What Are The Chances Of Contracting Stomach Infections Through Shared Dummies?

Hi, My 2 year old had bad diarrhea and vomiting for a few days while abroad, he ended up in hospital due to dehydration where they found elevated liver enzymes in his blood and suggested he may have hepatitis. He has got very foul smelling, paler than normal colour stools (dark mustard colour) not loose. He has gone through a few further tests currently, waiting for the results. I think it is a parasyte (like giardia lambia) due to drinking contaminated water. My question is if my 11 month old son could have developed the same disase as they are taking each others dummies, spoons etc... Since last week he has got yellowish coloured, foul snelling poops (definitely changed to what used to be his normal). He definitely not drank contaminated water and I really pay attention to sterilise his bottles and washing my hands all the time. No way he could come contact with my other boys faeces. So could he developed giardiasis or catch the same parasite due to sharing dummies? Sorry for the long post. A very concered mummy