How theoretically possible would it be for this, really?

Question

How theoretically possible would it be for, say, a girl or woman with HIV and a wobbly tooth/bleeding gums to infect a boyfriend with a mouth ulcer, simply by kissing? Any real, true-to-facts data on something like this? -- What about a person with hepatitis C biting a cookie, dropping & losing it, and a child picking it up off the sidewalk or carpet the next morning, eating it and getting infected (--- since they say that hepatitis C stays alive for 24 hours outside the body)? Yeah, I know its a wild scenario, but if those sorts of "contacts" happened, how much real danger if any would exist, and if it were indeed miniscule, who would ever bother themselves to care? I used to drink after siblings, even friends, as a child -- of course, I wouldn't allow backwash & wiped the top, afterwards; yet, you know that a lot of this stuff has been around unspoken about for years, and I don't trade sips on drinks & still refuse to eat off of a used fork. Ever think about it? Modern life.

Answer 1

As long as there is a 1 percent chance thats too much, bleeding gums could definitely get you infected, that risk would be really high.

Answer 2

You would get more accurate answers in the science or medical sections.