This document summarizes key aspects of epidemiology and the prevention and control of diseases and health conditions. It discusses how diseases are classified as acute or chronic and communicable or noncommunicable. The document outlines the chain of infection model for understanding transmission of communicable diseases. It also discusses multicausation models for noncommunicable diseases. Different levels of prevention are described including primary, secondary, and tertiary prevention strategies at both the individual and community levels.

1. Chapter 4
Epidemiology:
Prevention and Control
of Diseases and Health
Conditions
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)

2. • 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

3. 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

4. Biological Agents of Disease
Communicable Disease Model
Chain of Infection
• Step-by-step model to conceptualize the
transmission of a communicable disease from
its source to a susceptible host
Chain of Infection
• 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 host
• Portal of entry: where agent enters susceptible host

5. New host: susceptible to new infection being
established
Chain of Infection
• 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

6. 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
• Heart disease, stroke, cancer
• Complex etiologies (causes)
• Multicausation disease model
• Host: inalterable, unique genetic endowment
• Personality, beliefs, behavioral choices: impact
host

7. • Complex environment: exposes host to risk
factors
Multicausation Disease Model
Noncommunicable Disease Problems
• 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

8. • 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
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

9. 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

10. • Communities
• Chlorinating water supply, inspecting
restaurants, immunization programs for all
citizens, vector control, solid waste disposal
• Individuals
• Self-diagnosis, self-treatment w/home remedies
• Antibiotics prescribed by a physician
• Communities
• Controlling or limiting extent of an epidemic
• Carefully maintaining records; investigating
cases
• Isolation, quarantine, disinfection
Secondary Prevention of
Communicable Diseases
• Individuals
• Recovery to full health after infection; return to

11. normal activity
• Communities
• Preventing recurrence of epidemics
• Removal, embalming, burial of dead
• Reapplication of primary and secondary
measures
Tertiary Prevention of
Communicable Diseases
Primary Prevention of
Noncommunicable Diseases
• Individuals
• Education and knowledge about health and
disease prevention, eating properly, adequate
exercise, driving safely
• Communities
• Adequate food and energy supplies, efficient
community services, opportunities for
education, employment, and housing

12. 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

13. • 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?
Chapter 12

14. Alcohol, Tobacco, and
Other Drugs: A
Community Concern
Introduction
• Use, misuse, and abuse of mind-altering
substances predates recorded history
• Chronic alcohol and other drug abuse or
dependence is regarded as destructive behavior
in most cultures
• Affects individuals and the surrounding
community
Scope of the Current Drug Problem
• More deaths, illnesses, and disabilities can be
attributed to substance abuse than any other
preventable health condition
• Economic costs include direct costs (health

15. care, premature death, impaired productivity)
and indirect costs (crime and law enforcement,
courts, jails, social work)
• Those abusing are threats to themselves, their
families, and their communities
Annual Cost in Lives and Economic Cost
in $ Billions
Drug Use Among High School Seniors
Definitions
• Drug
• Psychoactive drugs
• Drug use
• Drug misuse
• Drug abuse
• Drug (chemical) dependence

16. • Psychological dependence
Factors that Contribute to Alcohol,
Tobacco, and Other Drug Abuse
• Risk factors – factors that increase the probability
of drug use
• Protective factors – factors that lower the
probability of drug use
• Both can be genetic or environmental
Inherited Risk Factors
• Most research related to drug dependence and
inherited risk is on alcoholism
• Research has shown genetic and biological
markers may predispose someone to increased
susceptibility to develop alcohol-related
problems

17. Environmental Risk Factors
• Personal factors
• Home and family life
• School and peer groups
• Sociocultural environment
Types of Drugs Abused and Resulting
Problems
• Legal drugs
• Alcohol, nicotine, nonprescription (over-the-
counter) drugs, prescription drugs
• Controlled substances and illegal (illicit) drugs
• Marijuana, narcotics, cocaine and crack
cocaine, hallucinogens, stimulants, depressants,
club drugs and designer drugs, anabolic drugs,
inhalants
Legal Drugs
• Can be legally bought and sold in the

18. marketplace
• Includes drugs that can be closely regulated,
likely regulated, and not regulated at all
Alcohol
• Number one drug problem in the United States
• Binge drinking
• Underage drinking
• Problem drinkers
• Alcoholism
• Blood alcohol concentration (BAC)
• Fetal Alcohol Spectrum Disorders
• Fetal Alcohol Syndrome
Nicotine
• Psychoactive and addictive drug present in
tobacco products
• Environmental tobacco smoke (ETS) or

19. secondhand smoke
• Synar Amendment
• Tobacco use is single most preventable cause
of disease, disability, and death in the U.S.
• Community efforts: tax increases on cigarettes
Over the Counter Drugs (OTCs)
• Legal drugs other than alcohol and tobacco
that can be purchased without a physician’s
prescription
• Carefully regulated by the Food and Drug
Administration (FDA)
• Most only provide symptomatic relief, not a
cure
• Subject to misuse and abuse
Prescription Drugs
• Can be purchased only with a physician’s

20. prescription because they have serious side
effects for some people
• Regulated by the FDA
• Subject to misuse and abuse
• Risk of dependence and unintentional
overdose
• Development of drug-resistant strains of
pathogens
Controlled Substances and Illicit Drugs
• Those regulated by the Controlled Substances
Act of 1970
• Cannot be cultivated, manufactured, bought,
sold, or used within the confines of the law
• Schedule I – high potential for abuse; no
accepted medical uses
• Schedules II-V – have medical uses; scheduled
based on potential for risk of dependence or

21. abuse
• Drug Enforcement Agency (DEA) responsible
for enforcing Controlled Substances Act
Marijuana
• Products derived from hemp plant
• Most abused illicit drug in the U.S.
• Often used in conjunction with other drugs –
polydrug use
• Acute effects – reduced concentration, slowed
reaction time, impaired short term memory,
impaired judgment
• Chronic effects – damage to the respiratory
system (if smoked), amotivational syndrome
Synthetic Marijuana
• Emerging cause for concern
• Chemically produced with properties similar to

22. THC
• Pose serious threat to communities – potential for
abuse and other adverse health effects, long-term
effects unknown
• In 2011, five chemicals used to produce synthetic
marijuana were added to Schedule I of the CSA
• States have banned synthetic marijuana
Narcotics
• Opium and its derivatives, morphine and
heroin, come from an oriental poppy plant
• Narcotics numb the senses and reduce pain
• High potential for abuse
• Opium poppies do not grow in U.S.; drug
trafficking problems
• Heroin addiction leads to significant
community health problems

23. Cocaine and Crack Cocaine
• Cocaine is the psychoactive ingredient in the
leaves of the coca plant
• Powerful and addictive euphoriant/stimulant
• Purified forms – salt (white powder), dried
paste (crack)
• In 2012, annual prevalence of cocaine use
among high school seniors at lowest reported
level of 2.7%
Hallucinogens
• Produce illusions, hallucinations, changes in
perceptions
• Synesthesia – mixing of the senses
• Both naturally derived and synthetic
• LSD, mescaline, peyote, mushrooms
Stimulants

24. • Drugs that increase the activity of the central
nervous system
• Amphetamines
• Schedule II prescription drugs; widely abused
• Methamphetamines often made in clandestine
labs
Clandestine Laboratory Incidents
Depressants
• Slow down the central nervous system
• May lower anxiety and inhibitions
• Tolerance develops
• Strong physical dependence
• Alcohol, barbiturates, benzodiazapines
Club Drugs and Designer Drugs
• Illicit drugs, primarily synthetic, most

25. commonly encountered at nightclubs and raves
• MDMA (ecstasy) most popular club drug
• Rohypnol – “date rape” drug
• Designer drugs – synthesized by amateur
chemists in secret labs
• Constantly change design to stay ahead of law
enforcement
Anabolic Drugs
• Protein-building drugs
• Anabolic/androgenic steroids, testosterone,
human growth hormone
• Have some legitimate medical uses
• Sometimes abused by athletes and body
builders
• Acute and chronic side effects
Inhalants

26. • Collection of psychoactive breathable
chemicals
• Paint solvents, motor fuels, cleaners, glues,
aerosol sprays
• Easy availability
• Low cost
• Often drug choice of young
• Acute and chronic effects
Prevention and Control of Drug Abuse
• Requires knowledge of:
• Causes of drug-taking behavior
• Sources of illicit drugs
• Drug laws
• Treatment programs
• Community organizing skills
• Persistence, and cooperation of various
individuals and agencies

27. Levels of Prevention
• Primary prevention aimed at those who have
never used drugs
• Secondary prevention aimed at those who have
used, but are not chronic abusers
• Tertiary prevention aimed at drug abuse
treatment and aftercare, including relapse
prevention
Elements of Prevention
• Education
• Treatment
• Public policy
• Law enforcement
• Education and treatment goals same:
• Reduce demand for drugs
• Public policy and law enforcement goals same:

28. • Reduce supply and availability of drugs
Governmental Drug Prevention and
Control Agencies and Programs
• Include a multitude of federal, state, and local
agencies
• Aim to reduce either the supply or demand for
drugs
Federal Drug Control Spending
Federal Drug Control Spending
Federal Agencies and Programs
• Office of National Drug Control Policy
• Department of Justice
• Bureau of Alcohol, Tobacco, Firearms, and
Explosives (ATF)

29. • Department of Health and Human Services
• Substance Abuse and Mental Health Services
Administration (SAMSHA)
• National Institute on Drug Abuse
• Department of Homeland Security
State and Local Agencies and
Programs
• State departments of health, education, mental
health, justice, and law enforcement all address
drug abuse prevention and control issues
• Some states have passed laws that conflict
with federal laws
• Local communities have individuals, task
forces, or agencies to prioritize problems and
decide approaches for solving them
Nongovernmental Drug Prevention and

30. Control Agencies and Programs
• Community-based drug education programs
• School-based drug education programs
• DARE, student assistance programs, peer
counseling programs
• Workplace-based drug education programs
• Employee assistance programs
• Voluntary health agencies
Discussion Questions
• How can risk factors for drug abuse be utilized
to aide in drug abuse prevention?
• How should federal, state, and local funds be
used to successfully deal with drug abuse
problems?