Thesis (M.S. - Nutrition and Food Science)--University of Arizona, 1986. / Includes bibliographical references (leaves 58-62).

Since their discovery in 1973, rotaviruses have been reported to be responsible for waterborne outbreaks of gastroenteritis. The simian rotavirus (SA11) was used as a model for the human strains during the development of the method for concentration of rotaviruses from drinking and naturally occurring waters. The microporous filter method developed was capable of recovering an average of 49% of the input virus from 20 liters of tap water and an average of 31% from 378 liters. Of the various eluents evaluated, a mixture of 10% tryptose phosphate broth and 3% beef extract (pH 10.0) was found to give the greatest efficiency of elution. The 1MDS filters were found to be superior to the 50S for the concentration of SA11. The method developed was successfully used to concentrate viruses from environmental waters. Indigenous viruses were isolated from waters in Bolivia and Colombia. Several treatment plants as well as raw surface and groundwaters were sampled for the presence of entero— and rotaviruses. Rotaviruses were isolated from one sample which had undergone complete treatment and met all current standards for potability. This study indicated that enteric viruses can be found in drinking waters considered safe due to the absence of indicator bacteria. Prior to this study there were no reports of the occurrence of enteric viruses in water in Colombia or Bolivia. The results of this study also indicate the need for some type of virus monitoring of waters which are contaminated with sewage in order to evaluate the impact of these viruses on the population.

Background: Access to improved water and sanitation are key measures of the World Health Organizations. However, while a community can be classified as having access to improved water and sanitation, the possibility of microbiological contaminations exists. Globally, there is a need to assess the quality of drinking water to better classify levels of microbiological quality in attempts to reduce diarrheal disease burden. Utilizing the test for hydrogen sulfide (H2S) producing bacteria test is a cost effective and easy to use method that may be comparable to the traditional yet more costly method (IDEXX Colilert Quantitray). Due to a paucity of data on the test for H2S producing bacteria, this study was performed to examine how well the test for hydrogen sulfide (H2S) producing bacteria compared to traditional measure of fecal indicator bacteria total coliforms and E. coli in drinking water. Furthermore, an analysis of the ability of the test for H2S producing bacteria to predict diarrheal disease was also examined. Methods: The following conditions for the H2S were examined in the study: 2 volumes (10mL or 90mL), 2 incubation times (24 and 48 hours) and the use of a semi-quantitative scoring system that measured the intensity of the black precipitate formed (H2S). To examine how well these conditions compared to E. coli and total coliform results, the following analyses were performed: 1) analysis of sensitivity and specificity to examine presence/absence of bacteria in both samples, 2) linear regression to examine how well a semi-quantitative H2S scoring system predicted bacterial concentrations and 3) logistic regression to examine how well the H2S test predicted risk of diarrheal disease. Results: Within the dataset, there were 816 observations among the 7 communities involved in the study. The H2S test condition that had the highest sensitivity and specificity (94.23% and 36.07% respectively) for total coliforms was 90mL volume at 48 hours. This test condition also produced the highest sensitivity and specificity for E. coli (97.82% and 78.67%, respectively). An analysis using linear regression demonstrated that a semi-quantitative H2S scoring system was able to predict both total coliform and E. coli concentrations in the same samples. In a logistic regression analysis of diarrheal disease, the test of H2S producing bacteria suggested an increase in diarrheal disease risk for higher levels of H2S (OR of 1.18 (p=0.03; 1.02 – 1.35)). Discussion: The initial results here suggest that the use of the test for H2S producing bacteria has potential with high sensitivity (>90%) for E. coli and total coliforms. The application of the semi-quantitative scoring system may also have applications in predicting concentration of E. coli and total coliforms and well as possibly predicting diarrheal disease. However, more work needs to be completed to standardize the semi-quantitative approach to reduce subjectivity of scoring as well as examine the role of the test in additional epidemiologic studies. INDEX WORDS: waterborne disease, E. coli, Dominican Republic, microbial testing

No description available.

Thesis (Ph.D. - Microbiology and Immunology)--University of Arizona. / Includes bibliographical references (leaves 132-134).

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisors: Yan Jin, Dept. of Plant & Soil Sciences; and Pei C. Chiu, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Nucleic acid hybridization (gene probe) and polymerase chain reaction (PCR) techniques have been used to detect viral nucleic acid in water. However, gene probe and PCR may not distinguish between infectious and noninfectious viruses. This study evaluated the ability of gene probe to detect viable poliovirus 1 (polio 1), from sterile and nonsterile groundwater, and the ability of PCR to detect infectious human immunodeficiency virus (HIV-1) from tap and wastewater. The plaque forming (BGM cells), and the tissue culture infectious dose fifty (TCID₅₀) (PLC/PRF/5 cells) procedures were used to detect infectious polio 1 and HIV-1, respectively. Detection of polio 1 by gene probe and cell culture was similar in nonsterile water and in filter sterilized water, but not in autoclaved water. These results suggest that in some natural waters, detection of polio 1 by gene probe may correlate to detection by cell culture procedures. Although detection of infectious HIV-1 by cell culture decreased gradually, until no virus could be found, detection by PCR remained positive throughout the study. Therefore, it was concluded that the use of PCR to assess the risk associated to the presence of HIV-1 in polluted waters, may not be adequate. The enteric adenovirus types 40 (Ead 40) and 41 (Ead 41) are considered the second most important cause of viral gastroenteritis in children, but their role as waterborne pathogens is uncertain. This study compared the survival of Ead 40 and Ead 41 with polio 1, and hepatitis A virus (HAV) in different types of water. The Enteric adenoviruses survived longer in tap and sea water than either polio 1 or HAV, but only slightly better in wastewater. These results suggest that the enteric adenoviruses may survive for prolonged periods in water, representing a potential route of transmission. This study evaluated also the concentration of Ead 40 by the filter adsorption-elution method. With negatively-charged filters, recovery efficiencies of 22, 36, and 38% were obtained from secondary sewage, tap and sea water, respectively. Using electropositive filters, Ead 40 was recovered from tap water with an efficiency of 26.5%. These results show that Ead 40 can be concentrated, from water, with an efficiency comparable to that of other enteric viruses.

The isolation of viruses from treated drinking water has raised concerns that water treatment methods may not always adequately insure the removal of viruses from water designated for human consumption. The isolation of enteroviruses and rotavIruses from treated drinking water in a distribution system and at a water treatment plant has been previously reported. Isolation of viruses from drinking water that met recommended levels of coliform bacteria, chlorine and turbidity. The question is raised as to whether or not current drinking water standards ensure safe drinking water. The isolation of enteroviruses and rotaviruses from treated drinking water In a distribution system and at a water treatment plant. This study reports the results of a more extensive investigation on the removal of naturally occurring viruses by water treatment processes including prechlorination/clarification, filtration, and chlorination at a fullscale water treatment plant. The removal of enteroviruses and rotaviruses was studied at a full scale 205 mgd water treatment plant involving chemical clarification, sand filtration and chlorination. Enteric viruses, as well as coliphages, indicator bacteria, physical and chemical variables were measured in water samples taken at each stage of the drinking water treatment facility. Linear intercorrel ations were analyzed for all the variables. The numbers of standard plate count bacteria and coliphage were positively correlated to the presence of enteroviruses in the raw water while coliphage counts were positively correlated to the presence of rotaviruses in the finished water. Samples were taken during the dry and rainy seasons. During the dry season, it was found that reduction of enteroviruses and rotaviruses averaged 81% and 93%, respectively, for the complete treatment process and were the least efficiently removed as compared to the other microorganisms. The greatest reduction of enterovIruses occurred during pre-chlorination/flocculation and filtration, while a significant reduction of rotav I ru ses occurred during prechlorination/ flocculation and final chlorination. Enteroviruses or rotaviruses occurred in 24% of the finished water samples containing chlorine levels of >0.2 mg/L, and meeting coliform bacteria (1/100 ml) and turbidity (1 NTU) standards. During the rainy season removals were found to be far less efficient for all the variables and rotaviruses were isolated from all finished water samples. The results of this study indicate that finished water having measurable levels of free residual chlorine and meeting standards for col iform bacteria, and turbidity cannot be assumed to be virus free.

The goal of this study was to assess the effect of residence time on the chemical and microbial quality of reclaimed water in two distribution systems located in southern Arizona. Utility A produced Class A water and utilized chlorine as a means of disinfection whereas Utility B produced Class A+ water and utilized UV radiation as a means of disinfection. Water-based pathogens were consistently detected in both distribution systems beyond the point of compliance, while microbial indicators like Escherichia coli was only detected in Utility B suggesting that treatment eliminated waterborne pathogens. Heterotrophic plate concentrations in samples from both utilities initially increased rapidly with increased distance from the point-of-compliance and were as high as 10⁹ CFU/100ml. Regardless of the initial level of treatment, the microbial quality deteriorated with increased residence time in the distribution systems. The second study was designed to evaluate the effect of reclaimed water storage on microbial and chemical quality of two classes of reclaimed water (Class A and Class A+). In Class A water, nitrification was observed during both field scale trials resulting in concentrations greater than 10mg/L while nitrification was not observed in Class A+. Chlorine residuals rapidly decreased within 48hours of storage. HPC concentration were as high as 10⁷ - 10⁸ /100ml. In both field scale trials, there was no observed growth of HPC during storage and waterborne indicator bacteria were rarely detected, and if detected, only at low concentrations. Based on this data, deterioration of microbial water quality during storage is minimal.

The use of nanoscale materials is growing exponentially, but there are also concerns about the environmental hazard to aquatic biota. Metal-containing engineered nanoparticles (NPs) are an important group of these new materials, and whilst there are undoubtedly a plethora of beneficial uses for these NPs, it is essential that an appropriate risk assessment is carried out in order to protect the environment and human health, with the consumption of contaminated fish a distinct possibility. The current study aimed to assess the bioavailability, uptake and toxicological effects of two metal-NPs (TiO2 NPs and Cu-NPs) to fish from both dietary and waterborne exposure routes and where appropriate compare them to their bulk counterpart. Whole body system effects were assessed along with the influences of the life stage of exposed fish and abiotic factors on toxicity. A technique to improve the quantification of Ti from TiO2 NPs in fish tissue was also developed. Effects from exposure to dietary TiO2 NPs manifested similarly to traditional dietary metal exposure, with no reduction in growth, but some sublethal affects. Exposure to waterborne Cu-NPs showed that rainbow trout were more acutely sensitive to CuSO4 than the NPs, but that despite limited uptake several body systems were affected (most notably ionoregulation). Larvae were more sensitive to CuSO4 than Cu-NPs, but no differences were seen with embryos, whilst larvae were more sensitive than embryos. Abiotic factors did have an effect on acute Cu-NP toxicity, though not always in a predictable manner, with some effects more pronounced than with CuSO4. Overall, it appears that metal-NPs are not as acutely toxic as their bulk counterparts, but sublethal effects, were routinely observed. As TiO2 NPs appear more toxic than its bulk counterpart, current legislation governing safe environmental limits may have to be adjusted, though the situation with Cu-NPs isn’t as clear and further investigation is required. However, the risk of human exposure via the consumption of NP contaminated fish fillets is extremely low.