Sexually transmitted infections (STIs)

Sexually transmitted infections (STIs)

Sexually transmitted infections (STIs) are infections that spread primarily through person-to-person sexual contact. STIs are of public health concern not only because of their high prevalence worldwide, but also because of their potential to cause serious and permanent complications in infected people who are not treated in a timely and effective way. These complications and sequelae include infertility, fetal wastage, ectopic pregnancy, anogenital cancer and premature death, as well as neonatal and infant infections. In addition STIs are known to facilitate human immunodeficiency virus infection/acquired immunodeficiency syndrome (HIV/AIDS).

There are more than 30 different sexually transmissible bacteria, viruses and parasites. The most common conditions they cause are gonorrhoea, chlamydial infection, syphilis, trichomoniasis, chancroid, genital herpes, genital warts, human immunodeficiency virus (HIV) infection and hepatitis B infection.

Several STIs, particularly HIV and syphilis, can also be transmitted from mother to child during pregnancy and childbirth, and through blood products and tissue transfer.

According to World Health Organization (WHO) more than 1 million people acquire a sexually transmitted infection (STI) every day globally. WHO estimates that 500 million new cases of one of four curable STIs (chlamydia, gonorrhoea, syphilis and trichomoniasis) occur each year worldwide.

STIs/RTIs (reproductive tract infections) are an important public health problem in India. A community based STI/RTI prevalence study conducted during 2002-03 by the Indian Council of Medical Research (ICMR) has shown that 6% of the adult population in India has one or more STI/RTI. This amounts to occurrence of about 30-35 million episodes of STI/RTI every year in the country.

 A large proportion of new STIs occur amongst adolescents and young adults who may not be aware that they are infected, which can have a negative impact upon their future sexual and reproductive health.



The majority of STIs are present without symptoms. A person can have an STI without having obvious symptoms of disease. Therefore, the term “sexually transmitted infection” a broader term than “sexually transmitted disease” (STD) is preferred.

Common symptoms of STDs include –

  • Unusual discharge from the penis or vagina
  • Sores or warts on the genital area
  • Painful or frequent urination
  • Itching and redness in the genital area
  • Blisters or sores in or around the mouth
  • Abnormal vaginal odour
  • Anal itching, soreness, or bleeding
  • Dysparuenia
  • Abdominal pain
  • Fever


STIs are caused by more than 30 different bacteria, viruses and parasites. The major STIs and their causes are:

  • Bacteria-Chlamydia trachomatis (disease-Chlamydia), neisseria gonorrhoeae (disease-Gonorrhea)  and Treponema pallidum (disease-Syphilis)
  • Viruses- Human immunodeficiency virus(HIV/AIDS), herpes simplex virus (HSV) (disease- Genital herpes), human papilloma virus (HPV)(disease- Genital warts), hepatitis B virus (disease-Hepatitis), and cytomegalovirus
  • yeasts and protozoan parasites-Trichomonas vaginalis (disease-Trichomoniasis) , pubic lice (disease- Pediculosis pubis), Sarcoptes scabiei (disease-scabies)

Transmission of STIs-

  • STIs spread predominantly by sexual contact, including vaginal, anal and oral sex.
  • Some STIs may spread via skin-to-skin sexual contact and through non-sexual means such as blood products and tissue transfer.
  • Many STIs (chlamydia, gonorrhoea, hepatitis B, HIV, HPV, HSV-2 and syphilis) can also be transmitted from mother to child during pregnancy and childbirth.

Factors which increase the risk of transmission-

Occurrence of STI depends on many factors, both biological and behavioural.

Biological factors- Certain biological factors influence the transmission of STIs. They are age, sex, immune status of the host and the virulence of the organism.

Age- women become infected at a younger age than men.

Sex- women can be more easily infected than men.

Immune status- The immune status of the host and virulence of the infective agent affect transmission of STIs. Certain STIs increase the risk of transmission of HIV and which in turn increases the transmission of some STIs and complications of STIs by weakening the immune system.

Behavioural factors: Many behavioural factors may affect the chance of getting an STI. Such behaviours are known as "risky behaviours”, include the following-

  •  changing sexual partners frequently;
  •  having more than one sexual partner;
  • having sex with casual partners, sex workers or their clients;
  • having unprotected  sex when either partner has an infection;
  •  having had an STI in the last year

Social factors: A number of social factors link sex and behavioural issues and may affect a person’s risk of getting an STI.

Other personal behaviours including skin piercing, use of unsterile needles to give injections or tattoos, use of alcohol may be associated with increased risk of STIs,

Population groups which are particularly vulnerable:

  • sexually active teenage girls;
  • sex workers and their clients;
  • men or women who have multiple sexual partners;
  • men or women whose jobs separate them from their regular sex partners for long periods of time, such as long-distance drivers, soldiers and migrant workers;
  • Men having sex with men including transgender;
  • Street children, prison inmates.



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. Where testing is available, it is often expensive and geographically inaccessible; and patients often need to wait a long time (or need to return) to receive results. As a result, follow up can be difficult and care or treatment can be incomplete.

The only inexpensive, rapid blood test currently available for an STI is for syphilis. This test is already used in testing of syphilis in pregnant women during antenatal care.

Several rapid tests for other STIs are under development and have the potential to improve STI diagnosis and treatment, especially in resource-limited settings.


STI case management is the care of a person with an STI-related syndrome or with a positive test for one or more STIs.

The components of case management include: history taking, clinical examination, correct diagnosis, early and effective treatment, advice on sexual behaviour, promotion and/or provision of condoms, partner notification and treatment, case reporting and clinical follow-up as appropriate. Thus, effective case management consists not only of antimicrobial therapy to obtain cure and reduce infectivity, but also comprehensive consideration and care of the patient’s reproductive health.STI case management consists of:

(a) Syndromic Management-WHO has recommended syndromic management, which is based on the identification of consistent groups of symptoms and easily recognized signs (syndromes) to guide treatment, without the use of laboratory tests.

This approach allows health workers to diagnose a specific infection on the basis of observed syndromes. Syndromic management is simple, assures rapid, same-day treatment, and avoids expensive or unavailable diagnostic tests. However, this approach misses the majority of STIs that do not demonstrate any syndromes. Flowcharts are used for the management of each syndrome provided as “National Guidelines on Prevention, Management and Control of Reproductive Tract Infections and Sexually Transmitted Infections” 2014 by Ministry of Health and Family Welfare, Government of India*. These national standardized treatment protocols for STIs help to ensure that all patients receive adequate treatment at all levels of health care services.

Effective treatment is currently available for several STIs.

• Three bacterial STIs (chlamydia, gonorrhoea and syphilis) and one parasitic STI (trichomoniasis) are generally curable with existing, effective single dose regimens of antibiotics.

 • For herpes and HIV, antiviral drugs are available that can modulate the course of the disease, though they cannot cure the disease.

 • For hepatitis B, immune system modulators (interferon) and antiviral medications can help to fight the virus and slow damage to the liver.

(b) Education and Counselling- Counselling is defined here as an interactive confidential process in which a care provider helps a patient to discuss on issues associated with STIs and to explore possible lines of action. Issues that should be addressed in a counselling session include:

  • Educate the patient on his/her present STI and how it was acquired. Inform the patient that bacterial STIs are curable, viral STIs may recur, and the effects of not taking treatment properly. (Patients with recurrent genital herpes and recurrent vulvovaginitis are usually very distressed and need repeated counselling sessions).
  • Inform the partner(s) or spouse about the STI diagnosis.
  • Assess the patient’s risk for HIV and deciding whether or not to undergo testing for HIV.
  • Help the patient to learn about complications of STIs, such as infertility and congenital syphilis.  
  • Inform the patient on how to deal with an incurable STI, such as herpes genitalis or genital warts, which may be transmitted to the partner (s) or spouse.
  • Educate the patient on how to prevent future infections, including strategies for discussing and introducing condom use with the partner (s) or spouse.
  • Tell the patient about confidentiality, disclosure and the risk of violence or stigmatizing reactions from spouse, partner(s), family or friends and ways to overcome these.
  • Enable patients to take control of their own life and their responsibilities for disease prevention.

(c) Manage and treat partner -Management of sexual partners is based on knowledge of the index patient’s diagnosis (syndromic or specific). The following three strategies can be adopted for the treatment of partners:

  • Offer immediate epidemiological treatment (treatment based solely on the diagnosis of the index patient) without any laboratory investigation.
  • Offer immediate epidemiological treatment, but obtain specimens for subsequent laboratory confirmation.
  • Delay treatment until the results of definitive laboratory tests are available.

WHO recommends that epidemiological treatment (with the same treatment regimen used for the index patient) should be given to all sexual partners.

(d) Offer HIV Counselling and testing- A consultation for an STI is a unique opportunity to provide education on the prevention of HIV and STIs to people who, by definition, are at risk for these infections.

(e) Follow up-Appropriate clinical follow up is a part of comprehensive case management of STI. The follow up schedules are prescribed for each syndrome in the respective flow charts (as provided by GOI*). Patients should be advised to return if their symptoms get worse or persist after the prescribed period of therapy.

References- *

Consequences of STIs:

  • STIs can have serious consequences not only on physical health, but also on the psychological and social well-being of those infected.
  •  If STIs were left untreated, both chlamydia and gonorrhoea can lead to pelvic inflammatory disease (PID) in females, which can cause infertility and ectopic pregnancies.
  • Gonococcal and chlamydial infection can cause epididymitis and infertility in men.
  • Mother-to-child transmission of STIs during pregnancy and childbirth can result in stillbirth, neonatal death, low-birth-weight and prematurity, sepsis, pneumonia, neonatal conjunctivitis, and congenital deformities.
  • HPV infection causes cervical cancer.
  • Infection with STIs can also increase the risk of acquiring infection with HIV. STIs like herpes and syphilis can increase the risk of HIV infection three-fold or more. People who are living with HIV are also more likely to transmit the virus to a partner if they are also infected with another STI.
  • Multi-drug resistant gonorrhea-Infections with antibiotic-resistant strains of gonorrhoea are becoming increasingly common. This is a major public health concern, particularly for the prevention of infertility in women.


Primary prevention or preventing infection in uninfected persons: This is the most effective strategy to reduce the spread of STI and can be easily integrated in all health care settings.

Secondary prevention: This prevents further transmission of that infection in the community and prevents complications and reinfection in the patient.

Counseling and behavioural approaches: Counseling and behavioural interventions offer primary prevention against STIs (including HIV).

These include:

  • Comprehensive sexuality education, STI and HIV pre- and post-test counselling;
  • Safer sex/risk-reduction counselling, condom promotion;
  • Interventions targeted at key and vulnerable populations, such as adolescents, sex workers, men who have sex with men and people who inject drugs.

Barrier methods: Use of barrier methods as condoms offers one of the most effective methods of protection against STIs, including HIV. Female condoms are effective and safe, but are not used as widely by national programmes as male condoms.


Safe and highly effective vaccines are available for two STIs: hepatitis B and human papilloma virus (HPV).

The vaccine against hepatitis B is included in Universal Immunization Programme. Hepatitis B vaccination is given in 4 doses: At Birth dose (within 24 hours); Primary three doses at 6, 10 & 14 weeks.(

HPV vaccination could prevent occurrence of cervical cancer. 2 doses of HPV vaccine for adolescent/pre-adolescent girls aged 9-14 years are advised. 

Research to develop vaccines against herpes and HIV, chlamydia, gonorrhoea, syphilis and trichomoniasis is in earlier stages of development.

Other biomedical interventions to prevent some STIs include adult male circumcision and microbicides.

  • Male circumcision reduces the risk of heterosexually acquired HIV infection in men by approximately 60% and provides some protection against other STIs, such as herpes and HPV.
  • Use of vaginal microbicide, showed mixed results in terms of the ability to prevent HIV infection, but has shown some effectiveness against HSV-2 infection.


Park’s Textbook of Preventive & Social Medicine, 22nd Edition, Sexually Transmitted Diseases, 303-313.

  • PUBLISHED DATE : Jan 05, 2016
  • PUBLISHED BY : Zahid
  • CREATED / VALIDATED BY : Dr. Aruna Rastogi
  • LAST UPDATED ON : Jan 05, 2016


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