Effects of Ozone and Storage Temperature on Giardia Cysts

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

doi:10.1002/j.1551-8833.1985.tb05591.x

Cited by 41 publications

(24 citation statements)

References 18 publications

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“…Ozone has been reported to be effective in inactivating cysts of Giardia lamblia [6,22,24], Naegleria gruberi [23], oocysts of Cryptosporidium parvum [10,12] and Acanthamoeba culbertsoni [5]. The discrepancy in the effect of ozone seen in the present study may be due to the fact that the subject of our testing is a helminth egg, which is basically different from the cyst or oocyst of a single cell protozoan.…”

Section: Discussioncontrasting

confidence: 56%

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Effect of Ozone Treatment on Toxocara canis Eggs.

Ooi

Lin

Wang

1998

The Journal of Veterinary Medical Science

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ABSTRACT. The effect of ozone treatment on the development and viability of Toxocara canis eggs was studied. Despite treatment with ozone, unembryonated T. canis eggs could develop into viable second-stage larvae when assayed by larvae recovery after oral inoculation into mice. The viability of second stage larvae of T. canis was also not affected by ozone treatment. No significant difference was observed in the larvae recovery count and migratory pattern of the ozone-treated larvae and the untreated control because the majority of the larvae were recovered from the liver and lungs on day 2 postinoculation. However, scanning electron microscopy of the ozone treated T. canis eggs showed many blebs on the surface of the protein coat at the basement of the honeycomb-like structures. The honeycomblike structures on the egg surface were also observed to be distorted after ozone treatment. Thus, in spite of inducing some surface morphological changes on the egg, ozone was observed to have no effect on the viability of the embryonated second stage larvae of T. canis. -KEY WORDS: egg, larvae viability, ozone, scanning electron microscopy, Toxocara canis.J. Vet. Med. Sci. 60(2): 169-173, 1998 for 10 min to remove the mucus and then diluted with saline. After washing by successive centrifugations at 1,500 rpm in more than three changes of saline, a portion of the eggs was incubated in a conical flask in a solution containing 0.5% formaldehyde at 27°C for three weeks. The development of the embryo to the second stage larva was confirmed by examining a sample of the eggs under light microscope. These embryonated eggs were then treated with ozone followed by oral inoculation into mice. The other portion of the unembryonated eggs were first treated with ozone, followed by culturing in 0.5% formaldehyde until they develop to second stage larvae, and then orally inoculated into mice.For ozone treatment, aliquots of 20,000 eggs in oxygendemand-free deionized water were treated in a steady stream of ozone being generated at 3 l/min by an ozone generator, model RXO-5 (Ozoair, San Francisco, U.S.A.). The amount of ozone exposed to the eggs was adjusted by varying the time of exposure and the residual ozone was measured using the Indigo calorimetric method. Eggs were exposed to ozone for either 20 or 40 min and then immediately washed by diluting with deionized water followed by centrifugation. In a separate experiment to determine the initial ozone concentration using the same ozone generator machine and under almost similar condition, we found that the treated solution had residual ozone concentration of 3.86, 3.86, 4.38 and 4.62 mg/l of ozone after 0.5, 1.0, 1.5 and 2 min of treatment, respectively.Mice: Groups of three 6 to 8-week-old male outbred ICR mice (National Laboratory Animal Breeding and Research Center, [NLABRC] Taipei, Taiwan), which were given commercial feed pellet (Autoclavable Mouse 9f Diet, NLABRC) and water ad libitum, were orally inoculated with ozone-treated eggs which had been cultured until embryonated wi...

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Section: Discussioncontrasting

confidence: 56%

“…Only the zoonotic water-borne protozoa such as Giardia spp. [22,24], Naegleria spp. [5], Acanthomoeba spp.…”

mentioning

confidence: 99%

Effect of Ozone Treatment on Toxocara canis Eggs.

Ooi

Lin

Wang

1998

The Journal of Veterinary Medical Science

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“…Microbiology has so often been seen as a purely descriptive science, and this belies the voluminous work done in mathematical biology applied to the food, home and personal care, and pharmaceutical industries. The`Ct' concept, obtained from disinfection rates, is used to set disinfection times against, for example, Giardia cysts (Baumann and Ludwig 1962;Wickramanayake et al 1985;Finch et al 1993). The rationale behind the canning process is based on thermal disinfection modelling, albeit it on a less than precise model (Anderson et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Advances in disinfection testing and modelling

Lambert

2001

J Appl Microbiol

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“…C × T was calculated according to the log integration method (USEPA, 1990) using O3 residuals measured in the effluent of each of the five reactive flow chambers (chambers 1B, 2A, 2B, 3A, and 3B in Figure 3). On the basis of disinfection studies available in the literature (Oppenheimer et al, 2000; Oppenheimer et al, 1997a; Oppenheimer et al, 1997b; Finch et al, 1994; Wickramanayake et al, 1985), 10 times greater C × T was assumed for Cryptosporidium inactivation than was specified in the SWTR guidance manual value for Giardia inactivation.…”

Section: Experimental Materials and Methodsmentioning

confidence: 99%

“…Ozone (O 3 ) can inactivate Cryptosporidium , but the necessary O 3 dosages are much greater than those currently used to meet existing disinfection requirements (e.g., 0.5‐log Giardia or 2‐log virus). On the basis of recent research, inactivation of Cryptosporidium will require an O 3 exposure or C × T (measured as the product of disinfectant residual concentration and reaction time) roughly 10 times higher than that needed to inactivate Giardia (Oppenheimer et al, 1997a; Oppenheimer et al, 1997b; Finch et al, 1994; Wickramanayake et al, 1985). Although O 3 is effective against Cryptosporidium , moderate to high O 3 dosages may be required to achieve 1‐or 2‐log Cryptosporidium inactivation.…”

Section: Introductionmentioning

confidence: 99%

evaluation of pH and ammonia for controlling bromate during Cryptosporidium disinfection

Williams¹,

Coffey²,

Krasner³

2003

Journal AWWA

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This research evaluated pH suppression and/or ammonia addition for controlling bromate formation under disinfection conditions for Cryptosporidium. Lowering pH before ozonation substantially reduced bromate formation over a range of inactivation levels and bromide concentrations in two different source waters. Although pH suppression was an effective bromate control strategy, the cost of adjusting pH—in moderate‐ and high‐alkalinity waters and for high inactivation levels—may be from two to nine times greater than the cost of generating the ozone. The efficacy of ammonia was highly dependent on the source water. Adding ammonia was an effective bromate control strategy for one of the source waters tested; however, adding aqueous ammonia increased pH and exerted an additional ozone demand, thus lowering the disinfection credit.

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Effects of Ozone and Storage Temperature on Giardia Cysts

Cited by 41 publications

References 18 publications

Effect of Ozone Treatment on Toxocara canis Eggs.

Effect of Ozone Treatment on Toxocara canis Eggs.

Advances in disinfection testing and modelling

evaluation of pH and ammonia for controlling bromate during Cryptosporidium disinfection

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