-
[show abstract]
[hide abstract]
ABSTRACT: The extraction and purification of nucleic acids is a critical step in the molecular detection of enteric viruses from environmental or fecal samples. In the present study, the performance of three commercially available kits was assessed: the MO BIO PowerVirus Environmental DNA/RNA Extraction kit, the Qiagen QIAamp Viral RNA Mini kit, and the Zymo ZR Virus DNA/RNA Extraction kit. Viral particles of adenovirus 2 (AdV), murine norovirus (MNV), and poliovirus type 1 (PV1) were spiked in molecular grade water and three different types of sample matrices (i.e., biosolids, feces, and surface water concentrates), extracted with the kits, and the yields of the nucleic acids were determined by quantitative PCR (qPCR). The MO BIO kit performed the best with the biosolids, which were considered to contain the highest level of inhibitors and provided the most consistent detection of spiked virus from all of the samples. A qPCR inhibition test using an internal control plasmid DNA and a nucleic acid purity test using an absorbance at 230nm for the nucleic acid extracts demonstrated that the MO BIO kit was able to remove qPCR inhibitors more effectively than the Qiagen and Zymo kits. These results suggest that the MO BIO kit is appropriate for the extraction and purification of viral nucleic acids from environmental and clinical samples that contain high levels of inhibitors.
Journal of virological methods 04/2013; · 2.13 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Effective individual microbiological water purifiers are needed for consumption of untreated water sources by campers, emergency use, military, and in developing counties. A handheld UV light device was tested to assess if it could meet the virus reduction requirements established by the United State Environmental Protection Agency, National Science Foundation and the World Health Organization. The device was found capable of inactivating at least 4 log(10) of poliovirus type 1, rotavirus SA-11 and MS-2 virus in 500 mL volumes of general case test water. But in the presence of high turbidity and organic matter, filtration was necessary to achieve a 4 log(10) reduction of the test viruses.
Food and Environmental Virology 01/2013; · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The occurrence and distribution of mold on household surfaces and the efficacy of bleach-based (sodium hypochlorite, NaOCl) disinfectants on mold viability and allergenicity was documented. Household microenvironments prone to increased moisture were specifically targeted. Using the sticky tape method, 1330 samples were collected from non-porous indoor surfaces of 160 homes across the United States, and analyzed for mold. Homes were randomly selected and recruited via phone interviews. Culture and immunoassays were used to measure the viability and reduction of allergenic properties of Aspergillus fumigatus following 2.4% NaOCl treatment. All homes and 72.9% of surfaces tested positive for mold. Windowsills were the most frequently contaminated site (87.5%) and Cladosporium the most commonly identified mold (31.0%). Five-minute exposures to 2.4% NaOCl resulted in a >3 to >6-log(10) reduction of culturable mold counts in controlled laboratory studies. Organisms were nonculturable after 5- and 10-min contact times on non-porous and porous ceramic carriers, respectively, and A. fumigatus spore-eluted allergen levels were reduced by an average 95.8% in 30 sec, as indicated by immunoassay. All homes are contaminated with some level of mold, and regrowth is likely in moisture-prone microenvironments. The use of low concentrations (2.4%) of NaOCl for the reduction of culturable indoor mold and related allergens is effective and recommended.
Journal of Occupational and Environmental Hygiene 11/2012; 9(11):663-9. · 1.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fomites are known to play a role in the transmission of pathogens. Quantitative analysis of the parameters that affect sample recovery efficiency (SRE) at the limit of detection of viruses on fomites will aid in improving quantitative microbial risk assessment (QMRA) and infection control. The variability in SRE as a function of fomite type, fomite surface area, sampling time, application media, relative humidity (rH), and wetting agent was evaluated. To quantify the SRE, bacteriophage P22 was applied onto fomites at average surface densities of 0.4 ± 0.2 and 4 ± 2 PFU/cm(2). Surface areas of 100 and 1,000 cm(2) of nonporous fomites found in indoor environments (acrylic, galvanized steel, and laminate) were evaluated with premoistened antistatic wipes. The parameters with the most effects on the SRE were sampling time, fomite surface area, wetting agent, and rH. At time zero (the initial application of bacteriophage P22), the SRE for the 1,000-cm(2) fomite surface area was, on average, 40% lower than that for the 100-cm(2) fomite surface area. For both fomite surface areas, the application medium Trypticase soy broth (TSB) and/or the laminate fomite predominantly resulted in a higher SRE. After the applied samples dried on the fomites (20 min), the average SRE was less than 3%. A TSB wetting agent applied on the fomite improved the SRE for all samples at 20 min. In addition, an rH greater than 28% generally resulted in a higher SRE than an rH less than 28%. The parameters impacting SRE at the limit of detection have the potential to enhance sampling strategies and data collection for QMRA models.
Applied and environmental microbiology 08/2012; 78(22):7915-22. · 3.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Enteric viruses are a cause of waterborne disease worldwide, and low numbers in drinking water can present a significant risk of infection. Because the numbers are often quite low, large volumes (100-1,000 L) of water are usually processed. The VIRADEL method using microporous filters is most commonly used today for this purpose. Negatively charged filters require the addition of multivalent salts and acidification of the water sample to effect virus adsorption, which can make large-volume sampling difficult. Positively charged filters require no preconditioning of samples, and are able to concentrate viruses from water over a greater pH range than electronegative filters. The most widely used electropositive filter is the Virosorb 1MDS; however, the Environmental Protection Agency has added the positively charged NanoCeram filters to their proposed Method 1615. Ultrafilters concentrate viruses based on size exclusion rather than electrokinetics, but are impractical for field sampling or processing of turbid water. Elution (recovery) of viruses from filters following concentration is performed with organic (e.g., beef extract) or inorganic solutions (e.g., sodium polyphosphates). Eluates are then reconcentrated to decrease the sample volume to enhance detection methods (e.g., cell culture infectivity assays and molecular detection techniques). While the majority of available filters have demonstrated high virus retention efficiencies, the methods to elute and reconcentrate viruses have met with varying degrees of success due to the biological variability of viruses present in water.
Food and Environmental Virology 06/2012; 4(2):41-67. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The ASTM Method D4994-89 has been used in the United States for almost two decades to assess the virological quality of biosolids.
However, the efficiency of this method for recovery of different enteric viruses has never been determined. The method was
found to recover several different enteroviruses and adenovirus 2 with an efficiency ranging from 18.1±5.5 to 24.6±7.8%.
KeywordsBiosolids–Adenovirus–Standard methods–Enteric viruses
Food and Environmental Virology 04/2012; 3(1):43-45. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to quantify the transfer of viral and bacterial pathogens in water used to dilute pesticides
sprayed onto the surfaces of cantaloupe, iceberg lettuce, and bell peppers. The average percent transfer of bacteria was estimated
to range from 0.00021 to 9.4%, while average viral transfer ranged from 0.055 to 4.2%, depending on the type of produce. Based
on these values the concentrations of hepatitis A virus (HAV) and Salmonella in water necessary to achieve a 1:10,000 annual risk of infection were calculated. Under worst case scenario assumptions,
in which a pesticide is applied on the same day that the produce is harvested and when maximum transfer values are used, concentrations
of 1.5×10−3 CFU Salmonella or 2.7×10−7 MPN HAV per 100ml of the water used for application would result in 1:10,000 annual infection risk to anyone who consumes
the fresh produce. If harvesting does not occur until at least 14days after the application, to produce the same risk of
infection, the numbers of Salmonella in 100ml of water used to dilute the pesticides will be greater by up to five orders of magnitude, while the HAV numbers
will have increased by up to two orders of magnitude. Based on the reported concentrations of enteric viruses in surface and
ground waters in the United States, a 1:10,000 annual risk of infection could easily be exceeded with some groundwater sources
used in the United States. To reduce the risks associated with the consumption of fresh produce, water used to prepare pesticides
in spray applications should be evaluated for its microbiological quality.
KeywordsPesticide spray application–Produce–Hepatitis A virus–
Salmonella
–Quantitative microbial risk assessment–Lettuce–Bell pepper–Cantaloupe
Food and Environmental Virology 04/2012; 3(2):86-91. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The objective of this study was to evaluate the potential role of fomites in human parainfluenza virus 1 (HPIV1) transmission
by assessing the occurrence of HPIV1 on surfaces in an adult setting (office). In 2004, a total of 328 fomites from 12 different
office buildings in five different cities were evaluated for HPIV1 viral RNA. HPIV1 was isolated using reverse transcriptase–polymerase
chain reaction (RT–PCR) and detected on 37% of all office fomites. HPIV1 RNA was frequently isolated on desk tops (47%), and
infrequently isolated on light switches (19%). Data revealed a statistically significant difference between the percentage
of HPIV1 positive fomites in office cubicles and conference rooms (Chi-square P<0.011, Fisher’s Exact P=0.054). A statistically significant difference was also found among positive fomites in different buildings (Chi-square
P<0.011). HPIV1 was consistently isolated on various indoor fomites in the 12 office buildings assessed during 2004, a low
HPIV incident year.
KeywordsParainfluenza 1 virus-Respiratory virus-Fomites-Offices-RT–PCR
Food and Environmental Virology 04/2012; 2(1):41-46. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To control the spread of avian flu (influenza) and other viruses of concern among commercial flocks, it is essential that
proper disinfection procedures be developed along with methods for assessing their performance. Such methods must be rapid
and inexpensive. Coliphages were used as indicators to demonstrate the efficacy of quaternary ammonium compounds and chlorine
bleach for the inactivation of viruses in chicken cages. The concentration of indigenous coliphages in chicken litter was
found to be 104–107 per gram and from 0 to 8,500 per 100cm2 of floor surface. To assess the effectiveness of the disinfectants, floor samples were collected pre and post disinfection.
These results indicated that chlorine bleach was more effective than quaternary ammonium compounds in reducing the amount
of indigenous coliphages. To obtain better quantitative data, MS-2 coliphage was sprayed onto cage floors, left overnight
to dry, and then the surfaces disinfected. Similar results were obtained with both indigenous coliphages and MS-2. There appears
to be no significant difference in coliphage reduction by increasing the contact time from 10 to 30min. To ensure at least
a 99.9% reduction of virus at least 236ml of household bleach per 3.78l should be used.
Food and Environmental Virology 04/2012; 1(3):155-160. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The goal of this study was to determine if a cytopathogenic effects (CPE) cell culture assay and an integrated cell culture
PCR (ICC-PCR) assay would yield similar or different results when used to assess virus survival in water. Poliovirus type
1 was added to dechlorinated tapwater and stored at room temperature (22.5–24°C) for a total of 50days. Samples were assayed
at defined time intervals by the most probable number (MPN) method on Buffalo green monkey kidney cells (BGM) by CPE and additionally
by ICC-PCR. Monolayers that were CPE negative on first passage were passed onto fresh monolayers of cells for a second and
third time if still negative. By CPE assay, second passage was observed to yield a greater titer (2,300 vs. 24,000MPN/ml)
and third passage also resulted in an increased titer. ICC-PCR proved to be a more rapid and sensitive method than conventional
cell culture for determining virus inactivation rates in water. Poliovirus survived in tapwater for up to 32days, as assessed
by both third passage ICC-PCR and CPE. There was no statistical difference in the inactivation rates between the two methods.
To determine the total number of infectious viruses, these findings indicate the need for performing three cell culture passages
or, alternatively, ICC-PCR on first passage.
KeywordsVirus detection-ICC-PCR-Cell culture-Survival
Food and Environmental Virology 04/2012; 2(4):225-230. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The advent of severe acute respiratory syndrome and its potential environmental transmission indicates the need for more information
on the survival of coronavirus in water and wastewater. The survival of representative coronaviruses, feline infectious peritonitis
virus, and human coronavirus 229E was determined in filtered and unfiltered tap water (4 and 23°C) and wastewater (23°C).
This was compared to poliovirus 1 under the same test conditions. Inactivation of coronaviruses in the test water was highly
dependent on temperature, level of organic matter, and presence of antagonistic bacteria. The time required for the virus
titer to decrease 99.9% (T99.9) shows that in tap water, coronaviruses are inactivated faster in water at 23°C (10days) than in water at 4°C (>100days).
Coronaviruses die off rapidly in wastewater, with T99.9 values of between 2 and 4days. Poliovirus survived longer than coronaviruses in all test waters, except the 4°C tap water.
Food and Environmental Virology 04/2012; 1(1):10-14. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Escherichia coli O157:H7 has been associated with water related outbreaks. It has been isolated from surface and ground waters. It is capable
of survival in water for days to weeks
Reviews in Environmental Science and Biotechnology 04/2012; 7(3):267-273.
-
[show abstract]
[hide abstract]
ABSTRACT: The antiviral properties of zeolite (sodium aluminosilicate) powders amended with metal ions were assessed using human coronavirus
229E, feline infectious peritonitis virus (FIPV), and feline calicivirus F-9. Zeolites containing silver and silver/copper
caused significant reductions of coronavirus 229E after 1h in suspension. The silver/copper combination yielded a >5.13-log10 reduction within 24h. It was also the most effective (>3.18-log10) against FIPV after 4 h. Other formulations were ineffective against FIPV. On plastic coupons with incorporated silver/copper-zeolites,
>1.7-log10 and >3.8-log10 reductions were achieved for coronavirus 229E and feline calicivirus within 24h, respectively. Silver/copper zeolite reduced
titers of all viruses tested, suggesting that it may be effective against related pathogens of interest [i.e., SARS coronavirus,
other coronaviruses, human norovirus (calicivirus)]. Of note, it was effective against both enveloped and nonenveloped viruses.
Metal-zeolites could therefore possibly be used in applications to reduce virus contamination of fomites and thus the spread
of viral diseases.
Food and Environmental Virology 04/2012; 1(1):37-41. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This article defines the term surrogate as an organism, particle, or substance used to study the fate of a pathogen in a specific environment. Pathogenic organisms, nonpathogenic organisms, and innocuous particles have been used as surrogates for a variety of purposes, including studies on survival and transport as well as for method development and as "indicators" of certain conditions. This article develops a qualitative surrogate attribute prioritization process and allows investigators to select a surrogate by systematically detailing the experimental process and prioritizing attributes. The results are described through the use of case studies of various laboratories that have used this process. This article also discusses the history of surrogate and microbial indicator use and outlines the method by which surrogates can be used when conducting a quantitative microbial risk assessment. The ultimate goal of selecting a sufficiently representative surrogate is to improve public health through a health-based risk assessment framework. Under- or overestimating the resistance, inactivation, or movement may negatively impact risk assessments that, in turn, will impact health assessments and estimated safety levels. Reducing uncertainty in a risk assessment is one of the objectives of using surrogates and the ultimate motive for any experiment investigating potential exposure of a pathogen.
Applied and environmental microbiology 03/2012; 78(6):1969-77. · 3.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The contribution of combined sewer overflows (CSO) to the viral contamination of receiving waters was determined. Adenovirus concentrations were determined using the Primary Liver Carcinoma (PLC/PRF/5) cell line and confirmed by Polymerase Chain Reaction (PCR). Norovirus concentration was determined using the Most Probable Number (MPN) and Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Seventy-five water samples were collected during dry weather and 50 samples were collected during wet weather. CSO events significantly increased the concentration of culturable viruses, adenoviruses, and noroviruses in the receiving waters (P < 0.01). During dry weather, 56% of samples were positive for total virus cytopathic effects (CPE), adenoviruses were detected in 41% of the positive cell cultures, and noroviruses in 6% of the concentrates by direct RT-PCR. During wet weather, 100% of the samples were positive by CPE, 84% for adenoviruses, and 40% in the concentrates for norovirus. Our results demonstrate that CSOs can contribute significant viral loading to receiving waters.
Food and Environmental Virology 03/2012; 4(1):34-40. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: People in developed countries spend approximately 90% of their lives indoors, yet we know little about the source and diversity of microbes in built environments. In this study, we combined culture-based cell counting and multiplexed pyrosequencing of environmental ribosomal RNA (rRNA) gene sequences to investigate office space bacterial diversity in three metropolitan areas. Five surfaces common to all offices were sampled using sterile double-tipped swabs, one tip for culturing and one for DNA extraction, in 30 different offices per city (90 offices, 450 total samples). 16S rRNA gene sequences were PCR amplified using bar-coded "universal" bacterial primers from 54 of the surfaces (18 per city) and pooled for pyrosequencing. A three-factorial Analysis of Variance (ANOVA) found significant differences in viable bacterial abundance between offices inhabited by men or women, among the various surface types, and among cities. Multiplex pyrosequencing identified more than 500 bacterial genera from 20 different bacterial divisions. The most abundant of these genera tended to be common inhabitants of human skin, nasal, oral or intestinal cavities. Other commonly occurring genera appeared to have environmental origins (e.g., soils). There were no significant differences in the bacterial diversity between offices inhabited by men or women or among surfaces, but the bacterial community diversity of the Tucson samples was clearly distinguishable from that of New York and San Francisco, which were indistinguishable. Overall, our comprehensive molecular analysis of office building microbial diversity shows the potential of these methods for studying patterns and origins of indoor bacterial contamination. "[H]umans move through a sea of microbial life that is seldom perceived except in the context of potential disease and decay." - Feazel et al. (2009).
PLoS ONE 01/2012; 7(5):e37849. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The Convection Dispersion Equation (CDE) was used to calculate PRD1 and Br(-) transport parameters in a subsurface flow constructed wetland. Transport parameters from Br(-) displacement were applied into the CDE to estimate a 0.96 day(-1) first order decay coefficient (k). The PRD1 breakthrough curves were also simulated to obtain effective cross-sectional area (Ac), longitudinal dispersion coefficient (D), convective velocity (v), and k. There was practically no difference between Ac and D for both tracers. However, the estimated convective velocity was higher for PRD1 than for Br(-). Further simulations were conducted by taking experimental concentrations from prior research on surface and subsurface flow constructed wetlands. Dispersion number (d) was estimated to be between 0.17 and 0.029 by using PRD1 and Br(-) transport parameters. These parameters were also used to calculate wetland dimensionless removal (K). An analytical solution for the zero moment of the observed breakthrough curves was applied to estimate PRD1 fraction recoveries in the wetland by using d and K. The results of the present study suggest that this analytical solution may be an alternative design tool for pathogen removal estimation in subsurface flow constructed wetlands.
Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 01/2012; 47(1):142-8.
-
[show abstract]
[hide abstract]
ABSTRACT: As a cost-saving measure, an increasing number of hospitals allow personnel to launder their uniforms, lab coats, and operating room scrubs at home. With rising nosocomial infection rates and increasing levels of multidrug-resistant bacteria in hospital settings, uniform contamination may be an environmental factor in the spread of infection.
We quantified the number and identity of bacteria found on swatches cut from unwashed operating room, hospital-laundered, home-laundered, new cloth, and new disposable scrubs.
Of the 29 unwashed hospital operating room scrub swatches analyzed, 23 (79%) were positive for some type of gram-positive cocci, with 3 (10%) of those classified as Staphylococcus aureus, and 20 (69%) were positive for coliform bacteria, 3 of which were Escherichia coli. Home-laundered scrubs had a significantly higher total bacteria count than hospital-laundered scrubs (P = .016). There was no statistical difference in the bacteria counts between hospital-laundered scrubs and unused new and disposable scrubs. In the home-laundered scrubs 44% (18/41) were positive for coliform bacteria, but no isolates were Escherichia coli.
Significantly higher bacteria counts were isolated from home-laundered scrubs and unwashed scrubs than from new, hospital-laundered, and disposable scrubs.
American journal of infection control 12/2011; 40(6):539-43. · 3.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The primary objective of this study was to determine the microbial water quality of a large irrigation system and how this quality varies with respect to canal size, impact of near-by communities, and the travel distance from the source in the El Valle del Yaqui, Sonora, México. In this arid region, 220,000 hectares are irrigated with 80% of the irrigation water being supplied from an extensive irrigation system including three dams on the Yaqui River watershed. The stored water flows to the irrigated fields through two main canal systems (severing the upper and lower Yaqui Valley) and then through smaller lateral canals that deliver the water to the fields. A total of 146 irrigation water samples were collected from 52 sample sites during three sampling events. Not all sites could be accessed on each occasion. All of the samples contained coliform bacteria ranging from 1,140 to 68,670 MPN/100 mL with an arithmetic mean of 11,416. Ninety-eight percent of the samples contained less than 1,000 MPN/100 mL Escherichia coli, with an arithmetic mean of 291 MPN/100 mL. Coliphage were detected in less than 30% of the samples with an arithmetic average equal to 141 PFU/100 mL. Enteroviruses, Cryptosporidium oocysts, and Giardia cysts were also detected in the canal systems. No significant difference was found in the water quality due to canal system (upper or lower Yaqui Valley), canal-size (main vs. lateral), distance from source, and the vicinity of human habitation (presence of various villages and towns along the length of the canals). There was a significant decrease in coliforms (p < 0.011) and E. coli (< 0.022) concentrations as travel distance increased from the City of Obregón.
Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 12/2011; 46(14):1708-12.
-
[show abstract]
[hide abstract]
ABSTRACT: Subscribe to Food Protection Trends for refereed articles on applied research, applications of current technology and general interest subjects for food safety professionals. This monthly publication is read by over 9,000 individuals around the world.
Food Protection Trends. 08/2011; 31(8):508-513.
