title: Detection of Toxoplasma gondii oocysts and surrogate microspheres in water using ultrafiltration and capsule filtration.
abstract: While reports on waterborne infections with Toxoplasma gondii are emerging worldwide, detection of this zoonotic parasite in water remains challenging. Lack of standardized and quantitative methods for detection of T. gondii oocysts in water also limits research on the transport and fate of this pathogen through aquatic habitats. Here, we compare the ability of hollow-fiber ultrafiltration and capsule filtration to concentrate oocysts in spiked tap water, fresh surface water, and seawater samples. Detection of T. gondii oocysts in concentrated samples was achieved using molecular methods, as well as visually via epifluorescent microscopy. In addition to oocysts, water samples were spiked with T. gondii surrogate microspheres, and detection of microspheres was performed using flow cytometry and epifluorescent microscopy. Results demonstrate that both water concentration methods followed by microscopy allowed for quantitative detection of T. gondii oocysts and surrogate microspheres. For T. gondii oocysts, microscopy was more sensitive than TaqMan and conventional PCR, and allowed for detection of oocysts in all water samples tested. Compared with flow cytometry, microscopy was also a more cost-efficient and precise method for detection of fluorescent surrogate microspheres in tap, fresh and seawater samples. This study describes a novel approach for quantitative detection of T. gondii oocysts in drinking and environmental water samples. The techniques described for concentrating and detecting surrogate microspheres have broad application for evaluating the transport and fate of oocysts, as well as the efficiency of water treatment methods for removal of T. gondii from water supplies.
authors.affiliation: Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA. kshapiro@ucdavis.edu
authors.forename: Karen
authors.initials: K
authors.lastname: Shapiro
authors.forename: Jonna A K
authors.initials: JA
authors.lastname: Mazet
authors.forename: Alexander
authors.initials: A
authors.lastname: Schriewer
authors.forename: Stefan
authors.initials: S
authors.lastname: Wuertz
authors.forename: Heather
authors.initials: H
authors.lastname: Fritz
authors.forename: Woutrina A
authors.initials: WA
authors.lastname: Miller
authors.forename: John
authors.initials: J
authors.lastname: Largier
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Conrad
mesh_terms: D000818:Animals; D005434:Flow Cytometry; D005618:Fresh Water / Q000469:parasitology; D008856:Microscopy, Fluorescence; D008863:Microspheres; D033661:Oocysts / Q000166:cytology*; D012623:Seawater / Q000469:parasitology; D014122:Toxoplasma / Q000302:isolation & purification*; D014462:Ultrafiltration / Q000379:methods*; D014867:Water / Q000469:parasitology* / Q000592:standards
chemical_list: D014867:Water