Avian gastric yeast (macrorhabdosis) in cockatiel, budgerigar and grey parrot: a focus on the clinical signs, molecular detection and phylogenetic evaluation

Macrorhabdus ornithogaster is a microorganism that causes nonspecific and general clinical symptoms and to this day, diagnosis and also treatment have been yet hard. The present study was conducted to survey the prevalence of macrorhabdosis and to characterize M. ornithogaster phylogenetically in Psittaciformes suspected of macrorhabdosis from January 2018 to May 2019 in Ahvaz, Iran. For this purpose, fecal samples were collected from Psittaciformes with signs of the disease. Wet mounts were prepared from fecal samples and examined carefully using a light microscope. Samples from parrots with gastrointestinal symptoms of the disease were chosen for molecular diagnosis of the organism and DNA was extracted from these samples. For detection of M. ornithogaster, primer sets (BIG1, Sm4) and (AGY1, Sm4) which target the 18S rDNA gene were selected and Semi-nested polymerase chain reaction (Semi-nested PCR) was performed. The PCR method confirmed the presence of M. ornithogaster in 14.00% of the samples. Purified PCR products were sequenced for more accurate confirmation and according to the gene sequence all sequences were owned by M. ornithogaster. The results disclosed a 96.03% - 100% identity when compared to other sequences of M. ornithogaster which had previously been deposited in the GenBank® from Germany and the USA. The results of this study proved the circulation of M. ornithogaster between cockatiel, budgerigar and grey parrot. The prevalence of macrorhabdosis was higher in cockatiel compared to budgerigar and grey parrot. As far as the authors know, this was the first record of macrorhabdosis in African grey parrots.