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

Individuals at high risk of Sexually Transmitted Diseases:

Prostitues and their clients

Homosexual men

Person’s involved in the use of illicit drugs such as crack cocaine and methamphetamine.

Classification of Sexually Transmitted Diseases:

A) Bacterial agents:

Neisseria gonorrhoeae

Chlamydia trachomatis

Treponema pallidum

Haemophilus ducreyi

Mycoplasma hominis

Ureaplasma urealyticum

Calymmatobacterium granulomatis

Shigella spp

Campylobacter spp

Group B streptococcus

Bacterial vaginosis-associated organisma

B) Viral agents:

Human (alpha) herpes virus 1 or 2 (herpes simplex virus)

Human (beta) herpes virus 5 (formerly cytomegalovirus)

Hepatitis B virus

Human papilloma virus

Molluscum contagiosum virus

Human immunodeficiency virus

C) Protozoal agents:

Entamoeba histolytica

Giardia lamblia

Trichomonas vaginalis

D) Fungal agents:

Candida albicans

E) Ectoparasites:

Phthirus pubis

Sarcoptes scabiei

It must be noted that sexually transmitted diseases were previously known as venereal diseases. Some of the sexually transmitted diseases are more commonly spread by other means other than during coitus.

Sexually transmitted diseases now include over 30 agents. The 5 classical venereal diseases prior to the discovery of the new ones are syphilis, gonorrhoea, chancroid, lymphogranuloma venereum and donovanosis.The more recently recognized STD’s  are now referred to as second generation STD’s, an example of which is AIDS.

Incidence and prevalence of STD’s-The Extent of the problem:

In all societies, STD’s are among the most common of all infectious diseases.

90% of the world’s STD’s are in the developing countries ,which account for 75% of the world’s population.Factors that account for this are population growth (especially among the adolescent and young-adult age groups), wars, poverty, rural-to-urban-migration etc.

The true incidence of STD’s will never be know because of the secrecy that surrounds them. However it is estimated that the prevalence may be as high as 14%.

WHO estimates that at least 333 million new cases of STD’s ,other than HIV occurred in 1997. Minimal estimates of yearly incidence of some of the STD’s are:

Bacterial STD-

Gonorrhoea     62 million

Genital Chlamydial infection   89million

Syphylis     12million

Chancroid    2million

Rough estimates of viral STD’s (because most are asymptomatic )are:

Genital herpes     20million

Genital human papilloma virus infection    30million

Protozoal

Trichomoniasis 170million but is has a much less public health importance

Common syndrome/sequelae of sexual transmitted diseases:

Male urethritis

Lower genital syndromes in women: vaginitis, cervicitis, urethritis

Genital ulceration

Proctitis and or colitis

Salpingitis

Epididymitis/orchitis

Infertility/ectopic pregnancy

Postnatal and perinatal morbidity

Hepatitis/hepatic carcinoma

Genital carcinoma

Acquired Immuno Deficiency Syndrome (AIDS).

Host Factors for the development of STD’s:

a)Sex: The overall morbidity rate (manifestation of the illness) is much higher in men than in women .But it is severe in women with pelvic inflammatory disease (PID) .

b)Marital status: The frequency of STD is higher among single, divorced and seperated individuals than among married couples.

c) Age:Highest rates are in the 20-24 year old age group.This is followed by the 25-29 year old age group and the 15-19 year age groups. Unfortunately it is the fetus and the neonate that has the most severe morbidity.

d) Socio-economic status: Individuals from the lowest socioeconomic group have the highest morbidity rates.

References:

Pages 253 to 256 ,Sexually Transmitted Diseases,Chapter 5,Epidemiology of Communicable Diseases, Park’s Textbook of Preventive and Social Medicine 17th Edition by K.Park

Pages 762 to 766 Part VI Infectious Diseases, Chapter 115,Sexually Transmitted Diseases: Overview and Clinical Approach by King K. Holmes. Volume I. Harrison’s Principles of Internal Medicine by Kasper Braunwald Fauci Hauser Longo and Jameson.16th Edition.