Final answer:
Communicable diseases can be transmitted through airborne transmission, direct contact, contact with infected body fluids, and sexual transmission.
Step-by-step explanation:
There are several ways in which communicable diseases can be transmitted. Some of the most common routes include airborne transmission, such as when pathogens in droplets are expelled from an infected person's respiratory system during coughing or sneezing. Direct contact between an infected person and a new host, through skin-to-skin contact or touching the same surfaces, is another way. Additionally, pathogens can be transmitted through contact with infected body fluids, such as blood or saliva, and through sexual transmission.