Inactivation of Single-Celled
            <i>Ascaris suum</i>
            Eggs by Low-Pressure UV Radiation

Brownell, Sarah; Nelson, Kara L.

doi:10.1128/aem.72.3.2178-2184.2006

Cited by 57 publications

(47 citation statements)

References 33 publications

(33 reference statements)

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“…All of the heated samples were incubated in 50-ml plastic centrifuge tubes in a water bath. The quasi-collimated beam used for the UV experiments has been described previously (5). In brief, the suspensions of eggs were placed in 50-mm glass petri dishes and gently stirred under a quasi-collimated UV beam.…”

Section: Vol 72 2006 Qpcr Quantification Of Viable Ascaris Eggs 7865mentioning

confidence: 99%

A Real-Time PCR Method for Quantifying Viable Ascaris Eggs Using the First Internally Transcribed Spacer Region of Ribosomal DNA

Pecson

Barrios

Johnson

et al. 2006

Appl Environ Microbiol

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Worldwide, 1.4 billion people are infected with the intestinal worm Ascaris lumbricoides. As a result, Ascaris eggs are commonly found in wastewater and sludges. The current microscopy method for detecting viable Ascaris eggs is time-and labor-intensive. The goal of this study was to develop a real-time quantitative PCR (qPCR) method to determine the levels of total and viable Ascaris eggs in laboratory solutions using the first internally transcribed spacer (ITS-1) region of ribosomal DNA (rDNA) and rRNA. ITS-1 rDNA levels were proportional to Ascaris egg cell numbers, increasing as eggs developed from single cells to mature larvae and ultimately reaching a constant level per egg. Treatments causing >99% inactivation (high heat, moderate heat, ammonia, and UV) eliminated this increase in ITS-1 rDNA levels and caused decreases that were dependent on the treatment type. By taking advantage of this difference in ITS-1 rDNA level between viable, larvated eggs and inactivated, single-celled eggs, qPCR results were used to develop inactivation profiles for the different treatments. No statistical difference from the standard microscopy method was found in 75% of the samples (12 of 16). ITS-1 rRNA was detected only in samples containing viable eggs, but the levels were more variable than rDNA levels and ITS-1 rRNA could not be used for quantification. The detection limit of the rDNA-based method was approximately one larvated egg or 90 single-celled eggs; the detection limit for the rRNA-based method was several orders of magnitude higher. The rDNA qPCR method is promising for both research and regulatory applications.

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Section: Vol 72 2006 Qpcr Quantification Of Viable Ascaris Eggs 7865mentioning

confidence: 99%

A Real-Time PCR Method for Quantifying Viable Ascaris Eggs Using the First Internally Transcribed Spacer Region of Ribosomal DNA

Pecson

Barrios

Johnson

et al. 2006

Appl Environ Microbiol

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“…Due to its resistance to biocontrol mechanisms (6) Ascaris is a model organism for developing environmentally safe disinfection methods (7,22). The eggs can be rendered nonviable through natural processes using extreme heat (Ͼ40°C) or with UV radiation (4). The use of short-chain fatty acids (SCFA) is another possible method of controlling Ascaris.…”

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confidence: 99%

Inactivation of Ascaris suum by Short-Chain Fatty Acids

Butkus

Hughes

Bowman

et al. 2011

Appl Environ Microbiol

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Ascaris suum eggs were inactivated in distilled water and digested sludge by butanoic, pentanoic, and hexanoic acids. The fatty acids (short-chain fatty acids [SCFA]) were effective only when protonated and at sufficient concentrations. The conjugate bases were not effective at the concentrations evaluated. Predictions from an inhibition model (50% inhibitory concentration [IC 50 ]) based on quantitative structure-activity relationships were congruent with inactivation data.The nematode Ascaris lumbricoides releases highly resistant, unembryonated eggs into the environment, causing ϳ1.3 billion illnesses worldwide (12). The swine parasite Ascaris suum is routinely used as a surrogate for the human parasite (22) and is often found in sludges. Due to its resistance to biocontrol mechanisms (6) Ascaris is a model organism for developing environmentally safe disinfection methods (7,22). The eggs can be rendered nonviable through natural processes using extreme heat (Ͼ40°C) or with UV radiation (4). The use of short-chain fatty acids (SCFA) is another possible method of controlling Ascaris. The toxicity of SCFA to bacteria, e.g., Escherichia coli (9), Streptococcus, and Staphylococcus (20), fungi (14, 23), insects (15), and birds (13) a Letters after viability measurements denote statistically significant differences among the percentages of viable eggs when compared to the water controls which were conducted with each round of testing (data not shown). The overall average percent survival for the water controls was 90.3 Ϯ 2.7%. Data marked "a" were tested with the Proc Mix of SAS (P Ͻ 0.01). Data marked "b" were tested with the Student t test (P Ͻ 0.05). SD, standard deviation.b ND, not done.

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“…Maya et al [4] reported that four genera of helminth eggs, i.e., Ascaris lumbricoides, Ascaris suum, Toxocara canis and Trichuris trichiura, are sensitive to environmental conditions in the larval state in the sludge. Furthermore, a proper combination of pH, dryness and contact time with temperatures above 60 °C can be applied to inactivate the eggs, efficiently [4,23]. Unfortunately, external energy and chemical-dependent technologies are in general not feasible for developing countries because they are complex, not sustainable and expensive in terms of investment and operation and maintenance costs [4,17,18,24].…”

Section: Introductionmentioning

confidence: 99%

Helminth Egg Removal Capacity of UASB Reactors under Subtropical Conditions

Yaya-Beas

Ayala-Limaylla

Kujawa-Roeleveld

et al. 2015

Water

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This research was conducted to study the anaerobic sludge filtration capacity regarding helminth egg removal in upflow anaerobic sludge blanket (UASB) reactors. Two 25 L lab-scale UASB reactors were operated at an ambient temperature which varied between 17.1 and 28.6 °C. Ascaris suum egg was selected as the model egg considering its similarity in terms of size and morphology to Ascaris lumbricoides, a human pathogen. Ascaris suum eggs were obtained from female parasites of infected pigs. The anaerobic sludge filtration capacity was performed applying upflow velocities between 0.09 and 0.68 m·h −1. Three sludge bed heights in the range of 0.30-0.40 m, 0.50-0.60 m and 0.60-0.70 m were applied. These sludge bed heights corresponded to 19%-25%, 31%-38% and 38%-44% of the total reactor height, respectively. Under the mentioned conditions, the average helminth egg removal efficiency was reciprocally correlated to the imposed upflow velocity. The studied lab-scale reactors reported an average helminth egg removal between 34%-100%, 30%-91% and 34%-56%, when the sludge bed in the UASB reactor OPEN ACCESSWater 2015, 7 2403 was 19%-25%, 31%-38% and 38%-44% of the total reactor height, respectively. The decreased filtration capacity at increasing sludge bed heights might be likely related to biogas production and channeling formation. The average helminth egg removal efficiency in the control experiments performed without any sludge bed, by plain sedimentation, varied between 44% and 66%.

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Inactivation of Single-Celled Ascaris suum Eggs by Low-Pressure UV Radiation

Cited by 57 publications

References 33 publications

A Real-Time PCR Method for Quantifying Viable Ascaris Eggs Using the First Internally Transcribed Spacer Region of Ribosomal DNA

A Real-Time PCR Method for Quantifying Viable Ascaris Eggs Using the First Internally Transcribed Spacer Region of Ribosomal DNA

Inactivation of Ascaris suum by Short-Chain Fatty Acids

Helminth Egg Removal Capacity of UASB Reactors under Subtropical Conditions

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