PEST & PARASITES
Distinguish between pests and parasites.
Discuss the types of micro organisms that
can cause disease
Describe how our body responds to infection
Explain how a vaccination works
Explain how AIDS is caused and its dangers
They are a nuisance.
They affect us in a
These are micro organisms that harm other
They live on or in that particular organism,
also known as the host.
* Note: Unlike parasites, pests do not cause
diseases; they can transmit organisms
What types of micro
organisms cause disease?
Bacteria & Viruses
Bacteria are unicellular organisms that
multiply and release toxins.
Not all are harmful- some exist naturally in
*bacterial diseases- typhoid, cholera, TB
Viruses are smaller than bacteria.
They invade living cells and cause more
*viral diseases-AIDS, measles, influenza (flu)
How does the body respond to
We detect these foreign bodies and destroy
These harmful micro organisms have a
chemical marker on their surface called an
An antigen is a substance that prompts the
generation of antibodies and can cause an
Immunity is the
diseases by antibodies.
They are two types:
Natural passive immunity involves antibodies
passing directly from mother to the foetus,
through the placenta and later in the breast
Natural active immunity involves the white
blood cells ( lymphocytes) producing
antibodies that destroy the antigens.
Artificial passive immunity occurs when the
body is injects with antibodies produced by
Artificial active immunity occurs when the
body is injected with weak strains of the
pathogen. we make antibodies and memory
cells against it so we can become immune to
the actual disease. It is also known as a
Which type of immunity is seen here?
Acquired immune deficiency
This is a disease caused by the Human
Immunodeficiency Virus (HIV).
This virus causes severe weakening of the
body’s immune system.
This results in the body not being able to
produce antibodies and therefore becoming
vulnerable to many diseases.
Describe the conditions which promote the
growth of micro organisms
Discuss the principles of food preservation
Discuss conditions that encourage the
breeding of household pests
Discuss the different types of waste
Discuss the need for personal & community
When micro organisms
feed on our food it spoils.
This action is caused by:
-the micro organisms first
breaking down food using
-then absorbing the soluble
Growth of micro organisms
The factors that influence this growth are:
* Most micro organisms develop rapidly in
moist conditions, because they need water to
germinate and grow.
How can we preserve food?
Can you recall some of these pests?
Household pests are a nuisance because of
the economic damage they cause.
They thrive best in dirty places filled with
garbage; these conditions provide good
Think about these conditions, how are pests
encouraged to breed there??
How can they be controlled?
Sanitary- keeping the surroundings clean
Chemical- using pesticides
Biological-using other animals to catch the
*Can you think of examples of each???
Pollution results from waste
substances of human activities.
They are harmful to all living
organisms & the environment.
These waste substances can be:
Micro organisms and pests, if given the right
conditions to thrive can cause diseases
Mosquitoes can cause malaria, dengue fever
Rats can cause leptospirosis
Other micro organisms can cause cholera,
typhoid and food poisoning
What are the symptoms of these diseases??
Can you make a list of
things that you can do to
prevent illness from micro
organisms and pests???
The members of your
community can also
play a role in the
prevention of diseases.
Can you think of some
of the ways to dispose
of this waste?