STDs, also known as sexually transmitted infections (STIs), are typically caused by bacteria or viruses and are passed from person to person during sexual contact with the penis, vagina, anus, or mouth. The symptoms of STDs/STIs vary between individuals, depending on the cause, and many people may not experience symptoms at all.
Many STDs/STIs have significant health consequences. For instance, certain STIs can also increase the risk of getting and transmitting HIV/AIDS and alter the way the disease progresses. STIs can also cause long-term health problems, particularly in women and infants. Some of the health problems that arise from STIs include pelvic inflammatory disease, infertility, tubal or ectopic pregnancy, cervical cancer, and perinatal or congenital infections in infants.
NICHD's research also focuses on understanding sexual risk-taking behaviors that increase the likelihood of individuals contracting STIs, on developing more effective educational interventions to prevent STIs, and on defining the consequences and optimal treatments for STIs, especially in pregnant women.
General Information
STDs/STIs are illnesses that pass from person to person during sexual intercourse, oral sex, or certain types of sex play. They can be caused by bacteria, viruses, or parasites.
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People with STDs/STIs may feel ill and notice symptoms, such as sores or warts or painful urination. Or, they may not have any symptoms at all.
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The major causes of STDs/STIs are bacteria, viruses, and parasites. Any STI can be spread through sexual intercourse, and some STIs also are spread through other sexual activity.
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Some infections can pass to the fetus during pregnancy or to the infant during delivery, causing short- and long-term health problems. Treatments can reduce or prevent transmission.
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Approximately 20 different infections, including chlamydia, HIV/AIDS, viral hepatitis, and Zika, are known to be transmitted through sexual contact. Treatments vary depending on the infection.
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Health care providers use a variety of methods, such as physical exams, tests of sores or fluids, Pap smear tests, and blood tests, to diagnose STDs/STIs.
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Viral STDs/STIs, such as HIV, genital herpes, hepatitis, and cytomegalovirus, cannot be cured. Some STDs/STIs caused by bacteria or parasites can be cured.
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Treatments for STDs/STIs can help minimize or eliminate symptoms and reduce the risk of transmission.
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Research
NICHD conducts and supports research on sexually transmitted diseases (STDs).
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NICHD conducts and supports a variety of clinical research projects related to sexually transmitted diseases (STDs).
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More Information
Find answers to other common questions about STDs/STIs, such as how to avoid getting an STD/STI, what are the links between STIs and infertility, and whether STIs can lead to cancer.
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Links to websites of groups that study or provide information about sexually transmitted diseases (STDs).
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