Transcript Phase 1

Introduction
• One of the major problems society faces is the spread of
sexually transmitted diseases, or STDs.
• Many of them are bacterial and some are viral.
• Of all the diseases we face STDs can disrupt our quality
of life and even cut it short.
• We’ll consider several of these topics in the next two
lectures.
Fig. 10-01
Bacterial Diseases
• Bacteria (pathogens) cause many diseases in
humans.
• Chlamydia, Gonorrhea, and Syphilis are all
caused by a bacteria.
• We also may call these diseases communicable
since they are spread by host to host contact.
• Some are also found in soil, water, food, etc.
Fig. 10Ab
Fig. 10Aa
How do we get around them?
• Most bacterial infections are treatable by simple
antibiotics. Good for us!
• Antibiotics kill bacteria according to where they
interfere in the bacteria’s metabolism.
• Resistance to treatment is always an issue.
• Antibiotics vs. bacteria will be a continuing war
for us all.
The Big Three
• Chlamydia
• Gonorrhea
• Syphilis
Chlamydia
• Pathogen: Chlamydia trachomatis
• This is the leading cause of STDs in the US!
• ~18% of women have it, and don’t know it!
• Nearly 50% infection rate on college campuses
estimated!
Chlamydia Symptoms
• Maybe none.
• Mild burning (18-21 days post sex) during urination.
• Vaginal discharge
• PID common side effect.
• Can affect babies during birth.
Chlamydia Treatment
• Single dose of Azithromycin, tetracycline or
erythromycin.
Fig. 10-02
Infant with Chlamydia infection. Occurrence post-birth.
Gonorrhea
• Another “popular” bact. infection!
• Caused by Neisseria gonorrhoeae.
• Although the occurrence of this disease has
declined drastically in reacent years, a rise in
infection rates has been noticed since the late
90’s in adloescents, young adults, and African
Americans.
Gonorrhea…
• Strangely enough, regular use of oral contraceptives in
women increases their likelihood of contracting this
disease. (Makes the birth canal more susseptable to
infections by pathogens.)
• A double whammy? People diagnosed with “G” often
also are diagnosed with “C.”
• Additionally, the presence of either (or both) of these
diseases increases the likelihood of HIV infection.
• Why?
Rates of Infection Gonorrhea
(1981-1999)
Gonorrhea Symptoms
• In men, this is relatively easy to detect. Why?
• Pain during urination, milky discharge 3-5 days post
coitally (or after contact with pathogen).
• Women show lesser symptoms or are asymptomatic!
May experience sever pain in the adbomial region due to
PID.
• Women using IUDs are very succeptable to PID from the
big “G.”
More symptoms…
• Gonorrhea of the anus??
Yep! Also known as
gonorrhea proctitis. Pain,
inflammation, blood or
pus in the feces.
• Eye contact can also
result in infection.
• Spreading to internal
parts of the body is also
possible.
Treatment for Gonorrhea
• Ladies, if your partner is infected, then you might as well
flip a coin if you’re worried about having sex with them
and becoming infected (Women: 50-60%, Men: 20%).
• Resistance is becoming more and more of an issue
since many men and women don’t realize they are
carriers. (Sharing of antibiotics also an issue…more
later.)
• New tests are being devleope, but most rely on blood
samples.
Syphilis
• Agent: Treponema
pallidum.
• This one has three
stages! Chancre, body
rash, and gummas.
• Chancre (right) is the site
where the bacterium
actually enters the body
cavity.
Syphilis
• Palms of the hand can
also be used to identify
carriers.
• Body rash in these
locations is obvious,
although the rash doesn’t
itch.
Syphilis
• Tertiary syphilis (gummas)
may not always evolve.
• This stage lasts until the
patient dies. Cure??
• Symptoms include
cardiovascular weakening,
aneurysms. Nervous system
disorders, blindness,
confusion, insanity.
Diagnosis and Treatment
• Diagnosis is often made by a blood test, or
microscopically.
• Blood: Reagin (antibody)
• Usually followed up by a microscopic evaluation,
since blood test may result in a falso positive.
• Penicillin will cure all stages if given in time and
of sufficient dosage!
Viral Pathogens
Herpes, HIV, Genital Warts, Hepatitis.
What a Virus Isn’t
• Not a bacterium
• Not an independently-living organism
• Cannot survive in absence of a living cell within
which to replicate
• Antibiotics do no harm to a virus, unless indirectly
• Treatment of a flu virus with antibiotics is only the
treatment of its symptoms
• You don’t kill the organism that causes the flu!
What are Viruses?
• Infectious agents composed mainly of nucleic acid with a
protein coat (capsid)
• Can only be seen with an electron microscope
• Range in size from 10 to 200 nanometers (nM)
• Carry on normal cell-like function unless free, then
infectious
• In infectious form, they neither grow nor respire
• Can enter living plant, animal or bacterial cell
What do Viruses Look Like?
• Most viruses have a capsid, core and genetic material (DNA/RNA)
• Capsid: outer shell of the virus which encloses genetic material (link:
chemical structure of capsid helps determine immune response to
virus)
• Capsid is made of many identical individual proteins, precisely
assembled
• Protein core under capsid protecting genetic material
• Sometimes an additional covering (lipid bilayer w/embedded proteins)
on outside known as an envelope
• Resembles a baseball
• Various forms: rods, filaments, spheres, cubes, crystals
What do Viruses Actually Do?
• All viruses only exist to make more viruses
• All, with the exception of some bacterial viruses,
appear to be harmful
• Their replication leads to the death of the cell which
the virus has entered
• Virus enters the cell by first attaching a specific
structure on the cell’s surface
• Depending on the virus, either the entire virus enters
the cell or only the genetic material is injected
The Virus Invasion
• Phase 1: spike and fibers attach themselves to the walls
of the cell or bacteria
• Phase 2: the sheath contracts and drives the core
through the cell wall (injection)
• Phase 3: the nucleic acid passes through the core, from
the capsid head, into the host cell
• Phase 4: nucleic acid disappears, afterwards (10m)
hundreds of virions appear causing the cell to rupture,
releasing hundreds of small viral replicates
• This is how it can replicate so quickly!!
The Virus Invasion
What Things Can Become
Infected by a Virus?
• All living things have some susceptibility to a particular
virus
• Virus is specific for the organism
• Within a species, there may be a 100 or more different
viruses which can affect that species alone
• Specific: for example, a virus that only affects one
organism (humans and smallpox)
• Influenza can infect humans and two animals.
Different Types of Viruses
• Major classification: animal, plant, bacterial
• Sub-classified by arrangement and type of nucleic acid
• animal virus group: double-stranded DNA, singlestranded DNA, double-stranded RNA, single-stranded
RNA, retrovirus
• influenza: SS-RNA
• for all viruses, regardless of the kind of arrangement of
genetic material, the virus is capable of replicating within
a living cell and can produce progeny
Human Viruses
“Best way not get hit is not be there when punch arrive.”
-Mr. Miagi (The Karate Kid II)
• Good advice! Applies to viruses too. Prevention of
transmission is the ultimate cure.
• Herpes, Genetal warts, and Hepatitis are problematic in
this area as they are very difficult to control outbreaks.
Herpes 1 and 2
• Herpes simplex virus 1 and 2
(HSV 1 and HSV 2) are difficult
to deal with.
• HSV 1: Cold sores primarily
• HSV 2: Genital herpes
• Cross-over symptoms work
both ways.
• 45 million people are
estimated to be infected.
Symptoms
• Tingling, itching followed by blisters on the genitals.
• Ruptured blisters are slow to heal (3 weeks) and painful.
• Fever and swollen lymph nodes in the groin also likely. (Copius
vaginal discharge in women.)
• Healed ulcers don’t mean cure! Only latent condition.
• Sun, stress, and menstrual cycles will trigger outbreaks.
• Newborns can also be affected when passing through the birth
canal. (Cesarean section avoids this!!)
Trasmission
• Transmission from infected individuals occurs
primarily during lesion outbreaks.
• Monogamous relationships go a long way
toward low risk.
• No cure. Multiple treatments for symptoms.
Treatment (cont.)
• Acyclovir and vidarabine: disrupt the viral
reproduction, but don’t stop it altogether.
• Ointment of acylovir works to relieve initial
symptoms, while oral drug valaciclovir (Valtrex)
is most often prescribed for treatment of
recurrent symptoms.
Genital Warts
• Caused by human papillomavirus (HPV)
• ~5.5 million people infected each year.
• A large cooccurence of genital warts and cervical cancer
in women.
• No cure once infected, although warts can be removed.
• Vaccines exist for some strains.
Hepatisis
•
•
•
•
•
Disease that attacks the liver.
Hep A: Sewage (aquired natural immunity possible)
Hep B: DNA virus spread by needle sharing
Hep C: infected blood (death)
Hep E: developing countries (rare in US)
• Vaccines available for Hep B (children get it now)
Fig. 10-08
HIV (AIDS)
• Aquired Immune Deficiency Syndrome (AIDS) is
caused by the human immunodefficiency virus
(HIV).
• Blood infection (64 million worldwide)
• While you’ve looked at this slide, at least 2 new
cases have occurred in heterosexuals!
HIV (AIDS)
• Most cases are reported
in Africa, many due to
unprotected sex with
infected men.
• How does HIV work? It’s
complicated. That’s why
our bodies haven’t
developed an immunity,
yet.
How AIDS Works
•
Lymphocytes in our blood
fight infection.
•
B-lymphocytes are
pathogen specific in action.
•
T-lymphocytes which kill
cells directly (T-killer cells)
or assist others work better
(“T-helper cells”) are the
primary line of cellular
defense against pathogens
•
HIV destroys T-helper cells:
ultimate result=immune
system compromised
AIDS Stages
• AIDS has three phases: Acute (Category A), Chronic
Infection (Category B), and AIDS (Category C).
• Most people die of secondary diseases also known as
opportunistic infections (ex. Pneumonia).
• HAART treatment used to fight disease involves
expensive drugs which disrupt replication of virus or help
to strengthen existing immune system.
• Newer drugs actually promote active immunity in
humans (turn on T-killer cells).
Other issues…
• “Vaginitis” caused by bacteria (Gardnerella vaginalis),
parasites (Trichomonas spp.) (L), or yeast (Candida
albicans) (R).
Crabs can also be problematic. Caused by a
louse, Phthirus pubis. Treated with Lindane.