Some common presentations include:

• Urogenital

Presentation can be simply that the genitals are red and sore to sometimes painful and swollen. There may be a burning sensation in urinating and a white or coloured discharge may be found from the vagina or penis. There may be sores, ulcers, blisters or warts.

• Systemic

If the infection has spread, there may be systemic effects [3]. The infective agent may affect the heart, kidneys, brain, eyes, joints, etc.

The work up includes blood sampling for culture and sensitivity. A swab sample of fluids may be collected from the throat, cervix, vaginal canal and/or rectum in females and throat, penile urethra and/or rectum in males.

Laboratory Tests Results

• Gram staining: Gram staining may be done to check for the organism involved.
• PCR: A Polymerase Chain Reaction test maybe done for more accurate results.
• C/S: Culture and sensitivity of either blood samples, urine or swab samples may be done for accurate results.

If the test results come positive for one STD, treatment is immediately started. Other STDs are also checked.

The exact treatment varies depending upon the type of STD it is. But generally, treatment is either oral or parenterally administered antibiotics. The common regime used these days for gonorrhea and chlamydia infection is Ceftriaxone, Azithromycin and Doxycycline given in a combination to prevent reoccurrence.

STDs, if treated adequately, have a good prognosis, unless it's an incurable one like AIDS. Symptoms are mild at first and if the diagnosis is made on time, and appropriate antibiotics are administered, symptoms regress completely.

However, if for example primary syphilis is left untreated and it progresses to tertiary syphilis, it may cause irreversible damage.

Complications

If left untreated, an STD may lead to:

Males

• Septic arthritis
• Epidydimisitis
• Oligospermia
• Sterility
• Systemic defects involving the heart, brain and joints

Females

• Pelvic Inflammatory Disease
• Septic arthritis
• Septic abortion
• Infertility
• Ectopic pregnancies
• Systemic defects involving the heart, brain and joints

A sexually transmitted disease is caused by microorganisms which are transferred from an infected individual to his/her sexual partner during intercourse.

Mode of Transmission:

• Sexual Transmission

This is the most common mode of transmission. An individual may knowingly or unknowingly transmit the pathogen to his or her sexual partner by either oral, vaginal or anal sex. Depending upon the kind of intercourse performed, the microbes may start an infection in that area. For example, anal sex leads to development of disease primarily in the rectum, oral sex leads to infection in the throat, etc. [10].

• Intravenous Drug Abuse

Drug addicts often share needles and syringes with each other and this unsanitary and unchecked misuse is also a leading cause of transferring infections. Of such, HIV is a very commonly transferred disease.

• Mother to child

Some STDs can be transferred from an infected mother to her child during childbirth when the baby passes through the infected birth canal. STDs like Gonorrhea can be transferred from mother to child during cord clamping as a fluid exchange may occur.

• Other

Other causes include exposure to a pathogen on an open wound, administration of donor blood that is contaminated with a microbe, etc.

Incidence

Studies conducted by the Centres of Disease Control reveal that there are 19.7 million new cases of sexually transmitted diseases occurring in the United States annually [1]. It is estimated that one in every 4 teenagers contracts an STI and/or STD each year.

Sex

Most STDs, though not all, are more common in women than in men. The exact prevalence varies with different types of STDs. Female to male ratios of some common STDs are mentioned below:

• Chlamydia infection occurs in 592.2 per 100,000 people in females as compared to just 219.3 per 100,000 people in males. 
• Gonorrhea occurs in 105.5 per 100,000 people in females as compared to just 91.9 per 100,000 people in males. 
• But in the case of Syphilis, the rate among men is much higher. The ratio being almost 1:7 in the US in 2009.

Age

STDs can occur at any age, ranging from in babies (in the case of gonorrhea which can be contracted by an infant during birth from an infected mother) to old age. But it is most commonly found in young people between 15-24 years of age.

Race

Most STDs are more prevalent in people belonging to the African-American race than in white people.

Most Prevalent STDs

• The most common STD in the world is Chlamydia infection.
• The second most common STD in the world is Gonorrhea.

When an affected individual has unprotected sexual intercourse with his/her sexual partner, the bacteria or other microbes enter into the genital tract. The primary area of infection depends upon the type of intercourse performed, for example, vaginal intercourse may cause the primary area of infection to be the vagina and cervix, anal intercourse leads to a primary infection in the rectum, oral sex leads to a throat infection, etc. [9].

Once a primary infection has been established, symptoms may or may not appear. The microbes may move from the genital tract to the lymphatic system and then enter the blood stream. If that happens, systemic effects appear [7].

Common STDs and Causative Agents:

Bacterial

• Chlamydia infection is caused by a bacterium called Chlamydia trachomatis.
• Gonorhea is caused by Neisseria gonorrhea.
• Syphilis is caused by Treponema pallidum.
• Chancroid by Hemophilius ducreyi.

Viral

• Human immunodeficiency virus (HIV) causes AIDS.
• Human papillomavirus (HPV) causes most commonly genital warts.
• Herpes simplex virus type 2 causes herpes [4].

Protozoal

• Trichomoniasis caused by Trichomona vaginalis.

Fungal

• Candidiasis is caused by Yeast.

Common Symptoms:

• Red, swollen genitals
• Pain and burning sensation during micturation
• Greenish-yellow or white coloured penile/vaginal discharge
• Spotting after sexual intercourse
• Bleeding between menstrual periods
• Lower abdominal and pelvic pain, sometimes mimicking pain of PID
• Ulcers on and around genitals
• Warts or blisters on and around genitals 
• Sore throat (oral sex)
• Swollen glands in the throat (oral sex)
• Pain in defecation (anal sex)
• Itching and general discomfort around anus and genitals

STDs can be easily prevented. Preventive measures include:

• Using latex condoms during intercourse [5]
• Getting checked for STDs, at least once a year if sexually active
• Having only one sexual partner
• No drug abuse
• Using syringes, donated blood, etc from reliable and well sanitised centres

Sexually transmitted diseases (STD) are a leading cause of hospital check ups in the world. Studied under a separate branch of science called Venereology, sexually transmitted diseases can be caused by a number of pathogens resulting in an extensive range of diseases.

It should be noted that the term STD should not be confused with STI (sexually transmitted infection). An STI indicates that a person is infected with a certain pathogen, but he is asymptomatic and that infection has not progressed to a disease yet [2]. An STD however, denotes that the infection is not latent anymore but has progressed to the disease. So it should be clear that the term STI has a broader range as it covers everyone with an infection by a known venereal disease causing pathogen and that person, symptomatic or not, has the potential to infect others as well.

Although very diverse on the basis of causative agents and signs, STDs may have a number of things in common. Some of these symptoms include: red, swollen and painful genitals, discharge from penis or vagina, ulcers or warts, burning micturition [8], etc.

Definition

A sexually transmitted disease is a bacterial, viral or fungal infection that infects the genital tract.

Cause

The microbes may enter the body through unprotected vaginal, anal or oral sex, or from contaminated needles and blood [6].

Signs and Symptoms

Common signs and symptoms include red swollen genitals, discharge from the penis or vagina, a feeling of burning pain during urination, warts, ulcers, etc.

Treatment

Treatment is usually of an antibiotics course.

Prevention

STDs can be very easily avoided if proper precautionary measures are taken. These include use of latex condoms during sex, regular testing for STDs if multiple sexual partners, spreading awareness among youngsters, etc.

1. Naidu KM. Epidemiology and Management. Community Health Nursing. Gyan Publishing House 2010. p. 248.
2. Department of Public Health, City & County of San Francisco (2011). STD Risks
3. Pearson R. Pinworm Infection. Merck Manual Home Health Handbook 2007
4. Verdonck K, González E, Van Dooren S, Vandamme AM, Vanham G, Gotuzzo E. Human T-lymphotropic virus 1: Recent knowledge about an ancient infection. The Lancet Infectious Diseases 2007 7 (4): 266. 
5. Villhauer T. Condoms Preventing HPV?. University of Iowa Student Health Service/Health Iowa 2005
6. Quilliam S. The Cringe Report.  J Fam Plann Reprod Health Care 2011. 37(2): 110–112.
7. Shafer MA, Moscicki AB. Sexually Transmitted Infections, 2006. pp. 1–8.
8. Oriel JD. The Scars of Venus: A History of Venereology. London: Springer-Verlag 1994
9. Gilbert MT, Rambaut A, Wlasiuk G, Spira TJ, Pitchenik AE, Worobey M. The emergence of HIV/AIDS in the Americas and beyond. Proc. Natl. Acad. Sci. U.S.A. 2007 104 (47): 18566–70. 
10. CBC News Staff, Study traces origins of syphilis in Europe to New World. January 2008