Chapter 4 Communicable and Noncommunicable Diseases: Prevention and Control of Diseases and Health Conditions Chapter Objectives (1 of 2) After studying this chapter, you will be able to: Explain the differences between communicable (infectious) and noncommunicable (noninfectious) diseases and between acute and chronic diseases and provide examples of each. Describe and explain communicable and multicausation disease models. Explain how communicable diseases are transmitted in a community using the “chain of infection” model and use a specific communicable disease to illustrate your explanation. Explain why noncommunicable diseases are a community and public health concern and provide some examples of important noncommunicable diseases. Explain the difference between primary, secondary, and tertiary prevention of disease and provide examples of each. Chapter Objectives (2 of 2) List and explain the various criteria that communities might use to prioritize their health problems in preparation for the allocation of prevention and control resources. List and discuss important measures for preventing and controlling the spread of communicable diseases in a community. List and discuss approaches to noncommunicable disease control in the community. Define and explain the purpose and importance of health screenings. Outline a chronic, noncommunicable disease control program that includes primary, secondary, and tertiary disease prevention components. Introduction Diseases and other health conditions are classified in several meaningful ways Classification can lead to prevention and control strategies Classification of Diseases and Health Problems In community health, diseases are usually classified as: Acute or chronic (<3 or >3 months) Communicable or noncommunicable Communicable versus Noncommunicable Diseases Communicable (infectious) diseases – those diseases for which biological agents or their products are the cause and that are transmissible from one individual to another Noncommunicable (noninfectious) diseases – those illnesses that cannot be transmitted from one person to another Identifying cause is difficult because many factors can contribute Acute versus Chronic Diseases and Illnesses Diseases classified by duration of symptoms Acute – diseases in which peak severity of symptoms occurs and subsides within 3 months Can be communicable or noncommunicable Chronic – diseases or conditions in which symptoms continue longer than 3 months Can be communicable or noncommunicable Communicable Diseases Infectivity: ability of a biological agent to enter and grow in the host Agent: cause of disease or health problem Host: susceptible person or organism invaded by an infectious agent Environment: factors that inhibit or promote disease transmission Pathogenicity: capability of a communicable agent to cause disease in a susceptible host Biological Agents of Disease Communicable Disease Model Chain of Infectio.

1. Chapter 4
Communicable and Noncommunicable Diseases: Prevention and
Control of Diseases and Health Conditions
Chapter Objectives (1 of 2)
After studying this chapter, you will be able to:
Explain the differences between communicable (infectious) and
noncommunicable (noninfectious) diseases and between acute
and chronic diseases and provide examples of each.
Describe and explain communicable and multicausation disease
models.
Explain how communicable diseases are transmitted in a
community using the “chain of infection” model and use a
specific communicable disease to illustrate your explanation.
Explain why noncommunicable diseases are a community and
public health concern and provide some examples of important
noncommunicable diseases.
Explain the difference between primary, secondary, and tertiary
prevention of disease and provide examples of each.
Chapter Objectives (2 of 2)
List and explain the various criteria that communities might use
to prioritize their health problems in preparation for the
allocation of prevention and control resources.
List and discuss important measures for preventing and
controlling the spread of communicable diseases in a
community.
List and discuss approaches to noncommunicable disease
control in the community.
Define and explain the purpose and importance of health
screenings.

2. Outline a chronic, noncommunicable disease control program
that includes primary, secondary, and tertiary disease
prevention components.
Introduction
Diseases and other health conditions are classified in several
meaningful ways
Classification can lead to prevention and control strategies
Classification of Diseases and Health Problems
In community health, diseases are usually classified as:
Acute or chronic (<3 or >3 months)
Communicable or noncommunicable
Communicable versus Noncommunicable Diseases
Communicable (infectious) diseases – those diseases for which
biological agents or their products are the cause and that are
transmissible from one individual to another
Noncommunicable (noninfectious) diseases – those illnesses
that cannot be transmitted from one person to another
Identifying cause is difficult because many factors can
contribute
Acute versus Chronic Diseases and Illnesses
Diseases classified by duration of symptoms
Acute – diseases in which peak severity of symptoms occurs and
subsides within 3 months
Can be communicable or noncommunicable
Chronic – diseases or conditions in which symptoms continue
longer than 3 months
Can be communicable or noncommunicable

3. Communicable Diseases
Infectivity: ability of a biological agent to enter and grow in
the host
Agent: cause of disease or health problem
Host: susceptible person or organism invaded by an infectious
agent
Environment: factors that inhibit or promote disease
transmission
Pathogenicity: capability of a communicable agent to cause
disease in a susceptible host
Biological Agents of Disease
Communicable Disease Model
Chain of Infection (1 of 3)
Step-by-step model to conceptualize the transmission of a
communicable disease from its source to a susceptible host
Chain of Infection (2 of 3)
Pathogen: disease-causing agent (virus, bacterium, etc.)
Reservoir: favorable environment for infectious agent to live
and grow (human, animal, etc.)
Portal of exit: path by which agent leaves host
Transmission: how pathogens are passed from reservoir to next

4. host
Portal of entry: where agent enters susceptible host
New host: susceptible to new infection being established
Chain of Infection (3 of 3)
Zoonoses – diseases for which the reservoir resides in animal
populations
Anthroponoses – diseases for which humans are the only known
reservoir
Modes of Transmission
Direct transmission – immediate transfer of disease agent
between infected and susceptible individuals
Touching, biting, kissing, sexual intercourse
Indirect transmission – transmission involving an intermediate
step
Airborne, vehicleborne, vectorborne, biological
Vehicles – nonliving objects by which agents are transferred to
susceptible host
Chain of Infection Example
Agent (cold virus), leaves reservoir (throat of infected person),
when host sneezes (portal of exit: nose and mouth). Direct
transmission (saliva droplets) enter respiratory tract of
susceptible host at close range (portal of entry: mouth). New
infection possibly established. If one link is missing, chain is
broken.
Noncommunicable Diseases
Nation’s leading causes of death

5. Heart disease, stroke, cancer
Complex etiologies (causes)
Multicausation disease model
Host: inalterable, unique genetic endowment
Personality, beliefs, behavioral choices: impact host
Complex environment: exposes host to risk factors
Multicausation Disease Model
Noncommunicable Diseases
Diseases of the heart and blood vessels
Coronary heart disease
Cerebrovascular disease (stroke)
Malignant neoplasms (cancer)
Chronic obstructive pulmonary disease
Diabetes mellitus
Chronic liver disease and cirrhosis
Prioritizing Prevention and Control Efforts
Criteria used to judge importance of disease to a community
Number of people who will die from a disease
Leading causes of death
Number of years of potential life lost
Captures issues affiliated with various groups
Economic costs associated with disease
Money spent at various levels of government; ex: alcohol and
other drugs

6. Prevention, Intervention, Control, and Eradication of Diseases
Prevention: planning for and taking action to prevent or
forestall onset of disease or health problem
Intervention: effort to control disease in progress; taking action
during an event
Control - containment of a disease; prevention and intervention
measures
Eradication: total elimination of disease from human
population
Levels of Prevention
Primary prevention
Forestall onset of illness or injury during prepathogenesis
period
Secondary prevention
Early diagnosis and prompt treatment before disease becomes
advanced and disability severe
Tertiary prevention
Aimed at rehabilitation following significant pathogenesis;
retrain, reeducate, rehabilitate
Primary Prevention of
Communicable Diseases
Strategies at each link in chain of infection
Individuals
Hand washing, using condoms, properly cooking food
Communities
Chlorinating water supply, inspecting restaurants, immunization
programs for all citizens, vector control, solid waste disposal
Immunity

7. Important component of primary prevention
Active immunity - occurs when exposure to a disease-causing
organism prompts the immune system to develop antibodies
against that disease
Passive immunity - occurs when a person receives antibodies
against a disease rather than their immune system producing
them
Secondary Prevention of
Communicable Diseases
Individuals
Self-diagnosis, self-treatment with home remedies
Antibiotics prescribed by a physician
Communities
Controlling or limiting extent of an epidemic
Carefully maintaining records; investigating cases
Isolation, quarantine, disinfection
Tertiary Prevention of
Communicable Diseases
Individuals
Recovery to full health after infection; return to normal activity
Communities
Preventing recurrence of epidemics
Removal, embalming, burial of dead
Reapplication of primary and secondary measures
Primary Prevention of
Noncommunicable Diseases
Individuals
Education and knowledge about health and disease prevention,
eating properly, adequate exercise, driving safely

8. Communities
Adequate food and energy supplies, efficient community
services, opportunities for education, employment, and housing
Secondary Prevention of
Noncommunicable Diseases
Individuals
Personal screenings (mammogram, pap test, PSA test), regular
medical and dental checkups, pursuit of diagnosis and prompt
treatment
Communities
Provision of mass screenings for chronic diseases, case-finding
measures, provision of adequate health personnel, equipment,
and facilities
Tertiary Prevention of
Noncommunicable Diseases
Individuals
Significant behavioral or lifestyle changes, adherence to
prescribed medications, following rehabilitation requirements
after surgery
Communities
Adequate emergency medical personnel and services: hospitals,
surgeons, nurses, ambulance services
Discussion Questions
Which components of the Multicausation Disease Model can
communities most effectively impact?
Which level of prevention is most important for better
community health outcomes and why?
Who plays a more significant role in preventing diseases,
individuals or communities?