Definition: Diseases not spread from one host to another or from person to person.
Example:
Tetanus: Acquired from environmental sources like soil. It cannot be transmitted from an infected person to another.
Communicable Diseases
Definition: Diseases that are spread from one host to another.
Examples:
Sexually Transmitted Infections (STIs): Spread through sexual contact from an infected person to another.
Contagious Diseases
Definition: A subset of communicable diseases that are spread easily and rapidly from one host to another.
Examples:
Influenza: Commonly spread through airborne droplets.
Measles: Extremely contagious; can be transmitted from a room that an infected person occupied up to 4 hours prior. If no immunity is present, there's over a 90% chance of contracting measles after exposure.
Summary
Noncommunicable Diseases: Not spread from person to person.
Communicable Diseases: Spread from one person to another.
Contagious Diseases: Easily and quickly spread from one person to another.