Sexual Health Guide

In 2018, there were 447,694 diagnoses of sexually transmitted infections (STIs) made in England, a 5% increase over 2017 [1]. Gonorrhoea increased the most – by 26% to 56,259 cases, the largest number since 1978 and there were 7,541 cases of syphilis – a 5% increase compared with 2017 [2].

Despite repeated warnings from public health doctors about the risks involved with unprotected sex, new cases of gonorrhoea and syphilis have been rising in recent years. The British Association for Sexual Health and HIV (BASHH) reported that the diagnosis of syphilis is at its highest since World War Two [3]. However, as a result of the National Chlamydia Screening Programme, there has been a 22% decline in Chlamydia cases since 2014.

Although cases of STIs continue to rise, as a nation we are increasingly taking our sexual health into our own hands by purchasing convenient at-home STI tests – in fact, last year Medichecks sold more STI tests than between 2009 and 2014.

If left untreated sexually transmitted diseases can cause a wide range of serious, life-threatening complications including cancers, infertility, ectopic pregnancy, spontaneous abortions, stillbirth, low birth weight, neurological damage and even death. Thankfully the growing popularity of discreet at-home testing kits is helping people to manage their sexual health more effectively and avoid these serious consequences.

A recent study of Medichecks’ data, based on 4,000 sexually active Brits, has revealed thirtysomethings are the biggest purchasers of STI tests, buying twice as many as those aged over 40 and 25% more than 18-30-year-olds. While the number of tests being taken by this age group is growing, it shows that people are taking charge of their sexual health by purchasing tests privately if they have concerns.

Homing in on the past three years of data also shows that people ordering tests from Northern Ireland were most likely to be clear of infection, with just a 1.1% detection rate. Those in the North East were most likely to have picked up a sexual infection, with a 6.6% positive rate.

There are 7 main sexually transmitted diseases – HIV, Chlamydia, Syphilis, Ureaplasma, Mycoplasma, Trichomoniasis and Herpes. Each has different symptoms and treatment options – we'll take a look at each of them in the following chapters.

What is HIV and AIDS?

Human immunodeficiency virus (HIV) is in fact two species of Lentivirus – a virus which attacks the body’s immune system and impairs its ability to fight diseases and infections. There is no cure for HIV and once you have contracted the virus it remains in your body for life. Current HIV combination medication is however very effective at controlling the virus, especially if treatment begins early, enabling most people with HIV now to lead long, healthy lives.

Without treatment, the damage caused by HIV can lead to the development of AIDS – acquired immune deficiency syndrome. This is the most advanced stage of HIV infection when the immune system becomes so compromised that it can no longer fight infection. Someone with AIDS will have HIV together with at least one opportunistic infection – ranging from tuberculosis to pneumonia but also including certain HIV-related cancers.

How did HIV originate?

HIV is widely believed to have originated in west central Africa as a simian version of the virus in non-human primates, which transferred to humans in the early twentieth century. The earliest known case of HIV infection in a human was detected in 1959 in Kinshasa.

The outbreak of AIDS was first observed in 1981 in the US amongst small groups of injecting drug users and gay men. The terms AIDS was first used in 1982 to describe cases of people with very compromised immune systems and the following year researchers identified the virus that was causing AIDS. The name HIV was given to the virus in 1986.

Symptoms of HIV

About 80% of people who contract HIV will experience acute symptoms from 2 to 6 weeks after infection. These flu-like symptoms may last a few days up to a couple of weeks and include:

• Fever
• Sore throat
• Rash on the body or chest

Once the initial symptoms have passed, people with HIV may not experience any further symptoms for many years. This is why it is so important to get tested after a potential exposure, even if no symptoms are experienced. Detecting the virus in the early stages of infection decreases the likelihood of it being transmitted to other people. The earlier treatment can begin, the earlier the progression of HIV can be stopped and the damage to the immune system minimised, or even reversed.

How do you get HIV?

The most common way to contract HIV in the UK is by having sex with another person who has HIV, without using a condom. HIV can be passed on by the following:

• Unprotected vaginal or anal sex
• Unprotected oral sex (relatively low risk)
• Sharing of needles
• From a mother to her baby (while pregnant, during birth or through breast feeding)

HIV resides in the blood and certain body fluids of the infected person – to become infected the virus has to pass from these fluids into your bloodstream. Infected fluids capable of transmitting the infection include semen, vaginal fluids, anal secretions, blood and breast milk.

HIV cannot be passed on by any of the following:

• Kissing, spitting or sharing saliva or utensils
• Contact with sweat or urine
• Being bitten or scratched
• Touching or holding hands
• Insect bites

You cannot get HIV if you have sex with an infected person who, as a result of antiretroviral treatment (ART), has undetectable levels of the virus in the blood.

What does the HIV virus do?

The HIV virus attacks and destroys a specific type of white blood cell in the immune system, called a CD4 cell or CD4+ T cell. These cells play a major role in fighting viral and bacterial infections.

HIV attaches to and enters the CD4 cells and uses the infrastructure of the cells to multiply and spread throughout the body, killing the CD4 cells in the process. This process is called the HIV life cycle. As the HIV virus spreads, CD4 cells are gradually depleted, weakening the body’s defence mechanism over a period of many years.

Normal, healthy people usually have a CD4 cell count of between 500 and 1,600 cells per cubic millimetre of blood (cells/mm3). If your cell count drops below 200 cells/mm3 you are at increased risk of serious infections and, in certain countries, you would be diagnosed with AIDS at this level.

Getting tested

It is vitally important to get tested if you think you may have been infected with HIV because you may not notice any symptoms for years. A blood test which is analysed in a laboratory is the most accurate method of testing for HIV infection – the most current tests are appropriate for testing from 28 days post-contact and test for antibodies in the blood (which the body produces in response to the HIV virus) and antigens which come direct from the virus itself.

The antibody response to a HIV infection varies from person to person. Around 95% of people will produce antibodies that can be detected at 4 weeks after exposure. At 12 weeks post-contact over 99.9% of people will have produced an antibody response that can be detected. While an antibody test at 4 weeks will give a good indication of your HIV status, you will need to wait until 12 weeks to confirm a negative result or a diagnosis of HIV infection.

If your initial blood test gives a positive result you will be advised to attend a sexual health clinic for further testing and to discuss your treatment options.

Treatment for HIV

HIV is treated using antiretroviral therapy (ART) involving a combination of different HIV drugs which target specific steps in the HIV lifecycle to halt the progress of an HIV infection. HIV will quickly become resistant to a single medication – the combination of drugs which act to block HIV in different ways has proved to be particularly effective in preventing damage to the immune system in people with HIV. HIV treatment involves taking pills (usually between 1 and 4) every day. You will be given a combination of drugs that works for you, taking into account possible side effects and potential interactions between medicines.

One of the main goals of HIV treatment is to reduce the amount of HIV in the body to an undetectable level. A HIV viral load test is used to measure the amount of HIV in the blood – and will be used to monitor the progress of treatment. An undetectable viral load means that the level of HIV in the blood is too low to be detected by this test.

Someone who has HIV but has an undetectable viral load will not be able to infect another (HIV negative) person through sex. Undetectable = Untransmittable (U=U).

If you have had a high-risk exposure (such as unprotected sex with someone you know has HIV) you can take post-exposure prophylaxis (PEP) medication which can reduce the chances of becoming infected. You must start PEP medication within 72 hours of exposure and it is most effective if started within 24 hours.

What is Syphilis?

Syphilis is a bacterial infection caused by the bacterium Treponema pallidum. It is a sexually transmitted infection and is usually transferred from one person to another during sexual contact.

Syphilis can have serious consequences if left untreated (especially in its later stages) so it is important to test for syphilis as soon as you can and get treatment right away. The development of syphilis comes in four distinct stages with different symptoms associated with each stage.

A syphilis infection can be treated relatively easily, but it is possible to be re-infected even if a previous infection has been treated successfully.

Around 7,500 new cases of syphilis were reported in England in 2018, a 5% increase on 2017. Diagnosis rates are highest amongst MSM (men who have sex with men) with HIV.

Where did syphilis come from?

Although no one is certain, it is likely that syphilis existed in the Americas before the arrival of Columbus in 1492. It is also likely that syphilis was brought back to Europe when Columbus returned from his expeditions, with the first documented outbreak occurring shortly after in Naples.

Syphilis was very common in Europe up until the start of the twentieth century largely due to the absence of effective treatment. The bacterium that causes the infection was identified in 1905 and the first effective treatment was developed in 1910. A number of well know historical people – including Schubert, Manet, Tolstoy and Al Capone – are known or thought to have had syphilis.

Symptoms of syphilis

Syphilis usually progresses in stages each of which has its own symptoms.

Primary stage

The first symptoms of syphilis generally occur a couple of weeks after infection, during what is known as the “primary” stage. The most common sign of syphilis during this stage is a single, small legion or sore – called a chancre – at the site of the infection. The sore tends to be (but is not always) firm and painless. Because it is usually painless, the sore often goes unnoticed.

Occasionally you may see more than one chancre. The sores are typically found on the genitals, around the anus or in and around the mouth and will usually disappear after 2 to 8 weeks. This does not mean that the infection has gone away. You should still get treated to prevent the infection moving to the secondary stage.

Secondary stage

The “secondary” stage usually begins a few weeks after the initial sore has disappeared, although it can sometimes start while the sore is still healing. The main symptoms in this stage include:

• A rough, red (or reddish-brown) rash that can appear anywhere on the body but often shows up on the palms of your hands and the soles of your feet (it is usually not itchy and can sometimes be very faint)
• Flat, broad, white lesions (like warts) on mucous membranes such as the vagina, anus or mouth
• Swollen lymph glands
• Fever, headaches, muscle aches and fatigue
• Patchy hair loss

It is quite common for these symptoms to recur and a significant proportion of people who do experience symptoms of secondary syphilis do not report having had the primary sore of the first stage.

As in the primary stage, the symptoms above will disappear after a few weeks with or without treatment. If you do not get treated your syphilis infection will progress to the “latent” stage and potentially to “tertiary syphilis”.

Latent stage

In the “latent” stage of syphilis the infection is still active but there are no outward signs or symptoms. This stage of the infection can last many years or even decades. The infection may still be contagious during the latent stage, although it is uncommon to pass it on to others after two years (from the time of infection).

Tertiary stage

Most cases of untreated syphilis do not progress to “tertiary syphilis”. If tertiary syphilis does develop, however, it can have very serious consequences affecting the brain, nervous and cardiovascular systems. The damage to internal organs and systems can result in death. Neurosyphilis is an infection of the central nervous system that can occur during tertiary syphilis, sometimes in the form of syphilitic meningitis. Symptoms of neurosyphilis include:

• Severe headaches
• Lack of coordination
• Paralysis
• Dementia

How do you get syphilis?

You can contract syphilis through direct contact with an infected sore – usually during vaginal, anal or oral sex.

Syphilis can also be passed on from an infected mother to her unborn baby. This is called congenital syphilis. Infection during pregnancy can be very dangerous for the baby, with increased risk of premature birth or being stillborn.

Getting tested

If you are concerned that you may have been infected with syphilis by having unprotected sex with an infected person, the only way to find out for sure is to get tested. If you have any ulcers or sores in the genital area then you should attend a sexual health clinic as examination of these can help in working out whether they are due to syphilis or another infection.

Besides a consultation and examination, you will also need to take a blood test to check for the presence of syphilis antibodies in your blood. Medichecks’ syphilis blood test checks for both IgG and IgM antibodies. The result will identify whether you have ever had syphilis but cannot differentiate between a current and a previous infection. It is recommended to wait for a week after potential infection to take a test – it is possible that you won’t have developed an antibody response before this time.

If you have a positive test result or if you are experiencing any symptoms, then you should visit your local sexual health clinic for specialist interpretation. This involves a consultation, examination and further tests – and it can take up to 12 weeks for these to be completed.

Treatment for syphilis

Syphilis can usually be cured with a short course of antibiotics (typically penicillin injected into the buttocks) – although the specific treatment will depend on the length of time you have been infected. The course of treatment will generally be more frequent and take longer for later stages of syphilis (i.e. the longer you have had the infection).

Although treatment will cure the infection it probably won’t be able to reverse any damage that has occurred before the treatment began.

Ureaplasma

Ureaplasma is an infection of the urinary tract, which is generally passed on during sexual activity. It is caused by the bacterium ureaplasma urealyticum and ureaplasma parvum. It is relatively common amongst sexually active adults and most people who are infected experience no problems. Those with symptoms may experience one or more of the following:

• A burning sensation when urinating
• Pain or irritation in the urethra – the tube that passes urine from the body
• A vaginal discharge, which can smell unpleasant
• A discharge from the tip of the penis

Ureaplasma can be passed from an infected mother to her unborn baby during pregnancy or during childbirth. If an unborn foetus becomes infected it raises the risk of miscarriage, stillbirth and premature birth. Infections in new-borns may lead to meningitis, pneumonia and other lung complications.

Ureaplasma is effectively treated with antibiotics. You should wait for 3-4 weeks before retesting once treatment has ended.

Mycoplasma

Mycoplasma genitalium (Mgen) is a strain of the Mycoplasma family of bacteria, several of which can cause infection in humans. Mgen is described as an emerging STI because it was only identified as recently as the 1980s and has since become the second most prevalent STI in many countries, behind chlamydia.

Mycoplasma lives in the cells that line the urinary and genital tracts and the infection is usually transmitted through unprotected vaginal and anal sex. Most people don’t have any symptoms, but women can experience:

• Discharge from the vagina
• Discomfort when urinating
• Bleeding after sex

Men can have similar symptoms including:

• Discharge from the end of the penis
• Burning or pain when urinating
• Soreness or irritation of the urethra (the tube inside the penis)

A mycoplasma genitalium infection can cause inflammation of the urethra (urethritis) in both men and women and can lead to pelvic inflammatory disease (PID) in women which can have serious consequences such as infertility and complications in pregnancy. It can also cause reactive arthritis, a kind of arthritis brought on by an infection.

Mgen infections are treated with antibiotics, although treatment is becoming increasingly difficult because the bacteria is becoming resistant to certain kinds of antibiotic. As a result, treatment will usually involve a combination of different antibiotics.

You should avoid having sex for at least 5 weeks after starting treatment and then retest to ensure the infection has completely cleared.

Trichomoniasis

Trichomoniasis is a common STI caused by the parasite Trichomonas vaginalis. In women it infects the vagina or the urethra (the tube that passes urine out of the body) and in men it mainly infects the urethra. It is usually passed on during unprotected vaginal sex.

Over half of people infected with trichomoniasis experience no symptoms and many do not realise that they are infected. Even without symptoms they will still be infectious and can pass it on to others. When they do present, symptoms usually occur between 1 and 4 weeks after exposure and in women may include:

• A frothy vaginal discharge, which may be discoloured and have an unpleasant smell
• Genital itching, burning or soreness
• Discomfort when urinating or during intercourse

In men symptoms include:

• Burning sensation when urinating or ejaculating
• Itching or irritation inside the penis
• A discharge from the penis

Being infected with trichomoniasis increases the chances of contracting or spreading other STIs. You are more likely to get HIV as a result of genital inflammation and also to pass it on. Pregnant women infected with trichomoniasis are at greater risk of having a premature birth or a low-birth-weight baby.

Trichomoniasis is treated with a course of antibiotics. Reinfection rates are relatively high – about 20% of people become infected again within 3 months of treatment. You should wait 10 days following treatment before having sex again.

What is herpes?

Herpes is a very common viral infection which is caused by the herpes simplex virus. Herpes can infect different parts of the body – oral herpes affects the mouth and face, genital herpes infects the genital and anal area while whitlows occur in the fingers and hands.

There are two types of the herpes simplex virus – HSV1 and HSV2. Both types can cause infections in different parts of the body, but HSV1 is more often associated with oral herpes and HSV2 more commonly causes genital herpes.

Genital herpes is a sexually transmitted infection and is usually passed from one person to another by vaginal, anal and oral sex. Symptoms usually appear between 5 and 21 days after becoming infected with the herpes virus. Many people infected with genital herpes will only experience mild symptoms, but for others the effects can be painful and include blisters on the infected area which burst leaving sores which can be very uncomfortable.

Herpes tends to recur in cycles, with outbreaks followed by inactive periods with no symptoms. The first outbreak is usually the most severe, but this is not always the case.

Antiviral drugs can be used to reduce the severity and frequency of episodes and ointments can relieve the pain caused by blisters. There is no cure for herpes and once infected it will stay with you for life.

Symptoms of genital herpes

Symptoms of genital herpes vary from person to person. Some people may be infected and won’t be aware that they have herpes because they have no symptoms. Many people will experience symptoms after a few days of becoming infected, although you may not see any signs for a couple of weeks. In some cases, symptoms only appear months or even years after infection. You may start to feel flu-like symptoms, including fever, headaches, muscle pains and swollen glands. This may be followed by more specific symptoms, including:

• Stinging, tingling or shooting pains in the genital or anal region
• Vaginal discharge
• Small, fluid-filled blisters around your genitals, anus, surrounding areas and thighs which burst after a day or two and leave sores which can be very painful
• Pain or burning when passing urine

Symptoms typically last for 2 to 4 weeks the first time you experience an outbreak. Sores tend to heal over 5-10 days but become less painful over time.

The symptoms of genital herpes tend to come and go in cycles – these are called recurrent outbreaks. The first episode is usually the most severe and most painful. Symptoms experienced in recurrent outbreaks tend to be milder than first time round and clear up more quickly and outbreaks usually become less frequent. Some people have tingling or shooting pains before an outbreak occurs which serves as a warning of an upcoming episode.

Once the virus is in the body it enters the nerves at the site of the initial infection and migrates to the nerve cell bodies where it remains latent until the next outbreak. As a result of the primary infection the body produces antibodies to the particular HSV virus which prevents future infection by that type of HSV in other parts of the body. This is the reason why recurrent outbreaks usually occur at (or near) the site of the first infection.

How do you get genital herpes?

Genital herpes is a sexually transmitted infection which is generally passed on through sexual contact with an infected person. The virus can infect the body through lesions or small cracks in the skin or through mucous membranes in the mouth, vagina, rectum and urethra.

Genital herpes can be passed on by the following:

• Unprotected vaginal, anal or oral sex
• Skin-to-skin contact with the infected area
• An active herpes sore on the hand or finger touching genitals
• A cold sore touching genitals

Herpes can also be passed on from a mother to her baby during birth. The risk of this happening is generally quite low, but it is higher if you are infected with genital herpes for the first time during the pregnancy, especially the later stages.

Recurrent outbreaks can be triggered by:

• A weakened immune system caused by illness or stress
• Ultraviolet light (from sunlight or sunbeds) on the affected area
• The menstrual cycle

Outbreaks may cease entirely after a period of time, which may be a year or two, or sometimes much longer.

What complications can genital herpes cause?

Genital herpes generally does not cause any serious complications, expect in rare circumstances.

If you are infected with genital herpes your risk of contracting HIV is increased and genital herpes can cause more serious problems for those already infected with HIV. This is because the CD4 cells that HIV targets and destroys are found in greater numbers at the site of healed genital herpes sores than in unaffected skin. If you have both HIV and genital herpes you should seek specialist attention from a sexual health clinic.

If you are pregnant, there is a small risk that herpes can be passed on to your baby during birth. Neonatal herpes can have serious and ultimately fatal consequences for a young baby, especially if the virus spreads to the organs. The risk of passing the virus on to your baby is very low if you are infected with genital herpes before you get pregnant, or during the first six months of pregnancy. If you get infected with genital herpes for the first time in the last three months of your pregnancy, and particularly during the last six weeks, the risk of transmission is higher because you won’t have had time to pass on immunity to your child. In such cases it is likely that you will be advised to have a caesarean delivery which reduces the risk of passing the virus on.

Getting tested

If you have symptoms of genital herpes you should go to a sexual health clinic for a check-up. You may be diagnosed with an infection based on an inspection of the affected skin, but usually this is accompanied by a swab test that will confirm the presence of the virus. A swab is wiped over the affected area and collects small fluid samples from the blisters and sores which are sent to a laboratory for analysis. The results will confirm whether the virus is present. A swab may not be able to detect the virus in the absence of any sores or lesions. A blood test can be used to determine if you have been infected with the herpes simplex virus in the past. It tests for IgG antibodies that the body produces in response to infection by a particular type of the virus. The test will tell you whether you have ever been infected, and by what type of HSV, but will not tell you if you have a current infection.

Treatment for genital herpes

There is no cure for genital herpes and it will clear up by itself over time. Treatment of genital herpes is designed to relieve the pain of the blisters and sores and to stop the virus from multiplying and the symptoms getting worse. Treatment with antiviral medicine should be commenced within 5 days of the symptoms appearing and can help reduce the duration of an outbreak and lower the risk of the virus being passed on. Antiviral medications are sometimes prescribed continually for people who get frequent recurrences. These are also available in creams which can be used to relieve the pain of the blisters and sores.

Ultraviolet light can trigger a recurrence of herpes. For people who tend to get recurrences in sun exposed areas the use of sunblock on the affected area can help to decrease the frequency and severity of attacks.

What is Chlamydia

Chlamydia is a very common sexually transmitted infection which is caused by the bacterium Chlamydia trachomatis. You can get it by having unprotected sex with an infected person.

Chlamydia is particularly common in young adults (under the age of 25) who are sexually active. The more sexual partners you have the more you will be at risk of becoming infected. Many people who are infected with chlamydia don’t experience any symptoms, but it can lead to serious health problems if left untreated. These include pelvic inflammatory disease (PID) in women which can lead to infertility.

A chlamydia infection can be treated effectively with antibiotics.

Symptoms of chlamydia

In women, chlamydia usually affects the cervix (the neck of the womb) and the womb itself. Up to 70% of women with chlamydia report having no symptoms, but those that do often experience:

• a burning sensation when urinating
• vaginal discharge
• bleeding or spotting between periods and after having sex
• pain in the abdomen or pelvic area, especially during sex

These symptoms usually appear after a couple of weeks and can disappear in a few days, although sometimes they don’t appear for months after infection.

Up to half of men infected with chlamydia experience no symptoms. It usually affects the urethra (the tube in the penis that passes urine and semen) and symptoms that are reported include:

• a feeling of pain or burning when passing urine
• a discharge from the tip of the penis (sometimes white or cloudy)
• pain in the testicles

A chlamydia infection can also affect the eyes – chlamydial conjunctivitis was once a leading cause of blindness worldwide – and it can also cause reactive arthritis (see below).

How do you get chlamydia?

Chlamydia is transmitted most commonly in the UK by having unprotected sex with an infected person. Chlamydia can be passed on by the following:

• unprotected vaginal, anal or oral sex
• contact with infected tissue or fluid (such as genital to genital contact or contact with semen or vaginal fluid)
• from a mother to her baby (while pregnant or during birth)

What complications can chlamydia cause?

In women, chlamydia can lead to pelvic inflammatory disease (PID) if left untreated, which is a generic term covering infections of the uterus, fallopian tubes or the ovaries. Scarring of the reproductive organs can cause the following serious complications:

• chronic pelvic pain
• difficulty getting pregnant (infertility)
• ectopic pregnancy (a potentially dangerous complication in which the embryo attaches outside the womb, usually in the fallopian tubes)

PID is usually treated with antibiotics and treatment may start even without confirmation of infection because of the serious complications that may result from a delay.

The risk of complications in pregnancy also increases for pregnant women with untreated chlamydia. These include premature birth, low birth weight and miscarriage. If you have untreated chlamydia during childbirth your baby may develop a chlamydial infection of the eye (conjunctivitis) or of the lungs.

In men, chlamydia can spread to the testicles causing epididymitis. This is also treated with antibiotics but in rare cases can lead to infertility if left untreated.

Reactive arthritis is an inflammatory arthritis caused by an infection elsewhere in the body, commonly chlamydia or a urinary tract infection. It can affect both women and men but is more common in men. Inflammation in the joints (usually knees, ankles and feet) is accompanied by inflammation of the eyes and urethra. It generally passes in a few months.

Getting tested

To find out if you have chlamydia you will need to get tested. If you are experiencing any of the symptoms above you should get tested – you should also get tested if you have no symptoms but are worried that you may have been infected by having unprotected sex with an infected person. Given that chlamydia can lead to serious health problems the sooner you get tested and treated, the lower the risk of future complications.

The test for chlamydia is a urine test or a swab test. You can get tested at any time but if you are tested within 14 days of potential exposure and the result is negative you should test again after 14 days to ensure the infection has had time to develop to the point where it can be detected.

If you are under 25 and sexually active you are encouraged to get tested at least once a year, or more often if you change sexual partner. There are national screening programmes in the UK which target those between 15 and 24 years.

Treatment for chlamydia

Chlamydia can be effectively cured with a course of antibiotics. You should avoid having sex for 7 days after treatment to ensure that you don’t infect others or become reinfected straight away.

Young people who are infected with chlamydia are recommended to get tested again 3 months after treatment to check for reinfection.

References

[1] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/806118/hpr1919_stis-ncsp_ann18.pdf

[2] https://www.bbc.co.uk/news/health-48509969

[3] https://www.bashh.org/news/news/bashh-tht-release-state-of-the-nation-report-on-stis-in-england/