1. 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

2. 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.

3. Risky Behaviors and the STI Epidemic
Ignoring Risks
Multiple Partners
Not Seeking Treatment

4. 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

5. 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.

6. 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.

7. 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

8. 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.

9. 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.

10. 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.

11. 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.

12. 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

13. 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.

14. 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.

16. 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.