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The Silent Epidemic • Any pathogen that spreads from one person to another during sexual contact is called a sexually transmitted infection, or STI. • More than 13 million new cases of STIs are reported each year in the United States and over 3 million occur in people under age 20. – some STIs are fatal Harmful Effects of STIs • short term, STIs may cause pain, discomfort, and embarrassment • long-term consequences of STIs – increased risk of certain cancers – and an increased risk of infertility in both men and women • Many STIs can be treated with medicines, but some are incurable. Risky Behaviors and the STI Epidemic • Ignoring Risks • Multiple Partners • Not Seeking Treatment Avoiding STIs • transmitted mainly through sexual contact, but a few are also transmitted through contact with the blood of an infected person. • Healthy behaviors to prevent getting – practicing abstinence – avoiding drugs – choosing responsible friends Kinds of STIs • The Most Common STIs – STIs are caused by pathogens, including bacteria, viruses, and protozoans. – spread from person to person through blood and body fluids such as semen, vaginal secretions, and breast milk. – Three of the most common STIs in the United States are trichomoniasis, human papilloma virus, and chlamydia. Main types of STIs • Trichomoniasis: caused by a protozoan that infects the urinary tract or vagina. (over 7 million people in the U.S. are infected) – In males, if not treated, can lead to inflammation of the lining of the urethra, called urethritis – In females, untreated trichomoniasis can lead to vaginitis, which is a vaginal infection or irritation • Human Papilloma Virus (HPV) – most common viral STI in the U.S. (more then 6 million effected each year – genital warts – cervical cancer in women. • Chlamydia (almost 3 million effected each year) – most common STI caused by bacteria – Infected males experience painful, frequent urination and discharge from the penis. – In females has no symptoms other than a yellowish vaginal discharge. – If untreated can cause a serious infection of the reproductive organs called pelvic inflammatory disease, or PID. Other STIs • Hepatitis – Hepatitis B and C are sexually transmitted infections that attack the liver (spread by blood-to-blood contact. – Both infections may lead to liver cancer or cirrhosis a condition in which normal liver tissue is replaced by scar tissue. – symptoms are fatigue, abdominal pain, nausea, and jaundice – No cure • Gonorrhea: bacterial STI that infects the urinary tract of males and females and the reproductive organs of females – Males usually have a thick, puslike discharge from the penis and painful urination and Females sometimes experience painful urination and a puslike discharge from the vagina or urinary tract Other STIs • Genital Herpes: virus that causes genital herpes is the herpes simplex virus. – symptoms include painful blisters that appear on or around the genitals or could be hardly noticeable – no cure for genital herpes. • Syphilis: is a serious bacterial STI that progresses through three distinct stages – is a serious bacterial STI that progresses through three distinct stages – In the second stage, sores appear in the mouth and flulike symptoms develop. – In the third stage, bacteria attack internal parts of the body. – Eventually, untreated syphilis can cause brain damage, paralysis, and heart disease. HIV Infection • Human immunodeficiency virus can lead to AIDS, or acquired immunodeficiency syndrome, which is an often fatal disease of the immune system. • Attacks specific cells of the immune system, disabling the body’s defenses against other pathogens. • When the immune system becomes severely disabled, the infected person has AIDS. • HIV infects helper T cells, which stimulate other cells of the immune system to produce antibodies against invading pathogens. • Inside a helper T cell, HIV reproduces, killing the cell in the process. • The new viruses are released from the cell and move on to destroy other helper T cells. Stages of HIV Infection • Asymptomatic Stage – Soon after exposure to HIV, an infected person may experience flulike symptoms, which usually go away after a few weeks. • Symptomatic Stage – Symptoms may include weight loss, a persistent fever, diarrhea, or fungal infections. • AIDS – marked by a very low number of helper T cells in the blood. At this stage, HIV-infected people are usually experiencing even more severe symptoms than in the symptomatic stage. Opportunistic Infections • opportunistic infections – attack a person with a weakened immune system • These opportunistic infections include • Tuberculosis, fungal infections, and a lung disease called pneumocystis carinii pneumonia • Certain types of cancer are also more common in people with AIDS, including cancer of the cervix and Kaposi’s sarcoma, a kind of skin cancer. Transmission of HIV and Risky Behaviors • People with HIV are infectious whether or not they have any symptoms of disease. • Individuals infected can pass the virus on to someone else through the exchange of blood, semen, vaginal secretions, or breast milk. • • • • Sexual Contact HIV Shared Needles HIV Contact With Blood HIV Mother to Baby HIV Safe Behaviors and Donors • HIV is not transmitted by casual contact. • Small amounts of HIV occur in saliva, tears, and perspiration. • the amounts are so small that infection from contact with these fluids is unlikely. • Blood that tests positive for HIV antibodies is discarded. • Potential donors are interviewed and are not allowed to give blood if they have engaged in behaviors that place them at risk for HIV infection. A Global Problem • With approximately 40 million people infected around the world, HIV and AIDS represent a global health problem. • Africa Sub-Saharan Africa accounts for more than half of all global infections. • Africa Sub-Saharan Africa accounts for more than half of all global infections. High-Risk Groups and Prevention • higher infection rates in women are often due to a lack of information about how to protect themselves or, in some cases, a lack of power to protect themselves. • The World Health Organization and the Joint United Nations Program on HIV/AIDS monitor the situation and recommend steps for stemming the epidemic in different countries.