More than 30 different bacteria, viruses, and parasites pass from one person to another through sexual contact, according to the World Health Organization. The CDC counts over 2.5 million cases of chlamydia, gonorrhea, and syphilis reported in the United States in a single recent year, and most people will contract at least one sexually transmitted infection (STI) during their lifetime. Despite how common these infections are, public understanding of the full list of STDs (sexually transmitted diseases) usually stops at a handful of names. That gap leaves real risk on your plate, because knowing which pathogen causes which disease, how each spreads, and what each one does to the body is the foundation for protecting both your health and your partner’s.
This reference covers every major sexually transmitted infection, from HPV and herpes to lesser-known parasitic infections, with transmission facts and a practical prevention plan.
The Major Categories That Organize Every STD
Sorting STDs by pathogen type turns a confusing list of more than 20 names into three practical buckets: bacterial, viral, and parasitic. That classification drives your decisions, because it tells you whether a short course of antibiotics will cure the infection or whether you will manage it for life.
Bacterial and Parasitic Infections That Respond to Treatment
Bacterial STDs include chlamydia, gonorrhea, and syphilis. Trichomoniasis, caused by a parasite, gets grouped with them because it responds to similar single-dose medication. These four account for the vast majority of curable sexually transmitted infections worldwide. A short course of prescribed antibiotics clears most cases, though drug-resistant strains of gonorrhea have made some regimens more complex. Parasitic skin infections like pubic lice (crabs) and scabies also fall into the treatable category, and your provider can clear them with the right prescription.
Viral Infections That Stay in the Body
Viral STDs include HIV, herpes simplex virus (HSV), human papillomavirus (HPV), and hepatitis B. Once a virus establishes itself, your immune system can usually control it, but it rarely eliminates it completely. That makes viral STDs typically manageable rather than curable. Antiviral medications suppress symptoms, reduce transmission risk, and limit long-term damage. Vaccines exist for HPV and hepatitis B, which makes prevention of those two infections a realistic goal for most people.
| Category | Common Examples | Treatment Outlook |
|---|---|---|
| Bacterial | Chlamydia, gonorrhea, syphilis | Curable with antibiotics |
| Viral | HIV, herpes, HPV, hepatitis B | Manageable, usually not curable |
| Parasitic | Trichomoniasis, pubic lice, scabies | Curable with medication or topical treatment |
The Complete Catalog of Sexually Transmitted Infections
Health authorities recognize more than 20 distinct STDs. Some appear constantly in clinic reports. Others are rare enough that many providers have never treated a case. The table below puts every major infection side by side so you can compare pathogen type, typical symptoms, transmission routes, and curability at a glance.
| Infection | Pathogen | Common Symptoms | Transmission Routes | Curable? |
|---|---|---|---|---|
| Chlamydia | Bacteria | Often none; burning urination, discharge | Vaginal, anal, oral sex | Yes |
| Gonorrhea | Bacteria | Often none; discharge, pelvic pain, sore throat | Vaginal, anal, oral sex | Yes (resistance growing) |
| Syphilis | Bacteria | Painless sore, then rash, then organ damage | Direct contact with sore; sexual contact | Yes in early stages |
| Trichomoniasis | Parasite | Itching, discharge, burning; often none | Vaginal sex | Yes |
| HIV | Virus | Flu-like illness early; often none for years | Blood, semen, vaginal fluid, breast milk | No, but controllable |
| Herpes (HSV-1, HSV-2) | Virus | Blisters or sores around mouth or genitals | Skin-to-skin contact, including oral sex | No |
| HPV | Virus | Usually none; sometimes genital warts | Skin-to-skin contact | No, but often clears naturally |
| Hepatitis B | Virus | Often none; jaundice, fatigue, nausea | Blood, semen, vaginal fluid | No, but vaccine prevents it |
| Chancroid | Bacteria | Painful genital ulcers | Sexual contact | Yes |
| Mycoplasma genitalium | Bacteria | Discharge, pelvic pain; often none | Sexual contact | Yes, though antibiotic resistance is rising |
| Molluscum contagiosum | Virus | Small, firm bumps on skin | Skin-to-skin contact | Often clears, but treatment available |
HPV stands out as the most prevalent STD worldwide. Nearly every sexually active, unvaccinated person will contract at least one strain of HPV during their lifetime. Most HPV infections clear on their own within two years, but high-risk strains, especially HPV 16 and 18, cause the majority of cervical, anal, and oropharyngeal cancers. That cancer risk is the single biggest reason HPV vaccination is recommended starting at age 9 through age 26, with catch-up vaccination available through age 45.
Chlamydia and gonorrhea dominate reported bacterial infections, especially among young adults aged 15 to 24. Both spread easily through vaginal, anal, and oral sex, and both frequently produce no symptoms at all. HIV, syphilis, herpes, and hepatitis B each carry a distinct risk profile, ranging from manageable to life-threatening without care. Less common infections, including chancroid, mycoplasma, and molluscum contagiosum, round out the full picture of the names of sexually transmitted infections your provider screens for.
How Transmission Actually Works and Why Symptoms Often Disappear
Every sexually transmitted infection spreads through some combination of bodily fluids (semen, vaginal fluid, blood) and direct skin-to-skin contact with an infected area. Vaginal and anal intercourse carry the broadest transmission risk because they expose mucous membranes (the moist linings of the body) to multiple fluid types. Oral sex transmits many of the same infections, including gonorrhea, syphilis, herpes, and HPV, often without the giver or receiver realizing exposure occurred.
Why Many STDs Spread Without Anyone Knowing
Asymptomatic transmission is the single biggest reason STDs spread so widely. Chlamydia shows no symptoms in roughly 70% of women and 50% of men. Gonorrhea is silent in about half of all cases. HPV almost always produces zero symptoms. Herpes can shed the virus from the skin even when no sores are visible. This means you or a partner can carry and pass an infection without any outward sign.
Condoms Lower Risk but Don’t Eliminate It
Condom use significantly reduces transmission for fluid-borne infections like HIV, gonorrhea, and chlamydia. For skin-to-skin infections like HPV and herpes, condoms offer partial protection because uncovered areas (the scrotum, upper thighs, outer labia) can still transmit the virus. Dental dams and consistent condom use during oral sex further reduce the risk of throat infections from gonorrhea, syphilis, and HPV.
Your individual risk rises with the number of sexual partners, your age group (young adults aged 15 to 24 account for half of all new STD infections in the US), and your immune status. People living with HIV or on immunosuppressive medications face higher susceptibility to co-infections.
Recognizing Symptoms and Understanding Complications
Warning signs vary widely, but the most common physical clues include unusual discharge from the penis or vagina, sores or ulcers on or around the genitals, persistent itching, burning during urination, pelvic or lower abdominal pain, and flu-like illness with fever and swollen lymph nodes shortly after exposure. Any of these symptoms warrants a clinic visit within a few days, especially if a new partner is involved.
The Silent Phase and Long-Term Damage
Many infections produce no symptoms for months or years. Women are more likely than men to carry chlamydia and gonorrhea without noticing anything, which drives untreated pelvic inflammatory disease (PID). PID can scar the fallopian tubes and lead to infertility, ectopic pregnancy (when a fertilized egg implants outside the uterus, usually in a fallopian tube), and chronic pelvic pain. Untreated syphilis can damage the heart, brain, and nerves decades after the initial infection. Untreated HIV slowly weakens the immune system, leaving the body vulnerable to opportunistic infections.
HPV and hepatitis B carry specific cancer risks that develop decades later. HPV causes nearly all cervical cancers, plus most anal cancers and a growing share of throat cancers. Chronic hepatitis B infection is a leading cause of liver cancer worldwide. Both outcomes are preventable with vaccination and routine screening.
Testing Options, Treatment Outlook, and Prevention Strategies
Testing is the only reliable way to know your status, because most STDs can hide for years. Annual chlamydia and gonorrhea screening is recommended for all sexually active women under 25, plus annual screening for men who have sex with men. HIV screening is recommended at least once for everyone aged 13 to 64, with more frequent testing for people at higher risk.
What Testing Actually Looks Like
Most STD testing involves a combination of methods. A urine sample can detect chlamydia and gonorrhea. Blood tests screen for HIV, syphilis, hepatitis B, and sometimes herpes. Swabs of the throat, rectum, or genitals catch infections that urine tests miss. A physical exam lets a provider spot visible sores, warts, or discharge. Many clinics offer a full panel that covers the most common infections in a single visit, and results often return within a few days.
Treatment: Short Course or Lifelong Management
Bacterial and parasitic infections typically clear after a single course of antibiotics or appropriate medication. Your provider will select the right option based on the specific pathogen and local resistance patterns. Viral infections cannot be cured outright, but antiviral medications can suppress HIV to undetectable levels, dramatically reduce herpes outbreaks, and limit hepatitis B liver damage. A diagnosis isn’t the end of the road for you. It’s the start of a management plan.
The Core Prevention Toolkit
- Get vaccinated. HPV and hepatitis B vaccines are safe, effective, and available for most age groups.
- Use condoms consistently. They lower the risk of fluid-borne infections significantly.
- Limit your number of partners. Mutual monogamy with a tested partner is the lowest-risk arrangement.
- Screen regularly. Annual testing catches silent infections before they cause damage or spread further.
- Treat promptly. Completing prescribed medication and notifying recent partners prevents reinfection cycles.
Navigating Conversations, Disclosure, and Stigma
Sexually transmitted infections are common health outcomes, not moral failures. Roughly one in five people in the US has an STI at any given time, according to CDC prevalence data. Reframing the conversation around shared health rather than shame makes it easier for you to ask a partner about testing before becoming sexually active.
Scripts for Testing and Disclosure
A direct approach works better than dancing around the topic. Before becoming sexually active, a simple opener like “I get tested every year. When were you last tested?” opens the conversation without accusation. After a diagnosis, disclose to recent partners as soon as possible, share what infection you tested positive for, and suggest they get screened. Many states have laws requiring disclosure of HIV and certain other infections before sexual activity, so knowing your local requirements protects you legally too.
Reducing Stigma and Finding Care
Internalized shame keeps people out of clinics. Most sexually active adults will encounter at least one STI during their lifetime. Confidential, low-cost testing is widely available through community health centers, local public health departments, telehealth platforms, and at-home test kits that you can order online and mail back for analysis.
A positive test result isn’t a verdict on your character. It’s a piece of medical information that you can act on, just like a high cholesterol reading.
Putting It Together
The full list of STDs includes more than 20 recognized infections, but only three categories matter for your decisions: bacterial, viral, and parasitic. Knowing which bucket an infection falls into tells you whether a short antibiotic course will clear it or whether you’ll need long-term management. Screening, vaccination, and condom use form the practical foundation for staying healthy and protecting your partners.
FAQ
What is the most common STD?
Infection rates place HPV (human papillomavirus) at the top of global sexually transmitted disease statistics. The CDC estimates that nearly every sexually active, unvaccinated person will contract at least one strain during their lifetime. Most infections clear on their own, but high-risk strains can cause cervical and other cancers years later.
Which STDs are curable?
Bacterial and parasitic STDs, including chlamydia, gonorrhea, syphilis, trichomoniasis, chancroid, and pubic lice, can be cured with antibiotics or appropriate medication. Viral STDs such as HIV, herpes, HPV, and hepatitis B are generally manageable but not curable, though vaccines can prevent HPV and hepatitis B entirely.
How do you know if you have an STD?
The only reliable way to know is to get tested. Many infections produce no symptoms for months or years. Warning signs that should prompt a clinic visit include unusual discharge, sores, itching, burning during urination, pelvic pain, and flu-like illness shortly after a new sexual encounter.
Which STDs usually have no symptoms?
Chlamydia, gonorrhea, HPV, and herpes often produce no symptoms, especially in the early stages. Trichomoniasis and HIV can also stay silent for extended periods. Routine screening is the only way for you to catch these infections before they cause complications or spread to partners.
How are STDs transmitted?
STDs spread through vaginal, anal, and oral sex, as well as through exposure to infected blood and other bodily fluids. Skin-to-skin contact with an infected area can transmit herpes, HPV, and syphilis even without intercourse. Consistent condom use lowers but does not fully eliminate your risk, particularly for infections that pass through skin contact.
