|Resistance and reinfection
May 8, 2001
I have been HIV+ for two years. I immediately started antiviral therapy, taking Combivir and Sustiva. This therapy had quick effect, reducing my viral load from 6,000 copies to undetectable, and improving my t-cells from 489/32 to ballpark 600/38. These numbers have held for the last year-and-a-half, during which I haven't missed a dose.
I am concerned about obtaining a drug-resistant virus via reinfection. I recently had a sexual encounter with another positive person (I do not know his viral load/t-cells, nor his therapy if any) in which there is a strong chance that I was exposed to his semen. What are the current theories on reinfection in that case? And with regards to resistence, if by some chance his virus, or a subspecies of his virus, is resistant to my drugs, is it possible that I could be reinfected with another virus(es) which will not be suppressed by my current therapy? Thank you.
Response from Dr. Little
Reinfection or co-infection with two different HIV variants does seem to be possible. The difficulty we have is typically in documenting it clearly in the U.S. The reason for the difficulty is that in North America and Europe, most individuals are infected with genetically related viruses (called B-subtype). It is almost always impossible to demonstrate clearly that reinfection has occurred because the "new" virus looks so much like the "old" virus. The one circumstance where this might be easier to do is in a case such as yours. While I have no reason to suspect that you were "reinfected", what doctors would look for is a sudden change in your treatment response (ie. you have been doing well with undetectable virus, then you have an exposure to someone who has resistance to one or more drugs you are taking, and then your viral load starts to rise, despite the fact that you continue to take every dose of your medications). Even though this senario has been identified in several cases that I am aware of, we still have a very difficult time PROVING that reinfection occurred. Unfortunately, that leaves us with recommendations that reinfection may occur and that until we can document the rate and frequency with which this occurs, it is better to avoid the risk.
worried about drug resistance due to illegal drug use
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