Detection of microsporidia in surface water: a one-year follow-up study

In order to estimate the rate and seasonal variation of Enterocytozoon bien eusi contamination of surface water, sequential samples of water from the R iver Seine in France were collected during a 1-year period. Each sample (30 0-600 l) was submitted to sequential filtrations, and the filters were then examined for microsporidia using light microscopy and nested polymerase ch ain reaction (PCR) for E. bieneusi. Amplified products were hybridized with a E. bieneusi-specific probe. Twenty-five samples of water were analyzed d uring 1 year. Microscopic examination of stained filters proved unreliable for the identification of spores. Using nested PCR, 16 of 25 specimens were positive (64%), Unexpectedly, E. bieneusi was identified in only one sampl e by specific hybridization underlining the lack of specificity of ours pri mers. Nevertheless, using DNA sequence analysis, unknown microsporidia spec ies were identified in eight cases, which had highest scores of homology wi th Vittaforma corneae or Pleistophora. This study shows a low rate of water contamination by E. bieneusi suggesting that the risk of waterborne transm ission to humans is limited. (C) 2000 Federation of European Microbiologica l Societies. Published by Elsevier Science B.V. All rights reserved.