1. Disease and Infection

2. Important terms: Pathogens - disease causing micro-organisms.
Disease - anything that causes your body to stop working properly.
Infectious diseases - diseases that can be spread.
Contagious diseases – infectious diseases that are easily spread.
i.e. Can be passed by simply touching an infected person or items touched by infected person.

3. Bacteria Viruses Parasites Fungi
Types of Pathogens
Bacteria
Viruses
Parasites
Fungi

4. Bacteria These are single celled, living organisms.
Can be killed with antibiotics such as penicillin.

5. Necrotizing Fasciitis
Caused by flesh eating bacteria.
Some bacteria are actually used to make cheese, milk, beer and wine.
Some bacteria are good and live in

6. Leprosy Caused by the bacteria Mycobacterium leprae/lepromatosis.
Leprosy is NOT very contagious and is spread between people via fluid contact often from the nose.
Limbs don’t just fall off, rather the peripheral nervous system becomes compromised leading to unidentified injuries which can become infected.

7. Bacteria: E.Coli patient…

8. Much smaller then bacteria and are non-living
Viruses
Much smaller then bacteria and are non-living
Insert themselves into your cells and use your body’s DNA to help them replicate and spread

9. Ebola Caused by viruses. Varicella Zoster . . . Chicken Pox
EBOLA on news... Its
Varicella Zoster Chicken Pox

10. Parasite
An organism that lives in or on another organism and benefits from the nutrients at the other’s expense.

11. Malaria Caused by parasite ‘plasmodium’. Carried by mosquitos.
Symptoms include fever, chills, muscle pain, nausea, diarrhea, headache, loss of appetite and nausea.

12. Parasite: Flatworm patient…

13. Fungi Caused by fungus. Feed off a protein in your skin.
Grows on skin, hair and nails.
Skin becomes red and very itchy.
Most are harmless.

14. Tinea )
Often called ringworm (no worms involved!).

15. Fungi: Candidiasis (Thrush)

16. Why aren’t we constantly sick?

17. We are constantly exposed to pathogenic microorganisms!
Germs in Your Kitchen
Youtube: Germs in your kitchen (CNN) -

18. How do pathogens get in? Method of Entry Examples of disease
Food and water
Food poisoning
Breathing in
Pneumonia and the flu
Exposed cuts and broke
Tetanus
Sexual contact
Syphilis
Other contact
Anthrax, leprosy.

19. The Immune System

20. Lines of Defence

21. First line – Physical Barriers
Purpose – To prevent pathogens from entering the body.
Includes
Skin – Acts as a barrier against pathogens.
Saliva – Wash away harmful substances from openings to the body.
Eye – Salty tears wash out eyes.
Mucous membrane/hairs – Mucous and hairs trap particles.
Acid in stomach kills many bacteria.

22. Second line - Inflammation
Damaged cells release chemicals to increase the blood flow to the area.
This causes the area become red, hot and swollen.
White blood cells come in the blood and eat any foreign substances in a process called ‘phagocytosis’.
They then die and become pus.

23. Third line – Lymphatic System
A series of vessels that carry fluid around your body, back to your heart.
They collect excess fluid and run it through lymph nodes where the pathogens are dealt with.
Two forms of attack.
B-Cells
T-Cells

24. B - Cell T - Cell Produce antibodies
Antibodies fit exactly onto a specific pathogen to prevent spreading.
Attack and destroy specific, recognised pathogens
The first time the body fights a pathogen, it is slow to respond.
Both B and T cells keep memory cells in case the pathogen attacks again.
This allows the pathogen to be killed quickly before it causes damage. This is known as immunity.

25. BAR
A virus to try and make it overcome the bodies defenses.

26. What can be done to prevent infection

27. Hygiene Some infections can be prevented by practicing good hygiene.
E.g. Gastroenteritis.
Caused by bacteria that lives in your bowel.
Makes us feel sick if we ingest (eat) it.

28. Vaccinations
Vaccinations cause your body to react as if it had met a pathogen.
Vaccine can be…
Dead pathogen
Living but weakened pathogen
Broken up parts of a pathogen.
Your immune system will make antibodies, making you immune to that pathogen.

29. Why Vaccines are important
It’s important to get vaccines so we are all immune. This is termed “Herd Immunity”.
Because some people are now stopping getting vaccinations, we are seeing some dangerous diseases appearing more frequently again eg. whooping cough
There are some risks associated with vaccinations but the benefit far outweighs the risk.

30. Practical: Modelling infection
What you need
Phenolphthalein indicator
1 M sodium hydroxide
Plastic cup
0.1 M hydrochloric acid
Pipette
Water
What to do
Add half a cup of water to each plastic cup.
Place all the cups on one table.
All students should turn their back while the teacher adds 2 mL of sodium hydroxide to one cup. This represents a student having an infection.
Students should then collect their cups and use the pipettes to exchange 3 mL of water with three other people. This is equivalent to shaking hands. 
Record who you ‘shook hands’ in a table like the one.
Add a few drops of phenolphthalein indicator to each cup to determine who caught the disease.
Use the information recorded in the table to determine who the original source of the infection was.
Repeat step 1–5, this time choosing whether or not to become vaccinated. This involves adding 2 mL of hydrochloric acid to your cup of water.
Repeat this activity, increasing the number of people vaccinated.
Person 1
Person 2
Person 3

31. Practical: Modelling infection
Discussion
How many people become infected without vaccination?
How many people become infected when a few people were vaccinated?
Did it make any difference if more people were vaccinated against the disease? Explain why you think this happened.
Can you think of any real-life examples of how vaccination can protect vulnerable members of the community?

32. End

33. How our body’s kill pathogens...
Non-specific defense:
This is the defense we are born with.
Our three lines of defense are involved in this defense type.
Our body kills off any pathogens it encounters
Some diseases are good at hiding from this type of defense, especially viruses

34. Each pathogen has a specific antibody that acts on it.
First time we are exposed to the pathogen, the body is slow to make antibodies to fight the pathogen.
Second time, antibodies are made much faster and pathogen is destroyed because you are now immune to that pathogen.

35. Bacteria
Virus
Parasites
Fungi
Microscopic
single celled microorganism
Over 1000 species, with more to be discovered.
Most types are not pathogens.
Treated with antibiotics.
Example of infection caused by bacteria – Meningococcal disease.
100x smaller than bacteria
Virus invaders host cell to make copies of itself.
Host cell is destroyed when cell bursts open and new viruses released.
New viruses infect other cells.
Example of Disease caused by virus - Cold, Flu, Ebola virus.
Organism living on or in the body of another organism (host).
Steals nutrients from the host.
Example of disease caused by parasite - Malaria
Fungal infections are contagious.
Spread through spores (single cells with tough skin).
Spores grow in warm moist environments.
Fungal infections treated with a fungicide (chemical that kills fungi).
Examples include Tinea.

36. How our body’s kill pathogens...
Specific Defense:
This type of defense targets specific pathogens.
Once we have been infected by a pathogen once before (eg. chickenpox) our specific defense makes memory cells especially for this disease.
These cells remember the disease if it enters our bodies again.
We can then kill the disease very quickly

37. Vaccines… These use the specific immune defense.
We get a de-activated form of different pathogens put into our body.
Our body then makes memory cells for the disease
If we ever get infected by the disease our body can kill it straight away