Tuberculosis is a disease that is caused by a bacterium. There are two types of bacteria that can cause the disease. Mycobacterium bovis and Mycobacterium tuberculosis. The Mycobacterium bovis is normally found in unpasteurised milk whilst the Mycobacterium tuberculosis is normally air borne. Transmission of TB through the air from one individual to another is normally achieved through sustained contact over a period of time. Typical examples include living with or working with a person.
Image supplied by Alila Medical Media for more images of bacterial cells click on the link. The diagram above provides more information than is needed for A level. However, it has been added to deepen your subject knowledge.
Very often when first infected with tuberculosis the bacteria will act as in the diagram above and at stage 3 they will lie dormant and then tend to activate at a later point. Tuberculosis is very much an opportunistic disease, it will activate when the immune system is weak. Examples of this include a person suffering from HIV or an elderly person.
Treatment for tuberculosis lasts 6-9 months. It normally involves taking multiple antibiotics. The course must be completed to avoid antibiotic resistance from developing.