Sexually transmitted diseases (STDs) — or sexually transmitted infections (STIs) — are generally acquired by sexual contact. The bacteria, viruses or parasites 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 mothers to their infants during pregnancy or childbirth, or through blood transfusions or shared needles.
STIs don't always cause symptoms. It's possible to contract sexually transmitted infections from people who seem perfectly healthy and may not even know they have an infection.
Scope of the problem
STIs have a profound impact on sexual and reproductive health worldwide.
More than 1 million STIs are acquired every day. In 2020, WHO estimated 374 million new infections with one of four STIs: chlamydia (129 million), gonorrhoea (82 million), syphilis (7.1 million) and trichomoniasis (156 million). More than 490 million people were estimated to be living with genital HSV (herpes) infection in 2016, and an estimated 300 million women have an HPV infection, the primary cause of cervical cancer. An estimated 296 million people are living with chronic hepatitis B globally. Both HPV and hepatitis B infections are preventable with vaccination.
STIs can have serious consequences beyond the immediate impact of the infection itself.
- STIs like herpes, gonorrhoea and syphilis can increase the risk of HIV acquisition.
- Mother-to-child transmission of STIs can result in stillbirth, neonatal death, low-birth weight and prematurity, sepsis, pneumonia, neonatal conjunctivitis and congenital deformities.
- HPV infection causes cervical cancer. Cervical cancer is the fourth most common cancer among women globally.
- STIs such as gonorrhoea and chlamydia are major causes of pelvic inflammatory disease (PID) and infertility in women.
STIs are classified according to different criteria: the type of pathogen, clinical manifestations, the possibility of cure, etc. The international classification lists STDs that cause obligate pathogenic microorganisms. Separate classifications are more of an additional nature and are used in the diagnosis, treatment and prevention of genital infections.
Sexually transmitted diseases are divided into: curable (most STIs); incurable (anogenital herpes, AIDS - acquired immunodeficiency syndrome).
At the heart of the syndromic classification of STIs are the clinical manifestations of the disease:
- Group 1 - sexual infections, characterized by the presence of erosive and ulcerative syndrome. Infectious agents that cause ulcers and erosions in the genital area and perineum include pathogens: anogenital herpes, syphilis, trichomoniasis, lymphogranuloma venereum, inguinal granuloma, chancroid, etc.;
- Group 2 - infections, which are characterized by the syndrome of urethro-genital discharge. The most common infections that cause vaginal discharge in women are bacterial vaginosis, thrush (candidiasis), and trichomoniasis.
Types of STIs depending on the etiological classification:
- bacterial infections - syphilis, chlamydia, mycoplasmosis, bacterial vaginosis, gonococcal infection, etc.
- viral infections - herpetic viral infection, hepatitis B and C, molluscum contagiosum, venereal warts, HIV, etc.
- protozoal diseases - trichomoniasis, amoebiasis
- lesions caused by fungi - candidiasis
- pathologies caused by ectoparasites - phthiriasis and scabies
STDs or STIs can have a range of signs and symptoms, including no symptoms. That's why they may go unnoticed until complications occur or a partner is diagnosed.
Signs and symptoms that might indicate an STI include:
- Sores or bumps on the genitals or in the oral or rectal area
- Painful or burning urination
- Discharge from the penis
- Unusual or odorous vaginal discharge
- Unusual vaginal bleeding
- Pain during sex
- Sore, swollen lymph nodes, particularly in the groin but sometimes more widespread
- Lower abdominal pain
- Rash over the trunk, hands or feet
Signs and symptoms may appear a few days after exposure. However, it may take years before you have any noticeable problems, depending on the organism causing the STI
Diagnosis of STIs includes the collection of information, examination, laboratory research methods. The collection of anamnesis and examination is carried out in an atmosphere of complete confidentiality. An indispensable source of information can serve as an anamnesis of the patient's sexual life.
Laboratory methods for diagnosing STIs:
- general blood analysis
- general urine analysis
- microscopic studies of stained or native preparations
- cultural study (bacteriological culture)
- cytoscopic methods
- immunofluorescent study
- linked immunosorbent assay
- immunoperoxidase methods
- latex agglutination
- PARD analysis
- specific tests (anticardiolipin test or syphilis RPR, VDRL or MRP - non-treponemal tests)
- molecular biological methods
Molecular biological methods are the most sensitive diagnostic methods for detecting STIs. These methods include: PCR - diagnostics (polymerase chain reaction); TMA, NASBA - transcriptional amplification reaction; SDA - chain shift reaction. These methods can detect the presence of any STI.
Treatment for bacterial infections is with antibiotics. However, some STIs — such as gonorrhea — appear to be developing a resistance to the antibiotics that doctors commonly prescribe to treat them.
It is essential to complete any type of antibiotic treatment, even if the symptoms disappear. Stopping treatment early may allow remaining bacteria to grow again, and symptoms may return. At this stage, the infection can become harder to treat.
Vaccines can help protect a person from HPV and hepatitis B. People can discuss their situation with a healthcare provider, who will advise about vaccinations.
Using a condom, or other barrier method of contraception can help prevent the spread of many STIs, though this will not prevent the transmission of infections that spread as a result of skin-to-skin contact.
Some other ways to reduce the risk of transmitting or contracting an STI include:
- talking to any new partners about protected sex and any past infections
- ensuring that both partners undergo testing before starting a new sexual relationship
- receiving vaccinations to protect against some infections