BIOLOGY UNIT 1- Section 1

1.1 -Pathogens

Microorganisms which cause disease are called pathogens

A disease suggests a malfunction of body or mind which has an adverse effect on good health.

For a micro organism to be a pathogen it must:

• gain entry to the host
• colonise the tissues of the host
• resist the defences of the host
• cause damage to the host tissues

Pathogens include bacteria, viruses and fungi.

If a pathogen gets into the host and colonises its tissue it results in an infection. Disease occurs when an infection leads to…