http://www.emedicinehealth.com...fection/page3_em.htm
You can get yeast infections every where. From Thrush in your mouth down through your esophagus into your stomach into your intestines IF you have a weakened immune system. I think one would have to be very ill for this to happen.
I thought it was more common, like the vaginal kind which can be transmitted between partners. I have known people that have had internal yeast infections but am now wondering if it was in their blood or in their GI tracts.