Flooding and heavy rainfall have been associated with waterborne infectious disease outbreaks, however, it is unclear to which extent they pose a risk for public health. Here, risks of infection from ...exposure to urban floodwater were assessed using quantitative microbial risk assessment (QMRA). To that aim, urban floodwaters were sampled in the Netherlands during 23 events in 2011 and 2012. The water contained Campylobacter jejuni (prevalence 61%, range 14- >103 MPN/l), Giardia spp. (35%, 0.1–142 cysts/l), Cryptosporidium (30%, 0.1–9.8 oocysts/l), noroviruses (29%, 102–104 pdu/l) and enteroviruses (35%, 103–104 pdu/l). Exposure data collected by questionnaire, revealed that children swallowed 1.7 ml (mean, 95% Confidence Interval 0–4.6 ml) per exposure event and adults swallowed 0.016 ml (mean, 95% CI 0–0.068 ml) due to hand-mouth contact. The mean risk of infection per event for children, who were exposed to floodwater originating from combined sewers, storm sewers and rainfall generated surface runoff was 33%, 23% and 3.5%, respectively, and for adults it was 3.9%, 0.58% and 0.039%. The annual risk of infection was calculated to compare flooding from different urban drainage systems. An exposure frequency of once every 10 years to flooding originating from combined sewers resulted in an annual risk of infection of 8%, which was equal to the risk of infection of flooding originating from rainfall generated surface runoff 2.3 times per year. However, these annual infection risks will increase with a higher frequency of urban flooding due to heavy rainfall as foreseen in climate change projections.
•Urban flooding was measured for enteric pathogens to assess risks for public health.•Health risks were quantified for flooding of different urban drainage systems.•The annual risk of infection for flooding originating from combined sewers was 8%.
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, Cryptosporidium, 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 Cryptosporidium 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 Cryptosporidium and Giardia, pose a possible health risk from occupational, accidental, and recreational exposure to surface waters in Amsterdam.
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.
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► Shower experiments were performed to determine pollutant release by bathers. ► Time-series data were used to create a model of the pollutant release in a shower. ► The model was validated at four swimming pool locations. ► Pre-swim showering reduces anthropogenic pollutants in swimming pool water.
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.
This study aims to identify governance conditions to realize urban bathing water sites using case study material from two cities in the Netherlands. Urban waters in Europe are increasingly considered ...an attractive feature for bathing, but research on the realization of urban bathing water sites has been limited. We find that it is important to account for the connectivity between water systems characteristics and governance conditions to increase effectiveness in the realization of urban bathing water sites. Ambitions regarding urban bathing water sites should be addressed in a wider policy context to create co-benefits, like other ambitions related to water quality, resilience and health. An analytical framework has been developed that could be used to support development and evaluation of future urban bathing water initiatives.
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.
Experimental analysis of the sedimentation velocity of Cryptosporidium parvum oocysts and Giardia lamblia cysts was compared with mathematical description of their sedimentation velocities by using ...measurements of (oo)cyst size and density and the density and viscosity of the sedimentation medium to determine if the sedimentation kinetics of freely suspended oocysts of C. parvum and cysts of G. lamblia can be described by Stokes' law. The theoretically calculated sedimentation kinetics showed a good agreement with the experimentally observed kinetics. Both showed a decline in sedimentation velocity over time, caused primarily by variation in (oo)cyst density. The initial apparent sedimentation velocities in Hanks balanced salt solution at 23 degrees C was 0.35 micrometer (.) s-1 for oocysts and l.4 micrometers (.) s-1 for cysts. (Oo)cysts that enter the surface water environment by discharges of biologically treated sewage may be attached to sewage particles, and this will affect their sedimentation kinetics. Therefore, (oo)cysts were mixed with settled secondary effluent (Oo)cysts readily attached to the (biological) particles in effluent; 30% of both cysts and oocysts attached during the first minutes of mixing, and this fraction increased to approximately 75% after 24 h. The sedimentation velocity of (oo)cysts attached to secondary effluent particles increased with particle size and was (already in the smallest size fraction 1 to 40 micrometers) determined by the sedimentation kinetics of the effluent particles. The observed sedimentation velocities of freely suspended (oo)cysts are probably too low to cause significant sedimentation in surface water or reservoirs. However, since a significant proportion of both cysts and oocysts attached readily to organic biological particles in secondary effluent, sedimentation of attached (oo)cysts after discharge into surface water will probably be a significant factor in the environmental ecology of C. parvum and G. lambl
Annual overviews of waterborne disease outbreaks associated with untreated recreational water use provided by authorities responsible for bathing-water quality and public health in The Netherlands ...revealed 742 outbreaks during 1991–2007 mainly comprising of skin conditions (48%) and gastroenteritis (31%) and involving at least 5623 patients. The number of outbreaks per bathing season correlated with the number of days with temperatures over 25°C (r=0·8–0·9), but was not reduced through compliance with European bathing-water legislation (r=0·1), suggesting that monitoring of faecal indicator parameters and striving for compliance with water-quality standards may not sufficiently protect bathers. Bathing sites were prone to incidental faecal contamination events or environmental conditions that favoured the growth of naturally occurring pathogens. Identification of all possible contamination sources, awareness of changes that might negatively affect water quality, and provision of adequate information to the public are important preventive measures to protect public health.
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.
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