What STDs Can Be Detected By A Blood Test?
Table of Contents
- Written by Dr. Andrea Pinto on 25 January 2022
When it comes to sexual health, it’s very important to know which types of tests you should be getting to screen for different sexually transmitted infections (STIs). Different samples can be used to detect STDs, including:
- Fingerstick blood sample
- Venous blood sample
- Genital swab
- Urine sample
- Lesion swab sample
Keep reading to find out what STDs can be detected by a blood test.
STDs that can be detected by a blood test
The HIV blood test is probably the most well-known STD blood test that exists currently. Over the years, new generations of HIV tests have been developed to be able to detect the virus with more sensitivity and specificity, which leads to more accurate results.
According to the CDC, there are different types of HIV tests which include:
- Nucleic acid test (NAT): these tests look for the presence of the virus in the blood, and they require a venous blood sample. This test is very accurate and it can detect HIV sooner when compared to other HIV tests, but it’s also very expensive and it’s not used for routine screening. The blood sample must be sent to a laboratory for testing, and results can take a few days to become available.
- Antigen/antibody test: this test also requires a venous blood sample, although there are also rapid antigen/antibody HIV tests that require a fingerstick sample. It looks for HIV p24 antigen and antibodies produced by your body. Results from this test are typically available within 30 minutes or less.
- Antibody tests: these tests can use blood from a finger prick or venous sample, or an oral swab. As its name suggests, this type of test only looks for HIV antibodies in your system, and results take 20 to 30 minutes to become available.
Getting tested for HIV is incredibly important once you become sexually active. HIV can remain asymptomatic for many years, but starting treatment as early as possible can help prevent the progression of HIV to AIDS.
HIV.gov recommends that everyone between the ages of 13 to 64 should get tested at least once, and you should get tested regularly afterwards if your sexual behavior puts you at increased risk of HIV transmission.
Syphilis is one of the oldest sexually transmitted diseases (STDs) known to humans and it’s caused by a bacteria called Treponema pallidum. The good news is that syphilis is quite easy to diagnose and treat thanks to modern medicine. According to a study published by the journal Neurology Clinical Practice, there are treponemal and nontreponemal diagnostic tests.
Treponemal tests detect antibodies that are specific to T. pallidum, while nontreponemal tests look for other substances that are produced during syphilis, but aren’t specific to this STD. A combination of treponemal and nontreponemal tests is typically used to confirm the diagnosis. Most syphilis tests use blood samples, although some tests can require fluid from an open sore, tissue, or spinal fluid.
According to the University of Michigan Health, the different types of syphilis tests can include:
- Venereal disease research laboratory (VDRL) test
- Rapid plasma reagin (RPR) test
- Rapid immunochromatographic test
- Enzyme immunoassay (EIA) test
- Fluorescent treponemal antibody absorption (FTA-ABS) test
- Treponema pallidum particle agglutination assay (TPPA)
- Darkfield microscopy
- Microhemagglutination assay (MHA-TP)
If a screening test is positive for syphilis, a different test will be performed to confirm the diagnosis.
Herpes is a common STD that causes fluid-filled blisters to appear around the mouth or on the genitals. Not all herpes tests are blood tests — in fact, the most reliable way to test for herpes is by taking a swab test from a herpes sore. Additionally, many people don’t need to receive a herpes test, since their healthcare provider can diagnose the infection based on physical signs.
However, blood tests for herpes can be performed in some cases. According to MedlinePlus, the type of test you get will depend on your symptoms and medical history. Blood tests for herpes look for antibodies against herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2). Although this type of test is less sensitive, it can be helpful when there are no active herpes sores.
Different tests can be used to determine whether someone has an active or old infection, or if they have antibodies to protect them against hepatitis B. According to The Hepatitis B Foundation, the tests for hepatitis B include:
- HBsAg (Hepatitis B surface antigen): this test can determine the presence of the hepatitis B virus (HBV) in your blood. However, further testing is needed to determine whether the infection is acute or chronic.
- anti-HBs or HBsAb (Hepatitis B surface antibody): a positive result indicates that the person is protected against hepatitis B. This protection could come from getting the hepatitis B vaccine or a past infection.
- anti-HBc or HBcAb (Hepatitis B core antibody): a positive test indicates a past or current infection, but it’s necessary to have the results from the other two tests to interpret its result.
You can learn more about STD testing and other topics related to your reproductive health at STDWatch.com.
Types of HIV Tests - cdc.gov
Who Should Get Tested? - hiv.gov
Diagnostic tests for syphilis - ncbi.nlm.nih.gov
Syphilis Tests - uofmhealth.org
Herpes (HSV) Test - medlineplus.gov
Hepatitis B Blood Tests - hepb.org
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