Candidiasis is a mycotic disease of the digestive tract of various avian species, including chickens, turkeys, and quail caused by Candida albicans. It commonly develops after use of therapeutic levels of various antibiotics or when using unsanitary drinking facilities. Lesions are most frequently found in the crop and consist of thickened mucosa and whitish, raised pseudomembranes. The same lesions may be seen in the mouth and esophagus. Occasionally, shallow ulcers and sloughing of necrotic epithelium may be present. Listlessness and inappetence may be the only signs. A presumptive diagnosis may be made on observation of gross lesions. Diagnosis can be confirmed by demonstrating tissue invasion histologically and by culture of the organism. However, culture alone is not diagnostic of disease, because the yeast-like fungus is commonly isolated from clinically normal birds. Young chicks and poults are most susceptible.
Improving sanitation and minimizing antibiotic use in poultry help reduce the incidence of candidiasis. Candidiasis can be treated or prevented with copper sulfate at 1:2,000 dilution in the drinking water, but its effectiveness is controversial. Nystatin, an antifungal medication, in the feed (220 mg/kg of diet) or drinking water (62.5–250 mg/L with sodium lauryl sulfate, a surfactant, at 7.8–25 mg/L) for 5 days may be effective for the treatment of affected turkeys.