For test preparation, students should be able to state the cause, transmission and effects of one human bacterial disease.
Tuberculosis (TB) Example of a Bacterial Disease
| Cause: | Caused by the rod-shaped bacterium called Mycobacterium tuberculosis. Stress, malnutrition, overcrowding help increase the chance of infection. |
| Transmission: | Passed by droplet infection via coughs of infected persons. Non-infected people breathe in the droplets of bacteria which enter the lungs and start to grow & divide there! |
| Effects: |
Phagocytes recognize the bacteria as an infection, taking individual bacteria in by endocytosis. The bacteria survives within the phagocytes and reproduces. The body responds by forming small rounded swellings known as tubercles around the infected phagocytes. These tubercles in the lung are visible with via X-Rays for diagnosis. Infections stay within the lung & become less severe over time. Reinfection may cause a chronic form of the disease where lung tissue slowly is destroyed. The person develops a fever, loses their appetite and becomes very thin. They develop a persistent cough & may cough up blood. At this point, the disease may spread to the lymph nodes, bones and gut. Death eventually occurs. About 3 million deaths occur worldwide each year due to TB. It had largely disappeared in the US, but has recently begun a comeback! |