Why are Homosexual men for prone to disease and infections?

It is true that Homosexual men are struck with diseases and infections more than Heterosexual men, I checked this out myself. My endeavor told me nothing about why they are, so I asked my doctor why this was so and he told me the likely reason is that the type of sexual activity Homosexual men have frequently brings them into contact with fecal matter. This is what my doctor told me, it is not my opinion. I would like to hear from Homosexual men as to why they think this is so. I would like to apologize if anything I have said offends, it is not my intention to offend anyone.

Homosexual men are at high risk of HIV infection because of all sexual activity, unprotected anal sex has the highest risk of transmission of HIV due to high risk of bleeding.