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Swimming pool-related Pseudomonas aeruginosa infections mainly result in folliculitis and otitis externa. P. aeruginosa forms biofilms on surfaces in the swimming pool environment. The presence of P. aeruginosa on inflatables and foam teaching aids in 24 public swimming pools in the Netherlands was studied. Samples (n = 230) were taken from 175 objects and analysed for P. aeruginosa by culture. Isolated P. aeruginosa were tested for antibiotic resistance by disk diffusion. P. aeruginosa was detected in 63 samples (27%), from 47 objects (27%) in 19 (79%) swimming pools. More vinyl-canvas objects (44%) than foam objects (20%) were contaminated, as were wet objects (43%) compared to dry objects (13%). Concentrations were variable, and on average higher on vinyl-canvas than on foam objects. Forty of 193 (21%) P. aeruginosa isolates from 11 different objects were (intermediate) resistant to one or more of 12 clinically relevant antibiotics, mostly to imipenem and aztreonam. The immediate risk of a P. aeruginosa infection from exposure to swimming pool objects seems limited, but the presence of P. aeruginosa on pool objects is unwanted and requires attention of pool managers and responsible authorities. Strict drying and cleaning policies are needed for infrequently used vinyl-canvas objects. [ABSTRACT FROM AUTHOR]

The use of roof-collected rainwater as a freely available and sustainable alternative to drinking water produced by drinking water companies increases worldwide. Initially, rainwater is free of microbial contamination, but it may become contaminated by animals and humans or, alternatively, human pathogens may grow in stored rainwater resulting in a significant human health risk from infectious diseases. This three-year study demonstrated that rainwater stored in different reservoirs in The Netherlands was frequently faecally contaminated and incidentally contained potential human pathogens such as Campylobacter, Cryptosporidium, Giardia, Aeromonas hydrophila and Legionella. Analysis of samples during a period with variable weather conditions showed a correlation between rainfall intensity and faecal indicator counts and increased detection of pathogens after heavy rainfall incidents. Outside temperature had a limited effect on both the temperature and the microbiological quality of the water in the reservoirs, which did not comply with Dutch drinking water legislation and should thus not be consumed without treatment. In general, a health risk may arise from exposure to pathogens when contaminated droplets are inhaled, ingested or come into contact with the skin. Health risks may be reduced by regular cleaning of the collection, storage and transport means, but to assess their efficacy field intervention studies are required. [ABSTRACT FROM AUTHOR]

Outbreaks of cercarial dermatitis which occurred in recreational lakes in the Netherlands were studied and a method for direct rapid detection of the parasite Trichobilharzia in water samples was developed. A standardized questionnaire with questions on health complaints and exposure was distributed to individuals who developed symptoms of cercarial dermatitis after visiting fresh water lakes. Snails from the suspected lakes were examined for the presence of Trichobilharzia by microscopy and PCR. Water samples were concentrated by filtration and examined by PCR. Water quality was tested according to European Bathing Water Directive 76/160/EEG. Trichobilharzia was detected in snails and water samples from lakes which met European bathing water standards. Despite a response of 25.5%, epidemiological data suggested that longer and more frequent exposure to the water resulted in increased reporting of symptoms of cercarial dermatitis and confirmed the importance of exposure as a risk factor. A novel method for direct detection of Trichobilharzia, which includes concentration of water samples by filtration and detection of the parasite by PCR proved to be a valuable and simple tool for confirmation of presumptive outbreaks, particularly when snails could not be found in the suspected water and public health protecting measures were necessary. [ABSTRACT FROM AUTHOR]

The water in the canals and some recreational lakes in Amsterdam is microbiologically contaminated through the discharge of raw sewage from houseboats, sewage effluent, and dog and bird feces. Exposure to these waters may have negative health effects. During two successive 1-year study periods, the water quality in two canals (2003 to 2004) and five recreational lakes (2004 to 2005) in Amsterdam was tested with regard to the presence of fecal indicators and waterborne pathogens. According to Bathing Water Directive 2006/7/EC, based on Escherichia coli and intestinal enterococcus counts, water quality in the canals was poor but was classified as excellent in the recreational lakes. Campylobacter, Salmonella, Cryplosporidiuin, and Giardia were detected in the canals, as was rotavirus, norovirus, and enterovirus RNA. Low numbers of Cryptosporidium oocysts and Giardia cysts were detected in the recreational lakes, despite compliance with European bathing water legislation. The estimated risk of infection with Cryptosporidium and Giardia per exposure event ranged from 0.0002 to 0.007% and 0.04 to 0.2%, respectively, for occupational divers professionally exposed to canal water. The estimated risk of infection at exposure to incidental peak concentrations of Ciyptosporidium and Giardia may be up to 0.01% and 1%, respectively, for people who accidentally swallow larger volumes of the canal water than the divers. Low levels of viable waterborne pathogens, such as Cryptosporidiuin and Giardia, pose a possible health risk from occupational, accidental, and recreational exposure to surface waters in Amsterdam. [ABSTRACT FROM AUTHOR]

In the past few years many waterborne outbreaks related to Cryptosporidium have been described. Current methods for detection of Cryptosporidium in water for the most part rely on viability assays which are not informative concerning the infectivity of oocysts. However, for estimation of the risk of infection with Cryptosporidium this information is required. For environmental samples the oocyst counts are often low, and the oocysts have been exposed to unfavorable conditions. Therefore, determination of the infectivity of environmental oocysts requires an assay with a high level of sensitivity. We evaluated the applicability of in vitro cell culture immunofluorescence assays with HCT-8 and Caco-2 cells for determination of oocyst infectivity in naturally contaminated water samples. Cell culture assays were compared with other viability and infectivity assays. Experiments with Cryptosporidium oocysts from different sources revealed that there was considerable variability in infectivity, which was illustrated by variable 50% infective doses, which ranged from 40 to 614 oocysts, and the results indicated that not only relatively large numbers of fresh oocysts but also aged oocysts produced infection in cell cultures. Fifteen Dutch surface water samples were tested, and the cell culture immunofluorescence assays were not capable of determining the infectivity for the low numbers of naturally occurring Cryptosporidium oocysts present in the samples. A comparison with other viability assays, such as the vital dye exclusion assay, demonstrated that surrogate methods overestimate the number of infectious oocysts and therefore the risk of infection with Cryptosporidium. For accurate risk assessment, further improvement of the method for detection of Cryptosporidium in water is needed. [ABSTRACT FROM AUTHOR]

The resistance ranking was very similar under different periods of incubation except the 17 and 24 h variants under plastic bags and with the presence or absence of Bayleton treatment. Very similar ranking was recorded also in the tests where four plot replicates were used, e.g. the reaction seventy was so close in different plot replicates that one plot per genotype seemed to be enough for serial resistance tests. The significant plot × genotype interaction shows that relative resistance ranking may vary to some extent, but basic changes do not occur. Also similar cultivar reactions were observed at different levels of disease severity resulting from inoculation with isolates differing in pathogenicity. An average reaction to these levels is closer to the genetically determined resistance. Analysis of the behaviour of a cuitivar at different disease severity levels helps to predict the field behaviour of a given genotype. The Bayleton treatment was ineffective against scab, although there was some interaction with cultivars. [ABSTRACT FROM AUTHOR]

Compares the sedimentation velocity of Cryptosporidium parvum oocytes and Giardia lamblia cysts. Methodologies used in velocity measurements; Sedimentation experiments conducted; Declined sedimentation velocity rate of oocytes.

Oocysts of Cryptosporidium parvum can survive for several months in surface water, one of the main factors determining their success in environmental transmission and thus their health hazard via water. Several factors in the environment, e.g. temperature, presence of predators and exo-enzymes will probably influence oocyst survival. The high persistence of oocysts may also limit the value of traditional faecal indicator bacteria. The aim of this study was to determine the rate at which C parvum oocysts, E coli, faecal enterococci and C perfringens spores die in surface water and the influence of temperature and the presence of autochthonous (micro)organisms on the die-off rate. Microcosms with autoclaved river water were inoculated with the organisms. Microcosms with untreated river water were inoculated with concentrated primary effluent containing the bacteria and with C parvum oocysts. Microcosms were incubated at 5°C or 15°C at 100rpm. Viability of oocysts was monitored by in vitro excystation and dye-exclusion; viability of the bacteria was determined on appropriate selective media. When pseudo first-order die-off kinetics were assumed, the die-off rate of oocysts at 5°C was 0.010 log10/d and at 15°C, 0.006-0.024 log10/d. These rates underestimate die-off since oocyst disintegration was not accounted for. Incubation in autoclaved or untreated water did influence the die-off rate of oocysts at 15°C but not at 5°C. The die-off rate of E coli and enterococci was faster in the non-sterile river water than in autoclaved water at both temperatures. At 15°C, E coli (and possibly E faecium) even multiplied in autoclaved water. In untreated river water, the die-off of E coli and enterococci was approximately 10x faster than die-off of oocysts but die-off rates of C perfringens were lower than those of oocysts. As for oocysts, die-off of the bacteria and spores was faster at 15°C than at 5°C. Oocysts are very persistent in river water: the time required for a 10x reduction in viability being 40-160d at 15°C and 100d at 5°C. Biological/biochemical activity influenced oocyst survival at 15°C and survival of both vegetative bacteria at 5 and 15°C. The rapid die-off of E coil and enterococci makes them less suitable as indicators of oocyst presence in water. As C perfringens survived longer in untreated river water than oocysts, it may prove useful as an indicator of the presence of C parvum. [ABSTRACT FROM AUTHOR]

In fish spas, clients may submerge their hands, feet or whole body in basins with Garra rufa fish, for dead skin removal. Skin infections may result from using these spas, transmitted from fish to clients, through either fish or water, or from client to client. The microbiological water quality was determined in 24 fish spas in 16 companies in the Netherlands through analysis of a single water sample per fish spa. Water samples were tested for the presence of Aeromonas spp., Vibrio spp.,Pseudomonas aeruginosa, nontuberculous mycobacteria,and faecal indicator bacteria by using standard culture methods. The majority of the examined fish spas contained Aeromonas spp. (n = 24), P. aeruginosa(n = 18), Vibrio spp. (n = 16) including V. cholerae non-O1/O139 and V. vulnificus, and several rapid growing Mycobacterium spp. (n = 23) including M. fortuitum, M.conceptionense, M. abscessus and M. chelonae. Faecal contamination of the fish spa water was low. Based on the detected concentrations of Aeromonas spp., Vibriospp., and P. aeruginosa, the detected Mycobacteriumspp., and the health implications of these bacteria, the health risk from using fish spas is considered limited for healthy people with an intact skin and no underlying disease.

During 2007-2010, over 4000 persons in The Netherlands contracted Q-fever, a zoonosis caused by the bacterium Coxiella burnetii. Goats and sheep are the main reservoir of C. burnetti and infected animals shed the bacterium with their urine, faeces and birth products. Human infections may occur through direct contact with infected animals, or through inhalation of contaminated dust particles or aerosols. Discharge of waste water from Q fever contaminated goat farms may result in the presence of C. burnetii in sewage water and aerosols at sewage water treatment plants (SWTPs) which may pose a health risk for workers or neighbouring residents. The objectives of this study were to determine the presence of C. burnetii at SWTPs and to optimize available detection methods. In March-July 2011, sewage influent and aeration tank samples from four SWTPs receiving discharge from Q fever positive goat farms were examined by using a multiplex real-time PCR detecting C. burnetii DNA by targeting IS1111 and com1 genes. Influent (44%; n=16/36) and active sludge (36%; n=13/36) samples were positive with low C. burnetii DNA content. Percentage positive samples per SWTP were 28-61%. Positive samples were most frequent in March 2011 and least frequent in May 2011. The presence of C. burnetii DNA in sewage water samples suggests that SWTPs receiving waste water from Q fever contaminated goat farms may contribute to the spread of C. burnetii to the environment. The low levels of C. burnetii DNA in sewage water during the decline of the Q fever outbreak in The Netherlands in 2011 indicate a low health risk for SWTP workers and residents., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

Pollutants, brought into a swimming pool by bathers, will react with chlorine to form disinfection by-products (DBPs). Some of these DBPs are found to be respiratory and ocular irritant and might be associated with asthma, or might even be carcinogenic. As DBPs in swimming pools are formed from bather-shed-pollutants, a reduction of these pollutants will lead to a reduction of DBPs. Until now, however, the release of pollutants by bathers has not been studied in detail. The study described in this paper focuses on the release of these pollutants, further called anthropogenic pollutants. The objective was to define and quantify the initial anthropogenic pollutants, by using a standardised shower cabin and a standardised showering protocol in laboratory time-series experiments and on-site experiments in swimming pools. The time-series experiments resulted in a definition of the initial anthropogenic pollutant release: the amount of pollutants released from a person in a standardised shower cabin during the first 60 s of showering. The data from the time-series experiments were used to create a model of pollutant release. The model can be used to predict the initial anthropogenic pollutant release as well as the effects of showering. On-site experiments were performed at four different swimming pools, including one outdoor pool. Results of these on-site showering experiments correspond with the time-series and model outcomes. Anthropogenic pollutant release (both chemical and microbiological) in swimming pool water can be reduced by pre-swim showering, very likely resulting in decreased DBPs formation and chlorine demand., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

In 2009, four bathing sites in The Netherlands were monitored for potentially human pathogenic Vibrio species to observe possible associations with environmental conditions and health complaints. Three slightly different enrichment procedures were used to isolate Vibrio species with different growth requirements. Waters were generally positive for Vibrio from May until October; median Vibrio concentrations ranged from 4 to 383 MPN per litre (maximum 10(5) MPN per litre). Isolated Vibrio species included V. alginolyticus (50.6%) and V. parahaemolyticus (8.5%) from bathing sites with salinities ranging between 2.8 and 3.5% and V. cholerae non-O1/O139 (6.9%) from sites with salinities ranging between 0.007 and 0.08%. Although more samples were positive for Vibrio at elevated water temperatures, a quantitative relation between Vibrio numbers in water samples and the water temperature was not observed which may be explained by maximum water temperatures of 21 ° C. Active surveillance yielded one case of a recreational water related Vibrio infection. V. cholerae non-O1/O139 was cultured from the patient's wound and the implicated recreational water; PFGE profiles of the water and patient isolates were not identical. The number of patients that contract a Vibrio infection through exposure to Dutch recreational waters seems low, but may be underestimated. The common occurrence of Vibrio species in these waters stresses the need for providing information on Vibrio to risk groups to prevent infections., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

The occurrence of Cryptosporidium and Giardia in indoor swimming pools in the Netherlands was studied at five locations. The backwash water from seven pool filters was analysed for the presence of Cryptosporidium oocysts and Giardia cysts for a period of 1 year. Of the 153 samples of filter backwash water analysed, 18 (11.8%) were found positive for either Cryptosporidium (4.6%), Giardia (5.9%) or both (1.3%). Oocysts and cysts were also detected in the water of one toddler pool and one learner pool. Although most of the (oo)cysts in the filter backwash water were dead, viable and potentially infectious oocysts were detected in the learner pool. On the basis of numbers of potentially infectious (oo)cysts detected in the learner pool, and assuming one visit to an infected pool per year, risk assessment indicated an estimated risk of infection with Cryptosporidium that exceeded the generally accepted risk of one infection per 10,000 persons per year. Guidelines for pool operators on how to manage faecal accidents and public information on the importance of hygiene in swimming pool complexes are recommended tools in controlling the risk of infection.

Aims: The reference methods for enumeration of total coliforms and Escherichia coli as stated in the European Drinking Water Directive were compared with alternative methods., Methods and Results: Laboratories used the reference method on Lactose TTC agar (LTTC), the Colilert/18 system, Laurysulphate Agar (LSA), Chromocult Coliform Agar and the E. coli Direct Plating (DP) method. They enumerated more total coliforms on LTTC than on LSA., Conclusions: LTTC is suitable for analysis of very clean water samples only, due to heavy background growth. Colilert/18 is a good alternative but it enumerates a broader group of total coliforms, resulting in higher counts. The DP method appeared to be the best choice for enumeration of E. coli because Colilert/18 produces lower counts and false-negative results., Significance and Impact of the Study: This study shows the limitations of the EU reference method on LTTC due to lack of selectivity and suggests alternative methods for the enumeration of total coliforms and E. coli.

Seven strains of Campylobacter jejuni, isolated from various sources [human (n = 2), chicken (n = 3), water (n = 2)], were studied under starvation conditions in filter-sterilized and pasteurized surface water by acridine orange direct count (AODC), viable count (DVC) and culture methods. Plate counts showed a rapid decline (2 log-units/day) for all strains under these conditions. Only one of the seven strains (14%) showed a (prolonged) viable, non-culturable 'state'. The ability of these viable, non-culturable cells to colonize the intestine was tested on day-old chicks. The infectious oral dose of freshly cultured cells of this model was 26-260 cfu; 1.8 x 10(5) viable, non-culturable C. jejuni were introduced to day-old chicks orally. Campylobacter jejuni was not isolated from the caeca of the chicks after incubation for 7 d. Also, passage through the allantoic fluid of embryonated eggs did not recover viable, non-culturable C. jejuni. These findings cast serious doubts on the significance of the viable, non-culturable 'state' in environmental transmission of C. jejuni.

Aeromonas strains (187) from human diarrhoeal stools and from drinking water (263) in The Netherlands were typed by three different methods. Biotyping alone was found to be of little value for epidemiological studies because 84% of all strains belonged to only 10 biotypes. Common biotypes could be further differentiated by serotyping. Gas-liquid chromatography of cell wall fatty acid methyl esters (FAME) was useful for species identification as well as for typing: 86% of all strains could be identified to the species level, and within this group 92% of all identifications corresponded with the biotype. Cluster analysis and principal component analysis of FAME profiles could be used for comparison of strains from different sources and gave the same general conclusions as bio- and serotyping. There was little overall similarity between Aeromonas strains from human (diarrhoeal) faeces and from drinking water, differences being most pronounced for Aeromonas caviae and least for A. sobria.