Updated: Jan 17, 2019
  • Author: Mudra Kumar, MD, MRCP, FAAP; Chief Editor: Russell W Steele, MD  more...
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First described by the French pediatrician Francois Valleix in 1838, thrush is an infection of the buccal cavity by Candida albicans. The disease is typically limited to infants and neonates, patients on antibiotics or steroids, and patients with polyendocrine disorders or underlying immune dysfunction. Thrush may be the first sign of human immunodeficiency virus (HIV) infection; its appearance in advanced HIV indicates poor prognosis. Children on inhaled steroids also have increased incidence of oral candidiasis.



C albicans causes thrush when normal host immunity or normal host flora is disrupted. Overgrowth of yeast on the oral mucosa leads to desquamation of epithelial cells and accumulation of bacteria, keratin, and necrotic tissue. This debris combines to form a pseudomembrane, which may closely adhere to the mucosa. This membrane is usually not large but may rarely involve extensive areas of edema, ulceration, and necrosis of the underlying mucosa.

Affected neonates are typically colonized by C albicans during passage through the birth canal. Hence, the risk for thrush is increased when the mother has an active vaginal yeast infection. Other sources of transmission to neonates include colonized breasts (for breastfed infants), hands, and/or improperly cleaned bottle nipples. Kissing has also been implicated.

C albicans frequently and asymptomatically inhabits the GI tract of many children and adults, and the GI tract has been implicated as a reservoir for yeast contamination of the perineum. Thus, candidal diaper rash frequently occurs in conjunction with thrush.

A systematic review and meta-analysis reported that the prevalence of oral candidiases caused by non-albicans Candida species in sub-Saharan African HIV patients was 33.5% [95% confidence interval (CI) 30.9-36.39%]. Non-albicans Candida species found included C. glabrata (23.8%; 109/458), C. tropicalis (22%; 101/458) and C. krusei (10.7%; 49/458). [1]  




United States

As many as 37% of newborns may develop thrush during the first months of life.


Thrush is universal and is more common in poorly nourished populations.


Thrush is usually a mild and self-limited illness, although it may cause discomfort sufficient to disrupt feeding in a newborn. Consider the possibility of an underlying immunodeficiency when thrush occurs after early infancy or without a reasonable explanation.


Thrush occurs equally in males and females.


Thrush is rare during the first week of life. Incidence peaks around the fourth week of life; thrush is uncommon in infants older than 6-9 months. Thrush can occur, however, at any age in predisposed patients.