Encephalitozoon hellem infection in aviary passerine and psittacine birds in Spain

• Severe intestinal microsporidiosis caused by Encephalitozoonhellem were diagnosed in a European goldfinch, a canary, and lovebird based on histopathological and histochemical findings, and PCR with nucleotide sequencing from paraffin-embedded intestinal tissue.
• These are the first documented cases of microsporidiosis and E. hellem infection in the European goldfinch and canary, and in passerine birds in the Northern hemisphere.
• Microsporidiosis previously described in lovebirds, but microsporidia were not typed except in studies of fecal shedding.
• All 3 birds died mainly of severe concurrent infections, but intense E. hellem infection of absortive intestinal epithelium may have contributed to exacerbated catabolism.

A European goldfinch (Carduelis carduelis), a canary (Serinus canaria), and a lovebird (Agapornis roseicollis) captive-bred at three different private aviaries in Spain were submitted for necropsy with a history of weakness and ruffled feathers, weight loss associated with glossitis, and respiratory disease, respectively. Microscopically, enterocytes in the jejunum and ileum contained colonies of gram- and Stamp-positive, oval to elliptical microorganisms within parasitophorous vacuoles in the apical cytoplasm. Nested PCR using MSP primers that target microsporidian RNA genes produced amplicons of expected size for Encephalitozoon species, and analysis of forward and reverse DNA sequences confirmed the presence of Encephalitozoon hellem in all cases. The main cause of death of all three birds consisted of concurrent infections. However, intestinal encephalitozoonosis may have contributed to exacerbated catabolism. Encephalitozoonosis (or microsporidiosis) has been rarely described in passerine birds.