Inactivation of Giardia lamblia cysts with ozone

Wickramanayake, G. B.; Rubin, Alan J.; Sproul, Otis J.

doi:10.1128/aem.48.3.671-672.1984

Cited by 60 publications

(19 citation statements)

References 6 publications

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“…The design of the experimental unit and the disinfection procedures have been described in detail elsewhere. 8,16 Giardia muris was used to study the effect of cyst age on inactivation by ozone. After isolation, the cysts were stored at 5°C and used in the inactivation studies (25°C and pH 7) at regular intervals.…”

Section: Methodsmentioning

confidence: 99%

“…Jarroll et al5 examined the effects of pH (6)(7)(8) and temperature (5" -25°C) on inactivation of G. lamblia cysts by chlorine. Disinfection efficiency increased with decreasing pH and with increasing temperature.…”

Section: Previous Studiesmentioning

confidence: 99%

“…' Disinfection studies with G. lamblia were all but impossible until the recent development of in vitro excystation methods.2.3 Using excystation as the criterion for viability, these procedures have been used to determine the effect of physical and chemical disinfecting agents on the viability of G. lamblia cysts.4. 8 One of the problems encountered in these studies has been the lack of cyst availability. Another is thevariability in excystation rates, which leads to unreproducible results.g As a result, investigators have been seeking a model organism that could be used in place of G.…”

mentioning

confidence: 99%

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Effects of Ozone and Storage Temperature on Giardia Cysts

Wickramanayake¹,

Rubin²,

Sproul³

1985

Journal AWWA

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The effects of ozone and storage temperature on the survival of Giardia lamblia cysts, the cause of human giardiasis, and Giardia muris, a parasite of mice, were compared. The viabilities of the cysts were similar over a period of 25 days of storage in the range of -6" to 37°C; the optimum temperature for their long-term survival was determined to be about 5°C. Ozone was extremely effective for inactivating cysts of both Giardia species, with G. muris being consistently more resistant than G. lamblia at pH 7 and 5°C and 25°C.

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Section: Methodsmentioning

confidence: 99%

Section: Previous Studiesmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of Ozone and Storage Temperature on Giardia Cysts

Wickramanayake¹,

Rubin²,

Sproul³

1985

Journal AWWA

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“…Because of difficulties in detection and viability determination, the requirement for G. lamblia was defined in terms of disinfectant concentrationtime products (21). Published ozonation values were based on the extrapolation of 99% inactivation of G. lamblia results from a single laboratory (22,23). More recently, other work on ozone inactivation of Giardia muris has been performed at pilot scale by the Metropolitan Water District of Southern California (24).…”

mentioning

confidence: 99%

Comparison of animal infectivity, excystation, and fluorogenic dye as measures of Giardia muris cyst inactivation by ozone

Labatiuk

Schaefer

Finch

et al. 1991

Appl Environ Microbiol

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Giardia muris cyst viability after ozonation was compared by using fluorescein diacetate-ethidium bromide staining, the C3H/HeN mouse-G. muris model, and in vitro excystation. Bench-scale batch experiments were conducted under laboratory conditions (pH 6.7, 22°C) in ozone-demand-free phosphate buffer. There was a significant difference between fluorogenic staining and infectivity (P c 0.05), with fluorogenic staining overestimating viability compared with infectivity estimates of viability. This suggests that viable cysts as indicated by fluorogenic dyes may not be able to complete the life cycle and produce an infection. No significant differences between infectivity and excystation and between fluorogenic staining and excystation (P c 0.05) were detected for inactivations up to 99.9%. Only animal infectivity had the sensitivity to detect inactivations greater than 99.9%. Therefore, the animal model is the best method currently available for detecting high levels of G. muris cyst inactivation.

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“…Previous studies on the inactivation of cysts of G. lamblia have been reported by Rice et al (9), Jarroll et al (7), and Hibler et al (5), who used chlorine, and by Wickramanayake et al (13), who used ozone. A similar study in our laboratory on the inactivation of Giardia muris cysts by free chlorine has also been described (8).…”

mentioning

confidence: 99%

Inactivation of gerbil-cultured Giardia lamblia cysts by free chlorine

Rubin

Evers

Eyman

et al. 1989

Appl Environ Microbiol

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Giardia lamblia cysts were harvested from Mongolian gerbils and exposed to free chlorine in buffered water at pH 5, 7, and 9 at 15°C. The contact times required to obtain a 2-log reduction in cyst survival (i.e., a 99% kill) were interpolated from survival curves generated at fixed concentrations of chlorine in the range of 0.25 to about 16 mg/liter. Concentration-time (C-t') products for 99% inactivation ranged from about 120 to nearly 1,500 mg-min/liter. These values are higher than those reported previously for free chlorine using G. lamblia cysts from infected humans. The cysts isolated from gerbils, as with other Giardia cysts, were unusually sensitive to chlorine in alkaline solutions.

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Inactivation of Giardia lamblia cysts with ozone

Abstract: Giardia lamblia cysts were inactivated in water with ozone at pH 7.0 and 5 and 25 degrees C. The concentration-time products for 99% inactivation were 0.53 and 0.17 mg-min/liter at 5 and 25 degrees C, respectively. These products were significantly lower than those reported for chlorine.

Cited by 60 publications

References 6 publications

Effects of Ozone and Storage Temperature on Giardia Cysts

Effects of Ozone and Storage Temperature on Giardia Cysts

Comparison of animal infectivity, excystation, and fluorogenic dye as measures of Giardia muris cyst inactivation by ozone

Inactivation of gerbil-cultured Giardia lamblia cysts by free chlorine

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