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 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
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