What are Sexually Transmitted Diseases (STDs)?

Sexually transmitted diseases (STDs) are infections that are passed from one person to another through sexual contact. STD is the broad term including infections caused by bacteria, parasites, and viruses. There are many types of sexually transmitted diseases (STDs) like Chancroid, Chlamydia, Genital herpes, Gonorrhea, AIDS, HPV (Human Papilloma Virus), Syphilis, and Trichomoniasis.  Most of these sexually transmitted diseases (STDs) affect both men and women but more in women. The World Health Organization estimates that there are around 498 million people aged 15-49 years who are infected each year with chlamydia, gonorrhoea, syphilis, and chancroid. 


Syphillis also known as Great imitator is a chronic systemic infectious disease caused by Treponema pallidum, the gram-negative spirochaete. It is classified as an acquired and congenital type. Symptoms associated with syphilis are the formation of chancre (painless genital ulcers), and enlargement of the lymph node in 7-10 days. This chancre may be tender due to secondary bacterial infection and may occur in extra-genital sites like oral, anorectal, breast, and digits. In the late phase of syphilis, highly contagious mass papules are formed which are termed condyloma lata. 

Other Signs and Symptoms: 

  • Hair – non-scarring hair loss in the occipital and parietal region.
  • Nail – Lusterless, brittle with pitting, splitting and onycholysis (nail separates from the skin underneath).
  • Mucous membrane – Irregular erosions or ulcers.
  • Symptoms like fever, malaise, arthralgia, myalgia, and headache are common.
  • Bilaterally symmetrical non-tender, discrete, firm lymph nodes.
  • Anemia, leukocytosis, and raised erythrocyte sedimentation rate.
  • Late-phase syphilis may appear years after infection affecting the cardiovascular system, or central nervous system, and may result in signs of meningitis. 

Management of Syphilis: 

Centers for Disease Control and Prevention (CDC) recommend parenteral administration of penicillin G procaine (2.4 million units, I.M.) for the treatment of all stages of syphilis.  Alternative regimens may be used in patients who are allergic to penicillin. However, pregnant women and patients with neuro-syphilis require treatment with penicillin even if they are allergic to the drug. In these patients, desensitization is necessary before penicillin therapy is initiated. 

Herpes Genitalis

It is one of the commonest occurring sexually transmitted diseases, which is caused by Herpes virus hominis. There are two types of Herpes simplex viruses: HSV-1 and HSV-2; HSV-2 is most commonly seen in the genital area. Herpes virus infects epidermal cells resulting in the degeneration of cells and forming multinucleate giant cells with intranuclear inclusion bodies.  Primary lesions occur usually with symptoms like fever, malaise, headache, and myalgia followed by skin lesions. The lesions start as grouped vesicles which soon rupture to form superficial ulcers with polycyclic margins. New lesions continue to occur for 8-10 days and viral shedding usually continues for the first 2 weeks. This leads to opportunistic secondary bacterial infection involving CNS causing aseptic meningitis, transverse myelitis, and sacral radiculopathy. Systemic involvement like hepatitis, and pneumonitis is more common in such immunocompromised states. 

Management of Herpes Genitalis: 

Standard first-line drugs include acyclovir, valacyclovir, and famciclovir. The antiviral action of these acyclic nucleoside analogues is based on their phosphorylation to monophosphate form by thymidine kinase (TK), the key enzyme of HSV-1 and HSV-2, with subsequent phosphorylation to di- to the triphosphate by cellular enzymes. This triphosphate nucleoside analogue inhibits viral DNA polymerase by incorporating it into the growing DNA chain as false enzyme substrates leading to chain termination. Acyclovir is the first choice therapeutic agent for HSV infections, including herpes genitalis, however, bioavailability is only 15–30% after oral administration. Valacyclovir is a prodrug (an L-valyl ester) of acyclovir suitable for oral administration with a bioavailability of 54%. 


Chancroid, also known as ‘soft sore’ is an acute infectious disease caused by gram-negative bacillus Haemophillus ducreyi. The incubation period is usually short, ranging from 1-14 days. It starts with a small inflammatory papule surrounded by erythema progressing to form well circumscribed painful ulcer covered with purulent exudates, Painful inguinal lymphadenopathy. The ulcer may bleed or produce contagious fluid-spreading bacteria during oral, anal, or vaginal intercourse. The Centre for Disease Control and Prevention recommends Azithromycin 1 gm, orally as a single dose or Ceftriaxone 250 mg, intramuscularly (I.M.) as a single dose or Erythromycin 500 mg, orally 3 times per day for 7 days or Ciprofloxacin 500 mg, twice a day for 3 days for the management of chancroid. 

Lymphogranuloma Venereum

Lymphogranuloma venereum (LGV) is a sexually transmitted infection caused by gram-negative intracellular bacilli Chlamydia trachomatis serovars L1, L2, L3. The incubation period varies from 1-2 weeks. 


Also known as ‘Granuloma inguinale’, it is a slowly progressive, chronic, mildly contagious ulcerative disease caused by Calymmatobacterium granulomatis. The incubation period ranges from 3 days to 3 months. 


It is caused by gram-negative diplococci Neisseria gonorrhoeae. The incubation period ranges from 1 to 14 days. Mucopurulent (pus-like) discharge per urethra is the most common complaint in men. Over 1-2 days, this discharge becomes thick, profuse, and purulent with an increased tendency of burning micturition. In females, a moderate degree of burning micturition, frequency, and urgency is the earliest complaint. Complications include epididymitis, prostatitis in men and salpingitis (inflammation of the fallopian tubes.), and Bartholin abscess in women. CDC recommends dual therapy or using two drugs to treat gonorrhea a single dose of 250 mg of intramuscular ceftriaxone and 1 g of oral azithromycin. 


Chlamydia is a common sexually transmitted infection caused by a gram-negative bacterium Chlamydia trachomatis that may not cause symptoms. Mild symptoms may include genital pain and discharge from the vagina or penis. Chlamydia infection is diagnosed by PCR (polymerase chain reaction) testing in a pathology laboratory of a sample of cervical or urethral discharge. The incubation period may be from 1-3 weeks. Chlamydia can be treated with a single dose of azithromycin or doxycycline twice daily for 7-14 days. 

Human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS)

AIDS is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV). A person may not show any symptoms following the initial infection or may show influenza-like illness followed by a prolonged period with no symptoms. As the infection progresses, it interferes more with the immune system, increasing the risk of developing common infections like tuberculosis and other opportunistic infections and tumors. These late symptoms of infection are referred to as acquired immunodeficiency syndrome (AIDS) which is oftenly associated with weight loss. HIV is spread primarily by unprotected sex (including anal and oral sex), contaminated blood transfusions, hypodermic needles, and from mother to child during pregnancy, delivery, or breastfeeding. No cure or any effective HIV vaccine is available for the treatment but the progression of the disease can be decreased by the HAART (highly active anti-retroviral therapy). Current HAART options are non-nucleoside reverse transcriptase inhibitor (NNRTI), and nucleoside reverse transcriptase inhibitors (NRTIs). Typical NRTIs include zidovudine (AZT) or tenofovir (TDF) and lamivudine (3TC) or emtricitabine (FTC).

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