How disease like tuberculosis and pneumonia transmit from and infected person to an healthy person?

Answer 1

For tuberculosis: it is transmitted by droplets, i.e. coughing or sneezing.

For pneumonia: viral pneumonia, again, droplets. Bacterial pneumonia, normal body bacteria from the skin and mucous membranes, travel to the lungs and cause infection in the presence of fluid in the lungs, like there would be if you were congested.

In all instances, having a suppressed immune system can increase the chances of getting the disease/illness.

Answer 2

You cannot spread TB meningitis from an infected person to another, unless the person with TB meningitis also has active pulmonary TB at the same time.

TB is only spread by coughing - if you do not have active lung infection at the time, then you cannot be contagious. We see people all the time who have TB in the spine, TB in the brain, or even TB in the lymph nodes -- as long as they have no TB in the lungs, they do not require isolation.

When you inhale TB, if you do not get treated, eventually it can spread through your lympatic vessels into the brain. Thus, years later you can develop TB meningitis long after any sign of lung disease is gone. So by the time you get TB meningitis - it is very very rare to be contagious at all.