Download Sexually Transmitted Diseases

Chapter 13
Immunity and Infection
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1
The Chain of Infection

Transmitted through a chain of infection
 Pathogen: Disease-causing microorganism
 Reservoir: Natural environment of the pathogen
○ Can be a person, an animal, or an environmental component
 Portal of exit
 Means of transmission
○ Direct transmission
○ Indirect transmission
 Vectors: Carrier of the pathogen from one host to another
 Portal of entry
○ Penetration of the skin
○ Inhalation through mouth or nose
○ Ingestion
 New host
○ Local infection or systemic infection
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The Body’s Defense System

Physical and chemical barriers
 Skin
 Mucous membranes
 Cilia

The immune system
 Immunological defenders
○ Neutrophils
○ Macrophages – “big eaters”
○ Natural killer cells
○ Dendritic cells – eat pathogens and activate lymphocytes
○ Lymphocytes
 T-cells
- Helper, Killer, and Suppressor
 B-cells
- Antibodies
 Memory T and B cells
○ Antigens
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The Immune System

The inflammatory response
 Histamine causes dilation of blood vessels, heat,
redness, and swelling
 Draws white blood cells to the area to attack
invaders

The immune response
 Natural (innate) response
 Acquired (adaptive) response
 Response has four specific phases
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Figure 13.1 The immune response
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The Immune System

Immunity
 An infected person will never get the same illness
again
 Acquired immunity

Symptoms and contagion
 Incubation: Viruses and bacteria are actively
multiplying
○ Will not feel symptoms until the second or third phase
of the immune response cycle
 Prodromal period: Symptoms first appear
 Symptoms often due to the immune response not
the illness
○ Cytokines – chemical messengers released by cells to
amplify and coordinate immune response, cause fever
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Contagion & Immunization
Epidemics and Pandemics


Epidemic: rapidly spreading disease or health-related concern
Pandemic: a widespread epidemic
Antigenic drift, antigenic shift


Immunization: process of ‘priming’ the body to
remember an encounter with a specific antigen
 Types of vaccines


Vaccine: Introduction of a killed or weakened pathogen to
stimulate the body to produce antibodies
 Active immunity: Person produces his or her own antibodies
to the microorganism
 Passive immunity: Injection of antibodies produced by other
human beings or animals
○
Gamma globulin
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7
Allergy: The Body’s Defense
System Gone Haywire

Allergies result from a hypersensitive and
overactive immune system
 Allergens: Substances that provoke response

The allergic response
○ Production of immunoglobulin E antibody (IgE)
○ Histamine: released by mast cells, causes inflammatory
response
○ Anaphylaxis: Most serious, but rare, kind of allergic reaction

Dealing with allergies
 Avoidance
 Medication
 Immunotherapy
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Pathogens and Disease

Bacteria: Microscopic single-celled organisms
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Pneumonia
Meningitis
Strep throat and other streptococcal infections
Toxic shock syndrome and other staphylococcal infections
Tuberculosis
Tickborne infections
Ulcers
○ Heliobacter pylori
 Antibiotic treatments
○ Both naturally occurring and synthetic substances that can kill
bacteria
○ When misused, pathogens can become resistant to their effects
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Figure 13.2 Pathogens and associated
infectious diseases
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Pathogens and Disease
 Viruses
 Parasites taking what they need for growth and

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reproduction, can’t reproduce by themselves, need host
Most common form of contagious disease
The common cold
Influenza
Chicken pox, cold sores, and other herpesvirus
infections
Viral hepatitis
○ Jaundice
 Human papillomavirus (HPV)
 Treating viral illnesses
○ Antiviral drugs
○ Most viral diseases must simply run their course
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Pathogens and Disease

Fungi
 Yeast infections, athlete’s foot, jock itch, and ringworm

Protozoa
 Microscopic single-celled organism
 Malaria, giardiasis, trichomoniasis, trypanosomiasis, and amoebic
dysentary

Parasitic worms
 Largest organisms that can enter the body to cause infection
 Tapeworm and pinworm

Prions

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Proteinaceous infectious particles
Linked to fatal degeneration disorders of the CNS
Lack DNA and RNA and consist only of protein
Do not trigger an immune response
Form deposits in the brain
Associated with transmissible spongiform encephalopathies (TSEs) that
cause sponge-like holes in the brain
 Creutzfeldt-Jakob disease (CJD)
 Mad cow disease (Bovine spongiform encephalopathy, or BSE)
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Emerging Infectious Diseases

Selected infections of concern
 West Nile virus
 Severe acute respiratory syndrome (SARS)
 Rotavirus
 Escherichia coli 0157:H7 (strain of E. coli)
 Hantavirus
 Ebola
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Factors Contributing to
Emerging Infections

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Drug resistance
Poverty
Breakdown of public health measures
Environmental events
Travel and commerce
Mass food production and distribution
Human behaviors
Bioterrorism
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Other Immune Disorders: Cancer
and Autoimmune Diseases
Immune system can break down
 Autoimmune diseases

 Rheumatoid arthritis
 Systemic lupus erythematosus
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15
Supporting Your Immune
System
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Eat a balanced diet and maintain a healthy weight
Get enough sleep (6-8 hours a night)
Exercise, but not when you’re sick
Don’t smoke
Moderation of alcohol
Wash your hands frequently
Avoid contact with contagious people
Practice safe sex and don’t inject drugs
Receive all recommended vaccinations
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The Major STDs
Also known as sexually transmitted infections (STIs)
Spread of an infection from person to person mainly
through sexual activity
 STDs that pose a major health threat:


1.
2.
3.
4.
5.
6.
7.

HIV/AIDS
Hepatitis
Syphilis
Chlamydia
Gonorrhea
Herpes
Human papillomavirus (HPV)
CDC (2008) estimated 65 million Americans were infected
with an STD, and about 19 million Americans become
newly infected with an STD each year
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17
HIV Infection and AIDS



Human immunodeficiency virus (HIV) is the
virus which causes AIDS (acquired
immunodeficiency syndrome)
Without treatment, AIDS kills nearly all of its
victims
Approximately 65 million people around the
world have been infected with HIV since the
epidemic began
 Nearly 1% of the world’s population
 About 3.5 million new infections per year

21% of HIV-infected Americans are unaware of
their condition
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What Is HIV Infection?

Chronic disease that progressively damages the
body’s immune system
 HIV attacks and invades CD4 T-cells and other essential
elements of the immune system
 HIV enters a human cell and converts its own genetic
material, RNA, into DNA
 Inserts this DNA into chromosomes of host cell
 The viral DNA takes over the CD4 cell and replicates,
destroys the immune functions of CD4 cell


People with AIDS are vulnerable to a number of
serious opportunistic (secondary) infections
Once initial symptoms resolve, the asymptomatic
period, also called the latency phase, may last
from 2 to 20 years
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19
Transmitting the Virus
HIV lives only within cells and body fluids
 Three primary means of transmission:

 Specific kinds of sexual contact
 Direct exposure to infected blood
 HIV-infected women to her fetus or to infant during
breastfeeding
 Not through casual contact
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20
Populations of Special Concern for
HIV Infection

Most common means of exposure:
 Sexual activity between men
 Injection drug use
 Heterosexual contact
African American men and women are
vastly overrepresented among people
newly diagnosed with AIDS
 Increasingly a disease that effects
minorities, women, and the poor

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21
Figure 13.3 Routes of HIV transmission
among Americans
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22
Symptoms of HIV Infection

Within a few days or weeks (on average, 2 to 4
weeks after exposure to the virus), some people
will develop symptoms of primary (acute) HIV
infection
 Specialized test HIV RNA assay

Symptoms take months or years to develop, but as
immune system weakens, variety of symptoms
develop
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Swollen lymph nodes
Lumps, rashes, sores
Pneumocystis pneumonia (fungal infection)
Kaposi’s sarcoma
Difficult-to-treat yeast infections in women
Tuberculosis
Weight loss, fevers, sweats
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23
Diagnosing HIV Infection

Most common tests check for the
presence of antibodies to the virus
 HIV antibody tests
 ELISA (first test)
 Western blot or immunoflourescence assay
is done to confirm results

If HIV-positive, the next step is to
determine the disease’s severity to plan
appropriate treatment
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Treatment

Antiviral drugs
 Reverse transcriptase inhibitors
 Protease inhibitors
 Entry inhibitors
 HAART and Postexposure Prophylaxis (PEP)
Treatments for opportunistic infections
 HIV and pregnancy
 Treatment challenges
 How can you protect yourself?

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25
Figure 13.4 What’s risky and what’s not: The approximate
relative risk of HIV transmission of various sexual activities
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26
Chlamydia
Most prevalent bacterial STD in the U.S.
 Can cause sterility in men and women

 In women, it can lead to pelvic inflammatory disease,
infertility and ectopic (tubal) pregnancy
 In men, chlamydia is the most common cause of epididymitis
(inflammation of sperm-carrying ducts), and causes half of
all cases of urethritis (inflammation of the urethra)

Symptoms
 Usually asymptomatic in women, some have vaginal
discharge, burning with urination, pain or bleeding with
intercourse, and lower abdominal pain
 In men, painful urination, watery discharge from penis, pain
around testicles and in lower abdominals
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Chlamydia

Diagnosis and treatment
 Laboratory tests on a urine sample or a small
amount of fluid from the urethra or cervix
 Once diagnosed, infected person and partner
are given antibiotics
 Expedited partner therapy
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28
Gonorrhea
330,000 new cases reported to the CDC in
2008
 Can cause arthritis, rashes, eye infections,
PID, epididymitis, urethritis, and gonococcal
conjunctivitis or gonorrheal infection of blood
or joints in infants of infected mothers
 Can infect throat or rectum through oral or
anal sex
 Symptoms

 Usually asymptomatic in women, may have painful
urination, increased vaginal discharge, and severe
menstrual cramps
 Thick yellow-white discharge, and painful urination in
men, lips of urethral opening might become inflamed
and swollen, lymph glands in groin may become
enlarged and swollen, half of men have minor or no
symptoms
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Gonorrhea
 Diagnosis
and treatment
 Microscopic exam of discharge can
diagnose infection
 Oral antibiotics can cure the disease
○ Growing number of drug-resistant strains of
gonorrhea is a major concern, only 1 class of
antibiotics remains consistently effective
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30
Pelvic Inflammatory Disease (PID)





Occurs when initial infection by chlamydia or
gonorrhea travels upwards into reproductive
organs
Often serious enough to require hospitalization and
surgery
25% of affected women have long-term problems
Leading cause of infertility in young women
Smoking, large number of sexual partners, and
IUD usage are all risk factors for infection
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Pelvic Inflammatory Disease (PID)

Symptoms
 Women can be asymptomatic
 Long and painful periods, discharge, spotting, abdominal pain,
fever, chills, nausea, and vomiting

Diagnosis and treatment
 Diagnosis made on basis of symptoms, physical examination,
ultrasound, and laboratory tests, may require laparoscopy
 Antibiotics and sometimes hospitalization are required for
treatment
 Very important that partners be treated, many men asymptomatic
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32
Human Papillomavirus (HPV)


Most common STD in the U.S.
Causes a variety of human diseases:
 Common warts
 Genital warts
 Genital cancers
Highly contagious, can spread through oral
sex
 Very common among young people
 Two vaccines for HPV: Gardasil and Cervarix

 Gardasil
○ Protects against four types of HPV virus that account for
90% of genital warts and 70% of cervical cancers
○ Most effective before the onset of sexual activity
○ Approved for boys and men
 Cervarix
○ Doesn’t protect against genital warts, but may be more
effective in protections against cervical cancer
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Human Papillomavirus (HPV)

Symptoms
 Small bump on the skin or a large, warty growth
 Cauliflower-like mass
 May cause irritation and bleeding , painful urination

Diagnosis and treatment
 Diagnosed based on the appearance of lesions
 Often detected during routine PAP tests
 Special tests can detect HPV and distinguish
among the more common strains, including those
that cause most cases of cervical cancer
 Treatment focuses on reducing the number and
size of warts
○ Cryosurgery (freezing)
○ Electrocautery (burning)
○ Laser surgery
○ Acid treatments
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34
Genital Herpes


1 in 5 adults in the U.S. has genital herpes
Two forms cause genital herpes and oral-labial
herpes (cold sores)
 HSV 1 (Type 1)
○ Usually exposed to virus during childhood
○ Oral-labial herpes (cold sores)
○ 50-80% of U.S. adults have antibodies to HSV-1
 HSV 2 (Type 2)
○ Almost always sexually transmitted
○ Usually occurs during adolescence and early adulthood
○ Asymptomatic in 80-90% of people

If you ever have an outbreak, consider yourself
always contagious and inform partners
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35
Genital Herpes

Symptoms
 90% of infected people have no symptoms
 First episode causes flulike symptoms and genital
lesions
 Recurrent outbreaks

Diagnosis and treatment
 Diagnosed through symptoms, physical examination,
lab tests
 No cure, carry virus for life
 Antiviral drugs taken at the beginning of an outbreak
can shorten the severity and duration of symptoms
 Vaccines are in development
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Hepatitis B (HBV)
 Inflammation of the liver which can cause serious and
permanent damage to the liver
 Highly contagious but preventable with vaccine
 Transmitted through the exchange of bodily fluids and
sharing needles or contaminated items
 Can spread through nonsexual close contact
 Symptoms
 Can be asymptomatic
 Flulike symptoms, nausea, vomiting, dark-colored
urine, abdominal pain, and jaundice

Diagnosis and treatment
 Diagnosed through blood tests
 Most people recover, but can be chronic
carriers
 Can be fatal, no cure
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37
Syphilis



Caused by bacterium: Treponema pallidum
Can be effectively treated with antibiotics
Symptoms
 Primary phase: 10-90 days after exposure
○ Characterized by painless ulcers, called chancres, highly
contagious
 Secondary phase: 3-6 weeks after chancre
○ Characterized by flulike symptoms and highly contagious
skin rash
 Late, or tertiary, phase
○ Damage to organs, dementia, cardiovascular damage,
blindness, and death

Diagnosis and treatment
 Diagnosed by examination of infected tissues and
with blood tests
 Treated by antibiotics but damage from late stages
of infection can be permanent
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38
Other STDs

Trichomoniasis
 Most common curable STD among young
women
 Single-celled organism

Bacterial vaginosis (BV)
 Most common cause of abnormal vaginal
discharge
 Caused by unhealthy species of normal vaginal
bacteria

Pubic lice and scabies
 Contagious parasitic infections
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39
What You Can Do
Education
 Diagnosis and treatment







Get vaccinated
Be alert for symptoms
Get tested
Inform your partners
Get treated
Prevention
 Think and talk about responsible sexual behavior
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40
Chapter 13
Immunity and Infection
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41