New filtration system for efficient recovery of waterborne Cryptosporidium oocysts and Giardia cysts

AimsTo develop a filtration unit for efficient recovery of waterborne Cryptosporidium oocysts and Giardia cysts ((oo-)cysts) in drinking water.Methods and ResultsThis unit utilizes a metallic filter and an ultrasound transducer for eluting (oo-)cysts, with a fixed retentate backwash volume; approx. 400l. Changes in the viability was evaluated by seeding wild type (oo-)cysts (1x10(4)) followed by sonication for 5, 10, 20 or 40s (five replicates for each period). Flow cytometry analysis showed negligible increase in the mortality of (oo-)cysts exposed to 5-10s of sonication. Recovery rate was assessed by seeding ColorSeed (10 replicates) into the filter unit followed by air backwash to a glass slide and counting of (oo-)cysts by epifluorescent microscopy. High recovery rates (meanSD) were found: 849%48 for Giardia cysts and 70%+/- 65 for Cryptosporidium oocysts. DNA of seeded wild type (oo-)cysts (1x10(2); 10 replicates) was successfully amplified using real-time PCR.ConclusionsThe use of a metallic filter, sonication and air backwash' were key factors for creating a highly efficient system for recovery of apparently undamaged protozoa.Significance and Impact of the StudyThis reagent-less system can be used for monitoring of parasite contamination in drinking water.