Concentrating Toxoplasma gondii and Cyclospora cayetanensis from surface water and drinking water by continuous separation channel centrifugation

Abstract

Aims: To evaluate the effectiveness of continuous separation channel centrifugation for concentrating Toxoplasma gondii and Cyclospora cayetanensis from drinking water and environmental waters. Methods and Results: Ready‐to‐seed vials with known quantities of T. gondii and C. cayetanensis oocysts were prepared by flow cytometry. Oocysts were seeded at densities ranging from 1 to 1000 oocysts l−1 into 10 to 100 l test volumes of finished drinking water, water with manipulated turbidity, and the source waters from nine drinking water utilities. Oocysts were recovered using continuous separation channel centrifugation and counted on membrane filters using epifluorescent microscopy. Recovery efficiencies of both parasites were ≥84% in 10 l volumes of drinking water. In source waters, recoveries ranged from 64% to 100%, with the lowest recoveries in the most turbid waters. Method precision was between 10% and 20% coefficient of variation. Conclusion: Toxoplasma gondii and C. cayetanensis are effectively concentrated from various water matrices by continuous separation channel centrifugation. Significance and Impact of the Study: Waterborne transmission of T. gondii and C. cayetanensis presents another challenge in producing clean drinking water and protecting public health. Detection of these parasites relies on effectively concentrating oocysts from ambient water, otherwise false negatives may result. Validation data specific to T. gondii and C. cayetanensis concentration methods are limited. Continuous separation channel centrifugation recovers oocysts with high efficiency and precision, the method attributes required to accurately assess the risk of waterborne transmission.

Surveillance for Toxoplasma gondii in California mussels (Mytilus californianus) reveals transmission of atypical genotypes from land to sea

“…An absence of data on the distribution of T. gondii oocysts in marine habitats is in part due to a lack of sensitive methods for detection of the parasite in large bodies of water. While numerous methods for T. gondii detection in water have been described (Isaac‐Renton et al ., ; Kourenti and Karanis, ; Dumetre and Darde, ; Aubert and Villena, ; Borchardt et al ., ; Shapiro et al ., ), none have successfully detected the parasite in seawater from marine ecosystems. Further, while commercial methods utilizing monoclonal antibodies are available to concentrate related protozoal pathogens such as Cryptosporidium and Giardia from water (U.S.EPA, ), such assays are not currently available for T. gondii .…”

The Life Cycle of Toxoplasma gondii in the Natural Environment

“…Moreover, two recent methodological advances should improve our knowledge of environmental contamination. First, new methods to detect oocysts in soil [185] and water [186,187,188] have been proposed, based on molecular detection or immunocapture. Being highly sensitive, these methods should allow researchers to better characterize areas and periods at risk of contamination.…”

A scoping review of the detection, epidemiology and control ofCyclospora cayetanensiswith an emphasis on produce, water and soil

“…Water. Two detection-method studies evaluated detection in water [20, 21]. Both examined river water, and one [20] also tested lake and drinking water.…”