OK I MUST go sleep soon but will explain this to you. HIV Subtype B is the subtype we have in USA and Europe (Western world). Subtype E is found in Thailand and now increasingly in other parts of Asia.
In the beginning of the HIV epidemic there was much said about the massive heterosexual epidemic that would be spread because of prostitution. It never happened. Even today prostitutes and heterosexuals in USA and Western Europe are not in an epidemic. And it is not because we have less or safer sex. So in researching as to why prostitution is not at the epicenter of some hetero epidemic and examining everything we know about OUR HIV(Subtype B) it has been concluded that there are certain statistical transmission probability rates per various risk acts. With Subtype B it needs access to blood, it is a blood borne disease. So two of the highest risk factors are IV Drug use (direct access of virus into bloodstream) and also **** (they censured that before so I will say UP THE BUM) sex as that is more likely to create tears and therefore an access to the bloodstream and finally it creates a vacuum and a sperm deposit gives high viral availability to transmit the virus. Heterosexual spread of Subtype B IS HARD. It means you have to have some kind of cut in most cases though not all. In the absence of access to the blood stream transmission is not likely.
Enter Thailand. Thai epidemic took off like NO OTHER, not even in Africa. Africa took a long time to get where they went, but within a span of 10 years Thailand had one of the highest per capita rates in the world. AND it was driven by their prostitution industry, something that baffled everyone as it initially affected homosexuals much the same as in the West. So again enter research and loads of it. Why did this happen? Well the virus mutated and recombined to form a new subtype, knows as subtype E though that is not its technical name anymore. What made Thai prostitutes and heterosexuals bear the brunt of this outbreak?
Well after research was done, it has been determined that in vitro, subtype E MUCH MUCH more readily affects langerhans cells. Langherhans cells are cells that are part of our immune response and are found all over and their job is to identify invaders and bring them to the lymph glands...this is where the big problem is. Firstly we are not talking about all langerhans but just the ones present in mucosal lining which are more susceptible to HIV Subtype E. The problem is that for one to be infected by HIV the HIV must replicate enough and establish itself in the host (the person getting infected). It does this by bypassing immune responses and sneaking into the lymph glands and once there, you are infected and will soon sero-convert. (become hiv positive by presence of serum antibodies). No keeping in mind that SUBTYPE B is blood borne, even infection with subtype b still gives your body one more chance to identify and fight it off (many people are thought to be able to fight hiv off before sero-converting so that the hiv never establishes itself). BUT what if the route of transmission is a cell that has direct access to the lymph glands? Well that is the case langerhans cells so infection with subtype E via these cells has a better "hit" ratio as well. So firstly, the body is more susceptible because unlike B that needs an in, E has its in already in place in all of us because we all have present langerhans cells on our mucosal body parts, that inlcludes the penis guys! Secondly once E infects those cells it has a quicker route right into its target...so it has a double advaneforum.xxxe over the HIV we are taught about!
That said, safe sex still works and one slip up does not mean you are dead. There are many other factors that affect hiv transmission including viral load and point of disease that your partner is in, other std's which increase viral shedding, and many more!!! So I hope I have explained this well enough if you have more questions I will answer them tomorrow as I am knackered!