Meaning of Syphilis
Syphilis is an infection that results from the bacterium Treponema pallidum. It is primarily transmitted through sexual contact when the syphilis chancre, also known as the syphilis sore, comes into contact during oral, vaginal, or anal sex. It can also be passed from a mother to her foetus during pregnancy or during childbirth.
The infection progresses through four stages:
- Primary
- Secondary
- Latent
- Tertiary
Different stages of syphilis present with varying signs and symptoms, which can persist for weeks, months, or even years. Initial symptoms may be mild and easily overlooked, allowing syphilis to go unnoticed. Consequently, individuals may unknowingly transmit the infection to others.
In the initial stages of infection, syphilis is the simplest to treat; however, if left untreated, it can lead to major health consequences, including organ damage. Treatment can still be beneficial, but it cannot reverse the damage. Untreated syphilis can potentially be fatal in rare situations.
Syphilis testing can aid in the early detection of the infection, when it is easiest to treat. Early detection and treatment of the infection can also help to avoid the transmission of syphilis to others.
This blog discusses the syphilis tests, the purpose of the tests, preparation for the tests, how to prepare, what to expect during and after the tests, the interpretation of the test results, and potential risks associated with the testing.
Syphilis Tests
Syphilis tests are laboratory procedures utilised to detect the presence of a syphilis infection. The most common tests are serological tests for syphilis (STS), which involve analysing a blood serum sample. These serological tests can be categorised into two types: nontreponemal and treponemal.
Nontreponemal tests, such as the venereal disease research laboratory (VDRL) test and the rapid plasma reagin (RPR) test, rely on identifying syphilis reagin, a specific type of serum antibody, in the blood sample.
On the other hand, treponemal tests, including the enzyme immunoassay (EIA), treponema pallidum hemagglutination assay (TPHA or TPPA), and fluorescent treponemal antibody absorption (FTA-ABS) test, detect treponemal antibodies. These antibodies targets and attacks the Treponema pallidum responsible for causing syphilis.
In most cases, the diagnosis of syphilis involves conducting both a nontreponemal and a treponemal test to increase diagnostic accuracy and confirm the presence of the infection.
Less frequently used syphilis detection methods include testing for the bacteria’s genetic material or checking for the bacteria itself. Among these tests are the following:
- Darkfield microscopy: This technique utilises a sample of fluid taken from a skin sore. The sample is examined under a specialised microscope, where the Treponema pallidum bacteria can be observed appearing bright against a dark background.
- Polymerase chain reaction (PCR) testing: This test detects the genetic material (DNA) of the Treponema pallidum bacteria.
Purpose of the syphilis blood tests
Syphilis testing serves the purpose of identifying the presence of a syphilis infection. It is used for screening, diagnosing, and monitoring purposes.
Screening
Screening for syphilis involves testing individuals who do not have any signs or symptoms of the disease. This is particularly important for individuals at high risk of contracting syphilis or those who may be more likely to transmit the infection to others. Screening helps in identifying asymptomatic individuals who may require treatment and preventing further transmission.
Diagnosis
Syphilis testing is recommended when individuals exhibit signs or symptoms that could be indicative of a syphilis infection. As the symptoms of syphilis can vary widely, testing may be advised even in cases where symptoms are not severe or specific to syphilis. Typically, diagnosing syphilis requires two tests: an initial screening test followed by a confirmatory test.
Monitoring post-treatment
After undergoing treatment for syphilis, regular monitoring is essential to ensure that the prescribed treatment is effective. Monitoring involves a physical examination to assess any changes in observable symptoms and laboratory blood tests to confirm a positive response to the treatment.
When is a syphilis lab test needed?
In situations where an individual experiences the symptoms of syphilis or their sexual partner has recently received a syphilis diagnosis, it is advisable to undergo testing for the infection. Typically, the symptoms of syphilis manifest around two to three weeks following the initial infection and encompass:
- A tiny, painless chancre (sore) appearing on the mouth, genitals, anus, or rectum
- Rough and red rash, typically found on the soles of the feet or palms of the hands
- Muscle pains or headaches
- Fever
- Swollen glands
- Sore throat
- Weight loss
- Fatigue
- Patches of hair loss
Regular testing is recommended for individuals at high risk of acquiring syphilis, even in the absence of symptoms. High-risk groups include those who engage in the following behaviours:
- Engaging in unprotected sex
- Having multiple sexual partners
- Having a partner with multiple sex partners
- Having another sexually transmitted disease, such as gonorrhoea
- Being sexually active with an HIV infection
- Engaging in sexual activity with men who have sex with men
How to prepare for a syphilis lab test?
There are no specific preparations required prior to a syphilis test that utilises a sample of fluid or blood from a syphilis sore; however,
- If an individual suspects they might have syphilis, it is advised that they abstain from sexual activity until they have undergone testing to confirm whether they are infected or not.
- In the case of someone who has already been diagnosed with syphilis and is undergoing re-testing, it is important for them to refrain from sexual intercourse until the test results indicate that they are no longer infected. Additionally, it is crucial for their sexual partners to undergo testing for syphilis and receive treatment if necessary.
- Individuals may be instructed to use the toilet before having a lumbar puncture to help empty their bowels and bladder.
What to expect during a syphilis test?
During a syphilis test, a healthcare professional may collect sample through any one of the following:
Blood sample
They will use a small needle to collect a blood sample from a vein in the individual’s arm. After inserting the needle, a small amount of blood is drawn into a test tube or vial. Some individuals may experience a slight stinging sensation during the needle insertion, and the entire process usually takes less than five minutes.
Sore sample
Sometimes healthcare professionals may collect a sample of fluid from an open sore (chancre) to conduct the testing.
The sample collection may involve the following steps:
- The sore is gently cleaned by wiping it with a little saline-soaked gauze, followed by dry gauze, removing superficial debris and crusts.
- The specimen will be collected directly on a glass slide or cover slip by pressing on the lesion.
- If needed, a drop of saline may be mixed
- The cover slip edges will be sealed with petroleum jelly
Spinal fluid sample
In cases where syphilis may be affecting the brain and nervous system, a syphilis test of the cerebrospinal fluid (CSF) may be necessary. The CSF is a clear fluid found in the brain and spinal cord. To obtain a sample of the CSF, a healthcare provider will perform a procedure known as a spinal tap or lumbar puncture. The process involves the following steps:
- The individual will be instructed to lie on their side or sit on an examination table
- The healthcare provider will clean the individual’s back and administer a local anaesthetic to numb the area. They may also apply a numbing cream beforehand
- Once the back is adequately numb, the healthcare provider will insert a hollow and thin needle between two vertebrae in the lumbar area (lower spine)
- A small amount of CSF will be withdrawn for testing, which typically takes around five minutes.
- It is crucial for the individual to remain very still during the fluid withdrawal.
Following the procedure, the healthcare provider may ask the individual to lie on their back for an hour or two to minimise the likelihood of post-procedural headaches.
By following these steps, healthcare professionals ensure the collection of the necessary samples for accurate syphilis testing, including the blood sample and, if required, the CSF sample obtained through a lumbar puncture.
What to expect after the syphilis test
- There are no restrictions on returning to normal activities once the test is completed.
- After a blood draw, patients may be instructed to put pressure on the site of injection and be given an adhesive bandage to prevent further bleeding.
- To avoid a headache following a lumbar puncture, patients may be encouraged to lie down for a few hours after the procedure has been performed. They may feel some discomfort and pain at the site of the needle’s insertion into their back. This pain is temporary and goes away over time.
How are syphilis blood test results interpreted?
The interpretation of syphilis test results depends on the type of test performed.
Nontreponemal testing results are typically reported as positive (reactive) or negative (non-reactive). If the test is positive, it may also indicate the level of antibodies detected in the sample.
A positive result from a nontreponemal test suggests the possibility of a syphilis infection. However, a confirmatory treponemal test is necessary to establish a definitive diagnosis. Negative results from the nontreponemal test suggest that syphilis is unlikely, although further testing may be required if symptoms are present.
Treponemal testing results are commonly reported as reactive or nonreactive. A reactive result suggests a previous infection with syphilis. It is important to note that even if you have received treatment for syphilis, reactive results can persist indefinitely. Therefore, doctors consider your medical history when interpreting positive test results. On the other hand, a nonreactive treponemal test result means that no antibodies to syphilis were detected, indicating a low likelihood of infection.
It is important to discuss the test findings with a medical professional to seek assistance in understanding the syphilis test results. If someone has recently received the results of a syphilis test, it would be beneficial for them to request additional information from their doctor to gain a better understanding of their specific result and to discuss any plans for future testing.
What are the risks associated with the syphilis tests?
The risks associated with syphilis tests are generally minimal. Here are the risks associated with each type of syphilis test:
- Blood Sample
The risk associated with a blood sample is minimal. A small bruise may develop at the site where the needle is inserted, but it is unlikely to cause any significant problems. - Sore Sample
Taking a sample from an open sore carries very little risk. There is a minimal chance of complications or adverse effects from this procedure. - Spinal Fluid Sample
Obtaining a spinal fluid sample through a lumbar puncture poses a low risk. Some individuals may experience a headache after the procedure, but it typically resolves within a week. Overall, the risks associated with a spinal fluid sample are minimal.(5)
Takeaway
Syphilis tests are vital for screening, diagnosing, and monitoring syphilis infections. The tests are generally safe, with minimal risks such as bruising or temporary headaches. Early detection and treatment through syphilis testing are crucial for managing and preventing the spread of this sexually transmitted infection. Regular screening is important, especially for high-risk individuals, to ensure timely intervention and control of syphilis.
