DOWN= Immune system. Immune deficiency has to be suspected if thrush is diagnosed. 'immuno-compromise' can be due to a virus (hiv, hepc etc.) or due to medications that suppress the immune system e.g. Steroids, meds for rheumatological disorders etc. Also recent antibiotics can alter 'the bacterial flora' of the body and may cause 'yeast infections' such vaginal yeast or thrush. The treatment is topical 'anti-fungals.