Occurrence of Protozoan and Bacterial Pathogens in Water Samples from Small Water Systems in Mountainous Areas of Taiwan

Giardia, Cryptosporidium, Salmonella, and Shigella have emerged as waterborne pathogens of concern. Thirty water samples were collected from 10 small water systems in mountainous areas of Taiwan and investigated for the occurrence of these pathogens. In addition, the basic characteristics of each small water system were recorded, and each water sample was tested for several water quality parameters. The occurrence frequency was 10.0% for Giardia spp., 3.3% for Cryptosporidium spp. and Shigella flexneri, and 16.7% for Salmonella enterica. The highest correlation was found between the presence of Salmonella enterica and low water temperature, followed by the correlation between water turbidity and fecal coliform concentration. A low correlation was found between the presence of Giardia and the concentration of heterotrophic bacteria. The water samples from small water systems with filtration devices had a lower occurrence of pathogen microorganisms than those without filtration devices. The proportion of water samples with pathogenic microorganisms increased with the consumer population of the water systems, and the pathogen occurrence differed among the regions of the sampling sites. In order to prevent parasitic infection, the use of disinfection devices in small water systems would be needed.     

Anchoring of c-myc on nuclear matrix proteins in process of mouse thymic T lymphocyte proliferation induced by ConA

Epidemiologic investigations of the Latin America cholera epidemic have repeatedly implicated untreated drinking water and water touched by hands during storage as important vehicles for disease transmission. To prevent such transmission, we provided a new narrow-mouthed, plastic, water storage vessel and 5% calcium hypochlorite solution for home disinfection of stored water to a Bolivian Aymara Indian community at risk for cholera. We evaluated acceptance of this intervention and its effect on water quality. Each of 42 families in the study obtained water from a household well; fecal coliform bacteria were found in water from 39 (93%) of 42 wells and 33 (79%) of 42 usual water storage vessels. One group of families received the special vessels and chlorine (group A), a second received only the special vessels (group B), and a third served as a control group (group C). Water samples collected every three weeks from group A special vessels had lower geometric mean fecal coliform colony counts (P < 0.0001) and lower geometric mean Escherichia coli colony counts (P < 0.0001) than water from group B or C vessels. Adequate levels of free chlorine persisted in these vessels for at least 5 hr. The special vessels and chlorine solution were well accepted and continued to be used for at least six months. Use of the vessel and chlorine solution produced drinking water from nonpotable sources that met World Health Organization standards for microbiologic quality.     

Feasibility of a Dune Infiltration System to Protect North Carolina Beaches from Fecal Bacteria Contaminated Storm Water

Storm water ocean outfalls discharging into recreational waters pose a human health threat because of increased potential exposure to bacteria and other pathogens. The dune infiltration system (DIS) was designed and implemented at two ocean outfall sites in response to concerns by the North Carolina Department of Transportation and the town of Kure Beach, North Carolina The systems were designed to divert storm water runoff from 1.9?ha (4.7 acre) and 3.2?ha (8.0 acre) watersheds into the beach dunes. Following construction, data were collected from 25 storms during March through October 2006. The systems captured a combined total of nearly 1,800??m3 (63,500??ft3), or 95% of the influent storm water runoff—a significant reduction of runoff volume and peak flow discharging directly onto the beach (p<0.0001). Fecal coliform and enterococci concentrations were measured in the inflowing storm water runoff and groundwater downslope of the systems. Both groundwater bacteria concentrations near the systems were significantly lower than the bacteria concentrations in the inflowing storm water (p<0.001). Furthermore, groundwater fecal coliform concentrations after implementing the DISs were statistically similar to preconstruction levels (p<0.05). The initial results are promising, and the system should be considered for more widespread use. However, further comprehensive research is recommended to more thoroughly understand the viability of the DIS as a storm water best management practice and the fate and transport of the bacteria within the dunes.     

Prevalence of and associated risk factors for shedding Cryptosporidium parvum oocysts and Giardia cysts within feral pig populations in California

Populations of feral pigs (Sus scrofa) may serve as an environmental reservoir of Cryptosporidium parvum oocysts and Giardia sp. cysts for source water. We conducted a cross-sectional study to determine the prevalence of and associated demographic and environmental risk factors for the shedding of C. parvum oocysts and Giardia sp. cysts. Feral pigs were either live-trapped or dispatched from 10 populations located along the coastal mountains of western California, and fecal samples were obtained for immunofluorescence detection of C. parvum oocysts and Giardia sp. cysts. We found that 12 (5.4%) and 17 (7.6%) of 221 feral pigs were shedding C. parvum oocysts and Giardia sp. cysts, respectively. The pig's sex and body condition and the presence of cattle were not associated with the probability of the shedding of C. parvum oocysts. However, younger pigs (< or = 8 months) and pigs from high-density populations (> 2.0 feral pigs/km2) were significantly more likely to shed oocysts compared to older pigs (> 8 months) and pigs from low-density populations (< or = 1.9 feral pigs/km2). In contrast, none of these demographic and environmental variables were associated with the probability of the shedding of Giardia sp. cysts among feral pigs. These results suggest that given the propensity for feral pigs to focus their activity in riparian areas, feral pigs may serve as a source of protozoal contamination for surface water.     

Bacteriological quality of drinking water in the City of Merida, Mexico

With the aim of knowing the microbiological quality of drinking water in Merida, Yucatan, 383 paired samples of drinking water (two per house) were studied. Three hundred sixty four (95%) city water system samples and 283 (73.89%) tap water samples met the microbiological standards for drinking water. It was concluded that microbiological quality of drinking water from the city water system is satisfactory, except for the water system district Merida III, which has a significant aerobic plate count contamination level (21.7% of the samples). Domestic storage systems preserve water quality, with the exception of district Merida I, which has the highest level of contamination (4.8% of the samples) possibly from sewage water and fecal sources.     

Study on preferential flow in dump leaching of low-grade ores

Preferential flow in dump leaching of low-grade ores was investigated in this paper. The production of the dump leaching plant at Dexing Copper Mining in China was significantly influenced by preferential flow due to the heterogeneity of the ores in dump. Surface tension, negative pore water pressure, matrix suction and permeability of dump were found to be correlated to particle size. Preferential flow, which occurred in the fine and coarse region, was determined by solution application rate. Experiments showed that preferential flow happened in the fine region at an application rate below 1070 L/m² min. Experiment of solute transportation under preferential flow was conducted by selecting NaCl as solute. The NaCl concentration of the outflow from the coarse region was greater than that of the fine region. The leaching rate increased slowly as the leaching process proceeded because NaCl dissolved in the immobile water could only be leached through diffusion. The percentage recovery of coarse region surpassed 100%. The preferential flow within the fine region under the condition of small application rate was confirmed.     

Bisphosphonates as anticancer drugs

During June 1996, water supplies of the city of San Pedro Sula, Honduras, were sampled to obtain an assessment of Cryptosporidium oocyst and Giardia cyst concentrations. Each sample was concentrated and stained with an indirect immunofluorescent antibody, and parasites were counted through microscopic analysis. In three surface water supplies, Cryptosporidium oocyst concentrations ranged from 58 to 260 oocysts per 100 L, and Giardia cysts were present in concentrations ranging from 380 to 2100 cysts per 100 L. Unlike the surface water samples, groundwater had a higher concentration of Cryptosporidium oocysts (26/100 L) than Giardia cysts (6/100 L), suggesting that the groundwater aquifer protects the water supply more effectively from larger Giardia cysts. Cryptosporidium oocyst concentrations are within the typical range for surface water supplies in North America whereas Giardia cyst concentrations are elevated. Efforts should be made to protect raw water from sources of contamination.     

An outbreak of giardiasis in a group of campers

Thirty-four of 54 campers on a 2 week trip in mountains of Utah had diarrhea during and after their trip. Twenty-two (79%) of 28 symptomatic campers' stools examined contained Giardia lamblia cysts, whereas 4 (29%) of 14 asymptomatic campers' stools had cysts. The temporal distribution of cases and the absence of clustering among food preparation subgroups suggested a common source exposure. Although the epidemiologic data and fecal coliform counts implicated the remote mountain stream used as water source by the group as the vehicle of transmission, Giardia lamblia cysts were not recovered from stream water nor were they found in intestines or feces of sampled mammals living in the drainage area. Twenty-five other campers had stools examined before and after a subsequent hiking trip in another area of Utah; none had Giardia cysts before, but 6 (24%) had them after return. Questionnaires returned by 133 of the campers showed that 5% had an illness compatible with giardiasis within 2 weeks after their trip. These surveys show that campers exposed to mountain stream water are at risk of acquiring giardiasis.     

Statistical Evaluation of Factors Affecting Indicator Bacteria in Urban Storm-Water Runoff

An urban watershed in Raleigh, North Carolina, was monitored for indicator bacteria during 20 rain events. Results showed elevated levels of E. coli, enterococci, and fecal coliform. Samples were compared based on seasonality and were found to be statistically different (p<0.05), with pairwise comparisons indicating significantly lower concentrations of E. coli and fecal coliform during the winter (p<0.05). Enterococci concentrations were substantially lower in the winter and fall, but no significant differences were found between seasons during pairwise comparisons (p<0.05). Correlation analyses showed multiple significant relationships between antecedent climate parameters, flow characteristics, and indicator bacteria concentrations. More detailed multiple linear regression yielded explanatory variables related to antecedent climate conditions. Variables were generally related to temperature and moisture conditions in the atmosphere and soil. The results of this study show indicator bacteria concentrations significantly vary based on season; however, this variability can partially be explained by antecedent climate data.     

Looking at homeopathy, by an allopath

A study was done to test the effectiveness of fecal occult blood as a screening test for invasive bacterial pathogens and as a substitute for the fecal leukocyte examination in adult and pediatric cases of acute diarrhea. United States citizens studying in Mexico and Mexican children, both with acute diarrhea had their stools cultured, examined for fecal leukocytes, and tested for occult blood. Using culture results as the criterion standard for detection of bacterial agents, and fecal leukocytes for diarrhea associated with diffuse colonic inflammation, occult blood was tested for its sensitivity, specificity, and predictive value using 2 x 2 tables. Analysis of the data found that occult blood negative samples were reliable indicators of a lack of invasive bacteria in both adult and pediatric patients (negative predictive values of 87% and 96%, respectively). Positive results for either test were not reliably predictive as indicators of invasive bacteria among adults. A positive occult blood test result was significantly more sensitive than a positive fecal leukocyte test result (79% versus 42%) in detecting invasive bacteria in the pediatric patients; however, the positive predictive value was only 24%. The fecal occult blood test is an uncomplicated, low-cost test that was reliable when giving a negative result in detecting a lack of invasive bacteria in adult and pediatric patients with diarrhea. In children, a positive result on a fecal occult blood test is sensitive but not specific in detecting invasive bacterial enteropathogens. These data also indicate that a commercially available test for occult blood represents a suitable alternative to microscopic examination of fecal samples for leukocytes obtained from patients with acute diarrhea.     

Modeling Fate of Pathogenic Organisms in Coastal Waters of Oahu, Hawaii

A comprehensive modeling study was undertaken to examine the transport and fate of pathogenic organisms in the coastal waters of Mamala Bay, the southern shore of the island of Oahu, Hawaii. Specifically, two mathematical models were developed, calibrated, and validated in an attempt to understand both the relative contributions of various outfall and shoreline sources to organism counts throughout Mamala Bay and the benefits achieved by various source control options. A three-dimensional hydrodynamic model was constructed to simulate the advective and dispersive processes observed in the bay. A near field plume model was coupled with the hydrodynamic model to realistically incorporate initial mixing dynamics. Results of the hydrodynamic model were then used by a pathogen fate model to predict the distributions of fecal contamination indicator organisms and specific pathogens at several locations throughout the bay. Two sources were identified as primary contributors of contamination within Mamala Bay: the outfall from the Sand Island wastewater treatment plant and the Ala Wai Canal. The relative importance of the sources was dependent on the indicator organism used to assess fecal contamination. Using the fate model results and assuming a seven consecutive day exposure, the maximum risk of infection at Waikiki Beach was estimated to be 1.3∕100 for virus and 3.1∕10,000 for Giardia. The upgrade of the Sand Island treatment plant to chemically-enhanced primary treatment reduced organism counts throughout the bay by about a factor of two. Additional reductions were achieved by adding disinfection or upgrading the plant to secondary treatment. The implementation of the evaluated source control options would reduce the risks of infection at Waikiki Beach.     

Risk factors of chloroquine resistance in Plasmodium falciparum malaria

Sources of asbestos in drinking water may be natural deposits or the use of asbestos cement for water distribution. 50 water samples were selected in Austria to detect fibre contamination from either geology or asbestos cement by comparison with control areas and by comparison of raw and treated water. Standardized EPA/BGA methodology with transmission electron microscopy, energy dispersive X-ray analysis and selected area electron diffraction was used to quantify concentrations of different sized amphibole and chrysotile fibres. In 10 areas with asbestos deposits and in 14 areas with use of asbestos cement pipes asbestos concentrations in drinking water were low and not significantly different from 6 control areas (median 32,000 total asbestos fibres per litre). The relative highest concentration was found in an area with natural deposits at the source of the water supply (190,000 per litre). In areas without natural deposits the increase of asbestos concentrations from origin to consumer of water was not significant and unrelated to water aggressiveness, age and length of asbestos cement pipes. This could be mainly due to the fact that in areas with aggressive water asbestos cement pipes have been coated in Austria. A sample from a cistern, however, showed considerable asbestos contamination and raises concern about the use of surface water for room air humidification.     

Selective enumeration of Bacteroides vulgatus and B. distasonis organisms in the predominant human fecal flora by using monoclonal antibodies

The genus Bacteroides represents about one-third of the isolates from human fecal samples. The proportions of the different species are difficult to estimate because there is no method for rapid identification of mixtures of anaerobes. Monoclonal antibodies against Bacteroides vulgatus and B. distasonis were prepared. They did not react with the other Bacteroides species of the B. fragilis group. These reagents allowed direct enumeration of B. vulgatus and B. diastasonis organisms in human fecal samples. Anaerobic bacteria resistant to 1-h contact with air were enumerated in fecal human samples, a filter was layered on the colonies, and then B. vulgatus colonies were identified by an immunoassay performed with the prepared monoclonal antibodies. Healthy human adult volunteers were tested. Most of them harbored B. vulgatus at high levels, while the B. distasonis levels were always lower. Kinetic studies suggested that time variations for each volunteer were small. The simplified quantification of Bacteroides strains at the species level described here will prove useful in complementing our knowledge of the factors which may influence the predominant human fecal flora.     

Coliphages as indicators of viral pollution of water supply

The paper presents the data of Russian and foreign authors, as well as these author's findings of the significance of coliphages as indicators of viral contamination of drinking water. Coliphages may be used as indicators of viral drinking water contamination and for evaluation of the efficiency of drinking water purification in waterworks.     

Isolation of new bacterial species from drinking water biofilms and proof of their in situ dominance with highly specific 16S rRNA probes

A polyphasic approach involving cultivation, direct viable counts, rRNA-based phylogenetic classification, and in situ probing was applied for the characterization of the dominant microbial population in a municipal drinking water distribution system. A total of 234 bacterial strains cultivated on R2A medium were screened for bacteria affiliated with the in situ dominating beta subclass of Proteobacteria. The isolates were grouped according to common features of their cell and colony morphologies, and eight representative strains were used for 16S rRNA sequencing and the development of a suite of strain-specific oligonucleotide probes. Phylogenetic analysis indicated that all of the isolates were hitherto unknown bacteria. Three of them, strains B4, B6, and B8, formed a separate cluster of closely related organisms within the beta 1 subclass of Proteobacteria. In situ probing revealed that (i) 67 to 72% of total bacteria, corresponding to more than 80% of beta-subclass bacteria, could be encompassed with the strain-specific probes and (ii) the dominating bacterial species were culturable on R2A medium. Additionally, two-thirds of the autochthonous drinking water population could be shown to be in a viable but nonculturable (VBNC) state by using a direct viable count approach. The comparison of isolation frequencies with the in situ abundances of the eight investigated strains revealed differences in their culturability, indicating variable ratios of culturable to VBNC cells among the strains. The further characterization of biofilms throughout the distribution network demonstrated strains B6 and B8 to be dominant bacterial strains in groundwater and distribution system biofilms. The other strains could be found at various frequencies in the different parts of the distribution system; several strains appeared exclusively in drinking water biofilms obtained from a house installation system.     

Prevalence and clonal nature of Escherichia coli O157:H7 on dairy farms in Wisconsin

A survey was conducted between March and October of 1994 to determine the prevalence and identify the sources of serotype O157:H7 isolates of Escherichia coli in Wisconsin dairy herds. A stratified sample of 400 farms was identified, and 70 farms with weaned calves less than 4 months old were included in the study. During the prevalence study, 5 of the 70 farms (herd prevalence, 7.1 +/- 4.5%) and fecal samples from 10 of 560 calves (animal prevalence, 1.8%) tested positive for serotype O157:H7. In a follow-up study, the five O157:H7-positive farms and seven of the O157:H7-negative farms identified in the prevalence study were visited again. An additional 517 fecal samples from cattle of various ages were tested, and a total of 15 animals from four of the five herds that were previously positive and 4 animals from two of seven herds that were previously negative tested positive for E. coli O157:H7. Observations made during the follow-up study suggested that horizontal transmission was an important means of E. coli O157:H7 dissemination on the farms. A total of 302 environmental samples, were examined, and 2 animal drinking water samples from one previously negative farm and 1 animal drinking water sample from a previously positive farm contained E. coli O157:H7. Analyses by the pulsed-field gel electrophoresis technique of contour-clamped homogeneous electric field electrophoresis revealed that isolates from the same farm displayed identical or very similar XbaI restriction endonuclease digestion profiles (REDP), whereas isolates from different farms typically displayed different REDP. However, more than one REDP was usually observed for a given herd over the 8-month sampling period. Analyses of multiple isolates from an animal revealed that some animals harbored O157:H7 strains that had different REDP, although the REDP of isolates obtained from the same fecal sample were very similar. Collectively, 160 bovine isolates obtained from 29 different animals and three water isolates displayed 20 distinct XbaI REDP. Our data revealed that there are several clonal types of serotype O157:H7 isolates in Wisconsin and indicated that there is probably more than one source of this pathogen on the dairy farms studied. However, animal drinking water was identified as one source of E. coli O157:H7 on one farm.     

Variations of bacterial populations in human feces measured by fluorescent in situ hybridization with group-specific 16S rRNA-targeted oligonucleotide probes

Six 16S rRNA-targeted oligonucleotide probes were designed, validated, and used to quantify predominant groups of anaerobic bacteria in human fecal samples. A set of two probes was specific for species of the Bacteroides fragilis group and the species Bacteroides distasonis. Two others were designed to detect species of the Clostridium histolyticum and the Clostridium lituseburense groups. Another probe was designed for the genera Streptococcus and Lactococcus, and the final probe was designed for the species of the Clostridium coccoides-Eubacterium rectale group. The temperature of dissociation of each of the probes was determined. The specificities of the probes for a collection of target and reference organisms were tested by dot blot hybridization and fluorescent in situ hybridization (FISH). The new probes were used in initial FISH experiments to enumerate human fecal bacteria. The combination of the two Bacteroides-specific probes detected a mean of 5.4 x 10(10) cells per g (dry weight) of feces; the Clostridium coccoides-Eubacterium rectale group-specific probe detected a mean of 7.2 x 10(10) cells per g (dry weight) of feces. The Clostridium histolyticum, Clostridium lituseburense, and Streptococcus-Lactococcus group-specific probes detected only numbers of cells ranging from 1 x 10(7) to 7 x 10(8) per g (dry weight) of feces. Three of the newly designed probes and three additional probes were used in further FISH experiments to study the fecal flora composition of nine volunteers over a period of 8 months. The combination of probes was able to detect at least two-thirds of the fecal flora. The normal biological variations within the fecal populations of the volunteers were determined and indicated that these variations should be considered when evaluating the effects of agents modulating the flora.     

Factors Affecting Inactivation Behavior in the Monochloramination Range

The effects of monochloramine application techniques, chlorine-to-ammonia-N (Cl:N) ratios, water matrices, and bacterial origins on fecal coliform bacteria inactivation behavior in the monochloramination range were studied in ammoniacal bacteria suspensions and wastewater samples containing either naturally occurring or reseeded laboratory-cultured fecal coliform bacteria. The time-dependent chlorine residual concentrations and the bacteria counts were measured. The inactivation behavior was strongly affected by the monochloramine application techniques and the initial chlorine and ammonia concentrations and ratios. When dosing free chlorine to the ammoniacal solution, a “two-stage” pattern that coupled initial inactivation by transitory free chlorine and extended inactivation by forming monochloramine was observed at a Cl:N ratio of 3:1, while, at a high initial ammonia concentration (20?mg/L), synergy without initial inactivation was found instead. The difference is explained with calculations of the free-chlorine CT values. The inactivation behavior of laboratory-cultured suspensions differed from that of wastewater effluents, which was primarily attributable to the variations in the water matrix, not to the bacterial origins. Conducting dose-response studies using autoclaved wastewater samples reseeded with field-isolated, laboratory-cultured bacteria was proposed as the solution.     

Effectiveness of Different Artificial Neural Network Training Algorithms in Predicting Protozoa Risks in Surface Waters

A neural network approach was employed to relate risky Cryptosporidium and Giardia concentrations with other biological, chemical and physical parameters in surface water. A set of drinking water samples was classified as “risky” and “nonrisky” based on the concentrations of full and empty oocysts, and cycsts of Cryptosporidium and Giardia, respectively. Given the constraints associated with collecting large sets of microbial data, the study was aimed at identifying an effective training algorithm that would maximize the performance of a neural network model working with a relatively small dataset. A number of algorithms for training neural networks, including gradient search with first- and second-order partial derivatives, and genetic search were used and compared. Results showed that genetic algorithm based neural network training consistently provided better results compared to other training methods.