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Viral Copies /ml Needed for Transmission

Jun 5, 2012

Hello There and greetings from Australia.

I am HIV+ and undetectable now for 5 years. I know that "undetectable does not mean not infectious", however I do know that that it significantly reduces my chances of passing the virus on to someone.

I'm not sexually active, however I was thinking about this the other day and have a question on transmission. Bearing in mind that HIV is in reality quite a difficult disease to catch (statistically speaking) how many copies/ml of virus would be a minimum level to infect someone? Is there such an amount? 1000 copies/ml? 10000?

Let's say someone had a viral load of 18 copies/ml. Would this be enough to infect someone who is negative if it entered their body somehow? Also, what happens if a very small amount of virus enters someone negative's bloodstream and they don't get infected? Is it because there aren't enough copies of the virus to replicate and/or reproduce? What would happen to this very small amount of virus that entered their body? Would it just "die off?" somehow?

How come some people get infected from a single exposure and others have many exposures and get nothing?

I'm just trying to understand more how this virus works!

Thanks in advance and thanks for all your good work here!

Response from Mr. Cordova

Hi, There:

Australia is on my list of places to visit! I really want to swim along the Great Barrier Reef.

You are correct, while it reduces the likelihood of transmission, you can still transmit the virus, even if your viral load is undetectable.

While it is hard to say exactly how many copies of the virus one would need for an infection to take place, we do know that transmission has occurred when the positive partner was undetectable. That means that at the very least, the viral load was less than 50 copies/ml when transmission occurred.

It is possible that someone could be exposed to the virus, but not in significant enough quantities to cause infection. If infection does not occur, then that means the virus is not present in the body. Some people can be infected from a one-time incident due to many factors. The type of activity they are engaging in, to the viral load of their partner, all factor into whether or not transmission is likely to occur. I hope this helps.

In health,


Hiv from breast milk
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