Detection of giardia cysts and cryptosporidium oocysts in central Taiwan rivers by immunofluorescence assay.

From November 1998 through 1999, water samples collected from the Faze, Kanwe, and Dajia rivers were analyzed using a combined immunofluorescence antibody method for detecting cysts of Giardia spp. and oocysts of Cryptosporidium spp. Water samples of the Kanwe River were collected downstream of a piggery; 5 to 469 cysts and 11 to 1,102 oocysts per 100 L were found in the water samples. The sampling site of the Faze River was upstream of the same piggery, and there were 110 cysts and 188 oocysts per 100 L of water samples. Water samples from the Dajia River were taken from an inlet of a water purification plant. There were 0 to 14.4 cysts and 14.3 to 50.5 oocysts per 100 L of water samples. Results indicate that the presence of Giardia cysts and Cryptosporidium oocysts in the surface water is closely related to the discharge of piggery wastes. Cysts and oocysts were found less often in the source water of a water purification plant.