STI Types

There are three basic types of sexually transmitted infections: bacterial, viral and parasitic. All three types can occur whether you’re having heterosexual (opposite gender) or homosexual (same gender) sex.

• Bacterial and parasitic infections can be cured.
• Viral infections can be treated but not completely cured.

Bacterial STIs

There are two basic types of bacterial genital infections: fungal (yeast) infections and bacterial vaginosis. Sometimes partners can reinfect each other with bacterial STIs through sex.

Fungal infection (vulvovaginitis) is caused by the fungus candida. Many women who are not sexually active have this infection, but it’s more common in sexually active women. It can be treated by creams, many of which are available without a prescription. It can also be treated by the oral prescription medication Diflucan.

Bacterial vaginosis is caused by several different types of bacteria that live in the vagina and bowel. Treatment includes antibiotics taken by mouth or antibiotic gels applied inside the vagina. Common infections related to bacterial vaginosis include:

• Chlamydia, caused by the bacteria Chlamydia trachomatis. It can lead to infertility if untreated. Chlamydia is usually treated with antibiotics, some of which can be taken for one day, others for seven to 10 days.
• Gonorrhea, caused by the bacteria Neisseria gonorrhea. The Centers for Disease Control and Prevention (CDC) recommends a single dose of two antibiotics to cure gonorrhea.
• Syphilis, caused by an organism called spirochete, which is considered a bacterium but also has characteristics of a parasite. Syphilis is easily treated with a penicillin injection.
• Pelvic inflammatory disease (PID), caused by multiple types of bacteria in the genital tract and bowel. PID, found only in females, is a severe infection of the uterus and sometimes ovaries. Treatment often includes draining any abscesses and a lengthy course of antibiotics (at least two weeks). Severe PID can lead to infertility.

Viral STIs

• Herpes is caused by the herpes simplex virus. It can be treated with antiviral medications at the time of outbreaks and daily antiviral medications to prevent frequent outbreaks. There is currently no vaccine or cure.
• Human papilloma virus (HPV) is also known as the genital wart virus. Certain subtypes can significantly increase a woman’s risk for cervical cancer. Condoms cannot prevent HPV. HPV can be treated with lotions and liquid nitrogen to freeze the warts. There’s no cure, but the HPV vaccine that’s recommended for all preteens and teens can prevent the virus.
• The hepatitis B virus is difficult to treat. People with chronic hepatitis B may need prolonged or even lifelong treatment with injectable medications, which are sometime quite toxic. Hepatitis B can also lead to liver failure and increases the risk for liver cancer. There is an effective vaccine for hepatitis B, but no cure.
• Human immunodeficiency virus (HIV) can be treated and the progression slowed by using a combination of antiviral medications – usually a minimum of three to four medications. There is currently no vaccine or cure.

Parasitic STI

Trichomoniasis is caused by a parasite called trichomonas vaginalis. Trichomoniasis is very common and is easily treated with antiparasitic and antibiotic medications.

Last reviewed: January 2020