1. EPIDEMIOLOGY AND NOSOCOMIAL INFECTIONS
CHAPTER 15
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

2. Infectious Disease Spread
What is Epidemiology?
Where, when and how of disease in populations
Promotion of a healthier society
Incidence
Number of new cases
Prevalence
Number of existing cases in any stage of disease
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

3. Epidemiological Terms
Morbidity
Ill effects suffered by individuals with disease
Mortality
Deaths
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4. Diseases in Populations
Endemic (b)
Disease with constant presence
Epidemic (c)
High incidence in a short time in a region
Pandemic
Global disease epidemic
Sporadic (a)
Occasional occurrence
Often imported due to air travel
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

5. Disease Spread Common Source Outbreak
Individuals exposed to the same contamination
Propagated Epidemic
Spread from person to person
Types of epidemiologic study
Descriptive
Analytical
Experimental
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

6. Reservoirs of Infection
Human
Disease sufferers
Those in incubation, convalescence
Inapparent infections
Animal (Zoonoses)
Waste
Contaminated meat, poultry
Animal products (hides, feathers)
Sick animals
Non-living
Soil and water
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7. Portals of Entry Skin Thick Waterproof Tight cellular junctions
Some worms, fungi
Mucus membrane
Simple epithelium
Thick mucous layer
Parenteral route
Injections
Punctures, bites, incisions
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8. Portals of Exit Waste products Secretions Blood/pus Milk
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9. Modes of Transmission Contact Vehicles Vectors Direct Indirect
Droplets less than 1m
Vehicles
Food
Water
Air (droplets more than 1m)
Blood
Vectors
Mechanical
Biological
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10. Challenges Carrier status STDs Education?? Zoonoses
Vaccination challenges
Disease Cycles
Immunity is not a constant over time
Herd Immunity
% immunity needed varies with the disease
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11. Controlling Disease Transmission
Isolation
Hospitals
Quarantine
Public exposed to potential pathogens
Immunization
Vector Control
Insect or rodent population control
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

12. Public Health Organizations
Centers for Disease Control (CDC)
Federal agency
Public educational mission
Epidemiology center
World Health Organization (WHO)
International agency
Notifiable Diseases
Infectious diseases harmful to community health
63 diseases as of 2011
Nationally Notifiable Infectious Diseases
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13. Nosocomial Infections
Exogenous versus Endogenous
Contributing factors
Patient susceptibility
Microbial virulence
Chain of transmission
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14. Exogenous Transmission
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15. Controlling Transmission
Universal Precautions
Use good hand-washing techniques
Careful personal hygiene
Single use packaging wherever possible
Sterilization/disinfection of shared equipment
Minimizing invasive procedures
Surveillance
Antibiotic use
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

16. Bioterrorism Airborne human pathogens Anthrax Toxins Ricin
Agricultural bioterrorism
Foot and mouth disease
Control measures
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.