Epidemiology: Prevention and Control of Diseases and Health Conditions

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Chapter 4
Epidemiology Prevention and Control of Diseases
and Health Conditions
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Classification of Diseases Health Problems

• 4 Classification Schemes
• Organ or Organ System
• i.e., heart disease, kidney disease, respiratory
  infection
• Causative Agent
• Biological Agents
• Chemical Agents
• Physical Agents

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Causative Agents for Diseases Injuries
Biological Agents
Viruses Rickettsiae Bacteria Fungi Protozoa Metazo
a
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Causative Agents for Diseases Injuries
Biological Agents
Chemical Agents
Viruses Rickettsiae Bacteria Fungi Protozoa Metazo
a
Pesticides Food additives Pharmacologics Industria
l chemicals Air pollutants Cigarette smoke
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Causative Agents for Diseases Injuries
Biological Agents
Chemical Agents
Physical Agents
Viruses Rickettsiae Bacteria Fungi Protozoa Metazo
a
Pesticides Food additives Pharmacologics Industria
l chemicals Air pollutants Cigarette smoke
Heat Light Radiation Noise Vibration Speeding
objects
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Classification of Diseases Health Problems

• Organ or Organ System
• i.e., heart disease, kidney disease, respiratory
  infection
• Causative Agent
• Biological Agents
• Chemical Agents
• Physical Agents
• Communicable vs Non communicable
• Communicable - infectious (biological agents or
  their products transmitted from one person to
  another)
• Non communicable - noninfectious (multicausation
  diseases)

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Classification of Diseases Health Problems

• Organ or Organ System
• i.e., heart disease, kidney disease, respiratory
  infection
• Causative Agent
• Biological Agents
• Chemical Agents
• Physical Agents
• Communicable vs Non communicable
• Acute vs Chronic
• Acute - peak symptoms within 3 months or sooner
  with recovery of survivors usually complete (ex.
  Influenza)
• Chronic - longer than 3 months - slow and
  sometimes incomplete recovery (ex. Tuberculosis)

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Types of Diseases
Examples
Acute Diseases Communicable
Noncommunicable Chronic Diseases
Communicable Noncommunicable
Common cold, pneumonia, mumps, measles,
pertussis, typhoid fever, cholera Appendicitis,
poisoning, trauma Tuberculosis, AIDS, Lyme
disease, syphilis, rheumatic fever Diabetes,
coronary heart disease, osteoarthritis, cirrhosis
of the liver
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Communicable Disease Model
Triangle
Epidemiologic
Model
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Communicable Disease Model
Agent
- originally referred to an infectious
microorganism Ex. Influenza Virus
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Communicable Disease Model
Agent
Host
- Any susceptible organism invaded by the
agent Ex. Human being
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Communicable Disease Model
Agent
Host
Environment
- Factors which
inhibit or promote disease transmission
(physical, biological, or social)
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Chain of Infection
A model to conceptualize the transmission of a
communicable disease from its source to a
susceptible hose
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Chain of Infection
Pathogen
- is the disease causing agent
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Chain of Infection
Pathogen
Reservoir
- is the habitat in which an infectious
agent normally lives grows
- Human symptomatic or asymptomatic - Animal
called zoonoses - Environmental plants, soil,
and water
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Chain of Infection
Portal of exit
Pathogen
- is the path by which an agent
leaves the source host
Reservoir
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Chain of Infection
- how pathogens are passed
Portal of exit
Pathogen
Trans- mission
Reservoir
Modes of Transmission Direct
- Direct contact - Droplet spread
Indirect - Airborne -
Vehicleborne - fomites - nonliving -
Vectorborne - vector - living
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Chain of Infection
Portal of exit
Pathogen
Portal of entry
Trans- mission
Reservoir
- agent enters susceptible host
Respiratory Oral Skin Intravenous Gastrointestinal
Urogenital tract
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Chain of Infection
Portal of exit
Pathogen
Portal of entry
New Host
Trans- mission
Reservoir
- Final link is a susceptible host
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Noncommunicable Disease Model
Your genetic endowment
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Noncommunicable Disease Model
Personality
Beliefs
Your genetic endowment
Behavioral choices
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Noncommunicable Disease Model
Environment
Health Care System
Personality
Beliefs
Economics
Your genetic endowment
Water Quality
Behavioral choices
Air Pollution
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Prioritizing Prevention Control Efforts

• Leading Causes of Death
• Years of Potential Life Lost
• Economic Cost to Society

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Prevention, Intervention, Control, and
Eradication of Diseases

• Prevention
• implies the planning for and taking action to
  prevent or forestall the occurrence of an
  undesirable event and is therefore more desirable
  than . . .
• Intervention
• which is defined as taking of action during an
  event
• Control
• general term used in the containment of disease
• Eradication
• total elimination of the disease

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Levels of Prevention

• Primary Prevention
• is the forestalling of the onset of illness or
  injury during the pre-pathogenesis period (before
  the disease process begins)
• Secondary Prevention
• is the early diagnosis (screening and lab tests)
  and prompt treatment of diseases before the
  disease becomes advanced and disability becomes
  severe
• Tertiary Prevention
• is to provide therapy, retrain, reeducate, and
  rehabilitate the patient who has already incurred
  disability

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Prevention Strategies Communicable Disease

• Primary Prevention
• Secondary Prevention
• Tertiary Prevention

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Prevention Strategies NonCommunicable Disease

• Primary Prevention
• Secondary Prevention
• Tertiary Prevention

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Chapter 4
Epidemiology Prevention and Control of
Diseases and Health Conditions