Most women self-treating a yeast infection in one study didn't have one
Candida yeasts live harmlessly on most of us, held in check by the immune system and by competing bacteria. When that balance tips, they cause thrush. Yet in a 2002 study only 33% of women treating themselves for a yeast infection actually had one; most had bacterial vaginosis or a mixed infection.
Candidiasis is a fungal infection caused by yeasts of the genus Candida, or by species recently moved into a genus called Candidozyma. More than 20 kinds can cause disease, with Candida albicans the most common. The yeasts are normal residents of the mouth, gut and especially the skin, and they need moisture to thrive, which is why long hours in wet swimwear are thought to raise risk and why they can cause nappy rash. C. albicans turns up in roughly 10 to 15% of healthy women who have few or no symptoms.
Trouble usually starts when something removes the yeast's competitors or weakens the body's defences. Antibiotics can wipe out the bacteria that normally crowd Candida out; corticosteroids, diabetes, HIV/AIDS, cancer treatment and transplant drugs all weaken immunity. Dentures matter too: Candida is involved in about 90% of cases of denture-related mouth inflammation. Detergents, douches and hormonal changes such as pregnancy can disturb the lactobacilli that keep vaginal flora in balance.
The infection is common. About 6% of babies under a month old get oral thrush, which is not considered abnormal unless it lasts beyond a few weeks. Around a fifth of people on cancer chemotherapy and a fifth of those with AIDS develop it, and about three-quarters of women have at least one vaginal yeast infection in their lifetime. In healthy people it usually stays local, on skin, nails or mucous membranes. In people with weakened immune systems it can spread into the blood, a condition called candidemia; almost 15% of immunocompromised people develop a systemic Candida illness.
Diagnosis often relies on a simple laboratory trick. A drop of 10% potassium hydroxide dissolves skin cells on a slide but leaves the yeast intact, revealing budding cells and branching filaments under the microscope. Cultures incubated at body temperature for several days can identify the organism by colony shape and colour. Evidence for probiotics, whether to prevent or treat infections, is thin.
Source: Candidiasis
