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Nature of Disease

Nature of Disease. Giardia. Streptococcus pneumoniae. Defense against pathogens. Pathogen = an organism that causes a disease. Ex: Bacteria, virus, fungus, protozoa, etc. Where do we get pathogens? Contaminated water/food Soil Infected animals/people Vectors (ex. Fly's)

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Nature of Disease

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  1. Nature of Disease

  2. Giardia Streptococcus pneumoniae Defense against pathogens • Pathogen= an organism that causes a disease. Ex: Bacteria, virus, fungus, protozoa, etc. • Where do we get pathogens? • Contaminated water/food • Soil • Infected animals/people • Vectors (ex. Fly's) • Any disease caused by a pathogen is called an infectious disease.

  3. Types of Disease and their Causes

  4. Koch’s Postulate Cause: Looking for cause of Anthrax Disease • Affects mainly sheep and cows Step 1)Discovered rod-shaped bacterium in dead animal red blood cells. Step 2)Cultured the bacteria on nutrients Step 3)Injected the cultured bacteria into healthy animals. • Healthy animal dies Step 4)Koch finds the same rod-shaped found in newly infected animal’s blood.

  5. Spread of Infectious Disease • Reservoirs (Source) of infectious disease can be living or non-living. • The main living source of disease is the human body.

  6. Types of Reservoirs • Reservoirs of infectious disease: • Living Reservoirs : the human body, animals, plant • Non-living Reservoirs: Soil and water Rabid dog is a living reservoir for the rabies infection

  7. Sewage Spills In San Diego’s • San Marcos Creek November 8,2010 the Department of Environmental Health said an estimated 5,440 gallons of waste flowed into the creek that empties into La Costa's Batiquitous Lagoon in Carlsbad and the ocean Submitted by Marina Dimova on 2010, November 8 - 12:38 Non-Living Reservoir Water

  8. Four Main Types of Disease Transmission • Direct contact: Cold, Influenza, STD’s • Direct body contact, exchange of body fluids • By an Object: Bacteria • Eating Utensils, Cups, Toys • Through the air: Streptococcus; Strep Throat • Through water droplets in cough and sneeze • By and intermediate organism • Vector: Fly, Mosquito, Rats perseverance

  9. Sneeze Videohttp://www.youtube.com/watch?v=LzH-yat-mBI

  10. Symptoms of Disease • Steps of infection: • Pathogen enters body • Immune system responds to invasion • May cause redness, swelling, fever, pus, inflammation • If pathogen overcomes the body’s defense pathogen metabolizes and multiplies. • May cause damage to tissues that it has invaded, host cells may die.

  11. Damage to Host Cell Virus -Host cell taken over by virus -Virus takes over genetic and metabolic function of cell -Host cell is damaged and may die Bacteria -Bacteria creates toxins that can be transported by blood to different areas in the body. -Serious and sometimes fatal effects occur

  12. Types of Damage • Bacterial toxins can- • inhibit protein synthesis in host cells, • destroy blood cells and blood vessels, • produce fever • cause spasm from damage to the nervous system.

  13. Types of Bacterial Toxins Tetanus bacteria- -Affects nerve cells and causes uncontrolled muscle spasm. -If left untreated may cause paralysis and death -Tetanus bacteria is found in soil Streptococcus bacteria- -Causes Strep Throat -Causes fever and severe sore throat Botulism bacteria- -Enters through the digestive tract or through a skin wound -Causes paralysis of the face and if left untreated may cause respiratory paralysis

  14. Patterns of Disease Endemic- A disease that is constantly present in a population. Example: Common Cold Epidemic- Many people in a given area are afflicted with the same disease at about the same time. Examples: Polio and Small Pox Polio – Epidemic in United States in the early 1950’s. Victims are left paralyzed or died. Those that survived often were required to go on the breathing machine the iron-lung.

  15. Polio • Polio – Epidemic in United States in the early 1950’s. Victims are left paralyzed or died. Those that survived often were required to go on the breathing machine the iron-lung.

  16. Antibiotic • An antibiotic is an substance produced by a microorganism that, in small amounts, will kill or inhibit the growth and reproduction of the of the microorganism. • Antibiotics a produced naturally by various species of bacteria and fungus. • Antibiotics do not affect viruses because they do not have a live and reproduce in a host cell.

  17. Resistant Bacteria • With continued use antibiotics certain bacteria can become resistant to certain antibiotics. • The bacteria evolve to become resistant to the bacteria. • Resistant bacteria can create enzymes to break down the antibiotic. • Streptococcus pneumonia is one type of penicillin resistant bacteria.

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