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Diseases transmissible by unprotected sex. New diagnoses of STIs in genitourinary medicine (GUM) clinics have been increasing, with the highest rates in young people and in men who have sex with men (MSM). In recent years the trend has been for increases in most common STIs, so prevention efforts need to be sustained.


Public Health England. Sexually transmitted infections (STIs): annual data tables last updated October 2020.

Not everyone with an STI will have signs and symptoms of the condition. Symptoms or signs may be found incidentally, e.g. when carrying out cervical screening. Presenting symptoms may include increased discharge, pain or ulcers. Left undetected and untreated, STIs can later result in serious complications.

Sexual history

A detailed sexual history is important and relevant for further management. The key elements are:

  • Presenting complaint
  • History
  • Symptoms (assess carefully)
  • Partners (exposure history)
  • Contraception and pregnancy risk
  • Previous STIs
  • Menstrual history
  • Past medical history
  • Cervical screening history
  • Drug/social history, risk behaviours

Contact tracing can be a sensitive issue; sexual partners of individuals found to have STIs should be screened and treated. Local responsibility for contact tracing should be determined. It is important that individuals know how they will be contacted with their results and by whom, or who they need to contact.


Most common bacterial STI in the UK. Perinatal transmission may result in neonatal conjunctivitis. Many cases remain undiagnosed.

Women: 80% asymptomatic; may be cervicitis, mucopurulent discharge, cervical bleeding, postcoital or intermenstrual bleeding, lower abdominal pain, dysuria. Untreated infection can cause chronic pelvic pain and lead to pelvic inflammatory disease (PID), ectopic pregnancy and infertility. Men: 50% asymptomatic; may be urethral discharge and/or dysuria; testicular/epididymal pain; anal/rectal discomfort (proctitis). Complications are rarer but can include epididymitis (pain and swelling around the testicles) and Reiter's syndrome (arthritis).

National Chlamydia Screening Programme (NCSP): a control and prevention programme targeted at the highest risk group for chlamydia infection in England, young people under 25 who are sexually active. One in 10 people under 25 years who have had a test are infected.

National Chlamydia Screening Programme

British Association for Sexual Health and HIV (BASHH). 2015 UK national guideline for the management of infection with Chlamydia trachomatis; updated 2018.

NICE Clinical Knowledge Summaries. Chlamydia - uncomplicated genital. Updated 2021.


Inflammation of the epididymides (tubes that transport sperm from testicles to penis), usually caused by an STI; called epididymo-orchitis if the testicles become inflamed.


Unilateral or bilateral testicular swelling (orchitis), painful ejaculation, general abdominal/pelvic pain, testicular pain, frequency and urgency. Can become chronic if not treated


Usually sexually transmitted in adults. Perinatal transmission results in eye infection, which is a notifiable condition. In older children, suspect sexual abuse.


Men: generally uretheral infection within 10 days. Usually mucoid purulent discharge or dysuria, but up to 10% asymptomatic. Rectal infection usually asymptomatic but can cause rectal/anal pain/discharge.

Women: possible cervical infection, low abdominal infection, pelvic pain, often asymptomatic. Mucoid purulent vaginal discharge in 50%.

Both sexes: pharyngeal infection with exudates (usually asymptomatic).

Human Immunodeficiency Virus (HIV) & AIDS

HIV is a retrovirus that infects T helper lymphocytes, cells that co-ordinate the actions of other immune system cells and carry the CD4 receptor. Over time the patient’s CD4 count declines, susceptibility to infections increases, symptoms develop, and become more severe until a diagnosis of AIDS (acquired immune deficiency syndrome) is made when CD4 count is 3.

HIV transmission is many sexual (60-70%); also by intravenous drug use, infected blood products, mother to child (vertical transmission), and accidental exposure, e.g. needlestick injury. 

According to the most recent figures from Public Health England, in 2012 an estimated 98,400 people were living with HIV. The development of successful anteretroviral therapy (ART) means people with HIV, who are diagnosed early and motivated to take their therapy, can expect a near normal life expectancy. 


Genital herpes is almost exclusively a sexually transmitted infection, generally caused by HSV-2, although the prevalence of genital HSV-1 is increasing. Most transmission occurs via sexual contact with an individual who may be asymptomatic but is still shedding the virus. There is some evidence that genital HSV increases the risk of acquiring (and transmitting) HIV infection.

Genital herpes in pregnancy – in early pregnancy is associated with an increased risk of spontaneous abortion, fetal growth restriction, preterm labour and congenital herpes. In later pregnancy, genital herpes caries an increased risk of neonatal infection. Primary genital HSV infection may be asymptomatic and pass unnoticed. Symptoms start with mild soreness and groups of small, painful blisters on the genitals and surrounding areas, and last about 3 weeks. May also be systemic symptoms (fever, malaise, tender lymph nodes). Recurrent eruptions can occur, generally less severe and more localised, resolving in 3-4 days. Transmission is by direct contact with lesions.

Herpes Simplex, Genital Patient. Professional reference

Genital herpes in pregnancy Patient. Professional reference

Pubic lice (Pediculosis pubis, ‘crabs’)

Tiny (up to 3 mm), grey-brown blood-sucking insects that live in coarse human body hair, most commonly pubic hair (but also eyelashes/brows, beards/moustaches, hair on abdomen or back) and cause itching and red spots. Females lay eggs as head lice (see in Parasites). Pubic lice do not wash or brush off with normal bathing with soap and water. Spread by sexual contact.

NICE Clinical Knowledge Summaries: Pubic lice; 2018.


Protozoan infection of the genital area. Generally sexually transmitted, uncommon.

Women: 50% asymptomatic; others present with vaginal discharge (copious, yellow, thin, smelly discharge, may be frothty. Vaginal soreness (dyspareunia), dysuria. Men: usually asymptomatic; occasionally urethritis, balanitis, prostatitis.


Inflammation of the male urethra. Symptoms (dysuria and/or discharge and/or urinary frequency), intermittent or persistent, varying severity. Predominantly sexually acquired: contact tracing needed (best done by GUM clinic).


Infection with bacteria-like spirochete Treponema pallidum. Transmitted during sexual intercourse and from an infected pregnant woman across the placenta to a developing baby.


Primary: generally presents as a painless and indurated ulcer (chancre) discharging clear serum, and regional lymphadenopathy, 9–90 days after exposure.

Secondary: multisystem involvement with polymorphic rash (non–itchy).

Tertiary: 2-20 years after initial infection: granulomas in connective tissue

Quartenary: cardiovascular or neurological complications

Practice Nurse featured articles 

Living with HIV: the role of the practice nurse Marie Therese Massey 

Patient. Human immunodeficiency Virus Professional reference

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