Candidiasis

Candidiasis is a fungal infection of the digestive tract in birds, most often affecting the beak, throat and crop. It is caused by the yeast Candida albicans, which lives in small amounts even in a healthy bird. The problem arises when the yeast multiplies out of control, usually because the bird is young, weakened or has recently been on antibiotics. With timely treatment the outlook is generally good.

Candida is a so-called opportunistic pathogen: it does not attack a healthy bird with good immunity, but takes advantage of any weakness. When the balance of microorganisms in the gut is disturbed, the yeast spreads over the mucous membrane and forms plaques.

The most common causes:

• hand-fed chicks – formula that is too cold, too thick or left standing too long, dirty feeding equipment and slow crop emptying create ideal conditions for yeast;
• after antibiotic treatment – antibiotics also kill the beneficial bacteria that normally keep candida in check;
• vitamin A deficiency – the lining of the mouth and crop becomes more vulnerable;
• stress, poor diet and other diseases that weaken immunity;
• poor hygiene – soured or spoiled food, dirty water bowls, sugary food.

In birds that feed their young from the crop, the disease can be passed on to the chicks, and it spreads more easily through a flock when conditions are poor.

The signs depend on which part of the digestive tract is affected. In chicks the disease often starts unnoticed and then progresses quickly.

Beak, mouth and crop:

• white or greyish plaques in the beak and throat, sometimes cheese-like;
• the crop empties slowly or is still full after several hours;
• a sour or unpleasant smell from the beak;
• vomiting or regurgitating food;
• difficulty swallowing – the bird tries to eat and then gives up.

General signs:

• loss of appetite and weight loss;
• lethargy, apathy and ruffled feathers;
• diarrhoea; the droppings may be discoloured (yellowish or dark green because the bird is eating little);
• a weaker voice, or no calls at all when the changes in the throat are pronounced;
• in chicks, stunted growth.

• a chick's crop has not emptied even after several hours, or is tight and smells bad;
• the bird vomits or regurgitates repeatedly;
• white plaques are visible in the beak;
• the bird has not eaten for more than a day or is visibly losing weight;
• it sits ruffled up on the floor of the cage with its eyes closed;
• the symptoms appeared during or after antibiotic treatment.

In chicks, crop disease is an emergency: crop stasis can quickly lead to dehydration and exhaustion.

The vet examines the beak and crop and takes a swab from the mouth or crop. Yeast cells can be seen under the microscope, and a culture is done if needed. Since small amounts of candida are also found in healthy birds, the quantity and form matter, so the assessment should be left to the vet. The underlying cause that triggered the disease is often looked for too.

The vet prescribes antifungal drugs. For an infection confined to the digestive tract, nystatin is often used, as it acts directly on the mucous membrane; for more severe or widespread forms, drugs such as fluconazole or itraconazole. Treatment usually lasts several weeks and must not be stopped as soon as the bird seems better.

It is just as important to remove the cause: correct the diet, improve feeding hygiene, make up for vitamin A if it is lacking, and treat other diseases. For weakened birds the vet also provides supportive care with fluids and nutrition.

Do not give the bird medicines on your own, and do not stop a prescribed course of antibiotics without talking to the vet.

• Put the bird in a warm, dark and quiet box or cage, away from draughts.
• Separate it from other birds and use separate equipment.
• Do not force-feed it or pour water into its beak, especially if it is vomiting or its crop is full.
• Wash the food and water bowls every day and dry them thoroughly.
• If you are hand-feeding a chick, wash and dry the equipment after every feed, and always prepare the formula fresh.

If you have found a sick wild bird, hand it over to a rescue centre or a vet. Wild birds in Croatia are protected and may not be kept at home long-term.

• When hand-feeding, monitor crop emptying and follow the instructions for preparing the formula.
• Wash and dry all feeding equipment after use.
• Do not leave soft food, fruit and sprouted seed standing for hours.
• Provide a varied diet with enough vitamin A (e.g. green leafy vegetables, carrots).
• Use antibiotics only when a vet prescribes them.
• Reduce stress and keep the cage clean and dry.

Candidiasis is a common but curable fungal infection, especially in hand-fed chicks and birds that have had antibiotics. White plaques in the beak, a slow crop and vomiting are reasons to see a vet without delay. Good hygiene and a balanced diet are the best protection.