Adenovirus is recognized as the most UV-resistant waterborne pathogen of concern to public health microbiologists. The U.S. EPA has stipulated that a UV fluence (dose) of 186 mJ cm ؊2 is required for 4-log inactivation credit in water treatment. However, all adenovirus inactivation data to date published in the peer-reviewed literature have been based on UV disinfection experiments using UV irradiation at 253.7 nm produced from a conventional low-pressure UV source. The work reported here presents inactivation data for adenovirus based on polychromatic UV sources and details the significant enhancement in inactivation achieved using these polychromatic sources. When full-spectrum, medium-pressure UV lamps were used, 4-log inactivation of adenovirus type 40 is achieved at a UV fluence of less than 60 mJ cm ؊2 and a surface discharge pulsed UV source required a UV fluence of less than 40 mJ cm ؊2 . The action spectrum for adenovirus type 2 was also developed and partially explains the improved inactivation based on enhancements at wavelengths below 230 nm. Implications for water treatment, public health, and the future of UV regulations for virus disinfection are discussed.UV disinfection is a well-accepted technology for inactivation of bacterial and protozoan pathogens. Until recently, UV was also considered a viable technology for disinfection of viruses. At UV fluences (doses) typically used in water disinfection, UV is very effective (Ͼ4-log inactivation) against almost all known pathogenic viruses, with the one exception of adenoviruses (5). Adenovirus has been recently listed on the U.S. EPA Candidate Contaminant List, which indicates that it is a high priority for possible future regulation and is known or anticipated to occur in public water systems, but significant data gaps need to be addressed before regulation can be invoked. According to recently published U.S. EPA regulations (17), the inactivation of adenoviruses to a level of 4 log requires a UV fluence of 186 mJ cm Ϫ2 , based on an 80% credible interval, as presented in the Draft UV Disinfection Guidance Manual (16). The U.S. EPA-regulated UV fluence for inactivation of all viruses is now based on the conservative case of adenoviruses. Yates et al. (18) provide an excellent review of the issues surrounding the UV inactivation of adenovirus.Although data sets for UV inactivation of adenovirus differ moderately, they all place adenovirus as the most UV-resistant health-related virus known. However, all peer-reviewed published studies to date have been performed using a low-pressure (LP) mercury vapor UV lamp source characterized by a monochromatic output in the UV range at 253.7 nm. Based on these LP UV irradiation studies, the UV fluence necessary to achieve 4-log inactivation of adenovirus varies from 120 to approximately 180 mJ cm Ϫ2 . For adenovirus type 5 (Ad5), the required UV fluence is 160 to 170 mJ cm Ϫ2 (1), which is similar to those required for Ad1 (9), Ad2 (1, 5), Ad6 (9), and Ad40 and Ad41 (8). However, there are two studies that repo...

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Information on the required chlorine dose or Ct value (concentration of free chlorine multiplied by contact time) is limited to only a few enteroviruses. In this study the Ct values of some of the reported more chlorine resistant enteroviruses were determined. The Efficiency Hom Model was used to predict the times for 2, 3. and 4 -log inactivation of echovirus 1 and 12, coxsackievirus B5 and poliovirus type 1 at pH 7.5 and 9 at 5 degrees C. Coxsackievirus B5 was the most resistant to chlorine with a Ct requirement of 11.5 mg x min/L at pH 7.5 at 5 degrees C compared to polio with a Ct of 5.3 mg x min/L under the same conditions. All the viruses were more resistant than polio 1 at pH 9.0.

The enhancement of water quality by artificial wetland systems is increasingly being employed throughout the world. Three wetlands were studied in Tucson, AZ to evaluate their individual performance in the removal of indicator bacteria (coliforms), coliphage, and enteric pathogens (Giardia and Cryptosporidium). A duckweed-covered pond, a multi-species subsurface flow (SSF) and a multi-species surface flow (SF) wetland were studied. Removal of the larger microorganisms, Giardia and Cryptosporidium, was the greatest in the duckweed pond at 98 and 89 percent, respectively. The lowest removal occurred in the SF wetland, 73 percent for Giardia and 58 percent removal for Cryptosporidium. In contrast, the greatest removal of coliphage, total and fecal coliforms occurred in the SSF wetland, 95, 99, and 98 percent respectively, whereas the pond had the lowest removals (40, 62, and 61 percent, respectively). Sedimentation may be the primary removal mechanism within the duckweed pond since the removal was related to size, removal of the largest organisms being the greatest. However, the smaller microorganisms were removed more efficiently in the SSF wetland, which may be related to the large surface area available for adsorption and filtration. This study suggests that in order to achieve the highest treatment level of secondary unchlorinated wastewater, a combination of aquatic ponds and subsurface flow wetlands may be necessary.

Determining the survival of zoonotic pathogens in livestock manure and runoff is critical for understanding the environmental and public health risks associated with these wastes. The occurrence and persistence of the bacterial pathogens Escherichia coli O157:H7 and Campylobacter spp. in a passive beef cattle feedlot runoff control-vegetative treatment system were examined over a 26-mo period. Incidence of the protozoans Cryptosporidium spp. and Giardia spp. was also assessed. The control system utilizes a shallow basin to collect liquid runoff and accumulate eroded solids from the pen surfaces; when an adequate liquid volume is attained, the liquid is discharged from the basin onto a 4.5-ha vegetative treatment area (VTA) of bromegrass which is harvested as hay. Basin discharge transported E. coli O157, Campylobacter spp., and generic E. coli into the VTA soil, but without additional discharge from the basin, the pathogen prevalences decreased over time. Similarly, the VTA soil concentrations of generic E. coli initially decreased rapidly, but lower residual populations persisted. Isolation of Cryptosporidium oocysts and Giardia cysts from VTA samples was infrequent, indicating differences in sedimentation and/or transport in comparison to bacteria. Isolation of generic E. coli from freshly cut hay from VTA regions that received basin discharge (12 of 30 vs. 1 of 30 control samples) provided evidence for the risk of contamination; however, neither E. coli O157 or Campylobacter spp. were recovered from the hay following baling. This work indicates that the runoff control system is effective for reducing environmental risk by containing and removing pathogens from feedlot runoff.

Adenoviruses are nonenveloped, double-stranded DNA viruses that infect humans, causing dysentery and respiratory infection. Adenovirus has become a focus of the water treatment community because of its apparent resistance to ultraviolet (UV) disinfection and is the basis for stringent new regulations from the U.S. Environmental Protection Agency regarding UV disinfection of all viruses. Most of the work done so far, however, has involved the use of monochromatic (254 nm) low-pressure UV sources and assay of viral inactivation in cell culture models. Adenovirus is most likely not truly resistant to UV damage but is instead damaged and then repaired in host cells during cell culture infectivity assays. Recent research has shown that newer, polychromatic UV sources are more effective than monochromatic low-pressure UV at inactivating adenovirus. The potential for viral DNA repair in cell culture necessitates the use of alternative assay methods to measure UV disinfection efficiency: these include molecular biology and animal infectivity assays. Research to help clarify the effects of UV on adenovirus should therefore address two major issues not addressed in most studies published so far: the nature of (a) the UV source used to inactivate the virus and (b) the assays used to determine inactivation and characterize viral response. In this review, the authors

Dairy foods provide a significant portion of the recommended daily nutrition for much of the US population. Improving the availability of safe and nutritious dairy products and decreasing the environmental impact of the dairy community continue to be high priorities for both industry and the public sector. In recognition of these shared priorities, scientists and other specialists from the USDA, National Dairy Council, industry, academia, and nongovernmental organizations participated in the "Elevating Dairy Research and Extension Through Partnership" meeting on June 19, 2018. The purpose of the meeting was to strengthen partnerships and identify dairy-related research and extension needs in human nutrition, environmental sustainability, food safety, and product innovation that would benefit from enhanced coordination and collaboration across the dairy community, academia, and government. To catalyze further progress on these topics, the meeting organizers agreed to leverage the content and expertise that emerged from the meeting to develop a dairy research and extension coordination roadmap. The roadmap will establish and articulate a vision for coordinated collaboration between USDA researchers, the National Dairy Council, university researchers, extension specialists, and other dairy community stakeholders in the private and public sectors. This article represents the proceedings of the meeting and is intended to broadly communicate the dairy research and extension discussion and next steps to the dairy research and extension communities and other stakeholders in industry, academic, and government sectors.

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