1. Role of Research in Prevention
Biomedical Technology I

2. Understanding the infectious cycle is critical to identifying the areas of prevention.
Direct person to person transmission may be inhibited by proper hygiene and sanitary conditions as well as by education about disease prevention.
The Infectious Cycle

3. Vector-borne diseases may be prevented by control measures that either kill the vector or prevent its contact with humans.
Infection by a pathogen or development of a pathogen within a host may be prevented by vaccination.
Drugs may be used to prevent infection or suppress the disease process.
Prevention

4. The prevention methods we have discussed are available to deal with some diseases.
For other diseases, the methods for control are inadequate, undeveloped, or nonexistent.
This is where basic research comes into play; Scientist are trying to develop new tools needed to banish infectious diseases.
Prevention

5. The human body has several general mechanisms for preventing infectious diseases referred to as:
1. Non specific defenses (Body’s primary defense)
*Anatomical barriers
*Physiological deterrents
*Presence of normal flora
Host Defenses

6. Host Defense Anatomical barrier examples:
* Nasal opening to the respiratory system, covered by mucous that traps airborne particles that prevents most of them from reaching the lungs.
* Skull and vertebral column protects the central nervous system, few pathogens are able to penetrate bone.
*Skin prevents the invasion of microorganisms.
Host Defense

7. Host Defense Physiological Deterrents *Tears flush debris from eyes
*Vaginal secretions are acidic which discourages the growth of many pathogens
*Tears, saliva and nasal secretions contain lysozyme, an enzyme that breaks down bacterial cell walls.
*Blood, sweat and some tissue fluids contain lysozyme as well.
Host Defense

8. White blood cells include several types of phagocytic cells that detect, track, engulf and kill invading bacteria and viruses.
Blood plasma contains clotting factors that initiate a clot at the injury site to prevent pathogens from invading the body.
The inflammatory response helps prevent infectious agents form spreading in the body.
Host Defense

9. Normal flora survive and grow on the skin and in the mouth, GI tract and other areas of the body and protect other invading organisms.
When the growth of Normal flora is suppressed , “opportunistic” agents are able to move in and infect and cause disease.
Host Defense

10. Specific Mechanisms of host resistance:
* This is the second, specific line of defense.
*White blood cells (lymphocytes) that includes T-cells and B-cells.
*Cell mediated response
*Antibody mediated response

11. When a host encounters an antigen that triggers a specific immune response for the second or later time, the memory lymphocytes recognize it and quickly begin growing and dividing, as well as producing high concentrations of lymphokines and antibodies.
Immunity

12. A vaccine is either a killed or weakened (attenuated) strain of a pathogen.
The body’s immune system will respond to these vaccines as if they contain the actual pathogen.
Memory lymphocytes will be present that respond when the actual pathogen is encountered.
Smallpox is the only disease that has been completely eradicated in the U.S.
Vaccinations