What is candidiasis?
The causative agent is called Candida albicans, which is a small yeast that lives in the alimentary tract (anywhere between the mouth and the vent). Infection is mainly associated with warm, humid environments, such as those found in brooders, so often affects young birds. However, it is frequently over-diagnosed in older birds! C. albicans can be a primary gastrointestinal pathogen, especially in finches, but it is more frequently secondary to another problem. The yeast infection affects the entire length of the gastrointestinal tract but does not usually become systemic, i.e. it does not pass into the rest of the body.
Clinical signs
Many of the clinical signs associated with a C. albicans infection are non-specific, and often there will be additional clinical signs that pertain to the primary cause. Affected birds may demonstrate regurgitation or vomiting with concurrent head flicking: often it is only the head movement that is noticed by owners. Birds may also suffer from lethargy and weight loss. These birds are unable to process the food passing through their body, so can starve even when seemingly eating normally. They may also have diarrhoea with undigested food present within it. Affected birds may experience moulting problems or breathing problems as a result of swelling of the gastrointestinal tract. This reduces the space internally for the airsacs to expand. They may therefore adopt a sitting position with a forward tilt so that the tail and coelom (the equivalent of the abdomen) are elevated. This increases the internal space and so eases breathing. Eye and skin lesions are also common.
Diagnosis
The diagnosis of an infection with C. albicans is relatively simple, and can be done from a crop wash, a feacal wet preparation (often less effective than a crop wash), and sometimes from skin scrapes. The presence of budding yeast indicates an active infection, but it is important to note that it is normal to have some Candida present in many birds!
Even once an active infection with C. albicans has been positively identified, the bird cannot be said to have been ‘diagnosed’ because the infection is often secondary to a change in gastrointestinal flora or to stress. In order to understand what is truly happening in that individual, the primary cause must be found and treated. This may include blood tests, faecal tests and further diagnostic imaging.
Treatment
Frequently, candidiasis is not treated at all: instead, we focus on finding the causative problem and rectifying it. However, some birds may become very unwell and require treatment, as part of a stabilisation process. These patients will require further investigation, and successful treatment does not indicate true resolution. Complete treatment only happens once the cause has been found an eliminated.
Treatment of C. albicans infection is with an oral medication, but this will only treat the yeast infection. Alternative medications are available and may be preferable in younger birds, but these have more dangerous side-effects. Nutritional and fluid support may be required, and pro-biotic formulas may aid rectification of the normal gastrointestinal flora. The most important part of treatment is treating the primary cause of stress or disease.
Can I get C. albicans myself?
C.albicans causes vaginal thrush in people. It is spread from affected birds in gastrointestinal fluids (droppings and regurgita), so providing that thorough hand-washing is performed after contact with secretions (including those on the bird), infection is unlikely.
