Becoming exposed to or infected with a microbe does not necessarily mean developing noticeable disease. Explain.

An infectious microbe is able to cause a disease only if the immune system of the infected person is unable to put Proper defense against it. Many-persons have strong immune system or have acquired immunity against the pathogen or the intensity of pathogenic attack is quite mild. As a result, despite exposure to infective microbe, the person will not catch the disease.