Communicable Diseases

Communicable Diseases

What Are Communicable Diseases?

Communicable diseases are infectious diseases that can spread from one organism to another. They are caused by pathogens, such as bacteria, viruses, fungi, and protists.

💡 Key Concept: These diseases can spread through direct contact, water, air, vectors, or bodily fluids.

Types of Pathogens

Pathogen Type

Examples of Diseases

How It Spreads

Bacteria

Salmonella, Tuberculosis

Contaminated food, water, air

Viruses

Measles, HIV, Influenza

Airborne droplets, bodily fluids

Fungi

Athlete’s foot, Rose black spot

Direct contact, spores in air

Protists

Malaria

Mosquito vectors

 

How Are Communicable Diseases Spread?

Method of Transmission

Example Disease

Air (droplets)

Influenza, COVID-19, Measles

Water (contaminated drinking water)

Cholera

Direct Contact

Athlete’s foot, STIs

Vector (e.g., insects)

Malaria (mosquitoes)

Contaminated Food

Salmonella

💡 Why Is This Important? Understanding how diseases spread helps us prevent infections.

 

How the Body Defends Against Pathogens

✔ Skin – Acts as a barrier to pathogens.
✔ Mucus & Cilia (Respiratory System) – Trap and remove microbes.
✔ Stomach Acid – Kills bacteria in food.
✔ White Blood Cells – Engulf and destroy pathogens, produce antibodies and antitoxins.

💡 Vaccines help protect us by training the immune system to fight infections.

Questions 

  1. What is a communicable disease?
  2. Name one disease caused by bacteria.
  3. How is malaria spread?
  4. What does stomach acid do?
  5. How do white blood cells protect us?

Summary 

  • Communicable diseases spread between organisms and are caused by pathogens (bacteria, viruses, fungi, protists).
  • Pathogens spread via air, water, direct contact, and vectors.
  • The body defends itself with the skin, mucus, stomach acid, and white blood cells.