Occurrence of human pathogenic microsporidia in irrigation water and ultraviolet light and chlorine inactivation of enteric adenovirus type 40 and feline calicivirus

Persistent Link:
http://hdl.handle.net/10150/290101
Title:
Occurrence of human pathogenic microsporidia in irrigation water and ultraviolet light and chlorine inactivation of enteric adenovirus type 40 and feline calicivirus
Author:
Thurston, Jeanette Ann
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The occurrence and disinfectant effectiveness for pathogens which are known or thought to be important in waterborne disease was evaluated. In the first study, the occurrence of human pathogenic microsporidia, Giardia cysts and Cryptosporidium oocysts in surface waters used for the irrigation of vegetable crops was determined. Twenty-eight percent of the irrigation water samples tested positive for microsporidia, 60% positive for Giardia cysts and 36% positive for Cryptosporidium oocysts. Concentrations of Giardia cysts and Cryptosporidium oocysts detected in water samples collected in Central America compared to the United States were 559 cysts and 227 oocysts, and 25 cysts and < 19 oocysts per 100 L, respectively. The presence of human pathogenic parasites in irrigation waters used for production of crops traditionally consumed raw suggests that there may be a risk of infection to consumers who come in contact with or consume these products. In the other investigations, the effectiveness of UV light and free chlorine on the inactivation of feline calicivirus (FCV) and enteric adenovirus type 40 (AD40) was assessed and compared to model viruses, poliovirus type 1 (PV-1) and coliphage MS-2. FCV was used as a model for members of the "Norwalk like virus" (NLV) group. The UV doses required to achieve 99% inactivation of AD40, coliphage MS-2 and FCV in buffered demand free (BDF) water were 108.6, 58.5 and 16.8 mWs/cm², respectively. For chlorine reactions, higher Ct values for high pH and low temperature conditions was observed for FCV and AD40. Both viruses were more resistant to chlorine than the well-studied PV-1. FCV and AD40 were inactivated rapidly by ∼0.5 mg/L free chlorine by ≥4.00- and ≥2.54-logs at pH 6 and 5°C whereas, PV-1 was not inactivated by 4.04-logs until 10 min contact time. Experiments conducted with aggregated FCV and PV-1 and experiments conducted in treated groundwater had slower inactivation kinetics than dispersed viral suspensions in BDF water. The high disinfectant decay rate of some experiments was most likely due to the decrease in chlorine concentration throughout the experiment. However, low disinfectant decay rates of the AD40 experiments suggest that aggregation or clumping of the viruses may have occurred. The results of these studies provide information on the effectiveness of two common water treatment disinfectants in waters with different physical and chemical qualities. The results of this study may provide a basis for the establishment of guidelines for proficient application in drinking water treatment.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Microbiology.; Agriculture, Soil Science.; Environmental Sciences.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water and Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Gerba, Charles P.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleOccurrence of human pathogenic microsporidia in irrigation water and ultraviolet light and chlorine inactivation of enteric adenovirus type 40 and feline calicivirusen_US
dc.creatorThurston, Jeanette Annen_US
dc.contributor.authorThurston, Jeanette Annen_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe occurrence and disinfectant effectiveness for pathogens which are known or thought to be important in waterborne disease was evaluated. In the first study, the occurrence of human pathogenic microsporidia, Giardia cysts and Cryptosporidium oocysts in surface waters used for the irrigation of vegetable crops was determined. Twenty-eight percent of the irrigation water samples tested positive for microsporidia, 60% positive for Giardia cysts and 36% positive for Cryptosporidium oocysts. Concentrations of Giardia cysts and Cryptosporidium oocysts detected in water samples collected in Central America compared to the United States were 559 cysts and 227 oocysts, and 25 cysts and < 19 oocysts per 100 L, respectively. The presence of human pathogenic parasites in irrigation waters used for production of crops traditionally consumed raw suggests that there may be a risk of infection to consumers who come in contact with or consume these products. In the other investigations, the effectiveness of UV light and free chlorine on the inactivation of feline calicivirus (FCV) and enteric adenovirus type 40 (AD40) was assessed and compared to model viruses, poliovirus type 1 (PV-1) and coliphage MS-2. FCV was used as a model for members of the "Norwalk like virus" (NLV) group. The UV doses required to achieve 99% inactivation of AD40, coliphage MS-2 and FCV in buffered demand free (BDF) water were 108.6, 58.5 and 16.8 mWs/cm², respectively. For chlorine reactions, higher Ct values for high pH and low temperature conditions was observed for FCV and AD40. Both viruses were more resistant to chlorine than the well-studied PV-1. FCV and AD40 were inactivated rapidly by ∼0.5 mg/L free chlorine by ≥4.00- and ≥2.54-logs at pH 6 and 5°C whereas, PV-1 was not inactivated by 4.04-logs until 10 min contact time. Experiments conducted with aggregated FCV and PV-1 and experiments conducted in treated groundwater had slower inactivation kinetics than dispersed viral suspensions in BDF water. The high disinfectant decay rate of some experiments was most likely due to the decrease in chlorine concentration throughout the experiment. However, low disinfectant decay rates of the AD40 experiments suggest that aggregation or clumping of the viruses may have occurred. The results of these studies provide information on the effectiveness of two common water treatment disinfectants in waters with different physical and chemical qualities. The results of this study may provide a basis for the establishment of guidelines for proficient application in drinking water treatment.en_US
dc.description.noteDigitization note: p. 112 missing from paper original and microfilm version.-
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Microbiology.en_US
dc.subjectAgriculture, Soil Science.en_US
dc.subjectEnvironmental Sciences.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineSoil, Water and Environmental Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGerba, Charles P.en_US
dc.identifier.proquest3016453en_US
dc.identifier.bibrecord.b41885776en_US
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