{"id":91,"date":"2023-01-01T12:00:57","date_gmt":"2023-01-01T12:00:57","guid":{"rendered":"http:\/\/moomango.co.uk\/ttfa\/?page_id=91"},"modified":"2024-10-30T11:36:59","modified_gmt":"2024-10-30T11:36:59","slug":"8-what-is-a-viral-load-test","status":"publish","type":"page","link":"https:\/\/i-base.info\/ttfa\/section-2\/8-what-is-a-viral-load-test\/","title":{"rendered":"2. 8 What is a viral load test?"},"content":{"rendered":"

A viral load test measures the amount of HIV in a small sample of blood. <\/strong><\/p>\n

This is reported as the number of copies of HIV per millilitre (copies\/mL). Information about units of measure for blood tests<\/span><\/a>.<\/span><\/strong><\/p>\n

When viral load is (less than 200 copies\/mL on ART, there is no risk of transmission during sex. This is even if you don’t use a condom. See: Undetectable = Untransmittable (U=U)<\/a>.<\/p>\n

Viral load\u00a0is a good surrogate marker<\/strong><\/a> of how much HIV is in your body. This is even though less than 1% of HIV is in your blood. Blood tests are also easier than trying to test lymph nodes or other body tissues.<\/p>\n

Viral load tests can be used on other samples. For example, for genital fluid, semen or spinal fluid.<\/p>\n

Types of viral load test<\/h2>\n
    \n
  • PCR. <\/strong>The main test uses polymerase chain reaction (written as PCR RNA). This is the most widely used type of test.<\/li>\n<\/ul>\n

    Two much older tests, are now used more rarely for HIV (if at all).<\/p>\n

      \n
    • bDNA.<\/strong>\u00a0Branched DNA is now used less often for HIV<\/li>\n
    • NASBA.<\/strong> Nucleic Acid Sequence Based Amplification.<\/li>\n<\/ul>\n

      These tests work in slightly different ways. PCR is the most widely used viral load test. PCR technology is also used to measure levels of HIV DNA in some circumstances.<\/p>\n

      How viral load tests work<\/h2>\n

      Viral load tests multiply virus found in a small sample of blood.<\/strong><\/p>\n

      Each stage of multiplication doubles the amount of virus to make it easier to count. But the result is still only a rough estimate.<\/p>\n

      Viral load tests can have a 3-fold margin of error. So, if a viral load result of 30,000, the real result could be anywhere between 10,000 and 90,000 copies\/mL.<\/p>\n

      Different sensitivity cut-offs<\/h2>\n
        \n
      • All viral load test has a sensitivity cut-off. This is the lowest level of HIV<\/strong> that the test can measure. It is a measure of how sensitive<\/strong> the test is.<\/li>\n
      • The main cut-off limit<\/strong> for viral load tests is\u00a050 copies\/mL<\/strong>. Many\u00a0tests now\u00a0have a\u00a0lower cut-off of\u00a020 copies\/mL<\/strong>.<\/li>\n
      • Specialist laboratory tests\u00a0can measure down to 5 copies\/mL or even to 1 copy\/mL. These are only used in research.<\/li>\n<\/ul>\n

        Using viral load and CD4 count to monitor HIV<\/h2>\n

        Used together, CD4 counts and viral load results show the\u00a0risk to your health from HIV. They also show how well HIV treatment (ART) is working.<\/strong><\/p>\n

        Viral load test results are the main way to monitor ART.<\/p>\n

          \n
        • On ART, viral load is more important than the CD4 count.<\/li>\n
        • The main goal of ART is to become undetectable (less than 50 copies\/mL). Otherwise, drug resistance can develop.<\/li>\n
        • Viral load tests are widely used in most countries, but are still difficult to get in others.<\/li>\n<\/ul>\n

          In some countries, viral load and CD4 tests cost much more than ART. Less expensive tests are being developed.<\/p>\n

          Even if you do not have a viral load test, it helps to understand how CD4 count and viral load are related.<\/p>\n","protected":false},"excerpt":{"rendered":"

          A viral load test measures the amount of HIV in a small sample of blood. This is reported as the number of copies of HIV per millilitre (copies\/mL). Information about units of measure for blood tests. When viral load is …<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":76,"menu_order":6,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-91","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/pages\/91","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/comments?post=91"}],"version-history":[{"count":0,"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/pages\/91\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/pages\/76"}],"wp:attachment":[{"href":"https:\/\/i-base.info\/ttfa\/wp-json\/wp\/v2\/media?parent=91"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}