2.  Mucous membranes –Conjunctiva –Respiratory –Gastrointestinal tract –Urogenital  Skin –Abrasions or bite  Parenteral –Puncture or injection Portals of Entry

3. Portal of Exit

4. Stages of Release of Microbes

5. Pattern of Transmission

6. Sneeze and Microbe Spread

7. How Did the Pathogen Leave the Host?  Active escape: Movement of pathogen to portal of exit Movement of pathogen to portal of exit  Passive escape: Excretion in feces, urine, droplets, saliva Excretion in feces, urine, droplets, saliva

8. Virulence and the Mode of Transmission  Direct contact: Less virulent  Vector-borne: Highly virulent in human host; relatively benign in vector  Greater ability to survive outside host: More virulent

10. Reduce or eliminate source or reservoir  Isolation of cases and carriers  Destruction of animal reservoir  Treatment of sewage  Therapy that reduces or eliminates infectivity of cases

11. Break Connection Between Source and Susceptible Individuals  Chlorination of water  Pasteurization of milk  Inspection of food and food handlers  Destruction of insect vectors