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PEP, p24 antigen

Feb 1, 2006

Dear Dr Franscino, Robert, Bob, or mate as I now refer to you. I have read most of the questions/ answers submited in the various forums, ranging from the sublime to the ridiculous but can`t seem to find a difinitive answer to my question. My question, why do some people test positive for p24 earlier 2-3-4 weeks than others 5-6-8 weeks and therefore why are people waiting up to 12 weeks. What affects the virus replicating (if not antibodies) in some and not others. The reason I am asking is not altruistic (unfortunately I`m not that nice) but my own concerns with regard to PEP`s affecting my own results. My GP says it would very unlikely for undetectable levels of HIV virus to be present after stopping PEP`s for 3 weeks, as viral rebound is quite prolific. I have obviously given you no information about my own (non specific) symptoms, or risk and would not expect you to give me a specific answer to my status, but in general, what are your own views on this. Yours A very worried, midly hypochondriac person from England. ps Do you accept foreign money.

Response from Dr. Frascino

Hello Worried "Midly" Hypochondriac person,

There are a variety of complex reasons why HIV-infected individuals seroconvert (become "detectably" positive) at different times. These reasons include:

1. Viral characteristics (viral strain, etc.)

2. Host immune system characteristics. (The immune response to infection varies from person to person due to age, concurrent infections and many other factors.)

3. Limitations of sensitivity and specificity of various testing assays.

You can access additional details about HIV testing techniques and limitations by searching the archives.

Regarding your particular situation, you are correct. Without additional information about your potential exposure, symptoms, test results and PEP treatment, it would be impossible for me to comment. I would suggest you review the information in the articles "Antiretroviral Post-exposure Prophylaxis After Sexual, Injection-Drug Use or Other Nonoccupational Exposures to HIV in the United States" published by the U.S. Department of Health and Human Services and the CDC. It too can be accessed in the archives!

Finally, regarding donations to my foundation, yes, we accept foreign money of all types. Donation information can be found on the Foundation's Web site at

Good luck!

Dr. Bob

I already Woo-ed, can I Hoo now?

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