Contagious vs. Infectious: How You Catch Diseases

Have you ever wondered why you sometimes catch a cold from a friend but not from a stranger on the bus? The answer lies in the distinction between infectious diseases and contagious diseases.

While the terms are often used interchangeably, they have important differences in how illnesses spread. This blog explores the concepts of infectious diseases vs contagious diseases, helping you understand how you can catch different illnesses. 

Infectious Disease: A Microscopic Culprit

An infectious disease is any illness caused by a microscopic organism that invades the body. These invaders can be:


Single-celled organisms can reproduce rapidly and cause a variety of illnesses, from strep-throat to food poisoning. 


Even smaller and simpler than bacteria, viruses rely on host cells to multiply and cause infections like the common cold or influenza. 


These organisms live off another living organism (the host) and cause diseases like malaria or giardia. 


While some fungi are harmless, others can cause infections like athlete's foot or ringworm. 

The Infectious Disease Spread Escape

infectious diseases can spread in various ways, not all of them involving direct contact. Here are some common transmission methods:

Airborne transmission: 

Coughing or sneezing releases tiny droplets containing viruses or bacteria that can be inhaled by others. (e.g., common cold, influenza)

Direct contact: 

Touching an infected person or contaminated object and then touching your face can transfer infectious agents. (e.g., colds, some skin infections)

Indirect contact: 

Touching a contaminated surface (doorknob, light switch) and then touching your face can spread germs.

Foodborne transmission: 

Consuming contaminated food or water can introduce bacteria, viruses, or parasites into the body. (e.g., food poisoning)

Vector-borne transmission: 

Mosquitoes, ticks, or other insects can transmit diseases like malaria or Lyme disease through bites.

Contagious Disease: Catching It from Someone Else

A contagious disease is a subset of infectious diseases that can be easily transmitted from one person to another. Contagious diseases typically spread through the methods mentioned above but with a high degree of ease. Examples of contagious diseases include:

  • The common cold
  • Influenza (the flu)
  • Measles
  • Mumps
  • Chickenpox
  • Head lice

Not All Infectious Diseases are Contagious

It's important to understand that not all infectious diseases are contagious. Here are some examples:


Caused by bacteria in soil or dust, tetanus enters through a wound and doesn't spread from person to person. 

Food poisoning: 

While some foodborne illnesses can be contagious (spread through contaminated food handlers), others are caused by toxins in spoiled food and are not contagious. 

Fungal infections: 

While some fungal infections like ringworm can be spread through contact, others, like athlete's foot, are not easily transmitted from person to person. 

Protecting Yourself from Infectious and Contagious Diseases

Here are some important steps to reduce your risk of contracting infectious diseases and contagious diseases: 

Frequent handwashing: 

Regular handwashing is widely recognized as the single most effective strategy to prevent the spread of germs.  

Practice good cough and sneeze etiquette: 

Cover your mouth and nose with a tissue or your elbow to prevent airborne transmission. 

Stay home when sick: 

Avoid close contact with others when you're feeling unwell to prevent spreading illness. 

Maintain a healthy lifestyle: 

Getting enough sleep, eating a balanced diet, and managing stress can help strengthen your immune system. 


Getting vaccinated against preventable diseases is important for both your individual health and community protection. 

Understanding the Difference

By understanding the distinction between infectious diseases and contagious diseases, you can take targeted steps to protect yourself and those around you. 

Remember, infectious diseases are caused by microscopic invaders, while contagious diseases are a specific type of infectious disease that spreads easily from person to person. 

Types of infectious diseases encompass a wide range, while types of contagious diseases are those readily transmitted through various means. 

By following these tips and staying informed, you can empower yourself to stay healthy and prevent the spread of illness. 

Be Aware and Take Care.

365Bloggy April 4, 2024
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