BIOLOGY - Infectious diseases

What is an Infectious disease?

A communicable disease

What are infectious diseases caused by?

Caused by Pathogens (bacteria, viruses, fungi, parasites).

What is a non-infectious disease?

A non-communicable disease that is not caused by pathogens.

What are non-infectious diseases caused by?

Genetics, lifestyle, or environmental factors.

Give examples of infectious pathogen types.

Cellular - Parasites, Protozoa, Fungi, Prokaryote

Acellular - Virus, Prion

What are the 2 kinds of pathogen?

Cellular and Acellular

What are the characteristics of a pathogen?

Small and often microscopic

Able to invade a host and multiply

Can disrupt normal bodily functions

Adapt to evade host immune responses

What are the stages of Pathogenic Infection?

1. Exposure: Pathogens come into contact with the body

2. Adhesion: Pathogens attach to host cells using specific molecules (adhesins) that bind to receptors on the host cell surface

3. Invasion: Pathogens enter through or between cells and begin to infect underlying tissues

4. Colonisation: Pathogens and spread within the tissue

   Toxicity: Pathogens may release toxins that damage or disrupt host cells.

5. Tissue damage & Disease: Toxins and the immune response lead to cell death, tissue damage, and symptoms of disease.

What is virulence?

The measure of ability of a pathogen to cause disease.

What does virulence depend on?

Numerous virulence factors of the pathogen.

The host (pathogens are highly specific for certain organisms).

Environmental conditions.

How do microbes help protect us from pathogens?

Killing pathogens (e.g. bacteriophages kill bacteria)

out-competing pathogens

helping the body’s immune system to respond to infections

What does pathogen survival depend on?

Ability to enter cells

Availability of nutrients and removal of wastes

Environmental conditions including temperature pH, moisture, anchorage & space

Ability to replicate and transfer to new hosts