Enumeration of Cryptosporidium oocysts from surface water concentrates by laser-scanning cytometry

• Published in: Water science and technology 2000-01, Vol.41 (7), p.197-202
• Main Authors: ZANELLI, F, COMPAGNON, B, JORET, J. C, DE ROUBIN, M. R
• Format: Article
• Language: English
• Subjects: Air. Soil. Water. Waste. Feeding; Antibodies; Applied sciences; Biological and medical sciences; Cryptosporidium; Cytometry; Data processing; Drinking water and swimming-pool water. Desalination; Enumeration; Environment. Living conditions; Exact sciences and technology; Flocculation; Flotation; Fundamental and applied biological sciences. Psychology; General aspects and techniques; Immunomagnetic separation; Lasers; Medical sciences; Oocysts; Pollution; Protozoa; Public health. Hygiene; Public health. Hygiene-occupational medicine; Purification; Scanning; Sucrose; Sugar; Surface water; Water analysis; Water purification; Water sampling; Water treatment and pollution
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2000.0133

The utilization of the ChemScan registered RDI was tested for different types of water concentrates. Concentrates were prepared by cartridge filtration or flocculation, and analysed either without purification, or after Immunomagnetic separation (IMS) or flotation on percoll-sucrose gradients. The enumeration of the oocysts was subsequently performed using the ChemScan registered RDI Cryptosporidium application. Enumeration by direct microscopic observation of the entire surface of the membrane was carried out as a control, and recoveries were calculated as a ratio between the ChemScan registered RDI result and the result obtained with direct microscopic enumeration. The Chemscan enumeration technique proved reliable, with recoveries yielding close to 100% in most cases (average 125%, range from 86 to 467 %) for all the concentration/purification techniques tested. The quality of the antibodies was shown to be critical, with antibodies from some suppliers yielding recoveries a low as 10% in some cases. This difficulty could, however, be overcome by the utilization of the antibody provided by Chemunex. These data conclusively prove that laser scanning cytometry, which greatly facilitates the microscopic enumeration of Cryptosporidium oocysts from water samples and decreases the time of observation by four to six times, can be successfully applied to water concentrates prepared from a variety of concentration/purification techniques.