In immunocompetent people, candidiasis can usually only be found in exposed and moist parts of the body, such as:
- the oral cavity (oral thrush)
- the vagina (vaginal candidiasis or thrush)
- folds of skin in the diaper area (diaper rash)
Children mostly in the age range, 3 years to 9 years can be affected by chronic mouth yeast infections. This is not a very common situation though. It is normally seen around the mouth as white patches.
Yeast organisms are always present in all people, but are usually prevented from "overgrowth" (uncontrolled multiplication resulting in symptoms) by naturally occurring microorganisms.
At least three quarters of all women will experience candidiasis at some point in their lives. The Candida albicans organism is found in the vaginas of almost all women and normally causes no problems. However, when it gets out of balance with the other "normal flora", such as lactobacilli (which can also be harmed by using douches), an overgrowth and symptoms can result. Pregnancy, the use of oral contraceptives and some antibiotics, and diabetes mellitus can lead to an increased incidence in yeast infections.
Symptoms include severe itching, burning, and soreness, and irritation of the vagina and/or vulva, and a whitish or whitish-gray discharge that may have a "yeasty" smell like beer or baking bread, known as a garria. It may resemble cottage cheese.
Many women mistake the symptoms of the more common bacterial vaginosis for a yeast infection. In a 2002 study published in the Journal of Obstetrics and Gynecology, only 33 percent of women who were self treating for a yeast infection actually had a yeast infection. Instead they had either bacterial vaginosis or a mixed-type infection. Currently, bacterial vaginosis can only be diagnosed by a doctor.
KOH (potassium hydroxide) preparation can be diagnostic. A scraping or swab of the affected area is placed on a microscope slide. A single drop of 10% solution of KOH is then placed on the slide. The KOH dissolves the skin cells but leaves the Candida untouched. When viewed under a microscope the hyphae and pseudo spores of Candida are visible. Their presence in large numbers strongly suggest a yeast infection.
Swab and culture is performed by rubbing a sterile swab on the infected skin surface. The swab is then rubbed across a culture medium. The medium is incubated for several days, during which time colonies of yeast and/or bacteria develop. The characteristics of the colonies provide a presumptive diagnosis of the organism.
Candidiasis is alleged to be successfully treated either with home remedies or, in the case of a more severe infection, with either over the counter or prescription antifungal medications. Home remedies for candidiasis include the consumption or direct application of yogurt, which contains lactobacillus (probiotics, "friendly" bacteria that kill yeast), acidophilus tablets or salves, and even lightly crushed cloves of garlic, which yield allicin, an antifungal. Boric acid has also been used to treat yeast infections when gelcaps are filled with boric acid powder and two are inserted at bedtime for three to four nights. Another remedy is to douche with a weak mix of bicarbonate of soda in water (1 teaspoon to 1 cup). Bi-carb soda is alkaline and changes the vagina's acidity temporarily to a higher pH environment in which Candida cannot survive as Candida thrives in an acid environment.
While home remedies can offer relief in minor cases of infection, seeking medical attention can be necessary because the extent of the infection sometimes cannot be judged well by the sufferer. Prescription medication is often the only solution to an infection; the antifungal drugs commonly used to treat candidiasis are topical clotrimazole, topical nystatin, fluconazole, topical ketoconazole. In severe infections (generally in hospitalized patients), amphotericin B, caspofungin, or voriconazole may be used. These medications are not effective against the more common bacterial vaginosis.
If indicated, an underlying reason should be looked for. As an example, oral candidiasis is often linked to the use of inhaled corticosteroids in asthma medication. Patients on long term inhaled corticosteroids should rinse their mouth after each dose of steroids. It can also be the first sign of a more serious condition, such as HIV. Babies with diaper rash should have their diaper areas kept clean, dry, and exposed to air as much as possible. Sugar assists the overgrowth of yeast; thus, the increased prevalence of yeast infections in patients with diabetes mellitus, as noted above. In the case of frequent yeast infections, sugar can be looked to as a culprit and should be avoided. Nutritionists often recommend avoidance diets, eliminating sugar and often many other foods for a period. Extensive antibiotic treatment is sometimes implicated, and probiotics are then recommended.
History and taxonomic classification
B. Lagenbeck in 1839 in Germany was the first to demonstrate a yeastlike fungus in thrush. He also found that a fungus was able to cause thrush, a human oral infection. The genera Candida, species albicans was described by Christine Marie Berkhout. She described the fungus in her doctoral thesis, at the University of Utrecht in 1923. Over the years the classification of the genera and species has evolved. Obsolete names for this genus include Mycotorula and Torulopsis. The species has also been known in the past as Monilia albicans and Oidium albicans. The current classification is nomen conservandum, which means the name is authorized for use by the International Botanical Congress (IBC).
The full current classification is available at Candida albicans.
The genus Candida includes about 150 different species. However, only about six are considered as causing human infections. Candida albicans is the most significant species. Other species responsable for human disease include Candida tropicalis, Candida glabrata, Candida krusei, Candida parapsilosis, and Candida lusitaniae.
Alternative medicine proponents also frequently diagnose people with "systemic candidiasis" using methods not deemed valid by mainstream, western medicine. This belief originated from a book published by Dr. William Crook which hypothesized that a variety of common symptoms such as fatigue, PMS, sexual dysfunction, asthma, psoriasis, digestive and urinary problems, multiple sclerosis, and muscle pain, could be caused by subclinical infections by Candida albicans; see . There are a variety of remedies available to treat these symptoms, Dr. Crook suggests, ranging from dietary modification to colonic irrigation. Mainstream western medicine has ignored these methods and they have not been tested using scientific analysis, and therefore are not considered valid by most in the mainstream western medical establishment; see also ,  for criticisms of these treatments. However, nutritionists have also proposed that these symptoms may be due to intestinal wall damage, known as leaky gut syndrome, due to Candida overgrowth or other effects.