Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-5 (of 5 Records) |
Query Trace: Cromeans TL[original query] |
---|
Aggregation of adenovirus 2 in source water and impacts on disinfection by chlorine
Kahler AM , Cromeans TL , Metcalfe MG , Humphrey CD , Hill VR . Food Environ Virol 2016 8 (2) 148-55 It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with human adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 degrees C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L x time in min) for 3-log10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water. |
Source water quality effects on monochloramine inactivation of adenovirus, coxsackievirus, echovirus, and murine norovirus
Kahler AM , Cromeans TL , Roberts JM , Hill VR . Water Res 2010 45 (4) 1745-51 There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and human adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 degrees C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log(10) reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log(10) CT values at 5 degrees C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log(10) CT values at 5 degrees C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 degrees C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans. |
Development of an RNA extraction protocol for detection of waterborne viruses by reverse transcriptase quantitative PCR (RT-qPCR)
Jothikumar N , Sobsey MD , Cromeans TL . J Virol Methods 2010 169 (1) 8-12 RNA extraction from environmental samples yields frequently an RNA preparation containing inhibitors of molecular reactions. Commercial RNA extraction kits commonly permit extraction of only 0.1 - 0.2ml sample volume. An RNA extraction buffer (RNAX buffer) was formulated for the extraction of viral RNA from 4.0ml using a silica column based protocol. To evaluate the RNAX buffer based protocol, we used hepatitis A virus (HAV) and coxsackievirus B3 (CVB3) to monitor the RNA extraction efficiency from environmental samples. For evaluation of viral RNA recovery from water concentrates which were prepared from river and pond water by PEG concentration. Serial ten fold dilutions of two waterborne viruses were added to the water concentrates for detection for evaluation by quantitative detection. Quantitative recovery of HAV and CVB3 was determined by reverse transcriptase quantitative real-time PCR (RT-qPCR). The extracted RNA was compatible with RT-qPCR and sensitivity of detection of 0.8 PFU per reaction was found with RNAX buffer and the developed protocol. This level of sensitivity was obtained using viral RNA extracted from 4.0ml of an inoculated water sample concentrate. The RNAX buffer developed in this study could be applicable to the detection of other pathogens in water and food. |
Source drinking water quality effects on chlorine disinfection of adenovirus, coxsackievirus, echovirus, and murine norovirus
Kahler AM , Cromeans TL , Roberts JM , Hill VR . Appl Environ Microbiol 2010 76 (15) 5159-64 More information is needed on the disinfection efficacy of chlorine for viruses in source drinking water. In this study, chlorine disinfection efficacy was investigated for USEPA Contaminant Candidate List viruses coxsackievirus B5 (CVB5), echovirus 1 (E1), murine norovirus (MNV), and human adenovirus 2 (HAdV2) in one untreated ground water source and two partially treated surface waters. Disinfection experiments using pH 7 and 8 source water were carried out in duplicate using 0.2 and 1 mg/L free chlorine at 5 and 15 degrees C. The efficiency factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, chlorine disinfection was most effective for MNV, with 3-log10 CT values at 5 degrees C ranging from ≤ 0.020-0.034. Chlorine disinfection was least effective for CVB5 in all water types, with 3-log10 CT values at 5 degrees C ranging from 2.3-7.9. Overall, disinfection proceeded faster at 15 degrees C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but no single source water had consistently different inactivation rates than another. CT values for CVB5 in one type of source water exceeded the recommended CT values set forth by USEPA's Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources. The results of this study demonstrate that water quality plays a substantial role in the inactivation of viruses and should be considered when developing chlorination plans. |
Inactivation of adenoviruses, enteroviruses, and murine norovirus in water by free chlorine and monochloramine
Cromeans TL , Kahler AM , Hill VR . Appl Environ Microbiol 2009 76 (4) 1028-33 Inactivation of infectious viruses during drinking water treatment is usually achieved with free chlorine. Many drinking water utilities in the United States now use monochloramine as a secondary disinfectant to minimize disinfectant byproduct formation and biofilm growth. The inactivation of adenoviruses 2, 40 and 41 (HAdV2, HAdV40 and HAdV41), coxsackieviruses B3 and B5 (CVB3 and CVB5), echoviruses 1 and 11 (E1 and E11) and murine norovirus (MNV), are compared in this study. Experiments were performed with 0.2 mg/L free chlorine or 1 mg/L monochloramine at pH 7 and pH 8 in buffered reagent grade water (RGW) at 5 degrees C. Ct values for 2-4-log10 (99-99.99%) reductions in viral titers were calculated using the Efficiency Factor Hom (EFH) model. The enteroviruses required the longest times for chlorine inactivation and MNV the least time. CVB5 required the longest exposure time, with Ct values of 7.4 and 10 mg-min/L (pH 7 and 8) for 4-log10 inactivation. Monochloramine disinfections was most effective for E1 (Ct values ranged from 8 to 18 mg-min/L for 2- and 3-log10 reductions, respectively). E11 and HAdV2 were the least susceptible to monochloramine disinfection, (Ct values of 1300 and 1600 mg-min/L for 3-log10 reductions, respectively). Monochloramine inactivation was most successful for the adenoviruses, CVB5, and E1 at pH 7. A greater variation in inactivation rates between viruses was observed during monochloramine disinfection than during chlorine disinfection. This data will be useful in drinking water risk assessment studies and disinfection system planning. |
- Page last reviewed:Feb 1, 2024
- Page last updated:May 06, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure