Yoshifumi Masago

A review on recent progress in the detection methods and prevalence of human enteric viruses in water

Waterborne human enteric viruses, such as noroviruses and adenoviruses, are excreted in the feces of infected individuals and transmitted via the fecal-oral route including contaminated food and water. Since viruses are normally present at low concentrations in aquatic environments, they should be concentrated into smaller volumes prior to downstream molecular biological applications, such as quantitative polymerase chain reaction (qPCR). This review describes recent progress made in the development of concentration and detection methods of human enteric viruses in water, and discusses their applications for providing a better understanding of the prevalence of the viruses in various types of water worldwide. Maximum concentrations of human enteric viruses in water that have been reported in previous studies are summarized to assess viral abundances in aquatic environments. Some descriptions are also available on recent applications of sequencing analyses used to determine the genetic diversity of viral genomes in water samples, including those of novel viruses. Furthermore, the importance and significance of utilizing appropriate process controls during viral analyses are discussed, and three types of process controls are considered: whole process controls, molecular process controls, and (reverse transcription (RT)-)qPCR controls. Although no standards have been established for acceptable values of virus recovery and/or extraction-(RT-)qPCR efficiency, use of at least one of these appropriate control types is highly recommended for more accurate interpretation of observed data.

Assessment of future flood inundations under climate and land use change scenarios in the Ciliwung River Basin, Jakarta

This study assessed flood inundation of the Ciliwung River Basin, Greater Jakarta to improve the urban water environment under climate change and unplanned urbanization. The 1-day maximum precipitation data for 50- and 100-year return period under current and future climate conditions were used to assess the impact of climate change. Precipitation output of the MRI-CGCM3, MIROC5 and HadGEM2-ES General Circulation Models (GCM) with RCP 4.5 and 8.5 emission scenario over periods 1985–2004 and 2020–2039 representing current and future climate conditions respectively were used. Similarly, land use data of 2009 and 2030 were used to represent the current and future conditions, respectively. The HEC-HMS model was used to simulate the river discharge at Katulampa, which represents the outlet location for the hydrologic modelling and the inlet location for the flood inundation modelling. FLO-2D, a two-dimensional hydrodynamic model, was used to simulate current and future flood inundation simulations. Increasing flood inundation areas and depths (6% to 31% for different GCMs) in the future reveal the need to improve flood management tools for the sustainable development of urban water environments.

Impacts of urbanization on the prevalence of antibiotic-resistant Escherichia coli in the Chaophraya River and its tributaries

River water samples were taken from 32 locations around the basin of Chaophraya River and its four major tributaries in Thailand to investigate resistance ratios of Escherichia coli isolates to eight antibiotic agents of amoxicillin, sulfamethoxazole/trimethoprim, tetracycline, doxytetracycline, ciprofloxacin, levofloxacin, norfloxacin and ofloxacin. Principal component analysis was performed to characterize resistance patterns of the samples. Relevancy of the obtained principal components with urban land use and fecal contamination of the river were examined. The ratio of antibiotic-resistant bacteria is likely to increase when urban land use near the sampling site exceeds a certain ratio. The resistance ratio to fluoroquinolones tends to be high in a highly populated area. Meanwhile, no significant contribution of fecal contamination was found to increase the resistance ratio. These results suggest that an antibiotic-resistance ratio is dependent on conditions of local urbanization rather than the upstream conditions, and that the major sources of antibiotic-resistant bacteria in the Chaophraya River basin are possibly point sources located in the urban area which contains a high ratio of resistant bacteria.

Applying a water quality index model to assess the water quality of the major rivers in the Kathmandu Valley, Nepal

Human activities during recent decades have led to increased degradation of the river water environment in South Asia. This degradation has led to concerns for the populations of the major cities of Nepal, including those of the Kathmandu Valley. The deterioration of the rivers in the valley is directly linked to the prevalence of poor sanitary conditions, as well as the presence of industries that discharge their effluents into the river. This study aims to investigate the water quality aspect for the aquatic ecosystems and recreation of the major rivers in the Kathmandu Valley using the Canadian Council of Ministers of the Environment water quality index (CCME WQI). Ten physicochemical parameters were used to determine the CCME WQI at 20 different sampling locations. Analysis of the data indicated that the water quality in rural areas ranges from excellent to good, whereas in denser settlements and core urban areas, the water quality is poor. The study results are expected to provide policy-makers with valuable information related to the use of river water by local people in the study area.

Assessment of Tangible Direct Flood Damage Using a Spatial Analysis Approach under the Effects of Climate Change: Case Study in an Urban Watershed in Hanoi, Vietnam

Due to climate change, the frequency and intensity of Hydro-Meteorological disasters, such as floods, are increasing. Therefore, the main purpose of this work is to assess tangible future flood damage in the urban watershed of the To Lich River in Hanoi, Vietnam. An approach based on spatial analysis, which requires the integration of several types of data related to flood characteristics that include depth, in particular, land-use classes, property values, and damage rates, is applied for the analysis. To simulate the future scenarios of flooding, the effects of climate change and land-use changes are estimated for 2030. Additionally, two scenarios based on the implementation of flood control measures are analyzed to demonstrate the effect of adaptation strategies. The findings show that climate change combined with the expansion of built-up areas increases the vulnerability of urban areas to flooding and economic damage. The results also reveal that the impacts of climate change will increase the total damage from floods by 26%. However, appropriate flood mitigation will be helpful in reducing the impacts of losses from floods by approximately 8% with the restoration of lakes and by approximately 29% with the implementation of water-sensitive urban design (WSUD). This study will be useful in helping to identify and map flood-prone areas at local and regional scales, which can lead to the detection and prioritization of exposed areas for appropriate countermeasures in a timely manner. In addition, the quantification of flood damage can be an important indicator to enhance the awareness of local decision-makers on improving the efficiency of regional flood risk reduction strategies.

CryptosporidiumQuantitative risk assessment of in a watershed

Publisher Summary This chapter calculates the risk of the infection of Cryptosporidium via drinking water following the ILSI/RSI quantitative risk assessment framework. In addition to the source water parameters, the effect of the rainfall was also incorporated in the annual risk calculation. Monte Carlo simulations were used to calculate the annual risk of the infection of Cryptosporidium via drinking water samples, which were collected from the Sagami River and its two tributaries Koayu and Nakatsu Rivers in Kanagawa prefecture in the Kanto area of Japan. Samples were brought to the laboratory and were filtered through cellulose acetate membrane disk filters. In Sagami River, Cryptosporidium oocysts were found in 41 of the 56 samples from six sites and the geometric mean concentration was found to be 9 oocysts per 100L. In Nakatsu River, Cryptosporidium oocysts were detected in 14 of the 29 samples from three sites and the geometric mean was 9 oocysts per 100L. In Koayu River, 21 samples from two sites were examined and Cryptosporidium oocysts were detected in all the samples and the geometric mean of the samples were 320 oocysts per 100L. The chapter concludes that there was a continuous presence of Cryptosporidium in the water of Sagami River. The geometric mean concentration of oocysts in the 76 positive samples was 24 oocysts per 100L. The maximum concentration was found to be as high as 11,000 oocysts per 100L.