Different ways by which communicable diseases are spread are :
a. Through air – some diseases like cold, influenza, tuberculosis spread through droplets in the air by a sneeze or a cough from a diseased person.
b. Through food and water – diseases like typhoid, dysentery, cholera and other intestinal infections spread through polluted water and contaminated food.
c. Through direct contact – some diseases like conjunctivitis and scabies spread through direct contact with the infected person.
d. By insects – Insects act as a carrier to spread infection by carrying the disease causing germs, e.g. Malaria, dengue are spread by the bite of infected mosquitoes.