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Chapter 17
Infectious Diseases
and Sexually
Transmitted
Infections:
Risks and
Responsibilities
PowerPoint® Lecture Slide Presentation
prepared by
Michael Hall
Copyright © 2008 Pearson Education, Inc.,
publishing as Pearson Benjamin Cummings
Objectives
 Discuss the risk factors for infectious diseases and
how your immune system works to protect you.
 Describe the most common pathogens.
 Explain the major emerging and resurgent diseases
affecting humans today.
 Discuss the various sexually transmitted infections.
 Discuss human immunodeficiency virus (HIV) and
acquired immunodeficiency syndrome (AIDS).
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Assessing Your Disease Risks
 Risk factors you cannot control
• Heredity
• Aging
• Environmental conditions
• Organism 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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The Body’s Defenses Against Disease-Causing
Pathogens
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Figure 17.1
Types Of Pathogens And Routes Of Transmission
 Direct/indirect contact
 Autoinoculation
 Airborne contact
 Food-borne infection
 Animal-borne infection
• Interspecies transmission
 Water-borne
 Insect-borne
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Routes of Disease Transmission
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Table 17.1
Bacteria




Single celled organisms
Three major types: cocci, bacilli, and spirilla
Bacterial toxins cause disease
Common bacterial infections:
• Staphylococcal – toxic shock syndrome
• Streptococcal – strep throat
• Meningitis
• Pneumonia
• Legionnaire’s disease
• Tuberculosis
• Periodontal diseases
• Rickettsia-caused diseases
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Viruses
 The smallest of the pathogens, consists of a protein structure
that contains RNA or DNA requires a cell host
 Common cold
 Influenza
 Infectious mononucleosis
 Hepatitis – A, B, C
 Mumps
 Chicken pox
 Measles
 Rabies
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Is it a Cold or the Flu?
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Figure 17.2
Ways in Which Hepatitis A, B, and C Are
Contracted
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Figure 17.3
Other Pathogens
 Fungi – hundreds of species, uni- or multicellular
plant organism: candidiasis, athlete’s foot, ringworm
 Protozoa – single-celled organisms: trichomoniasis,
giardiasis
 Parasitic worms – largest of the pathogens, pin
worms, tape worms
 Prions – self-replicating, protein based agent: mad
cow disease
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Your Body’s Defenses
 Skin – physical barrier against pathogens
 Enzymes – complex proteins in sweat that creates
inhospitable environment for pathogens
 Mucous membranes trap organisms
 Cilia – hair-like protrusions that sweep trapped
organisms toward body openings so they can be
expelled
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Keeping Defenses Healthy
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Table 17.2
The Immune System
 Immunity – a condition of being able to resist a
particular disease by counteracting the substance that
produces the disease
 Antigen – any substance capable of triggering an
immune response
 Antibody – produced by the body and are matched to
that specific antigen
 Cell-mediated immunity – a grouping of lymphocytes
that can attack and destroy the foreign invader
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Body Response
 Fever – a rise in temperature above 98.6°F
• Results from toxins secreted by pathogens that
interfere with the control of body temperature
 Pain – early sign of injury
• Referred pain – present in one location of the body
although the source is at another location
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The Immune Response
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Figure 17.4
Vaccines
 Consists of a killed or attenuated versions 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, 2006
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Figure 17.5
Emerging And Resurgent Diseases
 Factors: overpopulation, inadequate healthcare, drug
resistance, increased international travel
 Mad cow disease
 Dengue and dengue hemorrhagic fever
 West Nile virus
 Ebola hemorrhagic fever
 Severe acute respiratory syndrome (SARS)
 E. coli 0157:H7
 Cholera
 Hantavirus
 Listeriosis
 Malaria
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ABC News: Infectious Disease
Play
Video
| Infectious Disease
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ABC News: Infectious Disease
Discussion Questions:
 What is the difference between an epidemic and
pandemic?
 What animals, other than birds, have been identified
as having the “Bird flu?”
 What strategies have the Thailand Ministry of Public
Health and the Centers for Disease Control designed
to monitor the spread of the Bird Flu in Thailand?
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Factors Contributing to Emergent/Resurgent
Disease Spread and Possible Solutions
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Table 17.3
Sexually Transmitted Infections
 15.3 million new cases reported each year in U.S.
 More than 65 million people live with an incurable
STI
 2/3 of all STIs occur in people 25 years of age or
younger
 1 in 4 new STI infections occur 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 (STI)
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Figure 17.6
Chlamydia
 Often presents no symptoms
 Affects mostly women
 If left untreated can affect
• Men – prostate gland, seminal vesicles
• Women – cervix or fallopian tubes
• Both – arthritis like symptoms, damage to heart and
blood vessels
 Easily treated with antibiotics
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Pelvic Inflammatory Disease (PID)
 Term used to describe numerous infections of the
uterus, fallopian tubes, and ovaries
 Often results from an untreated STI
 Symptoms include: abdominal pain, fever, unusual
vaginal discharge
 Left untreated increases risk for infertility, chronic
pelvic pain, recurrent upper genital infections
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Gonorrhea
 700,000 cases per year
 Bacteria pathogen Neisseria gonorrhoeae
 Primarily infects the linings of the urethra, genital
tract, pharynx, and rectum
 High risk are males aged 20 to 24; females 15-19
 Treatment with antiobiotics
 If left untreated, can cause sterility
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Syphilis
 Caused by a bacterial organism
 Progresses in stages
• Primary – development of a chancre that disappears in three
to six weeks
• Secondary – 1 to 12 months after chancre disappears, a rash
or white patches on the skin appear which last a few weeks
or months
• Latent – infectious lesions, infection can be passed on to
fetus (congenital syphilis)
• Late – heart damage, central nervous system damage,
blindness, paralysis, dementia
 Treatment - antibiotics
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Pubic Lice
 Small parasites that are usually transmitted during
sexual contact
 Lay eggs at the base of pubic hairs
 Treatment – washing clothing, furniture, and linens
 Usually takes 2 to 3 weeks to kill all larval forms
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Genital Warts (HPV)
 Genital warts caused by human papillomavirus (HPV)
 Affects 5.5 million Americans per year
 2 types
• Full-blown genital warts
• Flat warts
 30% progress to precancerous cells
 Treatment for genital warts – podophyllin,
cryosurgery, simple excision, laser surgery, creams
containing 5-fluorouracil, interferon injections
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Candidiasis (Moniliasis)
 A yeast like fungus caused by Candida albicans
 Found naturally in the vaginal tract, become
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 – oral metronidazole
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General Urinary Tract Infections (UTIs)
 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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Herpes
 Caused by virus
 Genital herpes is caused by herpes simplex virus
(HSV)
 Two types of HSV
• Type 1
• Type 2
 No cure for herpes, although some drugs can ease
symptoms
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Preventing Herpes
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Table 17.4
HIV/AIDS
 Acquired immune deficiency syndrome affected 60
million people worldwide since 1981
 Human immunodeficiency virus causes AIDS
 Over 38.6 million people are estimated to be living
with HIV or AIDS
 4.1 million new cases were diagnosed worldwide in
2005
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Women And AIDS
 In 2005, women accounted for over 60% of AIDS
cases in U.S.
 AIDS is the leading cause of death in African
American women aged 25 to 44
 Women have been underrepresented in clinical trials
for HIV treatment and prevention
 Factors for disparities: economically disadvantages,
cultural norms, rape, sexual abuse, caregiving
burdens, less education, 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-lymphocytes
 Virus changes the genetic structure of the cells it
attacks
 The body begins to produce antibodies
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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 after initial infection of HIV before
symptoms appear
 Immune system changes occur over years
 May experience a number of opportunistic infections
 Colds, sore throats, fever, tiredness, nausea, 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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Tattoo and Piercing Safety
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Table 17.5