preventing disease.ppt

7/29/2019 Preventing Disease.ppt

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Chapter 20Preventing Disease


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Snow on Cholera

Time Frame Reference Ideas of Disease Causation

Demons

Divine retribution

Miasma theory

Problem with theaforementioned ideas ofdisease causation?


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Watercontaminatedwith deadlycholera flowedfrom the Broad

Street pump


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Distribution of Cases in Time from

August and September, 1854

0

20

40

60

80

100

120

140

160

19 21 23 25 27 29 31 2 4 6 8 10 12 14 16 18 20

Pump handle

removed

?


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Epidemiologic Triangle

Environment

AgentHost


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Epidemiology

Study of occurrence of disease when

where

how transmitted

Epidemic disease outbreak

affects many people

Pandemic

worldwide epidemic

Endemic

always present

Sporadic

occur only occasionally


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Methods of Epidemiology

Sources of information Public record

Questionnaires

Surveys

Hospital records

Notifiable diseases Physicians required to report certain diseases

Local agencies report to state and CDC

Morbidity and Mortality Weekly Report (MMWR link)

Statistics Incidence rate

rate of acquiring a disease during certain period

Prevalence rate

rate of having certain disease at specific time
http://www.cdc.gov/mmwr/http://www.cdc.gov/mmwr/


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Types of Epidemiological Studies Descriptive

general information about a disease incidence

prevalence

death rates

Surveillance tracks epidemics

monitor potential epidemic situations

follow progress of epidemic

assist in prevention or eradication Field and Hospital

investigate source and spread of diseaseoutbreaks


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Descriptive Epidemiology

geographicaldistribution oftuberculosis

Ethnic distributionof tuberculosis


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Surveillance Epidemiology

Example tracking smallpox

outbreaks

use of vaccinationprograms to limitspread of disease

result in

eradication ofsmallpoxworldwide


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13/21 2004 Wadsworth Thomson Learning


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Field Epidemiology

Investigative workgather information

collecting samples

infected vectors or animals

interviewing individuals

interpreting the data


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Hospital Epidemiology

Nosocomial infections hospital acquired infection

immunocompromised patients

invasive medical procedures

development of antibiotic resistance

examples

urinary tract infections--catheterizatoin

surgical wound infections

pneumonia

skin infections


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Public Health

Public health organizations Local health departments

State health departments

United States Public Health Service (USPHS) Center for Disease Control and Prevention (CDC)

World Health Organization


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Public Health

Areas of impact Clean water

Clean food

Personal cleanliness Insect control

Prevention of sexually

transmissible diseases

Prevention of respiratory diseases


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Immunization

Active immunization Develop immunity without disease

Vaccinations attenuated

microorganism or virus alive but incapableof causing disease

inactivated

killed by chemicals

acellular contain only antigen molecules; toxoids

DNA vaccines

contain only DNA which encodes a protein


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Acellular vaccine

Anti-toxin Toxoid

purified exotoxin

inactivated by

heat or chemical

Tetanus

Diphtheria

Figure 20.7


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Attenuated and Inactivated

Attenuated Live organisms

genetically altered

limited infection

advantages

organism

multiples

stimulates

strong immunity

long-lasting

immunity

Inactivated killed organisms

chemicals

destroys antigens

immunity not long

lasting

require multiple

injections


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Passive immunization

Protection without developing immunity gamma globulin

antibodies from pooled serum

human or animal

general or special preparations

advantages

protection for immunocompromised

immediate protection

temporary protection while immunity

develops

disadvantages

serum sickness (animal preparations)

no lasting immunity

preventing disease.ppt

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