The medical aspects of coprophagia – shit eating – are mostly clear. The eating of other people’s shit can be very risky because lots of bacteria are carried over within the shit. So there is a high risk of getting diseases such as Hepatitis, polio, influenza and some other things. There is also a risk that the shit carries some intestinal parasites. So you always should be prepared if you eat someones shit – protective vaccinations are one way to prevent against these diseases. But there will be always some risk!
In addition there are lot of different countries which prohibit the eating and playing with scat.
But still there is an increasing interest in shit playing and eating, especially in the BDSM scene!