Common Sexually Transmitted Diseases: STD 101 Developed by The Training and Health Communications Branch, in partnership with the Program Development and Support Branch, Division of STD Prevention Centers for Disease Control and Prevention (CDC) Modified by L.A. Privitera for WS/BIOL 350 Knowledge About STDs Among Americans 12 Unable to name any STDs 17 Believe all STDs are curable Unaware that STDs increase risk of HIV infection 56 0 10 20 30 40 50 60 Percentage of Americans 18-64 years old Source : Kaiser Family Foundation, 1996 4 Topics • Bacterial Infections: curable with antibiotics » Chlamydia » Gonorrhea » (Syphilis) • Viral Infections: no cure, but can alleviate or remove symptoms with medication » Herpes type 2 » HPV (genital warts) » Hepatitis B » HIV/AIDS • Other STDs Chlamydia (Chlamydia trachomatis) Epidemiology of Chlamydia • Incidence: Approximately 4 million new cases in U.S. per year • Currently, the most common STD in U.S. (and Hawaii), especially in indivs. <25 yrs old • Rates 4x higher in females than in males • Decreasing prevalence in selected areas with control programs that include clinic-based screening • High prevalence of co-infection in partners (>50%) • Perinatal transmission results in neonatal conjunctivitis in 30-50% of exposed babies Chlamydia rates by gender in the U.S., 1984–2001 Rate (per 100,000 population) 450 360 270 Men Women 180 90 0 1984 86 88 90 92 Source: CDC/NCHSTP 2001 STD Surveillance Report 94 96 98 2000 Chlamydia: Age- and sex-specific rates in the U.S., 2001 Men 3,000 Rate (per 100,000 population) 2,400 1,800 1,200 600 0 9.9 375.9 604.9 284.7 140.4 70.3 37.1 15.9 5.5 2.2 114.2 Age Women 0 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-54 55-64 65+ Total Source: CDC/NCHSTP 2001 STD Surveillance Report 600 1,200 1,800 2,400 3,000 139.8 2,536.1 2,447.0 824.6 301.9 119.1 51.4 18.1 5.1 2.9 436.3 Chlamydia rates by state: U.S. and outlying areas, 2001 231.3 212.7 104.9 165.4 217.9 169.2 156.3 303.6 241.2 169.9 244.5 312.8 194.7 231.0 187.3 241.8 352.0 250.9 134.5 301.0 307.8 279.6 331.7 343.8 225.0 303.7 129.7 259.1 249.3 219.7 274.6 273.5 272.3 382.1 Guam 278.4 414.6 326.6 413.4 334.5 399.2 437.7 235.4 VT NH MA RI CT NJ DE MD Rate per 100,000 population (n= 7) <=150 150.1-300 (n= 29) (n= 17) >300 332.7 Puerto Rico 72.2 Virgin Is. 120.6 Note: The total rate of chlamydia for the United States and outlying areas (including Guam, Puerto Rico and Virgin Islands) was 275.5 per 100,000 population. Source: CDC/NCHSTP 2001 STD Surveillance Report 104.8 111.9 163.8 277.8 226.6 193.9 356.4 295.3 Chlamydia rates among 15-24 yr. old women tested in family planning clinics by state: U.S. and outlying areas, 2001 6.2 5.8 3.1 3.2 4.0 4.3 4.4 7.5 3.4 4.2 5.2 4.3 5.6 3.8 7.5 5.1 6.5 7.0 5.0 5.6 4.1 6.0 6.7 5.4 5.7 2.7 4.3 8.1 3.9 6.9 4.9 6.6 7.6 13.5 7.7 8.3 8.4 10.8 3.7 VT NH MA RI CT NJ DE MD DC 5.5 5.5 Positivity (%) <4 4.0-4.9 >=5 5.4 Puerto Rico 6.1 3.4 5.9 5.2 7.0 5.0 6.3 5.8 5.1 6.1 Virgin Is. 13.9 Note: States reported chlamydia positivity data on at least 500 women aged 15-24 years screened during 2001. SOURCE: Regional Infertility Prevention Program; Office of Population Affairs; Local and State STD Control Programs; Centers for Disease Control and Prevention (n= 8) (n= 8) (n= 37) Presentation of Chlamydia Symptoms in Females: • 75% are asymptomatic • Abnormal vaginal discharge • Pain during urination or sex Symptoms in Males: • 40% asymptomatic • Discharge from the penis (may be runny, whitish) • Burning during urination Complications, if not treated: • Pelvic inflammatory disease (PID) • Infertility or ectopic pregnancy from damaged or scarred reprod. tissue/organs Complications, if not treated • Swollen and tender testicles (epididymitis) • Infertility from damaged or scarred reproductive ducts or organs Testing & Treatment for Chlamydia • Easily detected by a urine test or cervical tissue culture; and • Can be cured with antibiotics; but any damage to the body is not repaired by the antibiotics Gonorrhea (Neisseria gonorrhoeae) Epidemiology of Gonorrhea • One of the most common STDs in U.S.; about ½ million new cases per year • Incidence remains high in some groups defined by geography, age and race/ethnicity, or sexual orientation • As with chlamydia, rates in women are highest among teenagers and young adults • About half of infected patients also have an existing chlamydia infection • Associated with increased susceptibility to HIV infection Gonorrhea Gonorrhea: Reported rates in U.S. 1970–2001 Rate (per 100,000 population) 500 Gonorrhea 2010 Objective 400 300 200 100 0 1970 73 76 79 82 85 88 91 94 97 2000 Note: The Healthy People 2010 (HP2010) objective for gonorrhea is 19.0 cases per 100,000 population. Source: CDC/NCHSTP 2001 STD Surveillance Report Gonorrhea Gonorrhea rates by gender in U.S. 1981–2001 Rate (per 100,000 population) 600 Male Female 2010 Objective 480 360 240 120 0 1981 83 85 87 89 91 Source: CDC/NCHSTP 2001 STD Surveillance Report 93 95 97 99 2001 Gonorrhea Gonorrhea: Age- and gender-specific rates in U.S., 2001 Men 750 Rate (per 100,000 population) 600 450 300 150 0 8.2 307.5 563.6 328.4 203.9 134.3 90.5 46.8 17.2 4.5 128.6 Age 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-54 55-64 65+ Total Source: CDC/NCHSTP 2001 STD Surveillance Report 0 Women 150 300 450 600 750 51.8 703.2 664.1 249.4 112.7 57.8 31.2 9.4 2.0 0.9 128.5 Gonorrhea Gonorrhea rates by state: U.S. and outlying areas, 2001 50.7 11.5 11.1 8.7 33.4 54.9 5.9 112.1 38.3 15.6 117.5 48.5 116.0 69.5 87.9 74.2 76.4 186.4 193.4 114.7 9.8 68.8 57.2 VT 12.5 NH 14.2 MA 50.6 RI 79.2 CT 74.8 NJ 106.0 DE 221.2 MD 178.0 172.3 99.3 138.6 40.5 155.9 156.7 88.8 206.0 178.3 172.2 269.3 Guam 31.0 272.8 251.4 231.1 Rate per 100,000 population 144.0 274.2 72.9 134.7 <20 20-100 >100 (n= 9) (n= 21) (n= 23) 49.9 Puerto Rico 15.5 Virgin Is. 31.3 Note: The total rate of gonorrhea for the United States and outlying areas (including Guam, Puerto Rico and Virgin Islands) was 126.9 per 100,000 population. The Healthy People year 2010 objective is 19.0 per 100,000 population. Source: CDC/NCHSTP 2001 STD Surveillance Report Gonorrhea Gonorrhea rates among 15-24 yr old women tested in family planning clinics by state in U.S. and outlying areas, 2001 1.1 1.7 0.9 VT NH MA RI CT NJ DE MD DC 1.2 0.9 0.5 2.3 0.4 1.1 1.7 0.3 0.7 0.8 0.4 0.8 1.0 2.5 0.8 0.5 0.7 1.6 1.0 1.3 1.3 1.3 3.2 1.9 Positivity (%) 2.2 1.3 2.9 0.2 0.2 0.4 1.2 See * <1 1.0-1.9 >=2 0.1 Puerto Rico 0.1 Virgin Is. 1.6 *States reported gonorrhea positivity data on less than 500 women aged 15-24 years during 2001. SOURCE: Regional Infertility Prevention Program; Office of Population Affairs; Local and State STD Control Programs; Centers for Disease Control and Prevention (n= (n= (n= (n= 16) 17) 15) 5) Gonorrhea Symptoms in Males • Symptoms appear in 7090% of infected men (usually within 2-5 days, but up to 1 mo.) • Discharge from the penis (may be thick, milky white, yellowish, or greenish) Source: CDC/NCHSTP/Division of STD Prevention, STD Clinical Slides • Painful burning upon urination Complications in Males • Swollen or tender testicles (epididymitis), which can lead to infertility if untreated • Disseminated gonococcal infection (DGI), which can lead to skin infections and septic arthritis if untreated • Infection can spread up the urethra to the bladder, sex accessory glands and ducts, producing scar tissue that can lead to infertility Swollen or Tender Testicles (Epididymitis) Source: Health Awareness Connection, http://www.healthac.org/images.html Gonorrhea Symptoms in Females • Most women (75%) have no symptoms (at least in the early infectious stages) • For those that do show symptoms: • Painful urination • Pain during sex • Whitish or yellowish discharge from vagina or urethra • Abnormal uterine bleeding • Bartholin’s abscess Source: CDC/NCHSTP/Division of STD Prevention, STD Clinical Slides Bartholin’s Abscess Source: CDC/NCHSTP/Division of STD Prevention, STD Clinical Slides Complications from Gonorrhea in Females • Pelvic inflammatory disease (PID) and tubal blockage from scarring, which can lead to infertility • Disseminated gonococcal infection (DGI), which can lead to skin lesions and septic arthritis Disseminated Gonococcal (Gonorrhea) Infection Source: CDC/NCHSTP/Division of STD Prevention, STD Clinical Slides Pelvic Inflammatory Disease (PID) Source: Cincinnati STD/HIV Prevention Training Center Testing & Treatment for Gonorrhea • Easily detected by a simple lab test; and • Can be cured with antibiotics; but • Many antibiotic-resistant strains have evolved; and • Any damage to the body is not repaired by the medicine Syphilis Treponema pallidum Syphilis Hits record low in ‘00 Primary and secondary syphilis — Reported rates in the U.S., 1970–2001 Rate (per 100,000 population) 25 P&S Syphilis 2010 Objective 20 15 10 5 0 1970 73 76 79 82 85 88 91 94 97 Note: The Healthy People 2010 (HP2010) objective for primary and secondary syphilis is 0.2 case per 100,000 population. Source: CDC/NCHSTP 2001 STD Surveillance Report 2000 Primary and secondary syphilis rates by state: U.S. and outlying areas, 2001 1.0 0.0 0.1 0.0 0.4 0.7 0.1 0.4 0.1 0.2 1.6 0.2 0.8 0.6 0.4 0.5 3.3 1.6 0.5 3.5 0.9 1.7 1.0 2.5 0.7 0.3 0.5 1.4 1.2 5.5 5.8 1.8 5.9 Guam 7.8 4.9 3.2 5.1 2.3 3.9 0.0 VT NH MA RI CT NJ DE MD 4.3 3.0 Rate per 100,000 population <=.2 .21-4 >4 1.0 Puerto Rico 6.4 0.5 0.1 0.7 0.9 0.4 1.6 1.8 5.0 Virgin Is. 0.0 Note: The total rate of primary and secondary syphilis for the United States and outlying areas (including Guam, Puerto Rico and Virgin Islands) was 2.2 per 100,000 population. The Healthy People year 2010 objective is 0.2 per 100,000 population. Source: CDC/NCHSTP 2001 STD Surveillance Report (n= 10) (n= 34) (n= 9) Genital Herpes (Herpes simplex virus, or HSV) Epidemiology of Herpes-2 • The majority of genital herpes outbreaks in the U.S. are caused by HSV-2 (80%) • ~ 45 million people in U.S. (age 12 and over) are currently infected, with about one million new cases reported each year • 22% of adults over age 12 years have HSV-2 antibodies • HSV-2 infection rates show a correlation with level of sexual activity • HSV-2 infection rates are higher in HIV-infected persons and indivs. with low socioeconomic status Genital Herpes • There are two common kinds of Herpes (I and II) and both are caused by a virus • Herpes I most commonly affects the lips and mouth, causing lesions known as cold sores or fever blisters, but can also infect the genitals • Herpes II is the usual cause of genital herpes (80%), but can also infect the mouth and lips • Both types can also be transmitted to eyes, resulting in infection which can lead to blindness • Incubation Period: usually 2-7 days • Can survive for a few hours outside of the body (on moist surfaces) Common Symptoms of Genital Herpes • Small clear blisters that develop into painful red sores and then itchy ulcer-like lesions • Sores can last up to 2-3 weeks, and may be located on the: penis, labia, vaginal opening, perinium, anus, buttocks, thighs, mouth, or finger • Symptoms may also include swollen lymph glands, muscle aches, headache, fever, painful urination and sexual intercourse • Symptoms may or may not recur. On average, symptoms reappear approx. 5 times a year Genital Herpes in a Male Source: CDC/NCHSTP/Division of STD, STD Clinical Slides Herpes in a Male Source: Cincinnati STD/HIV Prevention Training Center Herpes in a Female Source: CDC/NCHSTP/Division of STD, STD Clinical Slides Source: Cincinnati STD/HIV Prevention Training Ce You can get herpes infections on other places on your body . . . Source: Cincinnati STD/HIV Prevention Training Center Herpes Complications • If not treated in adults, genital herpes may cause stress and pain • In women, some types can increase risk of developing cervical cancer • Often transmitted to fetus during birth (causing skin lesions, blindness or brain damage); can be avoided with C-section Testing & Treatment for Genital Herpes • Can be detected by various tests • You can still spread (http://www.ashastd.org/pdfs/blood_test.pdf) Herpes even if you are taking medicine! • Symptoms can be treated with prescribed medications, but… • There is no cure Human Papillomavirus (HPV) • Also known as “genital warts” • One of the most common and highly contagious STDs • HPV infection is strongly associated with cervical cancer and probably other anal, penile, vulvar, vaginal cancers Common Symptoms of Genital Warts in Males & Females • After a 3 wk - 9 month incubation period, symptoms may include single or multiple cauliflower-like warts around the penis, vagina, anus, urethra • May also include: itching, bleeding, or burning, and pain • Symptoms may recur from time to time • Like Herpes, there is no known cure, but warts disappear with certain medications, or can be physically removed by cryotherapy, heat cauterization or laser surgery Genital Warts in a Male Source: CDC/ NCHSTP/ Division of STD Prevention, STD Clinical Slides Source: Cincinnati STD/HIV Prevention Training Center HPV Penile Warts Source: Cincinnati STD/HIV Prevention Training Center Female Genital Warts Source: CDC/NCHSTP/Division of STD, STD Clinical Slides Female Genital Warts - Cervix Source: Cincinnati STD/HIV Prevention Training Center Oral Warts Source: Cincinnati STD/HIV Prevention Training Center Perianal Warts Source: Cincinnati STD/HIV Prevention Training Center Complications of Genital Warts (if untreated) • Can destroy body tissue around the genitals and anus • In women, can lead to cancer of the cervix (Over 99% of cervical cancers have HPV DNA detected within the tumor) Testing & Treatment for Genital Warts • Can be detected in a clinical exam; • Can be treated by removing the warts; • The virus cannot be destroyed, so the warts may grow back. Topics • Bacterial Infections: curable with antibiotics » Chlamydia » Gonorrhea » (Syphilis) • Viral Infections: no cure, but can alleviate or remove symptoms with medication » Herpes type 2 » HPV (genital warts) » Hepatitis B » HIV/AIDS • Other STDs Hepatitis B Hepatitis B One of several types of viral hepatitis (also Hep A, C, D, E), causing inflammation and damage to the liver. Can lead to cirrhosis (scarring of liver), liver cancer, and death. • Hep B is a highly contagious form that is transmitted via contact with infected person’s saliva, blood, semen or vaginal secretions. An infected mother can also transmit the virus to the baby during delivery or shortly thereafter. • 1.25 million are chronically infected in U.S. (1/3 acquired infection during childhood) •~75,000 new infections reported per year Hep B Symptoms • Early symptoms, which are flu-like, appear 6 wks – 6 mo. after infection and usually subside after 2-3 weeks (~90% of cases): • fatigue, loss of appetite, mild fever, aching muscles, joints, nausea, vomiting, diarrhea, tenderness in upper right abdomen • can also include itchy skin, dark urine, pale stool, and jaundice (yellowing of the skin and whites of eyes) • some people have no symptoms at all, but are silent carriers (can still transmit virus to other people) • infected person is contagious 4-6 weeks before symptoms appear and for an unpredictable time after. Most people get rid of the virus within 6 months. • about 1% of patients die due to liver damage in this early stage Chronic Hepatitis B ~10% of people infected with hep B develop a chronic, lifelong infection • People with chronic infection may have symptoms, but many never show symptoms. They are sometimes referred to as "carriers" and can spread the disease to others. • Chronic hep B increases chance of permanent liver damage, including cirrhosis (scarring of the liver) and liver cancer. • Risk of becoming chronically infected depends on the age at the time of infection: more than 90% of newborns, about 50% of children, and less than 5% of adults infected with hepatitis B develop chronic hepatitis. Source: MEDLINEplus, National Library of Medicine, NIH Hepatitis B Treatment • Bed rest and a healthy diet • Avoidance of alcohol and other non-essential drugs • In cases of liver failure, death can be averted only by liver transplantation • About 1/3 of chronic cases benefit from antiviral drug treatment Hepatitis B Prevention • Condoms, if used consistently and properly, can reduce risk of sexual transmission. • Immunization provides the only definitive protection against the virus: requires three vaccinations within a 6month period to achieve full immunity (~95%). • Vaccination of babies has become routine in pediatric care in the US. Source: MEDLINEplus, National Library of Medicine, NIH HIV infection (human immunodeficiency virus) HIV, cont. • HIV infection is a viral infection caused by the human immunodeficiency virus (HIV), which gradually destroys the immune system, resulting in infections that are hard for the body to fight. • Risk of getting infected is 2-10X greater if you have a current STD infection. • The vast majority of individuals infected with HIV will progress to AIDS (Acquired Immunodeficiency Syndrome) if not treated. • There is no known cure, but the progression to AIDS can be effectively delayed for many years by daily treatment with a triple drug cocktail. Source: MEDLINEplus, US National Library of Medicine, NIH Transmis sion How does HIV infect and multiply within the body? Infection step 1 Step 1: Proteins on the virus coating bind to both CD4 ptn receptors and co-receptors on the T-cell. CD4 T-Cell CD4 ptn receptors CCR5 co-receptor Modified from source at http://www.women-alive.org/images/fig1.jpg and http://www.women-alive.org/living/replica.htm Infection step 2 Step 2: Viral RNA enters the cell and is converted into doublestranded DNA by an enzyme called reverse transcriptase. Sources: http://www.women-alive.org/images/fig2.jpg and http://www.women-alive.org/living/replica.htm Infection step 3 Step 3: An enzyme called integrase incorporates the virus' genetic material into the T-cell's DNA. Sources: http://www.women-alive.org/images/fig3.jpg and http://www.women-alive.org/living/replica.htm Infection step 4 Step 4: Protease enzymes cut the viral proteins into shorter pieces so they can be incorporated into new viruses. Sources: http://www.women-alive.org/images/fig4.jpg and http://www.women-alive.org/living/replica.htm Infection step 5 Step 5: The new viruses bud off and attack other T-cells. Source: http://www.women-alive.org/images/fig5.jpg and http://www.women-alive.org/living/replica.htm Early Symptoms Primary or Acute HIV Infection - a condition that occurs in some HIV-infected people about 2 - 4 weeks after initial exposure. Symptoms resemble the flu or mononucleosis: • Fever • Headache • Fatigue • Sore throat • Diarrhea • Rash • Night sweats • Muscle aches/joint pain • Swollen lymph nodes • Abdominal cramps, nausea, vomiting • Symptoms may last from a few days to 2 wks, and then subside. Following the acute infection, there may be no further evidence of illness for the next decade. • Some people are asymptomatic (never show any symptoms) for up to 10 years, but are still infectious (able to transmit the virus to other people). Asymptomat ic stage After infection with HIV, antibodies to the virus can be detected in the blood. Converting from HIV negative to HIV positive usually occurs within 3 – 6 months after exposure. Natural progression of the disease is: acute HIV infection asymptomatic HIV infection symptomatic HIV infection AIDS early What is Asymptomatic HIV infection? • A period in which there is slow deterioration of the immune system without any overt symptoms. • There is frequently a in CD4 T-cell counts, an index of immune function. • Length of this phase varies greatly among individuals and correlates with level of replication of HIV, as well as genetic differences in the way the immune system handles the virus. • In some individuals, this phase can last 10 years or longer, while in others, clinical symptoms and worsening immune function may occur within one (or just a few) years from the time of original infection. AIDS •The vast majority (over 99%) of HIV-positive people inevitably progress to AIDS; however, there are a very small number of people who have unquestionably tested positive for HIV, but no longer test positive and have absolutely no signs of disease. These people (called non-progressors) are being carefully watched and studied, as they provide evidence that some people may posses a natural immunity or may be capable of eliminating the disease. At what point is HIV infection called AIDS? • When the CD4 T-cell count falls below 200/ul (the count is normally 800-1200 in healthy people or HIV+ people who are not yet sick) • As a result of the virus, the immune system begins to collapse and the AIDS patient develops one or more “opportunistic infections” or cancers HIV/AIDS Timeline HIV/AIDS Timeline Antibody level Viral load Window period – usually test negative (~3 mo) Incubation period (8-10 years ave.) AIDS Without effective drug treatments, life expectancy with AIDS is 1-2 yrs Topics • Bacterial Infections: curable with antibiotics » Chlamydia » Gonorrhea » (Syphilis) • Viral Infections: no cure, but can alleviate or remove symptoms with medication » Herpes type 2 » HPV (genital warts) » Hepatitis B » HIV/AIDS • Other STDs Common Parasitic STDS 1. Trichomoniasis • the most common curable STD in young, sexually active women, especially among 16-35 yrs olds • an estimated 5 million new cases occur each year in women and men • caused by the single-celled protozoan parasite • in women, the vagina is the most common site of infection • in men, the urethra is the most common site of infection • spread through penis-to-vagina intercourse or vulva-to-vulva contact with an infected partner • women can acquire the disease from infected men or women, whereas men usually contract it only from infected women Symptoms of Trichomoniasis • Most men do not have signs or symptoms. Those that do may have an irritation inside the penis, mild discharge, a frequent urge to urinate, and a slight burning after urination or ejaculation. • Many women do have signs or symptoms of infection. These usually appear within 5 to 28 days (but up to 6 months) of exposure and include: a frothy, yellowgreen vaginal discharge with a strong odor, pain or discomfort during intercourse and urination, irritation and itching of the female genital area and, in rare cases, lower abdominal pain. Complications? • In pregnant women, may cause premature rupture of the membranes and preterm delivery. • Also increases a woman's risk of acquiring HIV infection if she is exposed to HIV. Treatment? • Certain types of antibiotics are very effective at treating (and eliminating) the parasite Common Parasitic STDS 2. Pubic lice (“crabs”or genital “ukus”) (Phthirus pubis) • Similar to head lice (ukus), but a different species, usually spread through genital contact • Can also be contracted from bed linens, towels, or clothes, as it nits can live for 2-3 days off the body • Treated with medicated shampoos, same as head lice • Can also be transmitted to eyebrows or eyelashes during oral sex For more info For more information about HIV/AIDS and other STDs – talk to your doctor, visit a health clinic, contact the HIV Hotline (1-800342-AIDS) or STD Hotline (1-800-227-8922), or visit these Internet sites: • Planned Parenthood: www.plannedparenthood.org/STI/stis_index.html • American Social Health Association: www.ashastd.org • Centers for Disease Control and Prevention (CDC): www.cdc.gov/nchstp/dstd/disease_info.htm • Quest Diagnostics Incorporated: www.questdiagnostics.com/women Where can you go on Oahu to get anonymous or confidential screening for HIV and other STDs? 1. UH Student Health Center 2. STD/AIDS Prevention Branch Department of Health, Diamond Head Clinic 3627 Kilauea Avenue, #305 Honolulu, HI 96816 (808) 733-9281 3. Waikiki Health Center 277 Ohua Avenue Honolulu, HI 96815 (808) 922-4787 Review Questions on STDs 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. Name three sexually transmitted diseases (STDs) that are common among men and women under age 25. What types of STDs are caused by a bacterial infection? How are bacterial STDs treated? What types of STDs are caused by a viral infection? In what important aspect are viral STDs different from bacterial STDs? What is currently the most common STD in the US (has the highest number of new cases annually among men and women combined)? What types of STDs can result in PID and/or infertility if they are not treated at an early stage? What types of STDs are often asymptomatic in women? What types are often asymptomatic in men?? What types of STDs can be transmitted from mother to baby during vaginal delivery? What types of STDs are known to increase the risk of developing cervical cancer? What types of STDs are known to increase the risk of contracting HIV from an HIV-infected person? What type of STD is preventable by vaccination? How can HIV be transmitted from one person to another? How long is the "window period" for HIV (whereby an HIV-infected person may not test positive for HIV antibodies)? How long is the asymptomatic period? How does HIV attack and destroy the immune system (CD4 T-cells) of infected individuals? At what point is an HIV-infected person diagnosed with AIDS? What is trichomoniasis and how common is it?