[stana (OP)]

hey guys i was wondering, lets say a guy (a) had a disease only transferred by blood. and another guy (b) came along..withdrew blood from this guy(a)..and drank it..would guy (b) have his disease?

[another_someone]

Depends on the disease, but there is a significant likelihood.  It also depends on other factors, such as whether the guy has any ulcers, or other infection or damage within his mouth or throat.

[stana (OP)]

So if guy (b) has any ulcers or cuts leading to an immediate blood stream..there is a high chance he may contract the disease..so lets say guy (b) has no ulcers or cuts, could the blood pass through the whole digestive system and just be urinated out?

[another_someone]

Urine does not come from the digestive system.  Urine is produced by the kidneys, which extracts waste from the blood supply and produces urine as a way of disposing of the waste, but in order to get to the kidneys, it first has to get into the blood supply.

If something passes through the digestive system, then it will come out in the faeces, not the urine.

But I would consider it extremely unlikely that any blood born disease causing agent will pass through the entire digestive tract.  If a disease causing agent can only be spread through blood born contact, then it is probably a fairly fragile organism.  The digestive tract is a very hostile environment, so unless the organism is designed to be robust enough to survive it, it will almost certainly be destroyed somewhere in the digestive tract.

The question is whether the organism is capable of penetrating through the gut wall, or the lining of the mouth of throat, before it gets destroyed somewhere further down.

Part of the issue will depend on how much of the organism there is.  A low level of infection, or a small amount of blood, will be less likely to infect you; but if you consume a lot or the organism, then the likelihood that some of it will get to somewhere where it can cross into your bloodstream is so much the greater.