Allow me to explain one key thing about when it comes to the risk to the top as compared to the risk of the bottom…. When you're the bottom, you run the risk of the top's cock causing small tears in the lining of your insides from being stretched out and/or too much friction without a sufficient amount of lubrication. Given that the actual wounds in which the infection would enter are on the insides of the bottom and not on the dick of the top, simple physics would dictate that it becomes easier for the bottom to contract than it is from the top..... That being said however, don't kid yourself. If is still possible to contract HIV as a top, especially if more major damage has been done to the insides of the bottom. Also, there is also the fact that when the top cums and pulls out, the exposure to the body parts is removed. For the top, this pretty well severs the connection, however for the bottom who may still have cum inside of them, this increases the risk due to the fact that the residual residue of the sex itself still remains inside the bottom, long after the sex has stopped.
That being said however, calculating the risk factors is not exactly all that easy or straight forward either. One of the biggest factors to take into account when it comes to HIV transmission is the viral load of the HIV+ person. Simply put, the viral load is a laboratory marker of just how much, how strong, or how concentrated you will that the actual presence of HIV is within the person's blood stream. As a general rule, the higher the number equates to the higher the risk, however again, this is not an exact science because it also does not take into account the fact that there are people out there who are either a progressive developer or an elite controller. In these cases, the risk is reduced by that factor all unto itself. For those who do not know, a "progressive developer" is somewhat like it sounds. Due to the nature of their particular immune system, it takes substantially longer for the virus to develop within the system, thus triggering the point of seroconversion to appear on a test, and then later on, slows the progression process of the virus down. In most of these cases, medications are not generally needed until long after they would have been for an otherwise "normal" person. An elite controller on the other hand is much more rare of a concept. Simply put, it is someone whose immune system is capable of suppressing the virus of its own accord, thus maintaining an undetectable viral load, without the need for the meds.
Now as for yababioi's point about being undetectable, I will make something very clear. In the last 8 years, several studies have been done to try to quantify a risk factor that you can measure when it comes to sex among gay men. The only problem that all of these studies have had in common is that since the release of some of the newer medications around 1996, there hasn't been so much as a single case of HIV transmission noted from an HIV+ partner with an undetectable viral load. This is not to say that it is impossible to occur, because there is no evidence that proves that concretely, however it is very promising. Just think.... In the 8 year period that these studies have been happening, they have not been able to find so much as 1 case where the HIV+ partner is undetectable, even with frequent unprotected sex with ejaculation inside. That alone should speak for itself, especially since the pattern has held true for 8, almost 9 years now.
If risk is what you're concerned about, it's important to take all the factors into account. While it is true that generally speaking, there are factors that potentially elevate the risk of transmission from the top to the bottom, but this certainly does not preclude that there is still a risk of transmission from the bottom to the top. Generally speaking, it is not as likely due to the sheer physics of it, but again as I said, establishing potential risk is not necessarily so cut and dry. In some more extreme cases (such as my last ex), when the bottom was playing with an oversized novelty dildo, hurt themselves with it, and were bleeding internally on their insides enough to warrant medical attention prior to getting fucked, the impending risk for the top is substantially elevated as compared to had the internal damage not been done first. This is a big part of why health care professionals will generally not advise that the risk of transmission is not necessarily lower for the top. In other words, it's not an exact science, and potentially, the role you play (top or bottom) can sometimes make absolutely no difference in the risk.
All this being said however, in my opinion, if you're worried about the risk of transmission to begin with, you'd actually be better off to find yourself a sexual partner who identifies as being "undetectable", rather than "negative" or "clean". When they're "negative" (or so they claim), the test is only as accurate as up to 3 months before the time that the blood was drawn. If the day after that blood sample was drawn if that person engages in sexual activity, it is very well possible that they may have already seroconverted and become HIV+ by the time the negative test result came in and not even known it. That being said however, if you're playing around with someone who identifies as being "undetectable", sure, they may be HIV+, however you at least know that credible studies have been done that actually scientifically prove that the odds of contracting HIV from an HIV+ partner who has a high viral load (which is often the case when you reach the point of seroconversion) and uses a condom than it is to have unprotected sex to completion without pulling out with someone with an undetectable viral load. Statistically speaking, it is a reasonable claim to say that having unprotected sex with an HIV+ partner who is undetectable is proven to be safer than having sex with a condom with a partner who is HIV+ and has a high viral load.
So, yes... I do agree with yababyioi on the point that you Opiam should properly educate and inform yourself of all the facts before making statements that clearly are an embarrassment to yourself. I may not have the fancy paperwork to say that I'm a doctor and I know my shit, but I'll be very clear about 1 thing............ Having been diagnosed with HIV on March 14, 2009 and living with it ever since (6 years and counting now), I can assure you that I know WAY more about HIV and the way that medical care works for people who are HIV+ than far too many doctors in the medical field. In fact, in some cases, I have even been the one to have to explain to the doctor who was taking care of me at the time how to read the test results, what they mean, and what the next most logical step to provide proper care would be. If you're at all unsure of something, I would be more than happy to fill you in. Again, in the 6 years now that I have been living with HIV, I can assure you when I say that education is the only prevention for a lot of the common misconceptions that can lead to stigma, and in my case, criminal persecution of a person, solely because they are HIV+ and far too many people still at this day and age are still afraid of it.
I can assure you that it's not 1985 anymore and we've made some advancements in the medical community, some of which I am about to get involved with the further development of, such as the first round of trials in Canadian history of a proposed cure to determine whether or not it is effective. We're actually that close to the point of being able to say we found the cure.... Mark my words when I say within the next 5 - 10 years, it will be available to the masses.
