1. Microbiology
U11M6
Unit 11 Notes

2. How Disease is Spread
The germ theory of disease – infectious diseases are caused by microorganisms
For many pathogens, the human body provides just the right conditions for growth
Suitable temperature
Watery environment
Lots of nutrients
Unit 11 Notes

3. Agents of Disease Viruses invade & replicate within living cells
Attach to surface
Insert genetic material
Take over functions of host cell
Bacteria cause disease in one of 2 ways
Break down tissues of host for food
Release toxins that harm the body
Unit 11 Notes

4. Agents of Disease Protists cause some very damaging diseases
Malaria – caused by Plasmodium – spread by mosquito bite
African sleeping sickness – caused by Trypanosoma – spread by tsetse fly
Unit 11 Notes

5. Agents of Disease Worms – flatworms & roundworms Fungi
Live part of their life cycle in other organisms before infecting humans
Includes flukes, hookworms, tapeworms
Fungi
Athlete’s foot – Tinea species
Ringworm
Yeast infections
Unit 11 Notes

6. How Diseases are Spread
Physical contact
Coughs
Sneezes
Touching objects
Sexual contact
Behaviors can control transmission
Washing hands
Covering mouth when coughing or sneezing
Unit 11 Notes

7. How Diseases are Spread
Contaminated food
Food poisoning – eating food containing pathogens
Bacteria grow in warm, partially cooked food
Proper cooking & refrigeration can prevent
Contaminated water
Poor sanitation
Untreated water
Unit 11 Notes

8. How Diseases are Spread
Animal vectors
Insects – mosquitoes, fleas, lice, ticks
Mammals – rabies in wild animals, carriers of fleas, ticks
Birds – harbor some diseases that can be spread by insects – West Nile, etc.
Unit 11 Notes

9. Fighting Infectious Disease
Antibiotics – kill bacteria without harming cells of host
Many produced naturally by living organisms (molds & fungi)
Some are synthetic (man made)
Do not affect viruses
Antiviral drugs
Inhibit ability to invade cells & multiply
Over the counter drugs
Treat symptoms – cough, congestion, fever
Help you feel better, but do not treat infection
Unit 11 Notes