Infectious disease can spread in several ways. They are as follows:

1. Through Air: The infected particles spread by means of sneeze or cough of the infected person which releases little droplets containing the microbes. These droplets when inhaled by another person can get infected by the disease. Eg: Common cold, pneumonia.

2. Through water: The excreta of person suffering from the infectious disease get mixed with the drinking water supply. Then these diseases can spread. Eg: Cholera

3. Physical Contact: Infectious diseases such as AIDS, syphilis etc can spread by means of sexual contact. AIDS can even be infected by blood to blood contact and even through breastfeeding from mother to child.

4. Through vectors: Mosquitoes and the insects serve as vectors for the transmission of different disease. Eg: Malaria