It's also interesting that 70% of the immune system's activity is devoted to the protection of the intestines/cell/blood boundariies. This would also indicate that this mucosal layer, as an anti-pathogen barrier in the intestines, is indeed critical to the body's health defence with respect to neutrophils, eosinophils etc and infections in this regions.
Once dominant and established, candida tends to form profuse and impenetrable biofilms(built with the incorporation of heavy metals) in these mucosal regions with the consequent retreat of health, lowered immune system capability, with wide invitation to other pathogen species to also join the party. Normally mucosal pH in the upper intestines should be about 8.5 but becomes quite acidic from pathogen invasion and dominance.
Then, of course, we have Methylation Cycle Blockade problems which can create all manner of problems in the body including aberrant genes causing a 70% drop in body's neurotransmitter, lymphocyte and detox performance. Candida is well known to take advantage of a weakened or immuno-compromised system.
There can be many causes and reasons for candida fungal invasion or dominance in the human body and this is made even more complex when you also consider that about 80% of the worlds population has candida already living inside their intestines anyway.