What are Sexually Transmitted Diseases (STDs)?
Sexually Transmitted Diseases (STDs) are diseases caused by pathogens and are transmitted by blood, sperm, vaginal fluids or other body fluids during sexual intercourse (vaginal, anal and oral) with an infected partner. The pathogen, passing from an infected subject to a healthy subject, results in the onset of an infection identified as a sexually transmitted infection (STI) causing the sexually transmitted disease.
Transmission of STIs can also occur from an infected pregnant person to the child during pregnancy or at the time of delivery.
STDs are a global health problem and adolescents constitute the most vulnerable segment of the population. If not diagnosed in good time, they can also cause infertility.
What are sexually transmitted infections?
Pathogens responsible for sexually transmitted infections (STIs) can include bacteria (Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum, Gardnerella vaginalis, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Group B streptococcus), viruses (HPV, Herpes virus, Hepatitis B and C, HIV) or protozoa (Trichomonas vaginalis).
Chlamydia
Chlamydia: what is it?
Chlamydia is a microorganism sometimes responsible for bacterial infection of the genital tract caused by Chlamydia trachomatis. It is difficult to detect since infections in the initial state are asymptomatic. Symptoms usually begin one to three weeks after exposure to the aetiological agent and may be mild, heal spontaneously or have more significant manifestations.
What are the symptoms of Chlamydia?
Symptoms may include:
- Painful urination,
- Lower abdominal pain,
- Vaginal discharge in women,
- Penile discharge in men,
- Pain during sexual intercourse in women,
- Non-menstrual bleeding,
- Testicular pain in men.
Which tests should be carried out?
To diagnose a Chlamydia trachomatis infection, you can perform:
- A molecular investigation of the pathogen on different biological samples, such as: a swab (cervical-vaginal or urethral), urine, seminal fluid or prostate fluid. Examination by qualitative DNA detection carried out in Real-Time PCR identifies the presence of the bacterium.
- A blood sample, to search for IgM, IgG, and IgA antibodies by the immunoenzymatic method.
IgMs are indicative of a primary antibody response, and indicate a recent or ongoing infection; IgGs indicate a previous infection and are predictive of the body’s immune memory. IgA is predictive for protection against mucosal infections (respiratory tract, upper and lower respiratory tract and gastrointestinal tract, stomach and intestines).
Gonorrhoea
Gonorrhoea: what is it?
This is a bacterial infection caused by Neisseria gonorrhoeae that mainly infects the genital tract, but can also develop in the mouth, throat, eyes and anus. The first symptoms of gonorrhoea generally appear within 10 days of exposure. However, some people may be infected for months before obvious signs or symptoms develop.
What are the symptoms?
Symptoms may include:
- Thick, cloudy or bloody discharge from the penis or vagina
- Pain or burning sensation during urination
- Heavy menstrual bleeding or between cycles
- Painful and swollen testicles
- Painful bowel movements
- Anal itching
Which tests should be performed?
To diagnose an infection caused by Neisseria gonorrhoeae, you can perform:
- A molecular investigation of the pathogen on various biological samples, such as: a swab (cervical-vaginal or urethral), urine, seminal fluid or prostate fluid. Examination by qualitative DNA detection carried out in Real-Time PCR identifies the presence of the bacterium.
- A blood sample, looking for the presence of the antibody response mediated by IgM, IgG and IgA immunoglobulins with an immunoenzymatic method. IgMs are an indication of a primary antibody response, and indicate a recent or ongoing infection; IgGs indicate a previous infection and are predictive of the body’s immune memory. IgA is a predictive immunoglobulin for protection against mucosal infections (respiratory tract, upper and lower respiratory tract and gastrointestinal tract, stomach and intestine).
Syphilis
What is syphilis?
This is a bacterial infection caused by Treponema pallidum. The disease affects the genitals, skin and mucous membranes, but can also involve many other parts of the body, including the brain and heart. Syphilis symptoms can occur in three stages: primary, secondary and tertiary. Some people also experience latent syphilis, in which blood tests for molecular investigation of Treponema pallidum are positive, but no symptoms are present.
What are the symptoms of syphilis?
Initially, at the site of infection, usually the genitals, rectum, tongue or lips, only a small painless wound (ulcer) may be present. As the disease worsens, symptoms may include:
- A rash characterised by red or reddish-brown sores, as large as a coin, on any area of the body, including the palms of the hands and soles of the feet
- Fever
- Enlarged lymph nodes
- Fatigue and a vague feeling of discomfort
If left untreated, syphilis bacteria can spread throughout the body, causing serious damage to internal organs and the brain, and can lead to death even years after the initial infection.
Some of the signs and symptoms of advanced syphilis include:
- Lack of coordination
- Numbness
- Paralysis
- Blindness
- Dementia
There is also a condition known as congenital syphilis, which occurs when a pregnant woman with syphilis transmits the disease to the foetus. Congenital syphilis can be disabling, even life-threatening, so it is important that pregnant women with syphilis are treated.
At any stage, syphilis can affect the nervous system. Neurosyphilis may not cause signs or symptoms, or may cause:
- Headaches
- Behavioural changes
- Movement problems
Which tests should be performed?
Diagnosis of Treponema pallidum infection is carried out with:
- molecular investigation of the pathogen on biological materials or liquids. The examination allows qualitative detection of the DNA carried out in Real-Time PCR and identifies the presence of the bacterium.
- a blood sample, quantitatively investigating the presence of the antibody response with haemagglutination in chemiluminescence (TPHA research) or by assaying IgM, IgG immunoglobulins by enzyme immunoassay. IgMs are indicative of a primary antibody response, and indicate a recent or ongoing infection; IgGs indicate a previous infection and are predictive of the body’s immunological memory.
Gardnerella vaginalis, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Group B streptococcus
There are also bacterial infections caused by bacteria such as Gardnerella vaginalis, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, and Group B streptococcus.
What are the symptoms?
Symptoms include:
- Abnormal genital discharge
- Genital, anal or buccal itching
- Pelvic pain with possible bleeding during or after sexual intercourse.
Which tests should be performed for diagnosis?
To diagnose an infection caused by Gardnerella vaginalis, Mycoplasma genitalium, Mycoplasma hominis, or Ureaplasma urealyticum, it is possible to conduct a molecular investigation of the pathogen on various biological samples, such as: a swab (cervical-vaginal or urethral), urine, seminal fluid or prostate fluid. Examination by qualitative DNA detection carried out in Real-Time PCR identifies the presence of the bacterium.
For Group b streptococcus, it is possible to carry out the investigation by means of a microbiological sample culture test.
Trichomoniasis
Trichomoniasis, what is it?
Trichomoniasis is a protozoan, single-celled microscopic parasite, called Trichomonas vaginalis, that causes an STI. The protozoan spreads during sexual intercourse with an infected subject. The body usually infects the urinary tract in men but often does not cause symptoms; in women, it infects the vagina.
What are the symptoms?
Symptoms may appear within 5–28 days of exposure and range from mild irritation to severe inflammation. Symptoms may include:
- Clear, white, greenish or yellowish vaginal discharge
- Discharge from the penis
- Strong vaginal odour
- Vaginal itching or irritation
- Itching or irritation inside the penis
- Pain during sexual intercourse
- Painful urination
Which tests should be performed?
To diagnose an infection caused by Trichomonas vaginalis, a molecular investigation of the pathogen can be carried out on several biological samples, such as: a swab (cervical-vaginal or urethral) and urine. Examination by qualitative DNA detection carried out in Real-Time PCR can identify the presence of the bacterium.
It is also possible to search for this protozoa by microbiological sampling (vaginal or urethral swab) or by testing the urine. Microbiological investigation allows the presence of Trichomonas vaginalis to be detected even at minimum concentrations of micro-organisms.
Sexually transmitted diseases: without symptoms
Many sexually transmitted diseases have no signs or symptoms. Generally, the male population is asymptomatic of STDs. Even without symptoms, however, STIs can be transmitted to sexual partners. So it is important to use methods of protection, such as a condom during sex and to screen for sexually transmitted diseases so that an infection can be identified and treated before being transmitted.
STDs: how can they be prevented?
STDs can be avoided by adopting safe sexual practices for all intercourse (vaginal, anal and oral) with the use of a condom. It is good practice to undergo screening for early diagnosis in order to implement timely treatments to prevent its spread. For some sexually transmitted infections, vaccination is possible.
It is recommended for women of any age to undergo examination of the cervical-vaginal microbiota, a group of bacteria that reside in the vagina that can be detected with molecular genetics tools directly from vaginal secretion. Sampling can be carried out directly by the patient. A healthy balance of the vaginal microflora is fundamental to avoid dysbiosis due to bacterial vaginosis. This pathological condition is a risk factor for STDs caused by bacteria (Neisseria gonorrhoeae, Chlamydia trachomatis, and Mycoplasma genitalium), by viruses (HPV), and by protozoa (Trichomonas vaginalis).
Dr Angela Marano
Specialist in Pathology and Clinical Biochemistry
