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This unit explores the germ theory of disease, explaining how infectious diseases are caused by microorganisms. It covers the different agents of disease, including viruses, bacteria, protists, worms, and fungi, and how they invade and harm the human body. The notes also discuss various modes of disease transmission, such as physical contact, contaminated food and water, animal vectors, and behaviors that can help prevent transmission. The unit concludes by discussing methods for fighting infectious diseases, including antibiotics, antiviral drugs, and over-the-counter medicines for symptom relief.
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Microbiology U11M6 Unit 11 Notes
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
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
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
Agents of Disease • Worms – flatworms & roundworms • 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
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
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
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
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