Can I know when I caught HIV?
NOTE: This question from November 2006 was updated in July 2014. The STARHS test is now called RITA (Recent Infection Treatment Algorithm).
This is difficult, but you could think back to whether you remember having flu or flu-like symptoms since your last HIV test.
Perhaps 70% of people get some sort of symptoms, usually 2-3 weeks after they were infected, but sometimes a few weeks later still. These can include fever, tiredness, headache, aches etc.
This is probably your best clue – especially if it was a short time after a potential exposure: unsafe sex (without a condom), sharing IV drug needles, and needlestick injuries are all ways that HIV is spread.
Very heavy flu-symptoms after a high risk exposure taken from a careful history is udually good enough to consider a diagnosis for seroconversion (ie infection within the last 2-6 weeks).
In the UK, people who think they were infected within the last 6 months, can use a ‘detuned’ HIV test called STARHS (or RITA). Even though the test isn’t approved for getting certain results in individual patients, it is used when identifying people for trials of early HIV treatment. This uses a slightly less sensitive version of the ELISA HIV antibody test, and is free from any clinic.
You can also look at the pattern of results from your CD4 and viral load tests. If your viral load is still going down without using treatment, you may still be in primary infection and were infected within the last 3-12 months.
If your viral load is steadily going up over time, then you are likely to have been infected for several years, and you are now seeing the results of HIV progression. You could then look at how fast your CD4 count is falling each year and estimate backwards. When not on treatment, CD4 counts fall by an average of 50 cells per year. Depending on whether your results are changing faster or slower than this, you could decide whether you are a slow, fast, or average progressor.
Even with the benefit of interpretation from a very experienced doctor, this will only give you a general possible range of dates.
In theory, you could look at the viral evolution of your virus – ie looking at genetic variability in the structure of your HIV to see how different the populations of HIV have evolved – and then calculate backwards based on how fast the virus reproduces. But this is expensive and complicated and only available in specialist research settings. It is not a test that your doctor can do.
More importantly, your clinic would be unlikely to change the decisions regarding your medical care even if you did know your date of infection. These decisions are made based on results from monitoring your viral load and CD4 count over time.
It is probably more important to look forward now though in terms of dealing with this.