Seroconversion illness and antibodies/Seroconversion and HIV testing
Oct 30, 1996
Question 1: Firstly, thank you for your valuable advice. The work you do is abolutely invaluable! Could you tell me, assuming an individual suffers from a retroviral illness, how soon after this illness would you expect detectable antibodies (by ELISA) to appear? My doctor said that since such an illness is accociated with seroconversion the antibodies should show up a few days later (although 10 days is more normal). Any thoughts on this? Thanks again.
Question 2: If a person infected with HIV experiences acute retroviral syndrome, does that mean that s/he is in the process of seroconverting? Does seroconversion, once antibodies have begun to form, happen quickly (like over a few days) or does it take longer? Would a standard HIV antibody test given two weeks after recovering from acute retroviral syndrome usually return a positive, or at indeterminate (but not negative) result? I ask this because I have read (from answers to related questions) that a p24 antigen test would be positive during acute retroviral syndrome. I have also read that a p24 usually shows positive about a week before an ELISA test shows positive. Therefore, wouldn't two weeks after acute retroviral syndrome be enough time for an ELISA test to pick up antibodies? Thanks for your advice. You have been a providing a great service and I really appreciate your honesty in answering these questions!
Response from Mr. Sowadsky
Thank you for your question. It's really hard to determine how long a person will begin to produce antibodies after the Acute Viral Syndrome stage. Not all persons will have Acute Viral Syndrome, and the severity of this syndrome can vary greatly from person to person.
It can take up to 6 months for a person to test positive on the HIV antibody tests. A person may, or may not, show positive on the test during (or shortly after) the Acute Viral Syndrome. We can say that once HIV enters the body, there is a quick immune response against HIV. Antibody production is just one part of the immune system, and normally comes later in the initial immune response. So even if a person is not yet producing antibodies, that doesn't mean the body isn't mounting an immune response against HIV. During the Acute Viral Syndrome, the immune system may be very active against HIV, even though antibodies may not yet be present. Many people will start producing antibodies after the Acute Viral Syndrome, but I cannot say if most people will be antibody positive 10 days after this syndrome. Because symptoms of Acute Viral Syndrome are so much like the symptoms of the flu and other illnesses, it's hard to say if a persons symptoms are due to HIV, or another illness. One CANNOT assume they don't have HIV if the p-24 antigen test is negative while a person has flu-like symptoms. Also, one CANNOT determine if they are infected by waiting 10 days after having flu-like illness to take an antibody test. One must wait the full 6 months in order to get the most accurate HIV antibody test. This is regardless of any symptoms they may, or may not have.
In regard to the p-24 antigen test, this may, or may not, test positive during the Acute Viral Syndrome stage. However we can say that the p-24 antigen test will begin showing positive an average of 6 days before the start of antibody production. Once a person starts producing antibodies, the p-24 antigen test often reverts back to a negative result. The p-24 antigen test alone cannot be used to diagnose HIV infection. It has to be used in conjunction with other HIV tests for diagnosis of HIV.
So overall, it's difficult to say the exact relationship between Acute Viral Syndrome, and the start of antibody production. This is because it is often difficult to determine what is causing a persons flu-like symptoms. Is it due to HIV, the flu virus itself, or other viruses? The time between these two occurrences can vary greatly from person to person. All we can say is that the Acute Viral Syndrome, when it does occur, is seen within the first month or so after infection. Antibody production begins an average of 25 days after infection, and most (but not all) persons begin producing antibodies by 3 months after infection. By 6 months, more than 99% of infected persons will be producing antibodies. Testing at this 6 month time point is considered a conclusive test. So although a person can certainly show positive on an antibody test (or a p-24 antigen test) shortly after Acute Viral Syndrome, this does not change our recommendations regarding when to take the antibody tests for HIV diagnosis.
If you have any further questions, please feel free to call the Centers for Disease Control at 1.800.232.4636 (Nationwide). Rick Sowadsky MSPH CDS
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