Communicable diseases are the illnesses which are infected by microorganisms and transferred from an infected person or animal to another person or animal.
These diseases can be passed on by direct or indirect contact with an infected person or with their excretion.
Many numbers of diseases are spread via direct contact or close proximity as the viruses or causative bacteria are airborne in nature; i.e., they can be made in contact with the nose and mouth of the infected person and drawn in by anyone in the surrounding area. To name a few diseases of this nature- diphtheria, scarlet fever, measles, mumps, whooping cough, influenza, and smallpox.
On the other hand, some infectious diseases can be passed only indirectly, by and large through contaminated food or water. These diseases include typhoid, cholera and dysentery.
Yet there are some other kinds of diseases which are introduced into the body by an animal or insect carrier, e.g., rabies, malaria, encephalitis, Rocky Mountain spotted fever.
Please note that in specific cases such as tuberculosis, the disease may be passed on in several ways-by contact (human or animal), via used utensils or food and by the air. Management of communicable disease is based entirely upon the acknowledgment of the way in which transmission has taken place. It at times involves complete isolation of the person or even quarantine of persons with certain diseases.