Sexually Transmitted Disease(STD)
• More than 1 million people acquire a sexually transmitted infection (STI) every day.
• Each year, an estimated 500 million people become ill with one of 4 STIs: chlamydia,
gonorrhoea, syphilis and trichomoniasis.
• More than 530 million people have the virus that causes genital herpes (HSV2).
• More than 290 million women have a human papillomavirus (HPV) infection.
• The majority of STIs are present without symptoms.
• Some STIs can increase the risk of HIV acquisition three-fold or more.
• STIs can have serious consequences beyond the immediate impact of the infection itself, through mother-to-child transmission of infections and chronic diseases.
• Drug resistance, especially for gonorrhoea, is a major threat to reducing the impact of STIs worldwide.
Sexually transmitted infections (STI) are a group of infectious diseases where the epidemiologically important mode of transmission occurs during sexual intercourse or intimate genital contact. According to the WHO global summit (2012), there are 340 million new cases of syphilis, gonorrhea, chlamydiasis and trichomoniasis in the 15–49 age group. Sexually transmitted infections (STIs) are a public health problem, and their prevalence is rising even in developed nations. While the consequences of STIs can be serious, the good news is that many of these complications are
preventable if appropriate screening is done in high‑risk individuals, when infection is strongly suspected. STIs are caused by more than 30 different bacteria, viruses and parasites and are spread predominantly by sexual contact, including vaginal, anal and oral sex. Some STIs may be spread via skin-to-skin sexual contact. The organisms causing STIs can also be spread through non-sexual means such as blood products and tissue transfer. Many STIs – including chlamydia, gonorrhoea, hepatitis B, HIV, HPV, HSV2 and syphilis – can also be transmitted from mother to child during pregnancy and childbirth. A person can have an STI without having obvious symptoms of disease. Therefore, the term “sexually transmitted infection” is a broader term than “sexually transmitted disease” (STD). Common symptoms of STDs include vaginal discharge, urethral discharge in men, genital ulcers, and abdominal pain.
Eight of the more than 30 pathogens known to be transmitted through sexual contact have been linked
to the greatest incidence of illness. Of these 8 infections, 4 are currently curable: syphilis, gonorrhoea,
chlamydia and trichomoniasis. The other four are viral infections and are incurable, but can be mitigated or modulated through treatment: hepatitis B, herpes, HIV, and HPV. STIs can have serious consequences beyond the immediate impact of the infection itself.
• Some STIs can increase the risk of HIV acquisition three-fold or more.
• Mother-to-child transmission of STIs can result in stillbirth, neonatal death, low birth weight
and prematurity, sepsis, pneumonia, neonatal conjunctivitis, and congenital deformities. Syphilis in pregnancy leads to approximately 305 000 fetal and neonatal deaths every year and leaves 215 000 infants at increased risk of dying from prematurity, low birth weight or congenital disease.
• HPV infection causes 530 000 cases of cervical cancer and 275 000 cervical cancer deaths each
year.
• STIs such as gonorrhoea and chlamydia are major causes of pelvic inflammatory disease, adverse pregnancy outcomes and infertility.
Counselling and behavioural interventions offer primary prevention against STIs (including HIV),
as well as against unintended pregnancies. These include: comprehensive sexuality education, STI and HIV pre- and post-test counselling; safer sex/risk-reduction counselling, condom promotion; and interventions targeted at key and vulnerable populations, such as adolescents, sex workers, men
who have sex with men and people who inject drugs.
Accurate diagnostic tests for STIs are widely used in high-income countries. These are especially useful for the diagnosis of asymptomatic infections. However, in low- and middle-income countries, diagnostic tests are largely unavailable.
Molecular techniques for identifying and detecting microorganisms have been proven readily adaptable for use in the clinical diagnostic laboratory. Sexually transmitted diseases (STDs) constitute the commonest infectious diseases globally and bear significant consequences for the individual as well as public health of the community.
There are 3 broad types of assays used in molecular diagnostics:
• Hybridization techniques – e.g., NAH
• Amplification techniques – e.g., PCR
• Assays used in Epidemiological investigations – e.g., strain typing and identification.
The diagnostic tests for STIs serve many purposes. Apart from aiding in the diagnosis of typical cases, they help diagnose atypical cases, asymptomatic infections and also multiple infections. But, the test methods used must fulfill the criteria of accuracy, affordability, accessibility, efficiency, sensitivity, specificity and ease of handling.
The results must be rapid, cost‑effective and reliable. They are especially useful for microorganisms that cannot be, or are difficult to cultivate. With the newer diagnostic technologies, we are on the verge of a major change in the approach to STI control. When diagnostic methods are faster and results more accurate, they are bound to improve patient care.
References:
1. Sexually transmitted infections,World Health Organization 2014, Department of Reproductive Health and Research World Health Organization Avenue Appia 20, CH-1211 Geneva 27, Switzerlandhttps://www.who.int/reproductivehealth.
2. Sexually Transmitted Infections Treatment Guidelines July 23,2021. U.S. Department of Health and Human ServicesCenters for Disease Control and Prevention. Vol. 70 / No. 4.
3. Sumathi Muralidhar, Department of Apex Regional STD Teaching, Training and Research Centre, Vardhman Mahavir Medical College,Safdarjang Hospital, New Delhi, India Molecular methods in the laboratory diagnosis of sexually transmitted infections. Indian Journal of Sexually Transmitted Diseases and AIDS 2015; Vol. 36, No. 1.
4. M Díez, A Díaz Epidemiology Department on HIV and Risk Behaviors. Secretary of the National Plan on AIDS.Ministry of Health, Social Policy and Equality. National Centre for Epidemiology Health Institute Carlos II. Sexually transmitted infections: Epidemiology and control. Rev Esp Sanid Penit 2011; 13: 58-66.
5. Advanced techniques in diagnostic microbiology, pp 535-556.
