Expert: Terry B - 12/15/2006

Question
can we test p 24 testing after exposer immediately ? when best?

Answer
Dear Mr. Mr.

Peace and sorry for a delay in answering.  Your question sent me looking for latest news; what I found instead was some variety of opinions.

P-24 antigen testing seems, by my read, to be most accurate 28 days after exposure.  On the other hand, it is prone (close to 1 in 10) to false positives - creating undue anxiety.  Due to the cost and other considerations, many recommend just waiting four to six weeks and having an ELISA test.  Go to www.thebody.com and search "p-24" for more detail.

There are two other tests used primarily to measure viral load in a person already infected - Quantitative PCR and BDNA.  A Qualitative PCR test can be used to establish HIV infection; again, it is expensive and hard to find a site that offers it.  I am not sure if branch DNA testing has the same capacities.

I would recommend talking to your health department, local test site, or health provider.  Some large emergency rooms might have the information as well, as they are often the place to which emergency providers are sent for testing after an occupational exposure.

Sorry I could not give you a more definitive answer; I hope the directions in which I send you will be more profitable.  Please let me know what you learn.

Sincerely,

Terry