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Sexually Transmitted Diseases (STDs)


Sexually transmitted diseases (STD) are a group of diseases that are transferred through sexual intercourse. These diseases are extremely common in the world. STDs are the second most commonly occurring infectious diseases after the common cold in the United States. About 1 million people every year suffer from STDs in the world. The spectrum of diseases varies from moderately severe to extremely dangerous diseases like AIDS. Whatever the outcome, education about STDs is extremely important to prevent their occurrence.


STDs are spread through sexual intercourse. The organisms responsible for various STDs are:


Sexually transmitted diseases can be divided into three types depending upon the causative agents:

  • Viral STDs include AIDS, hepatitis B infection, herpes simplex infection, and human papillomavirus infection
  • Bacterial STDs include syphilis, gonorrhea, and chlamydia
  • Parasitic STDs include trichomoniasis

Risk Factors And Epidemiology

Risk factors for STDs include:

  • Multiple sexual partners
  • Unsafe sex (without the use of condoms)
  • Drug abuse
  • Previous history of STDs

Signs And Symptoms

Constitutional symptoms of STDs include:

  • Fever
  • Headache
  • Malaise
  • Nausea
  • Aching pains in bones
  • Fatigue

For each STD, specific clinical signs and symptoms help identify the type of disease and reach a diagnosis. These include:

  • Syphilis: Characteristic lesions called chancres are seen on male and female reproductive organs. These are solitary, raised, reddish lesions that are a few centimeters in diameter.
  • Chlamydia: mucopurulent (pus mixed with blood sometimes) discharge from male and female reproductive organs with extreme pain
  • Gonorrhea is characterized by a serous discharge that may become blood-tinged as the infection progresses, with severe lower abdominal pain upon sexual intercourse or even peeing.
  • Signs and symptoms of trichomoniasis consist of musty odor from the vagina, itching, irritation, and sometimes discharge.
  • Genital herpes causes multiple kinds of lesions that can be flat or raised in the form of vesicles or pustules that eventually form ulcers.
  • Human papillomavirus causes warts that cauliflower-like lesions on genital organs.
  • Hepatitis B is characterized by fever, malaise, right upper quadrant pain with varying degrees of hepatic enlargement.
  • AIDS has flu-like symptoms, and it is difficult to diagnose it early. It is generally diagnosed at later stages.


Complications of STDs include:

  • Cardiovascular disease- syphilis can cause aortic aneurysms
  • CNS diseases- dementia and stroke
  • Membranous glomerulonephritis
  • Irreversible end-organ damage


Specific lab tests are used for each type of STD. These include:

  • Venereal disease research laboratory test (VDRL) for syphilis is a non-treponemal serology test that detects antibodies formed against the organism in the body. It is low cost and cheap. Other tests for syphilis include a complete blood count and long bone x-rays.
  • For chlamydia, rectal, vaginal, or oral swabs are taken for serological testing of C. trachomatis.
  • Bacterial culture is the gold standard for gonorrhea using vaginal or urine samples.
  • Trichomoniasis is diagnosed by using molecular testing. Different types of rapid tests are used to detect the antigen.
  • PCR testing is done for the herpes simplex virus by taking skin scrapings of affected areas as samples.
  • Diagnosis of HPV infection can be made on clinical grounds. But colposcopy and pap smear can be done for biopsy and rule out cervical cancer.
  • For hepatitis B, serology for HBsAg is done. PCR can also be done to assess the viral load.

Differential Diagnosis

Differential diagnoses for STDs include:

Treatment And Medications

Bacterial STDs are curable, whereas viral SYDs are usually incurable, and only symptomatic relief can be provided till the natural course of the disease is completed. Specific anti-bacterial drugs are used for each bacterial STD.

  • For the treatment of syphilis, penicillin is the drug of choice that can be administered orally or given intravenously, depending upon the severity of the infection.
  • Doxycycline is the drug of choice for the treatment of chlamydial infections. However, azithromycin has also been used in certain parts of the world.
  • For gonorrhea, ceftriaxone is the drug of choice. 500mg oral or IV is given only once to treat the infection. Complicated infections may require treatment with ceftriaxone for longer durations.
  • For trichomoniasis, metronidazole is used. It can be taken as a single 2g dose or in divided doses of 500mg over a week.
  • Antiviral therapy is given to treat the herpes simplex virus.
  • Genital warts in HPV infection can be treated by surgical excision, cryotherapy, or chemical ablation. No antiviral therapy is currently being used to treat HPV infections.
  • Interferons are usually given to treat hepatitis B with symptomatic relief for other symptoms.
  • For AIDS, highly active antiretroviral therapy, also called HAART, is used depending upon the CD4 count of the patient.


Prognosis against STDs depends upon the type of infection, causative agent, extent, and developing complications. Bacterial STDs have a good prognosis with proper treatment and management. Viral STDs are generally incurable but have a good prognosis if appropriate care is taken with symptomatic relief and complications do not develop. Diseases like AIDS that progress to a later stage can have a poor prognosis.


  • The most important prevention step against STDs is to practice safe sex. This can be done by using condoms which is the most cost-effective method for safe sex identified so far.
  • It is important that once an STD has been diagnosed in a person, all the sexual partners of that person be contacted, screened, and treated for the same infection to stop the spread.
  • Certain STDs, particularly viral STDs, can be contagious, so healthcare workers should be given prophylaxis before handling such patients.
  • Certain STDs can be transferred from the infected pregnant mother to the baby, so it is important that diseases such as syphilis and gonorrhea are routinely screened in pregnant females.
  • Patients diagnosed with other forms of STDs should always undergo screening for HIV due to its life-threatening characteristics, as the symptoms for STDs can be overlapping.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 29, 2023.


Sexually transmitted infections (STIs) (who.int)


Covid-19: Sexually transmitted diseases surged in US during pandemic | The BMJ


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