If you’re the guy receiving, can you get any STD’s from getting a blowjob? Is it as bad as having unprotected sex or is it a safe alternative?
You can get/give herpes.
I believe herpes, for one, can go either direction during oral sex.
This cite doesn’t specify which direction herpes could travel, but does explicitly state it can be transmitted during oral sex. I don’t see why it would move only one direction, so I think it’s safe to assume it can go mouth to genitalia.
Yes you can although the risks are usually smaller than with other methods. You can get all the statistics you want with a simple google search. Try Herpes, HIV, and oral sex as search terms. Here’s a document from the CDC on HIV and Oral Sex.
Any STD that can be communicated to the mouth can be communicated from the mouth. An open sore will facilitate such transmission in many cases, but it is not necessary for most.
While there are several real differences, the mouth and the vagina are both bodiy cavities, lined with mucous membrane, that are generally moist and warm. What would you expect the differences to be when communicating disease?
Oh, the ability to spit (length of retention), acidity/alkalinity of the environment, probability of the presence of blood, permeability of the tissue involved…none of which are great barriers to infection it itself, but when taken together would probably have a significant effect in either promoting or inhibiting transmission, depending on who’s doing what to whom.
The (male) receiver is less likely to become infected than the (either sex) provider than a noninfected provider would be if performing fellatio on an infected individual since skin is less permeable and a poorer growth/maintenance environment than a mucous membrane area.
Would I bet my life on it? Nope.