The sexually transmitted disease (STD) are a group of communicable disease that are transmitted predominantly by sexual contact and caused by a wide range of bacterial, viral, protozoal and fungal agents and ectoparasites.

During the past few decades, STDs have undergone a dramatic transformation. First, the change in the name from venereal disease (VD) to sexually transmitted diseases (STD) indicates this transformation. The list of pathogens which are sexually transmissible has expanded from the 5 “classical” venereal diseases (syphilis, Gonorrhea, chancroid, lymphogranuloma venereum and donovanosis ) to include more than 20 agents. Secondly, attention is now given not only to specific diseases, but also to clinical syndromes associated with STDs. Most of the recently recognized STDs are now referred to as second generation STDs. AIDS, the most recent recognized, is a totally new disease.


A. Bacterial agents

  • Neisseria gonorrhoeae
  • Chlamydia trachomatis
  • Treponema pallidum
  • Haemophilus ducreyi
  • Mycoplasma hominis
  • Ureaplasma urealyticum
  • Calymmatobacterium granulomatis
  • Shigella spp.
  • Campylobacter spp.
  • Group B streptococcus
  • Bacteria/ vaginosis-associated organisms

B. Viral agents

  • Human (alpha) herpesvirus 1 or 2 (herpes simplex virus)
  • Human (beta) herpesvirus 5 (formerly cytomegaiovirus)
  • Hepatitis virus B
  • Human papilloma viruses
  • Molluscum contagiosum virus
  • Human immunodeficiency virus

C. Protozoal agents

  • Entamoeba histolytica
  • Giardia lamblia
  • Trichomonas vaginalis

D. Fungal agent

  • Candida albicans

E. Ectoparasites

  • Phthirus pubis
  • sarcptes scabiei

Extent of the problem


The true incidence of STDs will never be known not only because of inadequate reporting but because of the secrecy that surrounds them. Most of them are not even notifiable. All available data, however, indicate a very high prevalence of STD.

STDs have profound impact on sexual and reproductive health world-wide, and rank among the top 5 disease categories for which adults seek health care.

More than 1 million people acquire a sexually transmitted disease everyday. Each year, an estimated 500 million people acquire one of four STDs, i.e., chlamydia, gonorrhea, syphilis and trichomoniasis. More than 530 million people are living with HSV2 that causes genital herpes. More than 290 million women have an human papilloma virus infection, which is one of the most common STD.

STDs can have serious consequences beyond the immediate impact of the infection itself. Some STDs can increase the risk of HIV infection three-fold or more. Mother to child transmission of STDS 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 an increased risk of dying from prematurity, low-birth-weight or congenital disease.

Human papilloma virus causes 530,000 cases of cervical cancer and 275,000 cervical cancer deaths each year. Gonorrhea and chlamydia are major causes of pelvic inflammatory disease, adverse pregnancy outcomes and infertility.


Sexually transmitted diseases are becoming a major public health problem in India.

(a) Syphilis : Serological surveys continue to be the best source of information on the prevalence of syphilis. During 2013, about 33,570 cases of syphilis (18,081 male and 15,489 female) were reported in the country with 1 death.

(b) Gonorrhea : Information on the morbidity of gonorrhea is notoriously lacking as most cases are not reported. The general impression is that gonorrhea is more widely prevalent than syphilis. During 2013, about 97,180 gonorrhea cases (31,564 male and 65,616 female) were reported in the country.

(c) Chancroid : Chancroid or soft sore is reported to be fairly widely prevalent in India.

(d) LGV : It is reported to be more prevalent in the southern states of Tamil Nadu, Andhra Pradesh, Maharashtra and Karnataka than in the northern states.

(e) Donovanosis : Donovanosis or granuloma inguinale is endemic in Tamil Nadu, Andhra Pradesh, Odisha, Karnataka, and Maharashtra. A greater prevalence along the coastal areas has been reported.

(f) Other STDs : Information on the other STDs is not readily available, as there is no reprting system for these disease.

Epidemiological determinants

Agents factors

Over 20 pathogens have been found to be spread by sexual contact. A classification of these agents and the diseases caused by them are shown below :-

PathogenHost Disease or syndrome
Neisseria gonorrhoeaeGonorrhea, urethritis, cervicitis,
epididymitis, salpingitis, PID,
neonatal conjunctivitis
Treponema pallidumSyphilis
Haemophilus ducreyiChancroid
Chlamydia trachomatisLGV, urethritis, cervicitis, proctitis,
epididymitis, infant pneumonia,
Reiter’s syndrome, PIO, neonatal
Calymmatobacterium granulomatisDonovanosis (granuloma inguinale)
Herpes simplex virusGenital herpes
Hepatitis B virusAcute and chronic hepatitis
Human papillomavirusesGenital and anal warts
Human immunodeficiency virus (HIV)AIDS
Molluscum contagiosumGenital molluscum contagiosum
Candida albicansVaginitis
Trichomonas vaginalisVaginitis

Host factor

(a) Age : For most notifiable STDs, the highest rates of incidence are observed in 20-24 years old, followed by the 25-29 and 15-19 years age groups. The most serious morbidity is observed during fetal development and in the neonate.

(b)Sex : For most STDs, the overall morbidity rate is higher for men than for women, but the overall morbidity rate is higher for men than for women, but the morbidity caused by infection is generally much more severe in women a for example, pelvic inflammatory disease.

(c)Marital status : The frequency of STD infection is higher among single, divorced and separated persons than among married couples.

(d)Socio-economic status : individuals from the lowest socio-economic groups have the highest morbidity rate.

Demographic factors

Certain demographic factors will undoubtedly contribute to increase in STDs in the developing countries. These include population explosion and marked increase in the number of young people, the group at highest risk for STD in the population: rural to urban migration: increasing educational opportunities for women delaying their marriage and increase STD risks.

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