http://www.ck12.org Chapter 1. Human Biology
females. Many doctors recommend that females between the ages of 9 and 26 years receive the vaccine. Preventing
HPV infections in females is important because HPV can also cause cancer of the cervix.
A related herpes virus causes cold sores on the lips (Figure1.142). Both viruses cause painful blisters. In the case
ofgenital herpes, the blisters are on the penis or around the vaginal opening. The blisters go away on their own,
but the virus remains in the body. The blisters may come back repeatedly, especially when a person is under stress.
There is no cure for genital herpes. But drugs can help prevent or shorten outbreaks. Researchers are trying to find
a vaccine to prevent genital herpes.
FIGURE 1.142
This lip blister, or cold sore, is caused by a
herpes virus. The virus is closely related
to the virus that causes genital herpes.
The genital herpes virus causes similar
blisters on the genitals. If you’ve ever had
a cold sore, you know how painful they
can be. Genital herpes blisters are also
painful.Hepatitis Bis a disease of the liver. It is caused by a virus called hepatitis B, which can be passed through sexual
activity. Hepatitis B causes vomiting. It also causes yellowing of the skin and eyes. The disease goes away on its
own in some people. Other people are sick for the rest of their lives. In these people, the virus usually damages
the liver. It may also lead to liver cancer. Medicines can help prevent liver damage in these people. There is also a
vaccine to protect against hepatitis B.
HIVstands for "human immunodeficiency virus." It is the virus that causes AIDS. HIV and AIDS are described in
a previous lesson. HIV can spread through sexual contact. It can also spread through body fluids such as blood.
There is no cure for HIV infection, and AIDS can cause death, although AIDS can be delayed for several years with
medication. Researchers are trying to find a vaccine to prevent HIV infection.
Vocabulary
- chlamydia: Sexually transmitted bacterial infection; the most common STI caused by a bacteria.
- genital herpes: Sexually transmitted infection caused by a herpes virus; characterized by periodic outbreaks
of blisters on the genitals. - gonorrhea: Common sexually transmitted infection caused by bacteria.
- hepatitis B: Inflammation of the liver caused by infection with hepatitis B virus; often transmitted through
sexual contact. - HIV: Human immunodeficiency virus; virus that causes AIDS.
- HPV: Sexually transmitted virus that causes genital warts and cervical cancer.
- pathogen: Living thing or virus that causes disease.
- sexually transmitted infection (STI): Infection caused by a pathogen that spreads mainly through sexual