This study was carried out to estimate the prevalence and potential for human infectivity of Giardia cysts in Canadian drinking water supplies.
The presence of Cryptosporidium oocysts was also noted, but isolates were not collected for further study.
A total of 1,760 raw water samples, treated water samples, and raw sewage samples were collected from 72 municipalities across Canada for analysis, 58 of which treat their water by chlorination alone.
Giardia cysts were found in 73% of raw sewage samples, 21% of raw water samples, and 18.2% of treated water samples.
There was a trend to higher concentration and more frequent incidence of Giardia cysts in the spring and fall, but positive samples were found in all seasons.
Cryptosporidium oocysts were found in 6.1% of raw sewage samples, 4.5% of raw water samples, and 3.5% of treated water samples.
Giardia cyst viability was assessed by infecting Mongolian gerbils (Meriones unguiculatus) and by use of a modified propidium iodide dye exclusion test, and the results were not always in agreement.
No Cryptosporidium isolates were recovered from gerbils, but 8 of 276 (3%) water samples and 19 of 113 (17%) sewage samples resulted in positive Giardia infections.
Most of the water samples contained a low number of cysts, and 12 Giardia isolates were successfully recovered from gerbils and cultured. (...)
Mots-clés Pascal : Cryptosporidium, Sporozoa, Protozoa, Oocyste, Isolat, Eau potable, Canada, Amérique du Nord, Amérique, Caractérisation, Biotype, Caryotype, Qualité eau, Pouvoir infectant, Viabilité, Diplomonadida, Giardia
Mots-clés Pascal anglais : Cryptosporidium, Sporozoa, Protozoa, Oocyst, Isolate, Drinking water, Canada, North America, America, Characterization, Biotype, Karyotype, Water quality, Infectivity, Viability, Diplomonadida
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 96-0426781
Code Inist : 002B30A02A. Création : 10/04/1997.