Evaluation of recovery of Cryptosporidium parvum oocysts using membrane filtration

Abstract

Recovery of oocysts of Cryptosporidium parvum using 142 mm diameter 1.2 μm pore size acrylic copolymer membrane filters was evaluated. A mean recovery efficiency of 25.5% for oocyst concentrations of about 200 in 10 1 was achieved, making this method a simple and relatively efficient procedure compared with current standard methods.

Occurrence of Cryptosporidium oocysts and Giardia cysts in raw water from the Atibaia river, Campinas, Brazil

“…Presently, this method is considered particularly useful for rapid determination of the number of oocysts in raw water 3 . However, one disadvantage of the membrane acetone-dissolution is the hardening of the pellet containing oocysts (or cysts) after the centrifugation step, which may explain the 25.5% efficiency previously reported 3 ; the results of the control trial reveal Cryptosporidium and Giardia efficiency rates of 41.6% and 91.8% for RM procedure and 30.0% and 4.0% for ADM methods, respectively.…”

Recovery of Cryptosporidium oocysts from small and large volume water samples using a compressed foam filter system

“…1990 ;Dawson et al 1993 ;Smith et al 1993). In an extensive evaluation of methods, Wyn-Jones (1995, 1996) reported recoveries of 2-7% from tap and river water samples for polypropylene wound filters without a cleanup stage, and 0-12% following sucrose density flotation.…”

“…After filtration, the 142 mm diameter membrane filters were eluted by placing the membrane in a Minigrip ® sealable polythene bag with 20 ml of a 0·1% Tween-20 in PBS solution and rubbing the surface of the membrane for 5 min (Dawson et al 1993). The eluate was then collected from the bag and analysed.…”

“…A selection of concentrates was also subjected to a clean-up procedure prior to staining and microscopy. This consisted of a single density gradient flotation using potassium citrate with a density of 1·1820·05 at 20°C and centrifugation at 1000 g for 5 min (Dawson et al 1993). As much of the supernatant fluid as possible, including the interface, was recovered, without disturbing the pellet, prior to filtration onto 13 mm membranes and staining as for the raw concentrate samples.…”

“…Currently, the most commonly employed methods for the capture and recovery of oocysts from water rely on entrapment on either a wound polypropylene cartridge filter with 1 mm nominal pore size (Musial et al 1987 ;Anon. 1990) or membrane filters (Ongerth and Stibbs 1987 ;Dawson et al 1993). Although such filters can entrap up to 98% of seeded oocysts, losses arise when the oocysts cannot be effectively recovered or eluted from the cartridge or membrane (Smith et al 1993).…”