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EPIDEMIOLOGY AND NOSOCOMIAL INFECTIONS

CHAPTER 15

What is Epidemiology?

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Table 33-1

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Epidemiology

What is Epidemiology?

Etiology

Incidence

Prevalence

causation

a/a+b

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Epidemiological Terms

Morbidity

Mortality

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Figure 33-6

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Diseases in Populations

Endemic

Epidemic

Pandemic

Sporadic

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Figure 33-2

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Incidence Types

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Disease Spread

Common Source Outbreak

Propagated Epidemic

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Epidemiologic Studies Descriptive

Analytical

Experimental

The Basic Triad Of Descriptive Epidemiology

THE THREE ESSENTIAL CHARACTERISTICS OF DISEASE WE LOOK FOR IN DESCRIPTIVE EPIDEMIOLOGY:

TIME PLACE PERSON

Time Changing or stable?

Seasonal variation.

Clustered (epidemic) or evenly distributed (endemic)?

Point source or propagated.

Place Geographically restricted or

widespread (pandemic)? 

Relation to water or food supply. 

Multiple clusters or one?

Person Age

Socio-economic status

Gender

Ethnicity/Race

Behavior

The Basic Triad Of Analytic Epidemiology

THE THREE PHENOMENA ASSESSED IN ANALYTIC EPIDEMIOLOGY ARE:

HOST

ENVIRONMENTAGENT

Agents

Nutrients Poisons Allergens Radiation Physical trauma Microbes Psychological experiences

Host Factors

Genetic endowment

Immunologic state

Age

Personal behavior

Environment Crowding Atmosphere Modes of communication – phenomena in

the environment that bring host and agent together, such as:– Vector– Vehicle– Reservoir

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Infection Reservoirs

Human

Animal

Non-living

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Microbe Spread

Portals of Entry

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Microbe Spread

Portals of Exit

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Modes of Disease Transmission Contact

Vehicles

Vectors

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Problems in Disease Transmission

Disease Cycles Herd Immunity

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Controlling Disease Transmission

Biosafety

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Public Health Organizations

Center for Disease Control (CDC)

World Health Organization (WHO)

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Notifiable Diseases

Definition:

Nationally Notifiable Infectious Diseases

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Nosocomial Infections

Sources

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Nosocomial Infection Risks Susceptibility Transmission Universal Precautions

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Figure 33-9

Other17%

Blood-streaminfections14%

Urinarytractinfections32%Pneumonia

15%

Surgicalsite infections22%

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Risks Equipment/Procedures Sites of Infection

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Bioterrorism

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Anthrax

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Smallpox