Overview
ISO 15553:2006 - Water quality: Isolation and identification of Cryptosporidium oocysts and Giardia cysts from water specifies a validated laboratory method for the detection and enumeration of Cryptosporidium oocysts and Giardia cysts in water. The method applies to surface and ground waters, treated and mineral waters, swimming pools and recreational waters. It defines sampling, concentration, purification and microscopic identification steps, but does not determine species, host origin, viability or infectivity.
Key topics and technical requirements
- Sample volumes & sampling: Procedure supports small (≈10 L) to large (up to 1 000 L) sample volumes; choice depends on water type, turbidity and required sensitivity. On-site filtration may be needed for large volumes.
- Concentration by filtration and elution: Uses cartridge or membrane filtration systems (examples: Pall Envirochek STD/HV, IDEXX Filta-Max®) and manufacturer-specified elution buffers and pumps.
- Further concentration & purification: Immunomagnetic separation (IMS) using paramagnetic beads coated with specific antibodies to isolate oocysts/cysts from particulate matter.
- Staining & detection: Fluorescent monoclonal antibodies (e.g. FITC conjugates) plus nuclear stains (DAPI) are used. Examination is by epifluorescence combined with differential interference contrast (DIC) microscopy (total magnification ~1 000×).
- Equipment & reagents: Typical lab apparatus includes peristaltic pumps, centrifuges, magnetic particle concentrators, well slides, calibrated micropipettes and appropriate reagents/buffers (reagent preparation is detailed in annexes).
- Quality control & competency: For reliable results, analysts must be experienced, pass competency tests, perform regular recovery/positive control checks (Annex D), and participate in external quality assurance schemes. Annexes provide performance data and alternative methods.
Practical applications and users
- Environmental and public health laboratories monitoring microbial contamination in drinking water, source waters and recreational facilities.
- Water suppliers and utilities conducting routine surveillance and incident investigations.
- Regulatory agencies and consultants performing compliance testing, risk assessment and outbreak response.
Practical benefits include standardized procedures for comparable recoveries, documented QC, and guidance for selecting filtration and concentration techniques suited to sample type and turbidity.
Related information
- Prepared by ISO/TC 147 (Water quality), Subcommittee SC4 (Microbiological methods).
- Annexes cover reagent preparation, small-volume concentration, calibration of eyepiece graticules, recovery testing, performance data and alternative approaches.
Keywords: ISO 15553:2006, water quality standard, Cryptosporidium oocysts, Giardia cysts, immunomagnetic separation (IMS), filtration and elution, fluorescence microscopy, environmental testing, drinking water monitoring.
