Last data update: Oct 28, 2024. (Total: 48004 publications since 2009)
Records 1-24 (of 24 Records) |
Query Trace: Murphy JL[original query] |
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Chlorine inactivation of Elizabethkingia spp. In water
Holcomb DA , Riner D , Cowan B , Salah Z , Jennings WC , Mattioli MC , Murphy JL . Emerg Infect Dis 2024 30 (10) 2174-2177 We performed chlorine inactivation experiments for Elizabethkingia anophelis and E. meningoseptica bacterial strains from clinical and environmental sources. Free chlorine concentration × contact time values <0.04 mg·min/L achieved 99.9% inactivation of Elizabethkingia species, indicating chlorine susceptibility. Measures to control biofilm producing pathogens in plumbing are needed to prevent Elizabethkingia bacterial infections. |
An environmental evaluation of urine-diverting dry toilets in Hiloweyn Camp, Dollo Ado, Ethiopia
Brown TW , Murphy JL , Akers P , Patrick M , Hill V , Mattioli M , Tsige Y , Adow A , Abdirashid M , Mohamed MN , Githiri D , Handzel T . Sci Total Environ 2024 926 171838 Safe and hygienic management of human waste is essential in humanitarian settings. Urine-diverting dry toilets (UDDTs) can enable this management in some humanitarian emergency settings. A seeded, longitudinal environmental study was conducted in Hiloweyn refugee camp, Dollo Ado, Ethiopia, to measure Escherichia coli and Ascaris suum ova inactivation within closed UDDT vaults and to document environmental conditions (temperature, moisture content, and pH) that could influence inactivation. Hiloweyn camp represented an optimal location for a desiccation-based sanitation technology such as the UDDT. E. coli and Ascaris ova inactivation was observed in UDDTs under warm, dry, alkaline conditions at 6, 9, and 12 months of storage; UDDTs with samples containing <1000 E. coli/g total solids increased from 30 % to 95 % over 12 months, and a >2.8-log(10) reduction in Ascaris ova viability was observed after 6 months. Additional laboratory-based studies were conducted to provide insights into the field study findings and study the impact of hydrated lime on E. coli and Ascaris ova inactivation. Results suggest that adding hydrated lime to elevate pH > 12 may increase inactivation and decrease storage time. Overall, UDDTs could contribute to the safe and hygienic management of human waste in comparable warm and dry humanitarian settings. |
Evaluation of Sampling and Concentration Methods for Salmonella enterica Serovar Typhi Detection from Wastewater
Zhou N , Ong A , Fagnant-Sperati C , Harrison J , Kossik A , Beck N , Shirai J , Burnor E , Swanstrom R , Demeke B , Patel S , Scott Meschke J , Kang G , Giri S , Raghava V , Abraham D , Moe C , Kapoor R , Wang Y , Liu P , Feasey N , Rigby J , Dines Y , Elviss N , Alm E , Moniz K , Xiao A , Karmacharya D , Napit R , Poudel A , Muhammad S , Ashraf Z , Boyle D , Andrews J , Aiemjoy K , LeBoa C , Tamrakar D , Shrestha S , Shakya J , Murphy JL , Narayanan J , Brown TW , Taniuchi M , Islam Md O , Blake I . Am J Trop Med Hyg 2023 108 (3) 482-491 Salmonella enterica serovar (Salmonella Typhi) is the causative bacterial agent of typhoid fever. Environmental surveillance of wastewater and wastewater-impacted surface waters has proven effective in monitoring various pathogens and has recently been applied to Salmonella Typhi. This study evaluated eight sample collection and concentration methods with 12 variations currently being developed and used for Salmonella Typhi surveillance globally to better understand the performance of each method based on its ability to detect Salmonella Typhi and its feasibility. Salmonella Typhi strains Ty21a and Ty2 were seeded to influent wastewater at known concentrations to evaluate the following methods: grab sampling using electropositive filters, centrifugation, direct enrichment, or membrane filtration and trap sampling using Moore swabs. Concentrated samples underwent nucleic acid extraction and were detected and/or quantified via quantitative polymerase chain reaction (qPCR). Results suggest that all methods tested can be successful at concentrating Salmonella Typhi for subsequent detection by qPCR, although each method has its own strengths and weaknesses, including the Salmonella Typhi concentration it is best suited for, with a range of positive detections observed as low as 0.1-0.001 colony-forming units (CFU) Ty21a/mL and 0.01 CFU Ty2/mL. These factors should be considered when identifying a method for environmental surveillance and will greatly depend on the use case planned. |
Evaluation of sampling and concentration methods for Salmonella enterica serovar Typhi detection from wastewater (preprint)
Zhou NA , Ong AQW , Fagnant-Sperati CS , Harrison JC , Kossik AL , Beck NK , Shirai JH , Burnor E , Swanstrom R , Demeke B , Patel S , Meschke JS , Kang G , Giri S , Raghava V , Abraham D , Moe C , Kapoor R , Wang Y , Liu P , Feasey N , Rigby J , Dines Y , Elviss N , Alm E , Moniz K , Xiao A , Karmacharya D , Napit R , Poudel A , Muhammad S , Ashraf Z , Boyle D , Andrews J , Aiemjoy K , LeBoa C , Tamrakar D , Shrestha S , Shakya J , Murphy JL , Narayanan J , Brown TW , Taniuchi M , Islam Md O , Blake I . medRxiv 2022 08 Salmonella enterica serovar (Salmonella Typhi) is the causative bacterial agent of Typhoid fever. Environmental surveillance of wastewater and wastewater-impacted surface waters has proven effective in monitoring various pathogens, and has recently been applied to Salmonella Typhi. This study evaluated eight sample collection and concentration methods with twelve variations currently being developed and used for Salmonella Typhi surveillance globally to better understand the performance of each method based on their ability to detect Salmonella Typhi and feasibility. Salmonella Typhi strains, Ty21a and Ty2, were seeded to influent wastewater at known concentrations to evaluate the following methods: grab sampling using electropositive filters, centrifugation, direct enrichment, or membrane filtration and trap sampling using Moore swabs. Concentrated samples underwent nucleic acid extraction and were detected and/or quantified via qPCR. Results suggest that all methods tested can be successful at concentrating Salmonella Typhi for subsequent detection by qPCR, although each method has its own strengths and weaknesses including the Salmonella Typhi concentrations they are best suited for with a range of positive detections observed as low as 0.1-0.001 CFU Ty21a/mL and 0.01 CFU Ty2/mL. These factors should be considered when identifying a method for environmental surveillance and will greatly depend on the use case planned. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. |
Detection and identification of Giardia species using real-time PCR and sequencing.
Narayanan J , Murphy JL , Hill VR . J Microbiol Methods 2021 189 106279 We report a specific region of Giardia spp. 18S ribosomal RNA (18S rDNA) that serves as an ideal target for quantitative PCR (qPCR) detection and sequencing to identify Giardia species, including the clinically-relevant G. duodenalis, in clinical and environmental samples. The presence of multiple copies of the 18S rDNA gene and variations in the selected 18S genomic region enabled the development of a rapid, sensitive qPCR screening method for the detection of Giardia spp. The analytical sensitivity of the Giardia qPCR assay was determined to be a cyst equivalent of 0.4 G. duodenalis cysts per PCR reaction. Amplicon sequencing of the PCR product confirmed Giardia spp. detection and among the 35 sequences obtained, 31, 3 and 1 isolates were classified as belonging to G. duodenalis, G. microti and G. muris, respectively. The TaqMan assay reported here may be useful for the detection of low levels of Giardia in clinical and environmental samples, and further enables the effective use of direct sequencing of the PCR product for Giardia confirmation and to identify major species of Giardia, including G. duodenalis. |
Removal and Inactivation of an Enveloped Virus Surrogate by Iron Conventional Coagulation and Electrocoagulation.
Kim K , Jothikumar N , Sen A , Murphy JL , Chellam S . Environ Sci Technol 2021 55 (4) 2674-2683 It is imperative to understand the behavior of enveloped viruses during water treatment to better protect public health, especially in the light of evidence of detection of coronaviruses in wastewater. We report bench-scale experiments evaluating the extent and mechanisms of removal and/or inactivation of a coronavirus surrogate (ϕ6 bacteriophage) in water by conventional FeCl(3) coagulation and Fe(0) electrocoagulation. Both coagulation methods achieved ∼5-log removal/inactivation of ϕ6 in 20 min. Enhanced removal was attributed to the high hydrophobicity of ϕ6 imparted by its characteristic phospholipid envelope. ϕ6 adhesion to freshly precipitated iron (hydr)oxide also led to envelope damage causing inactivation in both coagulation techniques. Fourier transform infrared spectroscopy revealed oxidative damages to ϕ6 lipids only for electrocoagulation consistent with electro-Fenton reactions. Monitoring ϕ6 dsRNA by a novel reverse transcription quantitative polymerase chain reaction (RT-qPCR) method quantified significantly lower viral removal/inactivation in water compared with the plaque assay demonstrating that relying solely on RT-qPCR assays may overstate human health risks arising from viruses. Transmission electron microscopy and computationally generated electron density maps of ϕ6 showed severe morphological damages to virus' envelope and loss of capsid volume accompanying coagulation. Both conventional and electro- coagulation appear to be highly effective in controlling enveloped viruses during surface water treatment. |
Household illness and associated water and sanitation factors in peri-urban Lusaka, Zambia, 20162017
Hubbard SC , Meltzer MI , Kim S , Malambo W , Thornton AT , Shankar MB , Adhikari BB , Jeon S , Bampoe VD , Cunningham LC , Murphy JL , Derado G , Mintz ED , Mwale FK , Chizema-Kawesha E , Brunkard JM . NPJ Clean Water 2020 3 (1) In Zambia limited access to adequate water and sanitation is a key developmental challenge, particularly for rapidly expanding peri-urban areas. During 20162017, a cross-sectional household survey was conducted among 12,500 households representing ~60,000 individuals to assess the burden of household diarrheal and respiratory disease and to measure water, sanitation, and hygiene (WASH) characteristics in Lusaka, Zambia. We found that socio-economic factors, including having an additional household member, having children <5 years old in the household, living in a rental home, and higher annual household expenditure were associated with diarrhea and respiratory illness. We also found an increased risk for diarrhea associated with a number of WASH-related factorssuch as not covering all water storage containers, not using soap for handwashing, having an unimproved sanitation facility, and utilizing a heavily shared toilet (18 people). Detectable free chlorine residual in household stored water and more hours of water availability per day were associated with reduced odds of waterborne illness. In all, 75% of household stored water was contaminated with E. coli and households consuming less water (<20 L/day per person) for all purposes had lower odds of diarrhea than households consuming more waterthese findings highlight the need for enhanced WASH services within densely populated peri-urban areas and the importance of achieving universal access to safely managed water and sanitation services. |
Knowledge and Practices Regarding Safe Household Cleaning and Disinfection for COVID-19 Prevention - United States, May 2020.
Gharpure R , Hunter CM , Schnall AH , Barrett CE , Kirby AE , Kunz J , Berling K , Mercante JW , Murphy JL , Garcia-Williams AG . MMWR Morb Mortal Wkly Rep 2020 69 (23) 705-709 A recent report described a sharp increase in calls to poison centers related to exposures to cleaners and disinfectants since the onset of the coronavirus disease 2019 (COVID-19) pandemic (1). However, data describing cleaning and disinfection practices within household settings in the United States are limited, particularly concerning those practices intended to prevent transmission of SARS-CoV-2, the virus that causes COVID-19. To provide contextual and behavioral insight into the reported increase in poison center calls and to inform timely and relevant prevention strategies, an opt-in Internet panel survey of 502 U.S. adults was conducted in May 2020 to characterize knowledge and practices regarding household cleaning and disinfection during the COVID-19 pandemic. Knowledge gaps were identified in several areas, including safe preparation of cleaning and disinfectant solutions, use of recommended personal protective equipment when using cleaners and disinfectants, and safe storage of hand sanitizers, cleaners, and disinfectants. Thirty-nine percent of respondents reported engaging in nonrecommended high-risk practices with the intent of preventing SARS-CoV-2 transmission, such as washing food products with bleach, applying household cleaning or disinfectant products to bare skin, and intentionally inhaling or ingesting these products. Respondents who engaged in high-risk practices more frequently reported an adverse health effect that they believed was a result of using cleaners or disinfectants than did those who did not report engaging in these practices. Public messaging should continue to emphasize evidence-based, safe practices such as hand hygiene and recommended cleaning and disinfection of high-touch surfaces to prevent transmission of SARS-CoV-2 in household settings (2). Messaging should also emphasize avoidance of high-risk practices such as unsafe preparation of cleaning and disinfectant solutions, use of bleach on food products, application of household cleaning and disinfectant products to skin, and inhalation or ingestion of cleaners and disinfectants. |
A case of primary amebic meningoencephalitis caused by Naegleria fowleri in Bangladesh
Sazzad HMS , Luby SP , Sejvar J , Rahman M , Gurley ES , Hill V , Murphy JL , Roy S , Cope JR , Ali IKM . Parasitol Res 2019 119 (1) 339-344 We present the first recognized case of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri in a 15-year-old male from Bangladesh. He performed daily nasal rinsing with untreated ground water and bathed in untreated ground water or river water, which likely exposed him to N. fowleri. |
Cell culture infectivity to assess chlorine disinfection of cryptosporidium oocysts in water
Murphy JL , Arrowood MJ . Methods Mol Biol 2020 2052 283-302 This chapter provides a detailed protocol to assess disinfection efficacy of chlorine against Cryptosporidium oocysts including the core chlorine disinfection assay, the in vitro cell culture infectivity assay, and microscopy analysis and data interpretation. |
Efficacy of a solar concentrator to Inactivate E. coli and C. perfringens spores in latrine waste in Kenya
Murphy JL , Ayers T , Foote A , Woods E , Wamola N , Fagerli K , Waiboci L , Mugoh R , Mintz ED , Zhao K , Marano N , O'Reilly CE , Hill VR . Sci Total Environ 2019 691 401-406 Alternative sanitation options are needed for effective waste management in low-income countries where centralized, large-scale waste treatment is not easily achievable. A newly designed solar concentrator technology utilizes solar thermal energy to treat feces contained in drums. This pilot study assessed the efficacy of the new design to inactivate microbes in 13 treatment drums under field conditions in Kenya. Three-quarters of the drums contained <1000E. coli/g of total solids following 6h of solar thermal treatment and inactivation of thermotolerant C. perfringens spores ranged from <1.8 to >5.0log10. Nearly all (94%) samples collected from treatment drums achieved thermophilic temperatures (>50 degrees C) during the treatment period, however this alone did not ensure samples met the WHO E. coli guideline; higher, sustained thermophilic temperatures tended to be more effective in reaching this guideline. The newly designed solar concentrator was capable of inactivating thermotolerant, environmentally-stable microorganisms as, or possibly more, efficiently than a previous design. Additional data are needed to better characterize how temperature, time, and other parameters affect the ability of the solar concentrator to inactivate microbes in feces. |
An assessment of household water quality among Peace Corps volunteers in Guatemala
Murphy DE , Poe SA , Murphy JL , Ferguson RW , Henderson SJ , Jung P . Trop Dis Travel Med Vaccines 2019 5 2 Background: Gastrointestinal (GI) illness is the most commonly reported health concern among Peace Corps Volunteers (PCVs) serving in Guatemala. This project identified water types and treatment and storage practices used by PCVs and measured select water quality parameters in their household water. Methods: A survey about water types and practices was conducted of PCVs in Guatemala. The water type most frequently consumed in the household ("primary drinking water") and other water types present in the household ("secondary water") were tested for free chlorine residual (FCR) and for the presence of Escherichia coli and total coliforms. A negative binomial regression model was used to analyze data on incidence of self-reported GI illness. Results: Tambo (commercially purified water in a 5-gal bottle) was the water type most frequently (64%) reported as primary drinking water in 39 PCV households. Most (74%) PCVs reported drinking water other than primary drinking water >/=1 day per week; the incidence rate of GI illness per PCV per month was significantly lower among PCVs who reported never consuming water other than primary drinking water compared to those who did (0.4 and 1.6 GI illnesses per PCV per month, respectively) (p < 0.05). E. coli was not detected in any primary drinking water sample, but was detected in 35% of secondary water samples. Total coliforms were detected in more than two-thirds of primary drinking water and secondary water samples. Nearly all water samples had an FCR of < 0.2 mg/L. Conclusions: Consuming primary drinking water exclusively likely contributes to reducing the rate of GI illness among PCVs. However, most PCVs reported drinking multiple water types, which may include contaminated secondary water types in the household. All water intended for consumption, including secondary sources within and outside the household, should be properly treated and safely stored. |
Outbreaks associated with treated recreational water - United States, 2000-2014
Hlavsa MC , Cikesh BL , Roberts VA , Kahler AM , Vigar M , Hilborn ED , Wade TJ , Roellig DM , Murphy JL , Xiao L , Yates KM , Kunz JM , Arduino MJ , Reddy SC , Fullerton KE , Cooley LA , Beach MJ , Hill VR , Yoder JS . MMWR Morb Mortal Wkly Rep 2018 67 (19) 547-551 Outbreaks associated with exposure to treated recreational water can be caused by pathogens or chemicals in venues such as pools, hot tubs/spas, and interactive water play venues (i.e., water playgrounds). During 2000-2014, public health officials from 46 states and Puerto Rico reported 493 outbreaks associated with treated recreational water. These outbreaks resulted in at least 27,219 cases and eight deaths. Among the 363 outbreaks with a confirmed infectious etiology, 212 (58%) were caused by Cryptosporidium (which causes predominantly gastrointestinal illness), 57 (16%) by Legionella (which causes Legionnaires' disease, a severe pneumonia, and Pontiac fever, a milder illness with flu-like symptoms), and 47 (13%) by Pseudomonas (which causes folliculitis ["hot tub rash"] and otitis externa ["swimmers' ear"]). Investigations of the 363 outbreaks identified 24,453 cases; 21,766 (89%) were caused by Cryptosporidium, 920 (4%) by Pseudomonas, and 624 (3%) by Legionella. At least six of the eight reported deaths occurred in persons affected by outbreaks caused by Legionella. Hotels were the leading setting, associated with 157 (32%) of the 493 outbreaks. Overall, the outbreaks had a bimodal temporal distribution: 275 (56%) outbreaks started during June-August and 46 (9%) in March. Assessment of trends in the annual counts of outbreaks caused by Cryptosporidium, Legionella, or Pseudomonas indicate mixed progress in preventing transmission. Pathogens able to evade chlorine inactivation have become leading outbreak etiologies. The consequent outbreak and case counts and mortality underscore the utility of CDC's Model Aquatic Health Code (https://www.cdc.gov/mahc) to prevent outbreaks associated with treated recreational water. |
Pool water quality and prevalence of microbes in filter backwash from metro-Atlanta swimming pools
Murphy JL , Hlavsa MC , Carter BC , Miller C , Jothikumar N , Gerth TR , Beach MJ , Hill VR . J Water Health 2018 16 (1) 87-92 During the 2012 summer swim season, aquatic venue data and filter backwash samples were collected from 127 metro-Atlanta pools. Last-recorded water chemistry measures indicated 98% (157/161) of samples were from pools with >/=1 mg/L residual chlorine without stabilized chlorine or >/=2 mg/L with stabilized chlorine and 89% (144/161) had pH readings 7.2-7.8. These water quality parameters are consistent with the 2016 Model Aquatic Health Code (2nd edition) recommendations. We used previously validated real-time polymerase chain reaction assays for detection of seven enteric microbes, including Escherichia coli, and Pseudomonas aeruginosa. E. coli was detected in 58% (93/161) of samples, signifying that swimmers likely introduced fecal material into pool water. P. aeruginosa was detected in 59% (95/161) of samples, indicating contamination from swimmers or biofilm growth on surfaces. Cryptosporidium spp. and Giardia duodenalis were each detected in approximately 1% of samples. These findings indicate the need for aquatics staff, state and local environmental health practitioners, and swimmers to each take steps to minimize the risk of transmission of infectious pathogens. |
Assessment of drinking water sold from private sector kiosks in post-earthquake Port-au-Prince, Haiti
Patrick M , Steenland M , Dismer A , Pierre-Louis J , Murphy JL , Kahler A , Mull B , Etheart MD , Rossignol E , Boncy J , Hill V , Handzel T . Am J Trop Med Hyg 2017 97 84-91 Consumption of drinking water from private vendors has increased considerably in Port-au-Prince, Haiti, in recent decades. A major type of vendor is private kiosks, advertising reverse osmosis-treated water for sale by volume. To describe the scale and geographical distribution of private kiosks in metropolitan Port-au-Prince, an inventory of private kiosks was conducted from July to August 2013. Coordinates of kiosks were recorded with global positioning system units and a brief questionnaire was administered with the operator to document key kiosk characteristics. To assess the quality of water originating from private kiosks, water quality analyses were also conducted on a sample of those inventoried as well as from the major provider company sites. The parameters tested were Escherichia coli, free chlorine residual, pH, turbidity, and total dissolved solids. More than 1,300 kiosks were inventoried, the majority of which were franchises of four large provider companies. Approximately half of kiosks reported opening within 12 months of the date of the inventory. The kiosk treatment chain and sales price was consistent among a majority of the kiosks. Of the 757 kiosks sampled for water quality, 90.9% of samples met World Health Organization (WHO) microbiological guideline at the point of sale for nondetectable E. coli in a 100-mL sample. Of the eight provider company sites tested, all samples met the WHO microbiological guideline. Because of the increasing role of the private sector in drinking water provision in Port-au-Prince and elsewhere in Haiti, this assessment was an important first step for government regulation of this sector. |
Environmental survey of drinking water sources in Kampala, Uganda during a typhoid fever outbreak
Murphy JL , Kahler AM , Nansubuga I , Nanyunja EM , Kaplan B , Jothikumar N , Routh J , Gomez GA , Mintz ED , Hill VR . Appl Environ Microbiol 2017 83 (23) In 2015, a typhoid fever outbreak began in downtown Kampala, Uganda and spread into adjacent districts. In response, an environmental survey of drinking water source types was conducted in areas of the city with high case numbers. A total of 122 samples were collected from 12 source types and tested for E. coli, free chlorine, and conductivity. An additional 37 grab samples from seven source types and 16 paired large volume (20-L) samples from wells and springs were also collected and tested for the presence of Salmonella Typhi. Escherichia coli was detected in 60% of kaveras (drinking water sold in plastic bags) and 80% of refilled water bottles; free chlorine was not detected in either source type. Most jerry cans (68%) contained E. coli and had free chlorine residuals below the WHO recommended level of 0.5 mg/L during outbreaks. Elevated conductivity readings for kaveras, refilled water bottles, and jerry cans (compared to treated surface water supplied by the water utility) suggested they likely contained untreated ground water. All unprotected springs and wells and more than 60% of protected springs contained E. coli Water samples collected from the water utility were found to have acceptable free chlorine levels and no detectable E. coli While S Typhi was not detected in water samples, Salmonella spp. were detected in samples from two unprotected springs, one protected spring, and one refilled water bottle. These data provided clear evidence that unregulated vended water and ground water represented a risk for typhoid transmission.Importance Despite the high incidence of typhoid fever globally, relatively few outbreak investigations incorporate drinking water testing. During waterborne disease outbreaks, measurement of physical-chemical parameters, such as free chlorine residual and electrical conductivity, and microbiological parameters, such as the presence of E. coli or the implicated etiologic agent, in drinking water samples can identify contaminated sources. This investigation indicated that unregulated vended water and ground water sources were contaminated and were therefore a risk to consumers during the 2015 typhoid fever outbreak in Kampala. Identification of contaminated drinking water sources and sources that do not contain adequate disinfectant levels can lead to rapid targeted interventions. |
Removals of cryptosporidium parvum oocysts and cryptosporidium-sized polystyrene microspheres from swimming pool water by diatomaceous earth filtration and perlite-sand filtration
Lu P , Amburgey JE , Hill VR , Murphy JL , Schneeberger CL , Arrowood MJ , Yuan T . J Water Health 2017 15 (3) 374-384 Removal of Cryptosporidium-sized microspheres and Cryptosporidium parvum oocysts from swimming pools was investigated using diatomaceous earth (DE) precoat filtration and perlite-sand filtration. In pilot-scale experiments, microsphere removals of up to 2 log were obtained with 0.7 kg.DE/m2 at a filtration rate of 5 m/h. A slightly higher microsphere removal (2.3 log) was obtained for these DE-precoated filters when the filtration rate was 3.6 m/h. Additionally, pilot-scale perlite-sand filters achieved greater than 2 log removal when at least 0.37 kg/m2 of perlite was used compared to 0.1-0.4 log removal without perlite both at a surface loading rate of 37 m/h. Full-scale testing achieved 2.7 log of microspheres and oocysts removal when 0.7 kg.DE/m2 was used at 3.6 m/h. Removals were significantly decreased by a 15-minute interruption of the flow (without any mechanical agitation) to the DE filter in pilot-scale studies, which was not observed in full-scale filters. Microsphere removals were 2.7 log by perlite-sand filtration in a full-scale swimming pool filter operated at 34 m/h with 0.5 kg/m2 of perlite. The results demonstrate that either a DE precoat filter or a perlite-sand filter can improve the efficiency of removal of microspheres and oocysts from swimming pools over a standard sand filter under the conditions studied. |
Using molecular characterization to support investigations of aquatic facility-associated outbreaks of cryptosporidiosis - Alabama, Arizona, and Ohio, 2016
Hlavsa MC , Roellig DM , Seabolt MH , Kahler AM , Murphy JL , McKitt TK , Geeter EF , Dawsey R , Davidson SL , Kim TN , Tucker TH , Iverson SA , Garrett B , Fowle N , Collins J , Epperson G , Zusy S , Weiss JR , Komatsu K , Rodriguez E , Patterson JG , Sunenshine R , Taylor B , Cibulskas K , Denny L , Omura K , Tsorin B , Fullerton KE , Xiao L . MMWR Morb Mortal Wkly Rep 2017 66 (19) 493-497 Cryptosporidiosis is a nationally notifiable gastrointestinal illness caused by parasitic protozoa of the genus Cryptosporidium, which can cause profuse, watery diarrhea that can last up to 2-3 weeks in immunocompetent patients and can lead to life-threatening wasting and malabsorption in immunocompromised patients. Fecal-oral transmission of Cryptosporidium oocysts, the parasite's infectious life stage, occurs via ingestion of contaminated recreational water, drinking water, or food, or following contact with infected persons or animals, particularly preweaned bovine calves (1). The typical incubation period is 2-10 days. Since 2004, the annual incidence of nationally notified cryptosporidiosis has risen approximately threefold in the United States (1). Cryptosporidium also has emerged as the leading etiology of nationally notified recreational water-associated outbreaks, particularly those associated with aquatic facilities (i.e., physical places that contain one or more aquatic venues [e.g., pools] and support infrastructure) (2). As of February 24, 2017, a total of 13 (54%) of 24 states reporting provisional data detected at least 32 aquatic facility-associated cryptosporidiosis outbreaks in 2016. In comparison, 20 such outbreaks were voluntarily reported to CDC via the National Outbreak Reporting System for 2011, 16 for 2012, 13 for 2013, and 16 for 2014. This report highlights cryptosporidiosis outbreaks associated with aquatic facilities in three states (Alabama, Arizona, and Ohio) in 2016. This report also illustrates the use of CryptoNet, the first U.S. molecularly based surveillance system for a parasitic disease, to further elucidate Cryptosporidium chains of transmission and cryptosporidiosis epidemiology. CryptoNet data can be used to optimize evidence-based prevention strategies. Not swimming when ill with diarrhea is key to preventing and controlling aquatic facility-associated cryptosporidiosis outbreaks (https://www.cdc.gov/healthywater/swimming/swimmers/steps-healthy-swimming.html). |
A full-scale study of Cryptosporidium parvum oocyst and Cryptosporidium-sized microsphere removals from swimming pools via sand filtration
Lu P , Amburgey JE , Hill VR , Murphy JL , Schneeberger C , Arrowood MJ . Water Quality Research Journal 2017 52 (1) 18-25 Removal of Cryptosporidium parvum oocysts and Cryptosporidium-sized microspheres was evaluated in full-scale swimming pools via high-rate sand filtration (31–34 m/h) with coagulation. Results showed that at least 90% of C. parvum oocysts and microspheres were removed by filtration with an initial dosage of coagulant B (1.56 mg/L), D (1.9 mg/L or 305 g/m2), or F (1.56 mg/L) from each swimming pool. Filtration with an initial dosage of coagulant E (0.1 mg·Al/L) achieved 82% C. parvum oocyst removal and 97% microsphere removal. Coagulants B and F had a tendency to overdose over time with continuous feeding (based on corresponding pilot-scale experiments) and did not consistently achieve removals greater than 90% in the full-scale trials. As high as 99% of C. parvum oocysts and 98% of microspheres were removed with a continuous dosage of coagulant D. Up to 98% (1.7 log) of C. parvum oocysts and 93% (1.1 log) of microspheres were removed by continuous dosing of coagulant E at 27 m/h. Consistent oocyst and microsphere removal by aluminum-based coagulants (D and E) was achieved under the tested swimming pool conditions. |
Evaluating four measures of water quality in clay pots and plastic safe storage containers in Kenya
Murphy JL , Ayers TL , Knee J , Oremo J , Odhiambo A , Faith SH , Nyagol RO , Stauber CE , Lantagne DS , Quick RE . Water Res 2016 104 312-319 Household water treatment with chlorine can improve microbiological quality and reduce diarrhea. Chlorination is typically assessed using free chlorine residual (FCR), with a lower acceptable limit of 0.2 mg/L, however, accurate measurement of FCR is challenging with turbid water. To compare potential measures of adherence to treatment and water quality, we chlorinated recently-collected water in rural Kenyan households and measured total chlorine residual (TCR), FCR, oxidation reduction potential (ORP), and E. coli concentration over 72 h in clay and plastic containers. Results showed that 1) ORP served as a useful proxy for chlorination in plastic containers up to 24 h; 2) most stored water samples disinfected by chlorination remained significantly less contaminated than source water for up to 72 h, even in the absence of FCR; 3) TCR may be a useful proxy indicator of microbiologic water quality because it confirms previous chlorination and is associated with a lower risk of E. coli contamination compared to untreated source water; and 4) chlorination is more effective in plastic than clay containers presumably because of lower chlorine demand in plastic. |
A cluster randomized controlled evaluation of the health impact of a novel antimicrobial hand towel on the health of children under 2 years old in rural communities in Nyanza Province, Kenya
Slayton RB , Murphy JL , Morris J , Faith SH , Oremo J , Odhiambo A , Ayers T , Feinman SJ , Brown AC , Quick RE . Am J Trop Med Hyg 2015 94 (2) 437-44 To assess the health impact of reusable, antimicrobial hand towels, we conducted a cluster randomized, yearlong field trial. At baseline, we surveyed mothers, and gave four towels plus hygiene education to intervention households and education alone to controls. At biweekly home visits, we asked about infections in children < 2 years old and tested post-handwashing hand rinse samples of 20% of mothers for Escherichia coli. At study's conclusion, we tested 50% of towels for E. coli. Baseline characteristics between 188 intervention and 181 control households were similar. Intervention and control children had similar rates of diarrhea (1.47 versus 1.48, P = 0.99), respiratory infections (1.38 versus 1.48, P = 0.92), skin infections (1.76 versus 1.79, P = 0.81), and subjective fever (2.62 versus 3.40, P = 0.04) per 100 person-visits. Post-handwashing hand contamination was similar; 67% of towels exhibited E. coli contamination. Antimicrobial hand towels became contaminated over time, did not improve hand hygiene, or prevent diarrhea, respiratory infections, or skin infections. |
Effect of cyanuric acid on the inactivation of Cryptosporidium parvum under hyperchlorination conditions
Murphy JL , Arrowood MJ , Lu X , Hlavsa MC , Beach MJ , Hill VR . Environ Sci Technol 2015 49 (12) 7348-55 Cyanuric acid (CYA) is a chlorine stabilizer used in swimming pools to limit UV degradation of chlorine, thus reducing chlorine use and cost. However, CYA has been shown to decrease the efficacy of chlorine disinfection. In the event of a diarrheal incident, CDC recommends implementing 3-log10 inactivation conditions for Cryptosporidium (CT value = 15300 mg.min/L) to remediate pools. Currently, CYA's impact on Cryptosporidium inactivation is not fully determined. We investigated the impact of multiple concentrations of CYA on C. parvum inactivation (at 20 and 40 mg/L free chlorine; average pH 7.6; 25 degrees C). At 20 mg/L free chlorine, average estimated 3-log10 CT values were 17800 and 31500 mg.min/L with 8 and 16 mg/L CYA, respectively, and the average estimated 1-log10 CT value was 76500 mg.min/L with 48 mg/L CYA. At 40 mg/L free chlorine, 3-log10 CT values were lower than those at 20 mg/L, but still higher than those of free chlorine-only controls. In the presence of approximately 100 mg/L CYA, average 0.8- and 1.4-log10 reductions were achieved by 72 h at 20 and 40 mg/L free chlorine, respectively. This study demonstrates CYA significantly delays chlorine inactivation of Cryptosporidium oocysts, emphasizing the need for additional pool remediation options following fecal incidents. |
Efficacy of chlorine dioxide tablets on inactivation of Cryptosporidium oocysts
Murphy JL , Haas CN , Arrowood MJ , Hlavsa MC , Beach MJ , Hill VR . Environ Sci Technol 2014 48 (10) 5849-56 The ability of chlorine dioxide (ClO2) to achieve 2-log inactivation of Cryptosporidium in drinking water has been documented. No studies have specifically addressed the effects of ClO2 on C. parvum oocyst infectivity in chlorinated recreational water venues (e.g., pools). The aim of this research was to determine the efficacy of ClO2 as an alternative to existing hyperchlorination protocols that are used to achieve a 3-log inactivation of Cryptosporidium in such venues. To obtain a 3-log inactivation of C. parvum Iowa oocysts, contact times of 105 and 128 min for a solution containing 5 mg/L ClO2 with and without the addition of 2.6 mg/L free chlorine, respectively, were required. Contact times of 294 and 857 min for a solution containing 1.4 mg/L ClO2 with and without the addition of 3.6 mg/L free chlorine, respectively, were required. The hyperchlorination control (21 mg/L free chlorine only) required 455 min for a 3-log inactivation. Use of a solution containing 5 mg/L ClO2 and solutions containing 5 or 1.4 mg/L ClO2 with the addition of free chlorine appears to be a promising alternative to hyperchlorination for inactivating Cryptosporidium in chlorinated recreational water venues, but further studies are required to evaluate safety constraints on use. |
Ambient temperature incubation for the field detection of E. coli in drinking water
Brown J , Stauber C , Murphy JL , Khan A , Mu T , Elliott M , Sobsey MD . J Appl Microbiol 2011 110 (4) 915-23 AIMS: E. coli is the preeminent microbiological indicator used to assess safety of drinking water globally. The cost and equipment requirements for processing samples by standard methods may limit the scale of water quality testing in technologically less developed countries and other resource-limited settings, however. We evaluate here the use of ambient temperature incubation in detection of E. coli in drinking water samples as a potential cost-saving and convenience measure with applications in regions with high (>25 degrees C) mean ambient temperatures. METHODS AND RESULTS: This paper includes data from three separate water quality assessments: two in Cambodia and one in the Dominican Republic. Field samples of household drinking water were processed in duplicate by membrane filtration (Cambodia), Petrifilm(TM) (Cambodia), or Colilert(R) (Dominican Republic) on selective media at both standard incubation temperature (35 degrees C - 37 degrees C) and at ambient temperature, using up to 3 dilutions and 3 replicates at each dilution. Matched sample sets were well correlated, with 80% of samples (n = 1037) within risk-based microbial count strata (E. coli cfu/100ml counts of <1, 1-10, 11-100, 101-1000, >1000), and a pooled coefficient of variation of 17% (95% CI 15% - 20%) for paired sample sets across all methods. CONCLUSIONS: These results suggest that ambient temperature incubation of E. coli in at least some settings may yield sufficiently robust data for water safety monitoring where laboratory or incubator access is limited. SIGNIFICANCE AND IMPACT OF STUDY: Ambient temperature incubation of E. coli may be a promising option for reducing the complexity and costs associated with water safety monitoring for fecal indicator bacteria such as E. coli in a field context in resource-limited settings, as are often encountered in developing countries and after disasters. |
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