Candida Infections (Candidiasis) in Birds

What is Candida?

Candida albicans is an environmental yeast that can infect a bird’s digestive tract. It is a common cause of crop infections or “sour crop” (ingluvitis). Candida infection (candidiasis) is most common in young birds. It may be spread by:

• An adult bird feeding a young bird
• Living in a contaminated environment
• Drinking contaminated water
• Eating contaminated hand-feeding formulas

Candida, in small numbers, is usually considered a normal resident of a bird’s oral cavity and digestive tract. A disruption or imbalance of normal bacterial populations in the digestive tract may lead to a secondary overgrowth of Candida. 

Excessive sugar or carbohydrates in the diet may contribute to Candida overgrowth, as yeast and fungal organisms grow well in high-sugar environments. Overuse of certain antibiotics can disturb the normal flora of the digestive tract, allowing Candida organisms to multiply and cause candidiasis.

Often, other diseases compromise a bird’s immune system and predispose the bird to Candida infection. Steroid use, long-term antibiotic use, excessive stress, poor husbandry and hygiene, viral infections, and other chronic infections may cause immune suppression and lead to secondary candidiasis. 

In its advanced stages, Candida can affect a bird systemically, as it invades tissues outside the gastrointestinal tract and infects the rest of the body; however, systemic infection is rare. With a systemic infection, Candida can be found in the blood, certain body organs, and the bone marrow.

What are the signs of candidiasis?

Common clinical signs of candidiasis include:

• Lethargy
• Fluffed feathers
• Little to no appetite
• Vomiting or regurgitation
• Delayed crop emptying
• A distended crop full of mucus
• Occasionally a crop impacted with dry food, mucus, or other debris

How is candidiasis diagnosed?

Your avian veterinarian will start with a complete history, body weight, and physical examination of your bird. Since the clinical signs of candidiasis occur with many other diseases and are not specific to candidiasis, your veterinarian will likely advise a series of diagnostic tests to determine the exact cause of the disease.

Candidiasis is diagnosed by fungal culture and cytology (microscopic analysis) of fluid from either the crop or feces. Specific fungal culturing is recommended to differentiate Brewer’s yeast from Candida, as they can look similar under the microscope, and Brewer’s yeast is present in many baked goods and some hand-feeding formulas.

If your bird is not severely ill and has eaten baked goods or other yeast-containing foods within a day of the sample being taken, your veterinarian might suggest withholding all yeast-containing foods for a few days before rechecking a sample under the microscope. Severely affected birds should be treated regardless of whether they’ve eaten yeast-containing products.

The quality of the sample is essential. If a sample does not demonstrate yeast, especially if your bird is sick, it may indicate that the sickness is due to another illness. Further testing will be necessary to pinpoint the disease that is causing illness. It is common for candidiasis to develop secondary to other disease processes, so other tests are required to determine whether there are other problems predisposing your bird to secondary infection. Early diagnosis generally leads to faster resolution of underlying problems.

Can my bird be treated?

Yes, once diagnosed, candidiasis is treated with antifungal medications, and several medications are available. In addition to treating candidiasis, your veterinarian will diagnose and treat all predisposing factors or diseases.

Good hygiene, a clean environment, and fresh food and water are essential in managing this problem and maintaining your bird’s health. You can also help your bird to recover by correcting any dietary imbalances.

If your bird is diagnosed with candidiasis, follow your veterinarian’s recommendations in administering prescribed medications, eliminating foods that are high in natural sugars like treats and fruits, and ensuring your pet’s environment is adequately disinfected.