1. Infectious Disease

2. Many illnesses, such as ear infections and food poisoning, are caused by living things too small to see with a microscope. Organisms that cause disease are called pathogens. Diseases that are caused by pathogens are called infectious diseases.

3. Different infectious diseases are caused by specific types of pathogens. For instance, one kind of pathogen causes pneumonia, another causes chickenpox and another kind causes rabies.

4. 1.Bacteria - One-celled microorganisms that cause a variety of diseases (ear infections and food poisoning) 2.Viruses - Tiny particles, much smaller than bacteria. Viruses cannot reproduce unless they are inside living cells. The cells are damaged or destroyed in the process, releasing new viruses to infect other cells. (colds and flu) Four major groups of human pathogens

5. 3.Fungi - Molds and yeasts which can cause infectious disease. Grows in warm, dark and moist areas. (athlete’s foot and ringworm) 4.Protists - Malaria, a blood infection, is one disease caused by protists. Four major groups of human pathogens

6. Pathogens can spread through: Contact with an infected person Soil, food, and water A contaminated object Infected animal How pathogens are spread Like all living things, pathogens need food and a place to live and reproduce.

7. Infectious disease examples… Bacteria - Leprosy Chronic disease caused by a bacteria Mainly in Asia and Africa Bacteria multiplies very slowly - 20 years for symptoms Leprosy is not highly infectious. It is transmitted via droplets, from the nose and mouth, during close and frequent contacts with untreated cases. 6 - 12 month multi-drug treatment program

8. Infectious disease examples… Parasite - Bacteria - Elephantiasis Carried by parasitic worms which are transmitted by mosquitoes. The worm carries a bacteria Typically in tropical regions Obstruction of lymphatic system leads to swelling. Treatment kills parasites, but additional treatment is necessary for swelling

9. Infectious disease examples… Virus - Ebola Carried by primates such as monkeys Mainly in Africa Transmitted by direct contact with the blood, secretions or other body fluids of infected persons. Burial ceremonies and healthcare facilities are often places of transmission.

10. Video - How a virus invades your body http://www.youtube.com/watch?v=Rpj0emEGShQ