THE BASICS OF STD TESTING
Viruses & Bacteria
Note that many pathology laboratories will check for Gonorrhoea automatically when Chlamydia urine testing is requested. There was some controversy regarding possible “False positives” in 2015. A prominent pathology provider pointed out that positive results are confirmed with a further analysis on the same sample (a different test) and therefore a false positive result “would be rare.”
Increasingly Mycoplasma Genitalium is also tested for.
Viruses from a Blood Test: HIV, Hepatitis B, Hepatitis C. Hepatitis B & C are more likely to be caught through blood to blood contact (contaminated needles for example, or from overseas) than sexually.
Syphilis, a bacteria, is also tested from a blood sample.
Testing for Genital Warts
There is no practical STD testing for genital warts – you either have them or you don’t.
An experienced doctor can usually make a clinical diagnosis of a genital wart. A biopsy is required when the diagnosis is uncertain or you simply want the most effective way to remove the wart. Biopsy will confirm the diagnosis. On occasion, the biopsy will report a seborrhoeic keratosis that may look identical to a genital wart.
Testing for Genital Herpes
Active lesions means that you have genital herpes (see HSV diagnosis and treatment), but let’s look into a common request for routine blood testing for genital herpes just to see if you might have it.
There are two types of HSV: Type 1 and Type 2. A swab will distinguish the two types. Type 1 Herpes virus is the classical cause of cold sores (around or inside the mouth). Type 2 HSV is the classical ‘genital’ type. There is a lot of overlap, and both types can cause mouth or genital herpes.
A ‘positive’ blood test simply indicates past exposure to the virus. In Australia approximately 75% test positive to HSV 1, and between 10% and 15% test positive to HSV 2.
The summary is that you can get tested by swabbing a lesion, or a blood test for past exposure. However, there is no practical screening test for genital herpes. In other words, ‘random’ blood testing for HSV is not helpful. After all, a ‘positive’ blood result to HSV 1 simply means you were exposed to the ‘cold sole virus’ – most likely in childhood, and not a big deal. HSV blood test is not therefore part of routine STD testing.
There are situations when a blood test may be useful.
Let’s take the scenario where you have an outbreak of genital herpes that is caused by HSV 2, and you are concerned bout passing the virus on to your sexual partner. Your partner could get a blood test for HSV. A negative HSV 2 test would bring into focus the need for greater protective measures, for example, condom use or daily antiviral ‘suppressive’ medication.
How are the samples collected for a routine STD Check?
There are two types of test required for a full STD Check
- Urine Test and/or swabs that may be self-taken – for Chlamydia, Gonococcus, Trichomoniasis. Mycoplasma may also be tested.
- Blood Test – for HIV, Syphilis & Viral Hepatitis.
The latest generation generation of DNA testing means that you no longer need to have the tests performed by a doctor.
In 2019, Brisbane Pathology providers upgraded the dry swabs to ‘Dual Cobas’ Swabs in 2019.
The urine sample is a ‘first pass’ sample. The idea is for the urine to flush through any bugs hiding in the urethra (the end of the urinary tract). Therefore, the urine is collected at least 20 minutes after you last went. Only the first part of the urine is collected. Fill the container to around a third full (20 to 30mls). You then empty the rest of your bladder into the toilet.
A self-taken vaginal swab is better than a urine test in women. The self taken dry swab is simply inserted around 2-3 inches into the vagina and gently rotated for around half a minute. The clinic will provide you with the swab and form.
Men who have sex with men may also use self-taken swabs.
Men who have Sex with Men
Standard MSM STD guidelines recommend blood testing for Syphilis, Hepatitis B, Hepatitis C & HIV. Swabs should also be collected for Gonococcus & Syphilis. There is now good evidence to support self-taken samples¹ and the doctor will discuss this option with you. Self collection samples are taken in the privacy of your own home and then taken to your pathology provider of choice. You simply insert the swab into the rectum and rotate for 10 seconds. Throat swabs are taken by you or the doctor. The new Dual Cobas swab was introduced in 2019 by pathology providers in Brisbane.
What type of STD blood test does the laboratory perform?
HIV tests performed in Australian accredited laboratories are ‘4th generation’ and are positive 2 to 6 weeks after exposure.
Hepatitis B: The Hepatitis B surface antigen (HepBsAg) is a screening test for previous exposure to hepatitis B infection. For those at high risk for hepatitis B, additional tests may be requested: anti hepatitis B core antibody (anti-HBc) & anti hepatitis B surface antibody (anti-HBs). Around 1% of Australians are Hepatitis B positive – of whom around half are not aware they have the diagnosis. Hepatitis B is most likely acquired from previous ‘blood to blood contact’ such as contaminated needles than sexually. Most young people have been immunised against Hepatitis B and testing is therefore unecessary.
Hepatitis C: The Hepatitis C screening test is Hepatitis C Viral antibody (HCV antibody). Just under 1% of Australians are hepatitis C positive – of whom around 15% are not aware they have the diagnosis. Hepatitis C is most likely acquired from previous ‘blood to blood contact’ – for example, during intravenous drug use.
Syphilis testing: Antibody to the bacteria (Treponema) will detect past infection. Note that (only) 75% of people with a primary ulcer caused by Syphilis (primary chancre) will have a positive blood test – so anyone with a possible Syphilis ulcer will need a simple swab taken from the ulcer base.
What’s the best test for early HIV infection?
Antibodies to HIV take 6 to 12 weeks after exposure to become positive – so you have to wait at least 6 weeks for the 3rd generation HIV test.
The fourth generation test combines an Antibody test with the p24 Antigen. The 4th generation test is positive within 1 month of exposure (often from 2 to 3 weeks) and is the most commonly performed test in Australia.
A positive HIV test will only be known for sure after a second confirmatory test. The first test is a screen and may be falsely positive. The second test will distinguish HIV 1 from HIV 2.
How can I be tested for Syphilis?
There are a bewildering variety of blood tests for Syphilis.
The EIA test is a quick & accurate test for exposure to Syphilis, but you’d never want to hear that you have Syphilis based on just one test. The TPPA is an additional confirmatory test. The RPR indicates whether the disease is active. The RPR result is given as a number eg 1:4 is a low figure whilst 1:128 is a high figure. The higher the figure the more active the infection. The RPR is tracked after treatment and should drop over a few months.
Laboratories report The EIA first, and if this positive then The TPPA and RPR tests are automatically arranged.
All three test results are performed for a positive result. Interpreting these results is a specialist area. Positive EIA & TPPA with a negative RPR would generally indicate past exposure to Syphilis. When all three tests are positive, the disease is ‘active’ and treatment is generally required.
Note that a negative blood test does not rule out syphilis in the early days and may need to repeated.
Mycoplasma: An emerging cause of STD
Mycoplasma Genitalium is a bacteria that is increasingly diagnosed as a cause of STD in Australia. Symptoms of Mycoplasma may be very similar to that of Chlamydia – causing symptoms such as a discharge from the urinary tract in men or women, or proctitis. There is recent evidence of a link between mycoplasma and pelvic inflammatory disease (PID).
The diagnosis is confirmed on a urine DNA test. Chlamydia tests are performed in the same batch of tests as Gonococcus and Trichomoniasis whereas Mycoplasma needs to be requested separately.
Mycoplasma Treatment is with antibiotics. Mycoplasma is increasing resistant to Macrolide Antibiotics. The choice of antibiotic needs to be carefully considered.
In summary, think of Mycoplasma when STD symptoms such as a urethral discharge or PID have not resolved. In addition to this, Mycoplasma will increasingly be tested for routinely.
Rarer STDs include:
- Lymphogranuloma Venereum. This is caused by an invasive strain of Chlamydia Trachomatis. It’s common in MWM, and is diagnosed from a swab.
- Chancroid. This is rarely seen in Australia and normally caught overseas
- Dovonosis is on track for elimination.
Many genital conditions are not STDs at all.
Indeed, most genital lesions presenting at The STD clinic are not actually STDs at all.
Genital ulcers may of course be caused by Herpes. However, other causes include:
- Ordinary ‘apthous ulcers’ – this is underdiagnosed as a cause of genital ulcer.
- Crohns disease. The genitals can be very sore and ulcerated.
- Erosive Lichen planus
- Behcet’s disease
- Malignant conditions
How Common are STDs in Australia?
|STD Australia||Latest Data (new diagnoses)||Comparing with 2011|
|Hepatitis B||6502 (2015)||7,000 (approx)|
|Hepatitis C||11,949 (2016)||10,261|
Tell me more about Viral STDs
The Viral STD’s are divided into two types
- Blood-borne viruses that are usually included in standard STD Testing: HIV with or without Hepatitis B or Hepatitis C
- Herpes Viruses Types 1 & 2 which are diagnosed when symptoms occur
Tell me about the symptoms of Acute Hepatitis B
The incubation period is 1 to 6 months. Chronic Hepatitis B is usually only picked up during routine STD testing. Most people will not have any symptoms of acute infection, and when symptoms do occur they are not specific:
- Fatigue, muscle aches, poor appetite
- Right upper abdominal pain
- Low Grade Fever
Around half of Australians with Hepatitis B are unaware of the condition – because they had no symptoms of Acute Hepatitis B, or the illness was just like a normal viral infection and not recognised as Acute Hepatitis B.
Rarely, severe acute hepatitis B requires hospital admission (“fulminant hepatitis”).
Tell me about the symptoms of Chronic Hepatitis B
Hepatitis B causes severe liver disease in around 20% of people with chronic hepatitis B infection. Antiviral medication is proven to reduce the risk of future liver disease considerably.
The symptoms of Chronic Hepatitis B in those unfortunate people who do develop chronic liver disease are the same symptoms that occur in liver cirrhosis:
- Fatigue, Jaundice, Right upper abdominal discomfort, nausea.
- Symptoms and Signs of severe chronic liver disease – the person will likely be very ill at this stage.
All babies are now included in the Australian Childhood immunisation schedule. Immunisation in adults is also discussed at a common request at The Travel clinic. For people who have not been immunised, STD Testing will usually include a check for Hepatitis B.
The rash can be very painful but recurrences are milder.
PRIMARY (FIRST) INFECTION
What are the symptoms of genital herpes?
The first episode is more severe. Lesions are usually painful, tender to touch, and may be itchy. Red spots evolve into erosions that crust and heal over 2-3 weeks.
The diagnosis is confirmed by swabbing the lesion for viral DNA.
HSV-1 is the classical ‘cold sore virus and accounts for over half of genital herpes. HSV-1 generally leads to milder symptoms of shorter duration than HSV-2.
What is the treatment for a first episode of genital herpes?
A minimum of 7 days antiviral treatment is started as soon as possible. You may alleviate pain with salt baths, vaseline, and a local anaesthetic ointment.
I feel terrible having a new diagnosis of genital herpes
You are unlucky but it’s no-one’s fault.
75% of adults have antibodies to HSV-1, and 12% of adults have antibodies to HSV-2. Exposure to HSV may be considered to be a normal experience.
Most people are unaware that they have ever ‘had’ herpes, yet the virus is typically shed intermittently. Only one-third of those exposed to HSV-2 experience symptoms of a primary infection.
Let’s summarise these key facts.
Most people are unaware of a previous infection with HSV-1 or HSV-2 yet pass on the virus without knowing it.
The possibility that HSV can be passed to your partner is undoubtedly a cause of considerable distress for some people. HSV that lies dormant in the peripheral nerve (dorsal root ganglia) can travel to the skin causing a new episode of painful lesions. Recurrent episodes are generally milder and shorter in duration than the primary infection.
You should obviously abstain from sex when you have symptoms of genital herpes. As mentioned, the majority of new infections follow intimate contact with a partner who had no symptoms – ‘asymptomatic shedding.’ What can you do to reduce transmission to your sexual partner in future?
- Use barrier contraception such as condoms
- Take anti-viral medication on a daily basis
Daily antiviral medication substantially reduces the possibility of passing on the virus by asymptomatic shedding. However, there is no 100% effective way of preventing transmission of HSV other than abstinence. Bear in mind that that your sexual partner is likely to be already immune (at least to HSV-1), and that most people infected will never develop symptoms.
After your first episode, you will probably want to have on-demand antiviral medication available but the decision to start daily suppressive therapy is a personal one that depends on your circumstances.
Chlamydia: The No.1 Spot
Chlamydia is the most common STD.
I’m worried that I might have been exposed to Chlamydia – how long does it take to show up?
The time from exposure to symptoms is called the incubation period.
The incubation period for Chlamydia is 1 to 6 weeks but usually 1 to 3 weeks.
What are the Symptoms of Chlamydia?
Chlamydia is really very common and most people have no symptoms.
When Symptoms do occur, they may include:
- Males: Pain on passing urine or discharge (yellow or white). Pain and swelling in the testicle or scrotum (orchitis / epididymitis).
- Females: Stinging on passing urine, discharge (yellow or white), abnormal vaginal bleeding, pelvic or lower abdominal pain, fever, pain during intercourse.
Infection may also occur in the throat, causing pharyngitis, or conjunctiva, causing conjunctivitis.
Chlamydia causes no symptoms in most people, so why does it matter?
The main concern with chlamydia is infertility in women. How common is infertility after having chlamydia?
Around 15% of women with Chlamydia will develop pelvic inflammatory disease (PID). This occurs when the infection travels up to the fallopian tubes and typically causes abdominal and pelvic pain. The chances of developing infertility after PID caused by chlamydia is between 1% and 20% (frustratingly different figures hey?). The individual risk of developing infertility is low. On a population level, however, infertility caused by chlamydia is a significant issue.
PID may also lead to chronic pelvic pain, and there is an increased risk of pregnancy in the tube (ectopic pregnancy).
Chlamydia may also cause infection of the testicle or prostate in men.
What is The treatment for Chlamydia?
Chlamydia is so easy to treat with 2 doses of an antibiotic taken as a single dose. Side effects are uncommon but some people experience gastro type side effects such as nausea, vomiting, diarrhoea or abdominal pain.
Chlamydia may be resistant to the two-dose antibiotic. Another option with a different type of antibiotic that is taken twice daily for 7 days. Sensitivity to the sunlight occurs in 1% of people, so it is recommended to try to stay out of the sun.
Do I need a test of cure?
Test of cure involves repeat testing at least 3 weeks after treatment. Antibiotics work around 97% to 98% of the time but are not 100% effective so it is reasonable to have a discussion about test of cure. In the publicly funded UK national health service, test of cure is “not routinely recommended for uncomplicated genital chlamydia infection.”
Gonorrhoea: A heads-up
The incubation period usually is 2 -5 days. Unlike Chlamydia, most of those infected with Gonorrhoea have symptoms. Male genital symptoms include discharge and/or pain on passing urine. Females may experience abnormal vaginal discharge, lower abdominal pain, &/or pain on passing urine.
In contrast to Chlamydia, Gonorrhoea usually causes symptoms.
Gonorrhoea is treated with a course of antibiotics. Resistance to antibiotics is an important issue. Treatment guidance in this area is therefore changing. Currently, the Queensland health department’s Gonorrhoea guideline recommends an injection of an antibiotic followed by a course of oral antibiotics.
Gonorrhoea may cause complications similar to those of Chlamydia, including chronic pelvic pain, difficulties conceiving, and conjunctivitis. Men may experience infection of the testicle (orchitis) or prostate (prostatitis).
Does Syphilis still exist?
Absolutely! There’s been a resurgence with a one third increase in cases from 2011 to 2015.
What are the symptoms of the different stages of syphilis?
The incubation period usually is 2-3 weeks (range up to 3 months).
The first stage (primary syphilis) is a genital ulcer that is usually painless. The ulcer is usually solitary and is described as having a rolled edge. Any such ulcer should be swabbed for Syphilis DNA which is a very sensitive test. Antibiotics may be started immediately when the diagnosis is considered very likely, or you might wait for the test results. The ulcer occurs at the area of exposure to the bacteria and may therefore occur pretty much anywhere.
You may wonder why anyone might develop secondary or tertiary syphilis when the primary stage manifests as an ulcer and may be treated easily. There seem to be two main reasons:
- The chancre may be in an area that is out-of-sight.
- The chancre is painless and goes on its own in 4 to 8 weeks without treatment – which may happen before the person sees a doctor.
The secondary stage typically occurs 3-5 months later with a widespread spotty rash. The rash of secondary syphilis usually involves the trunk. A rash involving the palms or soles is a big clue. The person will generally feel unwell with symptoms such as sore throat, pains, fever, or headaches. Scalp hair loss may also occur. Rarely there are complications involving the eyes, nervous system, liver, bones or kidneys. Secondary Syphilis may recur for up to two years.
Tests for secondary and tertiary syphilis involve blood tests that are described above.
The feared tertiary syphilis is quite rare but does still occur with infected nodules in various internal organs such as the nervous system or heart.
Latent syphilis is quite a common finding at the clinic and is diagnosed on the basis of blood results in a person without any symptoms. Latent Syphilis is either ‘early’ or ‘late.’
Yup, Syphilis is complex!
How is syphilis treated?
The good news is that Syphilis is extremely sensitive to standard antibiotics. Primary or Secondary Syphilis is treated with a single injection of antibiotics into the muscle. Late Latent Syphilis requires 3 x weekly injections of antibiotic.
Blood tests are repeated every 3 months after treatment to prove that the infection has resolved. The RPR test drops to negative within around 12 months.
Why does Syphilis cause such fear when it is so easily cured?
HIV & Pre-Exposure Prophylaxis (Prep)
Pre-exposure prophylaxis (PrEP) describes the scenario where an HIV negative person takes regular anti-viral medication to reduce the risk of contracting HIV. The most widely used form of PrEP is a daily tablet. The medicare criteria for subsidised PrEP were broadened in April 2018. You can check the medicare eligibility by referring to Box 1 of the The Australian PrEP guidelines. Those not eligible may be directed to an online portal to obtain the prescription from overseas.
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