Abstract
Avian macrorhabdosis is a disease of wild and captive birds (psittacines, passerines and other species) distributed worldwide, and is caused by the opportunistic yeast Macrorhabdus ornithogaster. The disease is usually chronic, and is manifested by nonspecific clinical signs (emaciation, anorexia, depression, cachexia and ultimately death), or gastrointestinal signs (regurgitation or attempted vomiting, watery diarrhea, and weight loss despite preserved appetite). It can also occur in a subclinical form, while the clinical disease can last for weeks, months (or even years). Diagnosis and therapy are still challenging for bird specialists for many reasons. During life, the diagnosis is made directly from stool smears after Gram staining by finding characteristic large, Gram-positive, 20 μm - 80 μm long and 3 μm - 4 μm wide rods, as well as a smear of the isthmus (proventricular-ventricular junction) after dissection. Early detection is possible using newly developed PCR tests. The only available drug against avian macrorhabdosis is amphotericin B, which is not effective in many cases regardless of the dose and duration of therapy. Although many birds have the causative agent in their digestive system, the disease is most likely to occur as a result of weakened immunity due to stress, poor hygiene, improper housing conditions and improper feeding, so regular periodic testing for macrorhabdosis is necessary.
