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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.