Molecular characterization and genotyping of human related microsporidia in free-ranging and captive pigeons of Tehran, Iran.

Microsporidia are opportunistic pathogens in nature infecting all animal phyla. Samples of intestinal content from 147 pigeons from various regions of Tehran (Iran) were analyzed for occurred microsporidia by PCR and sequencing. The DNA isolated from 31 samples (21%) of microsporidia-positive was amplified with specific primers for the four most frequent human microsporidia. Enterocytozoon bieneusi was the most common species and was recognized in thirteen pigeons (42%). Four pigeons were positive for Encephalitozoon intestinalis (12.9%), six for Encephalitozoon hellem (19.3%) and two for Encephalitozoon cuniculi (6.4%). Mixed infections were detected in six another pigeons: E. bieneusi and E. hellem were detected in two cases (4.8%); E. bieneusi was associated with E. intestinalis in one case (0.8%); E. hellem and E. intestinalis coexisted in one; and E. hellem and E. cuniculi were identified in two pigeons. The genotypes of internal transcribed spacer (ITS) of the rRNA gene were determined for all isolates with single infections. Six isolates of E. bieneusi belonged to the genotype D (46.2%), three to the genotype M (23%), and four to the genotype J (30.8%). Sequences of four E. hellem isolates were same to genotype 1A and two were identical with genotype 3. In two cases of the pigeons, E. cuniculi genotype I, II were identified. This study implicates pigeons as potential sources of microsporidia infection for humans.