Macrorhabdus ornithogaster is a yeast that can cause infection in some bird species. It is often called megabacteria because microscopically it resembles extremely large bacteria. Because it is not bacteria macrorhabdosis have been proposed as the definitive name for this disease.
Originally, canaries and budgerigars were recognized as being infected with this organism. Other species commonly documented to be infected include lovebirds, cockatiels and parrotlets.
Signs of Illness
The most common presentation is a chronic condition, where the birds often appear healthy and look as though they are eating as well as or better than normal. They display the “masking” syndrome of appearing to eat, to avoid detection of weakness. Regurgitation is common. You may not see your bird vomit, but the appearance of sticky feathers on top of the head is the usual indication that it has been regurgitating. There may be diarrhea, increased urine, and for those birds that eat seed, you may see them passing undigested seed in the stool. These birds gradually lose weight, and by the time you notice that they are acting ill, they are often extremely emaciated.
To diagnose this disease, your veterinarian might see several indications on blood work. Also, the organism may be seen on a fecal examination from droppings. On larger birds, barium contrast study X-rays may give an indication of stomach ulceration and other changes in the intestinal tract.
Birds that are affected with other diseases, particularly circovirus, are predisposed to disease from macrorhabdosis due to their compromised immune system.
Other diseases that may cause these same symptoms include trichomoniasis (a protozoan parasite) candidiasis (another type of milder yeast infection), proventricular dilatation disease (PDD, which is a viral wasting disease) and toxicity from metals such as lead and zinc.
Treatment of an individual pet bird involves the use of an antifungal medication. Despite appropriate treatment, affected birds often do not survive a clinical infection. If you have multiple birds housed together or breeding birds, your veterinarian can help you devise a plan to control or eliminate this disease.
For more information on this subject, speak to the veterinarian who is treating your pet.
© 2005-2015 Teresa L. Lightfoot DVM, DABVP-Avian