Researchers at the Northeast Agricultural University in Harbin have discovered a high prevalence and wide genetic diversity of Enterocytozoon bieneusi of the types that can be transmitted to Man in pigs in northeast China.

They suggest that the co-occurrence of seven known genotypes in pigs and humans and four in pigs and wastewater indicate pigs may be a reservoir for human microsporidiosis and an important source of water contamination in China.

In the introduction to their paper published in Parasitology Research, W. Li and co-authors explain that, despite the advances in defining E. bieneusi genotypes worldwide, rarely have genotypic surveys been documented on this ubiquitous pathogenic protozoan in mammals in China, especially the role of pigs in zoonotic transmission of microsporidiosis remains unclear.

In this study, the distribution of E. bieneusi genotypes in 113 duodenal mucosal specimens of pigs with acute diarrhea from 15 cities in northeast China was determined by PCR and DNA sequence analysis of the ribosomal internal transcribed spacer.

The organism was detected in 51 (45.1 per cent) pigs from 12 cities, with infection rates of the nursery pigs (21/33, 63.6 per cent) significantly higher than in suckling piglets (25/61, 41.0 per cent) or growing pigs (5/19, 26.3 per cent) ones.

E. bieneusi has nine known human-pathogenic genotypes (D, EbpA, EbpC, EbpD, H, Henan-I, Henan-III, Henan-IV, and O) and eight new genotypes (CS-1 to CS-8). Genotypes D, EbpA, EbpC, EbpD, Henan-I, Henan-III, and Henan-IV have been found in human infections and D, EbpA, EbpC, and EbpD in wastewater in central China.

These new genotypes were genetically clustered into a group of existing E. bieneusi genotypes with zoonotic potential, Li and co-authors added.

Reference

Li W., R. Diao, J. Yang, L. Xiao, Y. Lu, Y. Li and M. Song. 2014. High diversity of human-pathogenic Enterocytozoon bieneusi genotypes in swine in northeast China. Parasitol Res. 2014 Mar;113(3):1147-53. doi: 10.1007/s00436-014-3752-9. Epub 2014 Jan 18.