when diagnosing tuberculosis.The treatment of tuberculosis lasts a long period of time, from six to nine months but it gives remarkably good results in patients. The treatment will contain a combination of two or three drugs taken at the same hour and for the recommended period of time in order to have any positive effect on the patient. Isoniazid is one of the used drugs. It is not expensive, it have little side effects and is easy to take. Other useful drugs are Rifampin, Streptomycin, Pyrazinamide, and Ethambutol. These drugs are combines as to assure the needed efficiency for the patient. In some cases the bacterium which is responsible for the disease might be resistant to one of the drugs and so the therapist will replace that drug with another one.The bacterium might be resistant due to a treatment which had not been completed or due to a wrong usage of the medicines.Luckily there still exist drugs which can replace the basic used drugs in therapy so there will be no problems in treating any patient.