Tuberculosis is a highly infectious disease of the lungs transmitted via aerosols. An aerosol in this instance will be caused by sneezing and coughing both of which produce small water droplets in which are carried living bacterial cells.
The cause of tuberculosis is the bacterium Mycobacterium tuberculosis. Infected water droplets ejected by a sneeze or cough from a person with the active pulmonary infection, are inhaled by another person who breathes in and retains the bacterial cells.
Useful link: http://bepast.org/docs/photos/MDR%20tuberculosis/AerosolTransmission.jpg
This is known as the Primary Infection.
The result is an infected individual who may or may not present symptoms of the disease to themself or to doctors. However, the bacteria cause tubercles in the lungs; these are localised collections (aggregates) of bacterial cells.
Useful link: http://bepast.org/docs/photos/MDR%20tuberculosis/tubercles%20on%20the%2… Image of tubercles on the ribcage
Although the individual may not know they are infected, their sensitivity is increased to the bacteria and the bacterium's metabolic products (hypersensitivity). A simple diagnostic test called unsurprisingly the Tuberculin Test will identify how great the hypersensitivity is.
Useful link http://www.kimicontrol.com/edu-e.html
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