An
infection is caused when a
host is invaded by a
pathogen and begins to multiply. Not all
hosts are susceptible to all types of
infection, since the immune system and general health, age and nutrition play a role in susceptbility. Many
hosts are also naturally resistant to certain types of
pathogens.
Pathogens can enter a
host body through these common
portals of entry:
All
infections start at a
reservoir; a
location where the
pathogen enters and multiplies in the
host body.
Reservoirs are also
locations from which
infections will spread.
Examples of
reservoirs include:
- Skin surface
- Mouth
- Nose
- Throat
- Vagina
- Colon
- Other moist areas of the body (in between toes, armpits, groin area)
- Infected food or drink
Effects of an infection
Most of the time a microbial invasion results in the
pathogen being destroyed before symptoms appear. However, if an
infection takes hold in a
reservoir, the
host body may
localize the
infection by separating it from the rest of the body. This usually involves the
inflammatory response and avoids virulent effects such as toxins from entering the bloodstream and causing widespread symptoms.
Some
pathogens can destroy
blood cells (including
white blood cells) and prevent
blood clotting. Others can enter the
blood and set up
secondary infection sites at a new
reservoir location. When a
pathogen enters the
blood, it can cause
septicemia, which is an
inflammatory response over the whole body.
Except where otherwise noted, content on this site is licensed under
1 - Anatomy and Physiology Basics