Causes of Sexually Transmitted Disease
Sexually transmitted diseases (STDs) are generally acquired by sexual contact. The organisms that cause sexually transmitted diseases may pass from person to person in blood, semen, or vaginal and other bodily fluids. Sometimes these infections can be transmitted nonsexually, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.

It's possible to contract sexually transmitted diseases from people who seem perfectly healthy, and who may not even be aware of the infection. STDs don't always cause symptoms, which is one of the reasons experts prefer the term "sexually transmitted infections" to "sexually transmitted diseases." Sexually transmitted infections can be caused by:
-- Bacteria (gonorrhea, syphilis, chlamydia)
-- Parasites (trichomoniasis)
-- Viruses (human papillomavirus, genital herpes, HIV)

Risk factors of STDs
1. Anyone forced to have sexual intercourse or sexual activity.
Dealing with rape or assault can be difficult, but it's important to be seen as soon as possible. Screening, treatment and emotional support can be offered.

2. Abusing alcohol or using recreational drugs.
Substance abuse can inhibit your judgment, making you more willing to participate in risky behaviors.

Injecting drugs. Needle sharing spreads many serious infections, including HIV, hepatitis B and hepatitis C.

3. Having unprotected sex.
Vaginal or anal penetration by an infected partner who isn't wearing a latex condom significantly increases the risk of getting an STI. Improper or inconsistent use of condoms can also increase your risk. Oral sex may be less risky, but infections can still be transmitted without a latex condom or dental dam. Dental dams - thin, square pieces of rubber made with latex or silicone - prevent skin-to-skin contact.

4. Having sexual contact with multiple partners.
The more people you have sexual contact with, the greater your risk. This is true for concurrent partners as well as monogamous consecutive relationships.

5. Having a history of STIs.
Having one STI makes it much easier for another STI to take hold.

6. Men who request prescriptions for drugs to treat erectile dysfunction.
Men who ask their doctors for prescriptions for certain drugs - such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) - have higher rates of STIs. Be sure you are up to date on safe sex practices if you ask your doctor for one of these medications.