2008 Volume 45 Pages 371-377
The objective of this study was to determine the occurrence of Cryptosporidium and Giardia in river water used for drinking water. Twenty-three river water samples were collected at 7 sites in tributary rivers of the Tonegawa River basin in Japan from October 2007 to February 2008. Cryptosporidium and Giardia were detected in 21 (91%) and 18 (78%) of the 23 samples (10 liters each), showing the highest concentration of 790 oocysts/10 L and 37 cysts/10 L, respectively. A single Cryptosporidium oocyst was isolated from the concentrated river water sample by using micromanipulation technique, followed by DNA extraction and nested PCR of the 18S rDNA gene. Fifty-six (15%) out of 376 single-oocyst samples were positive for the Cryptosporidium 18S rDNA gene, and subsequent direct DNA-sequencing revealed the presence of four genotypes: C. suis (48 samples, or 8 strains), C. andersoni (5 samples, or 4 strains), C. pig genotype II (2 samples, or 2 strains), and C. meleagridis (1 sample, or 1 strain).
