The problem is that it's difficult to get hard facts, as far as I can tell. Other people on here will know more about the research than I do, but I believe risks are calculated by asking people about their sexual habits and comparing that to infection rates. It would take honesty and good memories to get accurate results.

There are still arguments about a whole range of things, including stuff as 'simple' as whether there's a causal link between receiving cunnilingus and bacterial vaginosis.

Partly this is because some infections are easier to get research grants to look at, hence the popularity of HIV in studies. Good, long-term cohort studies don't come cheap.

Plus for a variety of reasons, including the annoying habit of ethics committees to say it's not ok to lock people up for a year and make them have certain kinds of sex with people already infected it is indeed quite difficult to do the research. People tend to have more than one kind of sex, for example.

This affects the perennial issue of the HIV risk of OWO. The study that gets pointed to looked at the behaviour of gay men in three cities in America. Because they didn't just have oral sex, some statistical work was done to come up with a figure of 0.04% per act, i.e. four infections in ten thousand OWO on HIV+ men. (There's good reason to think they'd all be CIM.)

Some people, including some whose views I generally respect, believe that's about right. Some people, including me, don't: as well as the study's assumptions being a bit dodgy, the 'confidence interval' on that figure went a little bit higher and way lower.

(What's that mean? There are a variety of statistical significance tests that say 'your answer is 0.04%, and there's a 95% chance that this is about right, and a 5% chance that it's absolute crap'. If it's not at least 95% 'about right', no-one believes it. Confidence interval tests say things like 'given this data, any figure between 0.0001% and 0.05% would still had a 95% chance of being "about right"' and this is what happened here. I think that 0.04%, while low, is still a big overestimate of the risk: there are many other studies reckoning the risk is nil to 'almost nil'.)

And this is twenty five years into the most studied STI epidemic.

I'm more worried about human papill*** infection (not sure how to spell it right sorry) which has cancer risks to women. 

'Human Papilloma virus' but that's why most people say 'HPV' There are lots of different types of HPV and it's only a handful which seem to be linked to various cancers - most (in)famously cervical cancer, but also some affecting both sexes, including anal cancer. The others are quite rare, and tend to appear more in people with compromised immune systems (e.g. people who have HIV).

There's been a rash of research on this published recently, probably because the makers of the incredibly expensive new vaccines want as many customers as possible before their patents run out.

any update Erica who started this thread? 

How interesting thank you very much for the meaningful post.