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7.1: Sexually Transmitted Diseases

Difficulty Level: At Grade Created by: CK-12
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What are they and how are they transmitted?

Sex can be a wonderful experience and a healthy part of life. But sometimes it can also be seriously harmful to your health and to your psychological well-being.

Did You Know?

Any sexually active person is at risk for getting an STD. Getting an STD does not have anything to do with who you are (your financial status, ethnic group, or whether you are male or female). It has to do with your sexual partner and the type of activity you engage in.

Sex can damage a young person's life if it results in unwanted pregnancy. Another way sex can endanger one's health is through sexually transmitted diseases (STDs). These are illnesses that are spread from one person to another through intimate sexual contact. Some STDs are no more than a nuisance and can be easily treated. Others have very serious consequences, including death. One in four sexually active teenagers will be infected with an STD in high school. Every 30 seconds, a teenager somewhere is getting infected.

Did You Know?

12 million new cases of STDs occur each year. Young people are particularly vulnerable to picking up sexually transmitted diseases. Currently two-thirds of all reported cases come from the 15-29 age group, nearly one-third from teenagers alone.

Perhaps neither you nor most of your friends will be exposed to sexually transmitted diseases. But others of your age will be. Hopefully, you will never suffer the consequences of these problems, but hundreds of thousands of others do. Knowing about these problems will help reduce the risk of them happening to you.

These are unpleasant topics, and they may make you uncomfortable. They can be especially difficult if you have had experience with them. You may also feel frightened by the possibility that any of this may happen to you. Be sure to discuss your fears with a parent, trusted adult, or counselor. Knowledge about these unpleasant topics is helpful for your personal safety, but it is not meant to bring you fear or distress.

Why are young people so much more at risk for acquiring STDs than older age groups? (See Did You Know? this page.)

A Teen's Story

Let's consider the experience of a high school student we will call Chris and his girlfriend Neeley.

Chris was getting together with his girlfriend Neeley one evening. He was uneasy about seeing her because he had been feeling sick lately. He was feeling an ache in his lower abdomen and had a fever. He knew it wasn't the flu though, because he had some other strange symptoms. Whenever he urinated, he felt a burning pain. What really made him nervous was a yellow discharge from his penis. Chris was really worried that his girlfriend Neeley might find out about these symptoms and be disgusted.

Just two nights ago Chris had talked Neeley into having intercourse with him, and he had felt a lot of pain. He hadn't used a condom because he didn't have any with him, and Neeley didn't say anything. He didn't want to do it again on the date tonight, because Chris didn't want her to notice the discharge, and he was feeling pretty sick. He decided to cancel their date and say he was sick.

The next morning, Chris's symptoms weren't any better. He began to panic and decided to go to the doctor. He knew that he didn't want his parents or anyone to know about his symptoms yet. But he decided if it was something serious that he would talk to his parents about it. In the meantime, though, he wanted a fast, reliable medical opinion.

Chris could have also gone to see the nurse or the family doctor. But what if he didn't want to talk about this to anyone who knew him personally? The American Social Health Association (ASHA) provides free information and keeps lists of clinics and private doctors who provide treatment for people with sexually transmitted diseases. So Chris called ASHA at its national toll-free telephone number, 1-800-227-8922, and made an appointment with a local doctor.

After hearing about Chris's symptoms, Dr. Brown told him he thought Chris had a sexually transmitted disease (STD). Dr. Brown thought this was an infection caused by microorganisms, typically bacteria or viruses transmitted through the exchange of bodily fluids, typically through sexual contact. Microorganisms are relatively simple living organisms that are too small to be seen by the naked eye.

Bodily fluids are fluids that are produced by various organs. The bodily fluids most likely to spread STDs are semen, vaginal fluid, and blood, including menstrual blood. These body fluids make it possible for bacteria and viruses to stay alive. Otherwise dryness will kill the microorganisms. These fluids also act as the means of transmission through various forms of sexual behavior.

There were a few key points Dr. Brown wanted Chris to know about STDs.

  1. STDs affect men and women of all backgrounds, ages, and ethnic groups. However, they are most frequently found among young adults. Two-thirds of cases involve people under the age of 25.
  2. The number of STD cases is rising, perhaps because young people are becoming sexually active earlier, and sexually active people today are more likely to have more than one sex partner or to change partners frequently.
  3. Some STDs cause no symptoms. When symptoms develop, people often confuse these symptoms with other illnesses that are not contracted through sexual contact. However, even when an STD shows no symptoms, it can be passed on to another person through sexual contact. An infected person who is not sick is called a carrier.
  4. Health problems caused by STDs tend to be more severe and more frequent for women than for men (except for AIDS).
  5. When diagnosed and treated early, many STDs can be treated effectively. While being treated for an STD, all sexual activity should be avoided.
  6. STDs are among the most common infectious diseases in the United States today. At least 20 STDs have now been identified, and they affect more than 12 million men and women in this country each year. Over 30 million people are infected at any given time.

Before Dr. Brown could accurately diagnose, or name, Chris's infection correctly, he needed to run a test on a sample of Chris's yellowish discharge.

When the lab tests came back, the doctor explained to Chris that he had gonorrhea, a sexually transmitted disease caused by bacteria. He explained to Chris that gonorrhea is passed through intimate contact like intercourse. It is not passed through casual contact, like shaking hands, touching a toilet seat, or using dirty towels. (Gonorrhea is discussed in more detail in the next section.)

He explained that symptoms like the ones Chris was experiencing were typical. As soon as Dr. Brown explained that, Chris knew how he had picked up gonorrhea. About a week ago, he was really angry and frustrated that Neeley wouldn't have sexual intercourse. He went to spend the night at his old girlfriend Terry's house, because he wanted to prove to himself that some women did find him sexy. He knew that Terry had been with other men since him, but he really wanted to prove to himself-and maybe even to Neeley-that he was attractive.

Chris didn't use a condom because Terry told him not to bother with it. He realized now how stupid that was. Neeley didn't want to have intercourse because of her views on sex and relationships, not because of her feelings towards Chris. And now he was infected with an STD because he had been impatient and cheated on her. Perhaps he had also infected Neeley.

  • Chris realizes he has to tell both his girlfriend, Neeley, and his old girlfriend, Terry, that he is infected. What are two reasons that he has to tell them?
  • If a person has sex with more than one partner, and their sexual histories are not known, what method of contraception provides the best protection against STDs?

Did You Know?

In 1928, the discovery of penicillin changed the medical world. This drug enabled doctors to treat diseases and infections (ranging from earaches to sexually transmitted diseases) that used to leave people either dead or disabled in some way.

Dr. Brown reassured Chris that because gonorrhea is a bacterial infection, it can be treated with antibiotics, such as penicillin. Treatment for gonorrhea includes five steps.

  1. As long as any symptoms of infection exist (including itching, redness, pain, unusual discharge, or odor) and until the doctor says you are cured, do not have intercourse. Intercourse may transmit the disease to a partner.
  2. All recent sexual partners must have a checkup and receive treatment. (This means Neeley should also see a doctor.)
  3. All medication must be taken until the prescription is finished.
  4. Treatment must be continued until two tests show that there is no more infection. Even after symptoms disappear, the bacteria can still maintain an infection.
  5. If there is sexual contact, condoms must be used to prevent any exchange of bodily fluids.

Chris didn't use a condom (though he had some) because Terry told him not to bother. She had had some vaginal discharge in the past, but it had gone away, so she thought she was fine. Over 50% of women show no symptoms when they are infected with gonorrhea. However, only 10% of men who are infected with gonorrhea show no symptoms of the disease after a while.

Dr. Brown stressed to Chris that prevention was as important as treatment. Preventing future infections should be part of his regular lifestyle. There are three key prevention steps Chris could follow:

  1. Abstinence: Don't have sex. Without the exchange of bodily fluids that occurs during sex, infection is nearly impossible.
  2. Condoms: Use a condom to protect against any bodily fluid exchange while having sex.
  3. Communication: Know your partner's sexual history. Has he or she ever been infected? How many partners does he or she have now, or has he or she had? Has he or she used condoms?

In addition, spermicides, typically used as a method of contraception, help decrease the likelihood of infection. Just as spermicides kill sperm, they can kill bacteria (in semen as well as in vaginal secretions) because the chemical agent breaks up the cell wall. Similarly, urinating after sexual contact can, in some cases, decrease the likelihood of infection.

Activity 6-1: What to Say and How?


Have you ever been in a situation in which you had to tell a friend something so devastating that you were afraid it would end your friendship? What went through your mind as you agonized over what to say and how to say it? What if this person was not just your friend but the person you loved?


  • Activity Report


Step 1 Your teacher will divide the class into pairs and assign each group a dialogue based on the story of Chris and Neeley in your textbook.

Step 2 SHHH! The dialogues must be written silently. Your teacher will explain the procedure to you.

Step 3 When they are finished, the scripts will be read aloud.

How might drugs and alcohol affect the spread of STDs?

Types of Sexually Transmitted Diseases

Sexually transmitted diseases have one thing in common. They are all transmitted through sexual contact. However, they are caused by a variety of microorganisms and cause different signs and symptoms. Signs such as skin lesions (open sores on the skin) can be seen by another person. Symptoms such as pain are experienced by the infected person. STDs are grouped by the types of microorganisms causing them. They generally belong to two categories-those caused by bacteria and those caused by viruses.

Campaign against STDs Design one button, one bumper sticker, and one sign promoting sexual health and the prevention of STDs. As a class, select a few and host an STD prevention week at school.

STDs Caused by Bacteria

Bacteria are single-cell organisms (singular bacterium). Gonorrhea is one example of an STD caused by bacteria. The disease has been known since the time of the ancient Egyptians and Greeks. It is typically transmitted during sexual intercourse. A woman has a 50% chance and a man has a 25% chance of catching the disease after a single act of unprotected intercourse with an infected person.

The symptoms of gonorrhea appear two to ten days after being infected. The primary symptom in the male is a discharge from the penis. This takes the form of a yellowish, pus-like liquid coming out of the tip of the penis and is accompanied by a burning sensation during urination. In women, the primary symptom is a vaginal discharge. However, women often have vaginal discharges due to other less serious infections. Therefore, simply because a woman has such a symptom does not mean that she has gonorrhea. Other symptoms in women tend to be mild, so much so that it is possible for a woman, even more so than a man, to be infected but not know it. But in either case, they can pass the disease on to a partner without being aware of it.

Gonorrhea is treatable with antibiotics, usually without lasting effects. However, it can lead to serious complications, including infertility (the inability to bear children), especially in women, if it spreads to other parts of the body and must be treated promptly.

Why would women have a higher risk of getting gonorrhea than men? (Hint: Think back to what you learned in the previous section about STDs.)

Figure 6.1 Sores caused by syphilis on the lips and genitals.

Chlamydia is the most common sexually transmitted disease in the United States and often occurs at the same time as gonorrhea. The symptoms of chlamydia are almost identical to the symptoms of gonorrhea for men-painful urination and discharge. Women suffer pain in the lower abdomen or during sexual intercourse. However, up to three out of four infected women have no symptoms. The same is true for some men, so they may unknowingly pass it on to their partner. Untreated, chlamydia and other infections cause PID, or pelvic inflammatory disease, among women. PID has many dangerous complications, including sterility (inability to reproduce).

Like gonorrhea, chlamydia can be successfully treated with antibiotics, but it is very important to get medical treatment as soon as symptoms appear so that complications are avoided.

The microorganism causing syphilis is actually not a bacterium but a corkscrew-shaped microorganism. Before the discovery of antibiotics, syphilis was the most serious STD. It caused very serious problems for a large number of people and could be fatal. But syphilis can now be treated successfully with antibiotics like penicillin.

The initial symptom of syphilis is a painless red sore that actually disappears in two to six weeks without treatment, but this does not mean the person has gotten well. The sore usually appears on the genital organs. But it may also be present on the lips or wherever the bacteria entered the skin.

This primary stage of syphilis, if untreated, will develop into a more serious stage that includes a rash, sore throat, headaches, and nausea. If allowed to go untreated, syphilis affects the brain and other vital organs, eventually causing death.

STDs Caused by Viruses

Viruses have simpler structures and are much smaller than bacteria. They cannot be seen under an ordinary microscope. The most serious STD they cause is AIDS, or acquired immune deficiency syndrome, which will be discussed in the next section.

Genital herpes is caused by skin-to-skin contact and typically causes small, painful bumps or blisters that can develop into sores. They usually appear on the genital organs, resulting in painful urination and intercourse. It is more difficult for women to see the sores or blisters than it is for men. Currently, there is no complete cure for herpes. The sores can disappear and reappear after infection. Once infected the virus stays in the body.

There are medications that can reduce the chance of recurrence and can decrease the pain. When the lesions are not active there are no symptoms, so some people merely think of herpes as an inconvenience, although a constant part of a person's sexual life. A person infected with herpes will always be infected with herpes and must therefore take steps to protect against infecting someone else. Most important in this case is not to engage in sex or have physical contact when the blisters are present. At other times there is only a small chance of infection. Touching the blisters and the skin may in itself spread the virus without necessarily having any sexual activity.

Another viral STD is genital warts. These are growths in the skin that are familiar to a lot of people because they may be present on other parts of the body.

Genital warts grow on the genitalia. They are usually painless but may cause itching and irritation. There are various treatments for warts but as yet no way of comfortably getting rid of them. Like herpes, the virus that causes genital warts can be spread just by touching warts and then touching another part of the body.

Figure 6.2 Genital herpes blisters can be seen on the penis.

Figure 6.3 Genital warts occur around the female vagina.

Activity 6-2: STD Handshake


When you have sex with someone, you are also being exposed to whatever that person's other sexual partners have come in contact with. It is important to remember that a person may carry an STD and still be symptom free. In this activity you see how one infected person can spread the disease to many other unsuspecting people.


  • One index card per person for each round played


Step 1 Your teacher will give you an index card. One index card has been marked on the back with an X. If your card has the X, do not let anyone else know.

Step 2 When your teacher says “Go,” walk around the room and shake hands with five people. Whoever shakes hands with you will sign your card. Keep the signatures in order, and stop when you have five signatures.

Step 3 Your teacher will ask the person who had the X to step forward and will explain that this person was infected with an STD (such as AIDS or gonorrhea). That person will then slowly read the names of the five people that he or she had contact with. Those people have now been infected with the same virus.

Step 4 If your name is on the list, you will then step forward when your teacher calls on you. Read the names of those people that you shook hands with AFTER having contact with the infected person. In other words, read the names of those people who signed your card AFTER the person who infected you signed your card.

Step 5 Those people that you have called out have been infected too. Next, they will read the names of anyone that they had contact with AFTER being infected by you.

Step 6 All people who have been infected will take turns doing this until all infected people have been identified. Your name may be called more than once, but you only need to read your list the first time. The second time just means that you were exposed again, but since you were already infected, it does not change the chain of people affected.

Step 7 Have all the infected people stand together on one side of the room. How many members of the class did the original person infect?

Step 8 Your teacher will give you a new set of index cards. One card will have an X, just like before. However, this time several cards will also be marked on the back with C + S. This stands for condom and spermicide and indicates that this person used precautions to reduce the risk of infection and pregnancy. Since no method other than abstinence can absolutely prevent infection, one card will be marked C + S failure, to indicate that although the person tried to prevent infection, he or she was unsuccessful. Do not let anyone know how your card is marked.

Step 9 Repeat the steps that you went through in the first round, shaking hands with five people and collecting their signatures.

Step 10 Identify the person with an X card and have that person read the list of people that he or she has infected.

Step 11 In turn, have the infected people read the names of those people that they had contact with AFTER being infected. If any of the people infected by the X card were wearing a condom and using a spermicide, they announce that they were NOT infected, and read the names of those people who were SAVED from infection by their actions. The person with the card marked C + S failure will announce that he or she is infected because the precautions failed. Everyone who came in contact with that person afterwards will be counted as infected, too.

Step 12 Keep track of those people who were infected. Keep track of those people who would have been infected but were saved from infection by using precautions. Remember that this includes anyone who would have been infected later on in the chain if effective precautions hadn't been taken. Compare the results of this round to the first one.

How would having a sexually transmitted disease affect your life and the lives of those around you?

Review Questions

  1. What are STDs and how do they spread?
  2. What kinds of symptoms might lead a person to suspect an STD?
  3. What is the general five-step procedure for treating STDs?
  4. Dr. Brown offered Chris some important advice about avoiding STDs. What three pieces of advice were suggested?
  5. What are two STDs caused by viruses?
  6. How do you cure viral infections? How do you cure bacterial infections?

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