Everyone has fungus on their bodies in limited amounts. It likes warm, moist places....Armpits, between toes, in the vagina, etc. Yeast infections occur when the fungus is allowed to grow unchecked in a hospitable environment like the vagina. This happens after women take antibiotics, which kills all the normal bacteria
that lives in the vagina, leaving space for the fungus to grow. Similarly, taking a lot of warm baths
, etc. Washes out the normal bacteria and can lead to infections. I am not aware of any link between thongs and yeast infections. Some evidence shows that eating probiotics like yogurt or pills replenish the normal bacteria that colonize the vagina and decrease the risk of yeast infections.