• Chlamydia, gonorrhea, and syphilis are sexually transmitted diseases caused by bacteria.
  
  
• Some sexually transmitted diseases may be asymptomatic; yet leaving them untreated can lead to serious health consequences.
  
  

1. Why are chlamydia infections particularly troublesome?
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2. What kinds of complications can accompany gonorrhea?
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3. What are the three stages of syphilis?
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Essential Study Partner

• Chlamydia

• Genital warts, herpes, hepatitis B and AIDS are sexually transmitted diseases caused by viruses.
  
  
• Genital herpes may be transmitted even if there are no apparent symptoms of the disease.
  
  
• There is no cure for sexually transmitted viral infections.
  
  

1. Can the herpes virus be transmitted even if a partner has no symptoms at the time?
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2. Genital warts are associated with what other medical condition in women?
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3. What organ in the body is most affected by a hepatitis infection?
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• Trichomoniasis is a sexually transmitted disease caused by a protozoan.
  
  
• A fungus is the cause of one form of vaginitis, an infection of the vagina.
  
  
• Many different types of animals cause infections in humans. Pubic lice are sexually transmitted.
  
  

1. How common is bacterial vaginosis and what are the possible consequences of an infection?
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2. What are the symptoms of trichomoniasis and why should it be treated?
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3. Can pubic lice be transmitted other than by sexual interactions?
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Animation Activity

• Trichomonas

• AIDS is caused by a Human Immunodeficiency Virus (HIV).
  
  
• Over 34 million people are estimated to be living with an HIV infection.
  
  
• New HIV infections are increasing faster among heterosexuals than homosexuals.
  
  
• There are three successive phases of an HIV infection.
  
  
• A person with AIDS dies from an opportunistic infection.
  
  

1. How many people in the world currently have an HIV infection? What country is particularly affected?
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2. What are the three categories of an HIV infection?
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3. What treatments are currently available for an HIV infection?
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Animation Activity

• HIV Replication

Reading

• The HIV/AIDS Epidemic: A Scientist's Perspective