Candida spp forms a normal part of the commensal flora, being found in between a fifth and half of asymptomatic women. However, the lifetime incidence of vulvovaginal candidiasis is estimated to be 50-75 percent. Potentially 30 percent of women of childbearing age experience recurrent episodes of thrush, and almost continuous symptoms are present in 1 percent of women.¹⁰

While C Albicans is the most common candidal species, present in around 80 percent of fungal isolates, other species are present and potentially pathogenic. Of growing interest is C glabrata, which for a long time had been considered harmless, but is increasingly being linked to disease states.³

Under the right conditions, Candida spp can become pathogenic by growing in filamentous forms which are difficult for the host immune system to detect. It can form biofilms, where microorganisms stick to each other and to the host tissue - in this case, the vaginal epithelium and mucosa - with a degree of protection from a polymeric surface coating.

Other "virulence factors" include the production of enzymes, such as proteinases, phospholipases, and lipases.³

Levels of Lactobacilli and other bacteria may be unaffected in vulvovaginal candidiasis, which may explain why pH levels stay below pH 4.5.^1,5