Analysis for Giardia cysts and Cryptosporidium oocysts in water samples from small water systems in Taiwan

Giardia and Cryptosporidium have emerged as waterborne pathogens of concern . Twenty-six water samples were collected from small water systems in Taiwa n and checked for the occurrence of both parasites. Water quality parameter s and characteristics of the sampling sites were also recorded. The frequen cies of occurrence for Giardia and Cryptosporidium were 46.2% for each; and their mean concentrations were 79.5 cysts/100 1 and 22.1 oocysts/100 1, re spectively. The concentrations of oocysts and heterotrophic bacteria exhibi ted the highest correlation and followed the concentrations of the two prot ozoa. The water samples from sites with filtration devices had a lower oocy st concentration than those from sites without filtration devices, while no significant difference was found for cysts. The level of each parasite had no direct relationship with altitude. The cyst concentrations increased pr oportionally with the consumer population using the water systems. Risk ass essment of the parasitic infections suggests that setting up disinfection d evices in the small water systems would be needed.