Even though there are two main species of bacterium that cause TB, the species responsible for bovine TB in cattle very rarely infects humans. Name the species of bacterium that is the principal cause of TB in humans.
Explain the route by which the pathogen named in (a) passes from a person with the disease to a person who is uninfected.
State the category of therapeutic drug used in the treatment of TB.
Fig. 4.1 is a photomicrograph showing a section of lung tissue from a person who has not been infected with the bacterial pathogen and who does not have TB. Blood vessels and some structures of the gas exchange system can be seen in Fig. 4.1. On Fig. 4.1, use a label line and label: a bronchus; a bronchiole; a blood vessel.
In some people with TB, regions called granulomas may develop in lung tissue as part of an immune response to the pathogen. Fig. 4.2 is a photomicrograph of a granuloma in lung tissue. With reference to Fig. 4.1 and Fig. 4.2, describe and explain how the changes that occur as a result of granuloma formation: • can affect gas exchange and harm the health of an infected person • may help to prevent TB developing in other parts of the body.