In recent years, Trichomonas gallinae emerged as the causative agent of an infectious disease of passerine birds in Europe leading to epidemic mortality of especially greenfinches Chloris chloris and chaffinches Fringilla coelebs. After the appearance of finch trichomonosis in the UK and Fennoscandia, the disease spread to Central Europe. Finch trichomonosis first reached Austria and Slovenia in 2012. In the present study the genetic heterogeneity of T. gallinae isolates from incidents in Austria and Slovenia were investigated and compared with British isolates. For this purpose comparative sequence analyses of the four genomic loci ITS1-5.8S-ITS2, 18S rRNA, rpb1 and Fe-hydrogenase were performed. The results corroborate that one clonal T. gallinae strain caused the emerging infectious disease within passerine birds and that the disease is continuing to spread in Europe. The same clonal strain was also found in a columbid bird from Austria. Additionally, the present study demonstrates clearly the importance of multi-locus sequence typing for discrimination of circulating T. gallinae strains.