Pictures of oral thrush, a type of yeast infection, are available from MedicineNet. Thrush is caused by the Candida fungus, which produces sores and white patches in the throat and mouth.
Candida is normally found on the skin and in the mouth, where it is prevented from developing into an infection by the body's immune defenses and by other microbes, as MedicineNet explains. Thrush develops when these defenses are interrupted. Thrush is rarely serious, and sometimes does not even require treatment. Adults are usually treated with antifungal mouthwash or lozenges. However, in patients with compromised immune systems, thrush can spread to other parts of the body and cause a system infection that requires immediate treatment.