Sexually transmitted diseases (STDs), also known as sexually transmitted infections (STIs), affect millions of people worldwide each year. Many STDs can be present without causing noticeable symptoms, making regular testing essential for anyone who is sexually active. While some STDs require urine samples or swabs for detection, several important infections can be identified through a simple blood test.
Understanding which STDs can be detected by blood tests helps you make informed decisions about your sexual health screening. This guide explains the infections that blood tests can identify and why early detection is so important.
STDs That Can Be Detected by Blood Tests
### HIV (Human Immunodeficiency Virus)
HIV is perhaps the most well-known STD detected through blood testing. The virus attacks the immune system and, if left untreated, can progress to AIDS (Acquired Immunodeficiency Syndrome). Modern HIV blood tests are highly accurate and can detect the virus in several ways:
Types of HIV blood tests:
Early detection of HIV is crucial because modern antiretroviral therapy can effectively suppress the virus, allowing people with HIV to live long, healthy lives and preventing transmission to partners.
### Syphilis
Syphilis is a bacterial infection caused by Treponema pallidum. Without treatment, it progresses through several stages and can cause serious complications affecting the heart, brain, and other organs. Blood tests for syphilis include:
Non-treponemal tests:
These tests detect antibodies produced in response to cellular damage caused by the infection. They are useful for screening and monitoring treatment response.
Treponemal tests:
These tests detect antibodies specific to the syphilis bacterium and confirm a positive screening result. Once positive, treponemal tests typically remain positive for life, even after successful treatment.
Syphilis is easily treated with antibiotics when caught early, making regular screening vital for sexually active individuals.
### Herpes (HSV-1 and HSV-2)
Herpes simplex virus comes in two types: HSV-1 (commonly causing oral herpes) and HSV-2 (typically causing genital herpes). However, either type can infect either location. Blood tests for herpes detect antibodies to the virus:
Type-specific antibody tests:
Herpes blood tests are particularly useful when:
While there is no cure for herpes, antiviral medications can manage outbreaks and reduce transmission risk.
### Hepatitis B
Hepatitis B is a viral infection that attacks the liver and can become chronic in some individuals. It spreads through blood, semen, and other bodily fluids. Blood tests can detect:
A hepatitis B vaccine is available and highly effective at preventing infection. For those with chronic hepatitis B, regular monitoring through liver function tests is essential to assess liver health.
### Hepatitis C
Hepatitis C is another viral infection affecting the liver. Unlike hepatitis B, there is no vaccine, but highly effective treatments can now cure the infection in most cases. Blood tests include:
Many people with hepatitis C have no symptoms for years while the virus silently damages their liver. Early detection through blood testing allows for treatment before significant liver damage occurs.
### HTLV (Human T-Lymphotropic Virus)
HTLV is a less well-known virus that can be transmitted sexually. It is associated with certain types of leukaemia and neurological conditions. Blood tests detect antibodies to HTLV-1 and HTLV-2. While relatively rare, testing may be recommended for individuals from areas where HTLV is more common.
STDs That Require Other Testing Methods
Not all STDs can be detected through blood tests. Some infections require different sample types:
Chlamydia – Detected through urine samples or swabs from the infected area. Read our comprehensive guide to chlamydia and chlamydia testing for more information.
Gonorrhoea – Similarly requires urine or swab samples for accurate detection.
Trichomoniasis – Detected through vaginal swabs or urine samples.
HPV (Human Papillomavirus) – Detected through cervical screening (smear tests) in women; no routine test available for men.
For complete sexual health screening, a combination of blood tests and other sample types may be necessary.
The Window Period: When to Get Tested
The window period is the time between potential exposure to an infection and when a test can accurately detect it. Testing too early may produce a false negative result. Here are typical window periods for blood-detectable STDs:
If you have had a recent potential exposure, you may need to test again after the window period has passed to confirm your results.
Why Early Detection Matters
Early detection of STDs through blood testing offers several important benefits:
Who Should Get Tested?
The following individuals should consider regular STD blood testing:
Confidential STD Testing in London
At Private Blood Tests London, we understand that sexual health testing can feel sensitive. Our CQC-registered clinic in South Kensington offers confidential STI testing in a discreet, professional environment. Our experienced healthcare team ensures your comfort throughout the process, and results are delivered securely and quickly.
Explore our comprehensive [STI testing services](/sti-testing) and [sexual health screening packages](/health-screening).
Whether you need a single test or comprehensive sexual health screening, we are here to help. Taking control of your sexual health starts with knowing your status.
Book your confidential STD blood test today.