Sexually transmitted diseases (STD) are illnesses that have a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex. While in the past, these illnesses have mostly been referred to as STDs or veneral diseases (VD), but in recent years the term sexually transmitted infections (STIs) has been preferred, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without having a disease. 

Common sexually transmitted infections include: 

  • related to the upper genital tract (ovaries, uterus, fallopian tubes): pelvic inflammatory disease (PID), endometriosis
  • related to the lower genital tract (vagina, cervix, vulva): gonorrhea, syphillis, Chlamydia, genital herpes, the human papillomavirus (HPV), genital warts, and human immunodeficiency virus (HIV)

In ART treatment process, it is mandatory to have negative tests for:

  • HIV 1 and 2
  • hepatitis B virus (HBV)
  • hepatitis C virus (HCV)
  • syphilis

There are more than 30 different causes of STIs including: 


  • Neisseria gonorrhoeae
  • Chlamydia trachomatis
  • Treponema pallidum (Syphillis)


  • human immunodeficiency virus (HIV)
  • herpes simplex II
  • human papilloma virus (HPV)
  • hepatitis B

HPV, a virus which has been implicated in certain types of cancer, causes genital warts that occur in clusters in the genital area (Pic. 1). Genital herpes is caused by the Herpes simplex virus and has symptoms such as lesions on the genitalia (Pic. 2), pain, and itching. HIV (Pic. 3), the virus that causes AIDS (acquired immune deficiency syndrome), is spread via blood, semen, or vaginal fluid and ultimately causes the immune system to fail.

As may be noted from the name, sexually transmitted infections are transmitted from one person to another by certain sexual activities, rather than being actually caused by those sexual activities. It is not possible to catch any STI from a sexual activity with a person who is not carrying a disease; conversely, a person who has an STI contracted it from contact (sexual or otherwise) with someone who had it, or his/her bodily fluids. Some STIs can also be transmitted via the use of intravenous drug needles after its use by an infected person, as well as through childbirth or breast feeding.Some STIs such as HIV can be transmitted from mother to child either during pregnancy or breastfeeding. 

Testing may be for a single infection, or consist of a number of tests for a range of STIs, including tests for syphilis, trichomonas, gonorrhea, chlamydia, herpes, hepatitis and HIV. No procedure tests for all infectious agents.

Early identification and treatment results in less chance to spread disease, and for some conditions may improve the outcomes of treatment. There is often a window period after initial infection during which an STI test will be negative. During this period, the infection may be transmissible. The duration of this period varies depending on the infection and the test. Diagnosis may also be delayed by reluctance of the infected person to seek a medical professional. 

Treatment options vary depending on the disease:


  • cryotherapy for Genital Warts


  • topical treatment for genital warts
  • antibiotics – Cephalosporin (Gonorrhoea), Azithromycin or Doxycycline (Chlamydia), Penicillin (Syphilis)
  • nucleoside analogue for Herpes Simplex Virus (Aciclovir)


  • surgical removal of genital warts

An option for treating partners of patients (index cases) diagnosed with chlamydia or gonorrhea is patient-delivered partner therapy, which is the clinical practice of treating the sex partners of index cases by providing prescriptions or medications to the patient to take to his/her partner without the health care provider first examining the partner.


Not all STIs are symptomatic, and symptoms may not appear immediately after infection. In some instances a disease can be carried with no symptoms, which leaves a greater risk of passing the disease on to others. Depending on the disease, some untreated STIs can lead to infertility, chronic pain or even death.


  • females often asymptomatic
  • urethral discharge (men)
  • skin lesion (Pic. 4)
  • painful urination


  • often asymptomatic
  • cloudy white/yellow cervical discharge (Pic. 5)
  • vaginal bleeding
  • vaginal discharge
  • penile discharge


  • genital ulcer
  • lymphadenopathy (abnormal size, number or consistency of lymph nodes)
  • diffuse rash
  • fatigue
  • mouth ulcer (Pic. 6)


  • vomiting
  • anorexia
  • fatigue
  • fever 
  • nausea
  • anxiety
  • pain

Herpes simplex II:

  • genital ulcer (Pic. 7)
  • lymphadenopathy
  • painful urination in women

Human papilloma virus:

  • genital warts

Associated diseases

  • gonorrhea
  • syphillis
  • chlamydia
  • genital warts
  • genital herpes
  • AIDS (Acquired Immune Deficiency Syndrome)
  • hepatitis B and C
  • pelvic inflammatory disease
  • endometritis


The problem with most STIs is that they can occur symptom-free and can thus be passed on unaware during unprotected sexual intercourse. On an individual level, complications can include pelvic inflammatory disease (an infection of the reproductive organs in women) and possibly lead to ectopic pregnancies and infertility. Female adolescents are likely to have a higher risk of contracting an STIs than their male counterparts as their partners are generally older and hence more likely to be infected. Additionaly, the risk is higher for female adolescents as their cervical anatomic development is incomplete and especially vulnerable to infection by certain sexually transmitted pathogens.

Risk factors

  • unprotected sexual intercouse
  • sexual contact with multiple partners
  • prior STIs
  • drug use (injecting)
  • alcohol drinkng
  • young age (especially <25)
  • birth control pills as a sole form of contraception


The most effective way to prevent sexual transmission of STIs is to avoid contact of body parts or fluids which can lead to transfer with an infected partner. Not all sexual activities involve contact: cybersex (virtual sex encounter), phonesex (telephonic sex encounter) or masturbation from a distance are methods of avoiding contact. Proper use of condoms reduces contact and risk. 

Healthcare professionals suggest safer sex, such as the use of condoms, as the most reliable way of decreasing the risk of contracting STIs during sexual activity, but safer sex should by no means be considered an absolute safeguard. The transfer of, and exposure to, bodily fluids, such as blood transfusions and other blood products, shared injection needles, needle-stick injuries (when medical staff are inadvertently jabbed or pricked with needles during medical procedures), shared tattoo needles, and childbirth are other avenues of transmission. These different means put certain groups, such as medical workers, hemophiliacs (their blood doesn't clot normally), and drug users particularly at risk.

Vaccines are available that protect against some viral STIs, such as hepatitis A, hepatitis B, and some types of HPV. Vaccination before initiation of sexual contact is advised to assure maximal protection. The development of vaccines to protect against gonorrhea is ongoing.

A delayed or untreated sexually transmitted infection (STI) could be one of the causes of damage to both female and male reproductive systems. 

Especially gonorrhea and Chlamydia as the most common STIs as well as being a largely symptomless disease, it can often go undiagnosed and, therefore, untreated. If persistent Chlamydia infection left untreated, women are at risk of developing pelvic inflammatory disease (PID). This is a serious condition involving inflammation of the upper female genital tract and supporting structures. It causes various complications including chronic pelvic pain, increased risk of ectopic pregnancy and tubal factor infertility (TFI), which is a significant cause of infertility. The extent to which Chlamydia infection impacts on male fertility is still uncertain. Chlamydia can cause inflammation of the epididymis, testes and accessory glands which can ultimately damage sperm. In men, fertility problems are usually the result of reduced semen characteristics (e.g. low numbers or poor quality of sperm).

Biological changes caused by HIV, including systemic illnesses, stress, and weight loss, may affect the function of reproductive organs and result in infertility. Newly diagnosed HIV infection may cause psychological trauma and decrease in sexual drive and sexual activity. Hypogonadism especially in men with AIDS is one of the important endocrine disorders that causes infertility.

Chronic viral hepatitis B and C can cause impairment in sperm concentration, motility, morphology, and viability, whereas HPV primarily affects sperm motility. The semen has been associated with decreased sperm concentration and reduced motility. In HIV-infected women, chronic HPV infection increases the risk of cervical cancer development and possibly leads to infertility.

Infections in the mother may impact both maternal and fetal health and transmission may occur during pregnancy, delivery and in the post-partum period, therefore the risks of diagnostic and therapeutic procedures must be considered in pregnant women. HIV, syphilis and hepatitis B serologies are normally done during pre-natal visits, whereas those for Chlamydia and gonorrhea are often neglected. In addition, even if these serologies are performed, pregnant women are often not told about the results due to negligence or disorganization of the health system.

Prognosis varies greatly depending on the disease and treatment. The STIs that can affect fertility and/or neonatal health include Chlamydia, gonorrhoea, human immunodeficiency virus (HIV), genital herpes, syphilis and Mycoplasma genitalium. 

Most STIs are treatable or curable. Of the most common infections, syphilis, gonorrhea, chlamydia, trichomoniasis are curable, while herpes, hepatitis B, HIV/AIDS, and HPV are treatable but not curable. Resistance to certain antibiotics is developing among some organisms such as gonorrhea.

Untreated Chlamydia causes tubal infertility and ectopic pregnancy in women and urethritis, prostatitis (inflammation of urethra, prostate or epididy and epididymis) that impair sperm quality and fuction in men. Untreated gonorrhoea Mycoplasma genitalium leads to pelvic inflammatory disease (PID) in both men and women. PID increases the risk of blockage of the fallopian tubes and thus increases the risk of ectopic pregnancy. Genital herpes does not affect the pregnancy at all, but it could be transmitted to the baby during delivery.

HIV infected women may have decreased reproductive potential in terms of ovarian response to stimulation, fertilization, and implantation. Additionaly, there is a higher risk of concomitant sexually transmitted diseases that are known to contribute to tubal blockage. Biological changes caused by HIV, including systemic illnesses, stress, and weight loss, may affect the function of reproductive organs and result in infertility. Newly diagnosed HIV infection may cause psychological trauma and decrease in sexual drive and sexual activity. Additionaly, there is a high risk of congenital HIV for baby and thus ART treatment is highly recommended for HIV patients.

If the syphilis is treated (especially in early stages), there are no trouble conceiving or carrying a baby due to previous infection. If the syphilis persists, there is a high risk that the infection passes from the mother to the child through the placenta or during the delivery.

Find more about related issues


Sexually transmitted infections: a guide for lesbian and bisexual women ―by Order of Perpetual Indulgence of Perpetual Indu licensed under CC BY-SA 2.0 UK
Sexually transmitted infection ―sourced from Wikipedia licensed under CC BY-SA 3.0
HIV Infection and Infertility ―by Khawcharoenporn and Sha licensed under CC BY 3.0
Sexually Transmitted Diseases (STDs) ―sourced from Boundless licensed under CC BY-SA 4.0
Sexually Transmitted Infections ―sourced from PCPaedia licensed under CC BY-NC 3.0
HIV infection ―sourced from Fertilitypedia licensed under CC BY-SA 4.0
HIV-budding-Color ―by Goldsmith licensed under CC0 1.0
HPV after surgical removal ―by Sasavant licensed under CC BY 3.0
Gonococcal lesion on the skin PHIL 2038 lores ―by unknown licensed under CC0 1.0
Primary stage syphilis sore (chancre) on the surface of a tongue ―by Centers for Disease Control and Prevention licensed under CC0 1.0
SOA-Herpes-genitalis-female ―by SOA-AIDS Amsterdam licensed under CC BY-SA 3.0
SOA-Herpes-genitalis-male ―by SOA-AIDS Amsterdam licensed under CC BY-SA 3.0
SOA-Chlamydia-trachomatis-female ―by SOA-AIDS Amsterdam licensed under CC BY-SA 3.0
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