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Component 1: Introduction to Health
Care and Public Health in the U.S.
1.8: Public Health Part II
1.8a: Public Health and
Communicable Disease
Communicable Disease (CD)
• Communicable (also “infectious” or “transmittable”)
diseases are those that are a result of organisms such
as bacteria, protozoans, fungi, and viruses entering the
body
• Control of infectious diseases has been mainly due to
– clean water and better sanitation – examples are the drastic
reduction of typhoid and cholera, scourges of the early 20th
century
– antimicrobial therapy – examples are control of infections such
as tuberculosis and sexually transmitted diseases (STDs)
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Health IT Workforce Curriculum
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Public Health Triumphs
• Although there continue to be new communicable
diseases (see emerging infections, later in this unit), and
there is no shortage of existing diseases that are a
continued struggle for control (such as tuberculosis,
STDs, drug resistant infections, others), two of the
brightest triumphs of public health are encouraging • Polio
• Smallpox
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Smallpox
• Contagious and often fatal, smallpox is caused by a virus that has
been around for thousands of years
• 1796 Edward Jenner discovered that milkmaids who had caught
cowpox did not catch smallpox
• 1800: Technique of smallpox vaccination introduced into the US
• 1949 - Last case of smallpox in the United States
• 1966 - International Smallpox Eradication program established
• 1977 - last naturally occurring case in the world, Somalia
• 1977 - Worldwide eradication of smallpox following global
vaccination program
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Smallpox – Current State
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Routine vaccination against smallpox among the general public was
stopped after eradication
Other than laboratory stockpiles, the variola virus has been eliminated from
the world
A valid terrorism concern?
– CDC has detailed plan to protect Americans against smallpox as a
biological weapon: includes the creation and use of special teams of
health care and public health workers to immediately control spread of
the disease
– Vaccination within 3 days of exposure will completely prevent or
significantly modify smallpox for most
– US has stockpiled vaccine – it is a live vaccine to a related virus,
vaccination involves repeated pricking of skin with a two-pronged
needle
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Polio
• History - evidence of polio in an Egyptian stone engraving over
3,000 years old
• Virus that mainly affects children <5 years of age. Spread by contact
or by ingestion of fecal contamination in food or water
• Highly infectious, the virus invades the nervous system. While up to
95% of people may not even have symptoms, those that do can
have severe effects including paralysis
• 1955: Salk polio vaccine licensed. Rapid eradication in industrialized
countries
• Current: Polio has been effectively eliminated in industrialized
countries, but still a risk in other countries
• World Health Organization (WHO) continues its efforts at global
eradication of polio
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Public Health Communicable
Disease Activities
• State and Local Health Department activities include –
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Monitor (surveil) incidence of CDs
Investigate outbreaks
Intervene/treat populations
Report data to CDC
• CDC activities include:
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Gathering national data on infectious diseases
Managing national prevention and surveillance programs
Distributing funding and other resources
Collaborating with state and local public health in outbreak
response
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Food Poisoning – A Very
Simplified Case Study
Following is an extremely simplified fictional outbreak investigation. Although the reality is
much more complex than this quick example, it does illustrate some of the steps that public
health takes in its unending efforts to safeguard the population.
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Public Health receives laboratory reports for an enteric disease-causing organism such as
Salmonella or Shigella
Public Health Epidemiologists or “disease detectives” investigate the reports
Samples are sent to the Public Health Laboratory to be closely identified
Fieldwork determines that a significant number of ill patients ate at a company picnic
Questionnaires and statistical analyses identify the culprit as contamination in a dairy product served
at the picnic
Further investigation reveals a sanitation issue at the dairy has led to contamination in their product
A product recall is issued
The dairy fixes the sanitation problem, and further tests show the product is now free of
contamination
Public health reviews and evaluates the study and how to help prevent further such incidences
Data reported to CDC become part of the national data set
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Infectious Disease Topics
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Animal-Related Diseases
Bioterrorism Agents/Diseases
Childhood Diseases
Drug Resistant Infections
Emerging Infectious Diseases
Food-Related Diseases
Healthcare-Related Infections and Issues
HIV/AIDS
Insects and Arthropod-Related Diseases
Sexually Transmitted Diseases
Water-Related Diseases
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Sampling of Communicable
Diseases
• Animal-related – example Rabies
– A fatal viral infection, caused when the virus is introduced into
breaks in skin (such as by an animal bite)
– Some Public Health Responses: monitoring, managing
treatment, education for responsible pet ownership
• Food-related – example E. coli O157:H7
– Bacterial infection usually traced to food contaminated with cow
feces. Can lead to very severe health outcomes, including death
– Some Public Health Responses: monitoring, interventions,
outbreak investigation, education on prevention
• Sexually transmitted diseases – example Gonorrhea
– Bacterial infection transmitted by sexual contact or during birth.
Can lead to permanent health problems.
– Some Public Health Responses: monitoring, interventions,
outbreak investigation, education on prevention and treatment
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Sampling of Communicable
Diseases (cont)
• Water-related – example Cryptosporidiosis
– Microscopic parasite, ingested by drinking water contaminated with
animal or human feces
– Some Public Health Responses: monitoring, outbreak investigation,
education on water treatment
• Healthcare-related - example Methicillin-resistant Staphylococcus
Aureus (MRSA)
– Bacteria resistant to certain antibiotics, in healthcare settings may be
introduced by visitors or by health care providers
– Some Public Health Responses: monitoring, outbreak investigation,
education on prevention for both patients and health care providers
• Childhood diseases – example Chickenpox
– Viral infection causing fever and itchy rash, highly contagious, spread by
coughing, sneezing, contact
– Some Public Health Responses: monitoring of disease and
vaccinations, outbreak investigation, education on prevention through
vaccination
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Sampling of Communicable
Diseases (cont)
• HIV / AIDS – The human immunodeficiency virus (HIV),
which can lead to acquired immune deficiency syndrome
(AIDS)
– Viral infection transmitted by sexual or other body fluid contact
– Some Public Health Responses: monitoring of disease and
treatments, outbreak investigation, education on prevention and
testing
• Emerging Infectious Diseases – example Dengue
infection
– Viral infection, transmitted by mosquito. Endemic to Puerto Rico
and many popular tourist destinations in Latin America and Asia.
No vaccine or specific medication
– Some Public Health Responses: monitoring of disease, outbreak
investigation, education on avoidance and mosquito control
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