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Chapter 17
Infectious Diseases
and Sexually
Transmitted
Infections:
Risks and
Responsibilities
Lecture Outline
Copyright © 2010 Pearson Education, Inc.
written by Bridget Melton, Georgia Southern University
Objectives
• Explain how your immune system works to protect
you, and what you can do to boost its
effectiveness.
• Discuss actions that you can take to protect
yourself from the most common infectious
diseases today.
• Describe the most common pathogens infecting
humans today and the typical diseases caused by
each.
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Objectives (cont.)
• Explain the major emerging and resurgent
diseases affecting humans nationally and
internationally; discuss why they are increasing in
incidence and what actions are being taken to
reduce risks.
• Discuss the various sexually transmitted
infections, their means of transmission, and
actions that can be taken to prevent their spread.
• Discuss human immunodeficiency virus (HIV) and
acquired immunodeficiency syndrome (AIDS),
trends in infection and treatment, and their impact
on special populations.
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The Process of Infection
• Pathogens are disease-causing agents. There are
six major types.
• Bacteria
• Viruses
• Protozoans
• Parasitic worms
• Fungi
• Prions
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The Process of Infection (cont.)
• Multifactorial diseases are caused by interactions of
several factors.
• The host must be susceptible.
• Immune system is compromised.
• Transmitting agent is present.
• Environment must be hospitable to the pathogen.
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The Body’s Defenses against DiseaseCausing Pathogens
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Assessing Your Disease Risk
• Risk factors you cannot control
• Heredity
• Aging
• Environmental conditions
• Organism virulence and resistance
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Assessing Your Disease Risk (cont.)
• Risk factors you can control
• Personal habits
• Dosage, virulence, and where agent enters the body
• Age at time of infection
• Preexisting level of immunity
• Health and vigor of immune system
• Genetic factors controlling immune response
• Nutritional status of host
• Comorbidities
• Environmental surroundings
• Psychological factors
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Routes of Transmission
• Direct or indirect contact
• Autoinoculation
• Airborne contact
• Foodborne infection
• Animal-borne infection
• Interspecies transmission
• Waterborne
• Insectborne
• Perinatally
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Activity Break: How Does It Transfer?
• In groups of three to five, come up with one
example per group of an infection and how it
transfers.
• Example: Mononucleosis is transferred directly.
• No repeats of examples are allowed.
• When your group has an example, send one
person from the group to the front.
• If you have a repeat example, you must return back
to your group to think of another example.
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Your Body’s Response
• Skin is a physical barrier against pathogens.
• Enzymes are complex proteins in sweat that create
an inhospitable environment for pathogens.
• Mucous membranes trap organisms.
• Cilia are hair-like protrusions that sweep trapped
organisms toward body openings so they can be
expelled.
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The Immune System
• Immunity is the condition of being able to resist a
particular disease by counteracting the substance
that produces the disease.
• Antigen is any substance capable of triggering an
immune response.
• Antibodies are produced by the body and are
matched to specific antigens.
• Cell-mediated immunity refers to a grouping of
lymphocytes that can attack and destroy a foreign
invader.
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The Immune Response
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Body Response
• Fever is a rise in temperature above 98.6°F.
• Caused by toxins secreted by pathogens that
interfere with the control of body temperature
• Pain is an early sign of injury.
• Referred pain is pain that is present in one location
of the body although the source is at another
location.
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Vaccines
• Consist of a killed or attenuated version of a
disease-causing microorganism, or an antigen that
is similar to but less dangerous than the disease
antigen
• Acquired immunity
• Natural immunity
• Active immunity
• Passive immunity
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Recommended Adult Immunization
Schedule, by Vaccine and Age Group, 2007
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Examples of Four Major Types of Pathogens
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Bacteria
• Single-celled organisms
• Three major types: cocci, bacilli, and spirilla
• Bacterial toxins cause disease.
• Antibiotics
• Resistance
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Prevention of Drug-Resistant Pathogens
If someone you know has MRSA, take precautions.
• Wash your hands and shower with soap and hot
water.
• Keep personal items personal.
• If you suspect infection
• use towels only once.
• tell close friends and health care providers.
• Keep wounds clean, sterile, and covered.
• At the gym, wipe down surfaces you touch with
antibiotic washes.
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ABC News Video: Report on the MRSA Superbug
| Attack of the Superbug: Report on the
MRSA Superbug
Discussion Questions
1. Had you heard of MRSA before watching this clip?
What did you know about it?
2. How do you recognize a MRSA infection?
3. MRSA is becoming even more resistant to
medication. What do you think should be the next
step in addressing the overall problem?
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Other Pathogens
• Fungi are hundreds of species of uni- and
multicellular plant organisms that cause diseases
such as candidiasis, athlete’s foot, and ringworm.
• Protozoans are single-celled organisms that cause
diseases such as trichomoniasis and giardiasis.
• Parasitic worms are the largest of the pathogens;
they include pin worms and tape worms.
• Prions are self-replicating, protein-based agents.
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Viruses
The smallest of the pathogens, viruses have a
protein structure that contains RNA or DNA that
requires a cell host.
• Common cold
• Influenza
• Infectious mononucleosis
• Hepatitis A, B, or C
• Mumps
• Chicken pox
• Measles
• Rabies
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Colds and Influenza
• Colds are endemic, that is, always present.
• You can “catch” a cold from the airborne droplets of
another’s sneeze or contact.
• You cannot catch a cold from a chill.
• Five to 20 percent of Americans get the flu each
year.
• Three major varieties exist of the flu virus, each
having many different strains.
• Those who should be vaccinated include seniors,
pregnant women, those with heart and lung
diseases, and those with certain other diseases.
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Is It a Cold or the Flu?
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Streptococcal Infections and Meningitis
Streptococcal infections
• Group A streptococci (GAS), or “strep throat”
• Necrotizing fasciitis, or “flesh-eating strep”
• Group B streptococci can cause illness in newborns
and immunocompromised adults
Meningitis
• An infection of membranes that surround the brain
and spinal cord
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Necrotizing Fasciitis
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Emerging and Resurgent Diseases
• Factors include overpopulation, inadequate health
care, drug resistance, and increased international
travel.
• Mad cow disease
• Dengue and dengue hemorrhagic fever
• West Nile virus
• Ebola hemorrhagic fever
• Severe acute respiratory syndrome (SARS)
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Emerging and Resurgent Diseases (cont.)
• Escherichia coli 0157:H7
• Cholera
• Hantavirus
• Listeriosis
• Malaria
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Sexually Transmitted Infections
• Each year, the United States sees 15.3 million new
cases.
• More than 65 million people live with an incurable
STI.
• Two-thirds of all STIs occur in people 25 years of
age or younger.
• One in four new STIs occurs in teenagers.
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Modes of Transmission
• Sexual intercourse
• Oral–genital contact
• Hand–genital contact
• Anal intercourse
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Signs or Symptoms of Sexually
Transmitted Infections
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Chlamydia
• Often presents no symptoms
• Affects mostly women
• If left untreated, can affect
• Men: prostate gland, seminal vesicles
• Women: cervix, fallopian tubes
• Both: arthritis-like symptoms, damage to heart and
blood vessels
• Easily treated with antibiotics
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Gonorrhea
• More than 700,000 cases per year
• Caused by bacterial pathogen Neisseria
gonorrhoeae
• Primarily infects the linings of the urethra, genital
tract, pharynx, and rectum
• At highest risk are males age 20 to 24
• Treatment with antibiotics
• If left untreated, can cause sterility
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Gonorrhea (cont.)
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Pelvic Inflammatory Disease
• Pelvic inflammatory disease (PID) describes
numerous infections of the uterus, fallopian tubes,
and ovaries.
• Often results from an untreated STI
• Symptoms include abdominal pain, fever, and
unusual vaginal discharge.
• If left untreated, increases risk for infertility, chronic
pelvic pain, and recurrent upper genital infections
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Syphilis
• Caused by a bacterial organism
• Progresses in stages
• In the primary stage, a chancre develops that
disappears in 3 to 6 weeks.
• In the secondary stage, 1 to 12 months after the
chancre disappears, a rash or white patches on the
skin appear and last a few weeks or months.
• In the latent stage of infectious lesions, infection can
be passed to a fetus (congenital syphilis).
• In the late stage, heart damage, central nervous
system damage, blindness, paralysis, and dementia
occur.
• Treatment is with antibiotics.
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Syphilis: Penis
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Syphilis: Hands
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Syphilis: Arm
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Activity Break: You Be the Judge
Fred and Sally have had a great marriage for 5 years.
On a business trip to Seattle, Fred got drunk and
ended up having sexual intercourse with a local
woman. Fred felt bad afterward but soon forgot
about it. A few weeks later, he noticed an open sore
on his penis. His doctor said it was syphilis and
treated it with penicillin. Fred knew that Sally was
infected. He did not want to tell her he had infected
her, yet he could not remain silent. Fred and Sally
were planning on having their second child in about
a year.
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Activity Break: You Be the Judge (cont.)
1. What alternatives are open to Fred?
2. How might Sally react when she finds out?
3. Is a casual, drunken act in Seattle sufficient to
destroy a marriage and a family?
4. What would you do if you were Fred?
5. If you were Sally, how would you react to Fred’s
disclosure?
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Herpes
• Caused by virus
• Genital herpes is caused by herpes simplex virus
(HSV).
• Two types of HSV
• HSV-1
• HSV-2
• No cure for herpes, although some drugs can ease
symptoms
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Herpes: Genital
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Herpes: Mouth
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Genital Warts
• Genital warts are caused by human papillomavirus
(HPV).
• Affects 6.2 million Americans per year
• Two types
• Full-blown genital warts
• Flat warts
• Thirty percent of HPV cases progress to
precancerous cells.
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Genital Warts (cont.)
• Treatments for genital warts include podophyllin,
cryosurgery, simple excision, laser surgery, creams
containing 5-fluorouracil, or interferon injections.
• Vaccination
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Genital Warts: Male
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Genital Warts: Female
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ABC News Video: Human Papillomavirus Vaccine Mandatory
| Human Papillomavirus Vaccine Mandatory
Discussion Questions
1. Do you agree with this proposed law?
2. How would you explain this vaccine to your 11- or
12-year-old daughter?
3. What are opponents of the vaccine concerned
about? Do you agree or disagree?
4. Why do you suppose this vaccine is to be
mandated and not left as a choice by parents?
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Candidiasis (Moniliasis)
• A yeast-like fungus caused by Candida albicans
• Found naturally in the vaginal tract, becomes
problematic when normal chemical balance is
disturbed
• Factors that affect chemical balance
• Antibiotics
• Changes in hormone levels due to pregnancy,
breastfeeding, or menopause
• Douches or spermicides
• Sexual intercourse
• STIs
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Trichomoniasis
• Caused by a protozoan
• Many carriers experience no symptoms.
• Symptoms may include foamy, yellowish,
unpleasant-smelling discharge; burning sensation;
itching; and painful urination.
• Transmitted by sexual contact and spread by toilet
seats, wet towels, or other items with discharged
fluids on them.
• Treatment is with oral metronidazole.
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Pubic Lice
• Small parasites that are usually transmitted during
sexual contact
• Also known as crabs, they lay eggs at the base of
pubic hairs.
• Treatment is by washing clothing, furniture, and
linens.
• Usually takes 2 to 3 weeks to kill all larval forms
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Pubic Lice (cont.)
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General Urinary Tract Infections
• Urinary tract infections (UTIs) are caused by various
factors.
• Invading organisms travel up the urethra and enter
the bladder.
• Prevention is aided by diligent hand washing.
• Treatment depends on the organism.
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HIV/AIDS
• Acquired immunodeficiency syndrome (AIDS) has
affected 60 million people worldwide since 1981.
• Human immunodeficiency virus (HIV) causes AIDS.
• Over 38.6 million people are estimated to be living
with HIV or AIDS.
• In 2005, 4.1 million new cases were diagnosed
worldwide.
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Women and AIDS
• In 2005, women accounted for over 60 percent of
AIDS cases in the United States.
• AIDS is the leading cause of death in African
American women age 25 to 44.
• Women have been underrepresented in clinical
trials for HIV treatment and prevention.
• Factors for disparities include economic
disadvantages, cultural norms, rape, sexual abuse,
care-giving burdens, less education, and a passive
role in negotiating safe sex.
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How HIV Is Transmitted
• HIV enters the host from an infected host.
• Mucous membranes of the genitals and anus are
easiest route of entry.
• Once inside the host, the virus begins to multiply.
• Virus begins to destroy helper T cells.
• Virus changes the genetic structure of the cells it
attacks.
• The body begins to produce antibodies.
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Sources of HIV Infection in Men and
Women in the United States
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High-Risk Behaviors
• Exchange of body fluids
• Injecting drugs
• Receiving a blood transfusion prior to 1985
• Mother-to-infant (prenatal) transmission
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Symptoms of HIV Disease
• Months or years can pass after initial infection of
HIV before symptoms appear.
• Immune system changes occur over years.
• An infected person may experience a number of
opportunistic infections.
• Colds, sore throats, fever, tiredness, nausea, and
night sweats, generally appear as pre-AIDS
symptoms.
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Testing For HIV Antibodies
• ELISA test detects presence of HIV antibodies.
• Western blot test is a more expensive confirmatory
test.
• Positive results do not ensure the infected person
will develop AIDS.
• Early detection is important so that infected
individuals can receive immediate treatment.
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New Hope and Treatments
• New drugs have slowed the progression from HIV to
AIDS.
• Protease inhibitors block the HIV protease enzyme
from cutting protein chains to form new viruses.
• Protease inhibitors are difficult to manufacture.
• No cure is known.
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Preventing HIV Infection
• Avoid risky behaviors.
• Take responsibility for your own health.
• Seek information from health educators or other
health professionals.
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Where to Go for Help
• Arrange a confidential meeting with a health
educator or health professional at your college.
• Others can assist with your questions.
• Local physicians
• Counselors
• Professors
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