1. Over 3000 years ago, the Chinese and Hebrews advocated for cleanliness in food, water, and personal hygiene to promote better health. 2. The document defines a pathogen as an organism that lives in or on another organism and is capable of causing disease. Examples of pathogens include fungi, bacteria, prions, viruses, and macroparasites. 3. For a pathogen to be considered "successful", it must have enough virulence to cause disease and be able to enter the body and survive despite the body's defenses, which normally aim to keep pathogens out.

1. HSC Biology
• Module 3: The Search For Better Health
Students Learn to:
1. Over 3000 years ago
the Chinese and
Hebrews were
advocating cleanliness
in food, water and
personal hygiene
1. • Identify the conditions under which an
organism is described as a pathogen
2.

2. Pathogen

3. An organism living in or on
another organism that is
capable of causing a
disease Fungi Bacteria
Prion MacroparasitesVirus
Pathogen

4. Microscopic Visible to the naked Eye

5. Visible to the naked Eye
Virus
Microscopic
Prions

6. Visible to the naked Eye
TapewormVirus
Prions
Microscopic

7. When are pathogens ‘successful’?
1
Firstly, it depends if the pathogen has enough virulence,
which is how severe and poisonous it can be, and whether
it’s able to produce a disease or not in the body.
2 Secondly, a pathogen can be considered “successful”, if you
want it call it that, if it can enter the body and survive in there.
• Generally, pathogens can’t survive due to the body’s
lines of defence aimed at keeping the bugs out.
• Pathogens can occasionally get in, but they have to
get through 3 lines of defence first.

8. What are the conditions under which an organism is
described as a pathogen?
1
It should be able to move from one
host organism to another, and be
able infect another person.
A pathogen must also be able to
survive the movement from one
host to another.
2