Risk factors for gastroenteritis associated with canal swimming in two cities in the Netherlands during the summer of 2015: A prospective study

Improving suitability of urban canals and canalized rivers for transportation, thermal energy extraction and recreation in two European delta cities

Canals and canalized rivers form a major part of surface water systems in European delta cities and societal ambitions to use these waters increase. This is the first assessment of how suitability of these waters can improve for three important uses: transportation, thermal energy extraction (TEE) and recreation. We assess suitability with Suitability Indices (SIs) and identify which alterations in the water system are needed to improve SI scores in Amsterdam, The Netherlands, and Ghent, Belgium. The results show spatial variability in suitability scores. Current suitability for transportation is low (SI score = 1) to excellent (SI score = 4), for TEE fair (SI score = 2) to excellent (SI score = 4), and suitability for recreation is low (SI score = 1). Suitability could improve by enlarging specific waterway dimensions, increasing discharge and clarity, and by enhancing microbiological water quality. The same methodology can be applied to optimize designs for new water bodies and for more water uses.

Infectious Diseases Associated with Hydrometeorological Hazards in Europe: Disaster Risk Reduction in the Context of the Climate Crisis and the Ongoing COVID-19 Pandemic

Hydrometeorological hazards comprise a wide range of events, mainly floods, storms, droughts, and temperature extremes. Floods account for the majority of the related disasters in both developed and developing countries. Flooding alters the natural balance of the environment and frequently establish a favorable habitat for pathogens and vectors to thrive. Diseases caused by pathogens that require vehicle transmission from host to host (waterborne) or a host/vector as part of their life cycle (vector-borne) are those most likely to be affected by flooding. Considering the most notable recent destructive floods events of July 2021 that affected several Central Europe countries, we conducted a systematic literature review in order to identify documented sporadic cases and outbreaks of infectious diseases in humans in Europe, where hydrometeorological hazards, mainly floods, were thought to have been involved. The occurrence of water-, rodent-, and vector-borne diseases in several European countries is highlighted, as flooding and the harsh post-flood conditions favor their emergence and transmission. In this context, strategies for prevention and management of infectious disease outbreaks in flood-prone and flood-affected areas are also proposed and comprise pre- and post-flood prevention measures, pre- and post-outbreak prevention measures, as well as mitigation actions when an infectious disease outbreak finally occurs. Emphasis is also placed on the collision of floods, flood-related infectious disease outbreaks, and the evolving COVID-19 pandemic, which may result in unprecedented multi-hazard conditions and requires a multi-hazard approach for the effective disaster management and risk reduction.

Relationships between extreme flows and microbial contamination in inland recreational swimming areas

Inland recreational swimming sites provide significant social value globally. This study focused on public recreational swimming sites across the Murrumbidgee River and its tributaries in the Australian Capital Territory (ACT) throughout the swimming season (September-April) from 2009 to 2020 to determine whether high intestinal enterococci concentrations could be predicted with flow exceedance and routinely monitored physical and chemical parameters of water quality. Enterococci concentrations were positively correlated with the turbidity associated with high-flow conditions. The predictive accuracy of high enterococci levels during high-flow conditions was good (mean percentage correctly classified, 60%). The prediction of high enterococci levels at low flows was significantly less reliable (mean percentage correctly classified, 12-15%). As the ACT is expected to experience decreases in rainfall overall but increases in extreme rainfall events due to climate change, understanding the drivers of elevated intestinal enterococci under extreme flow conditions remains important from a public health perspective.

Comparison of heat-illness associations estimated with different temperature metrics in the Australian Capital Territory, 2006-2016

While the associations of heat with health outcomes is well researched, there is less consensus on the measures used to define heat exposure and the short-term and delayed impacts of different temperature metrics on health outcomes. We investigate the nonlinear and short-term relationship of three temperature metrics and reported incidence of three gastrointestinal illnesses: salmonellosis, campylobacteriosis and cryptosporidiosis in the Australian Capital Territory (ACT). We also examine the nonlinear association of these illnesses with extreme heat (5th, 75th, 90th percentile of all heat measures). Generalized linear models with Poisson regression accounting for overdispersion, seasonal and long-term trend, weekly number of outbreaks and rainfall were developed for mean and maximum weekly temperature and the heat stress index (EHI_accl). Bacterial illnesses (salmonellosis and campylobacteriosis) showed an overall positive association with extreme heat (75th and 90th percentile of all three heat measures) and an inverse association with low temperature (5th percentile). The shape of the exposure-response curve across a range of temperatures and the lagged effects varied for each disease. Modelling the short-term and delayed effects of heat using different metrics across a range of illnesses can help identify the most appropriate measure to inform local public health intervention planning for heat-related emergencies.

Evaluating health risks associated with exposure to ambient surface waters during recreational activities: A systematic review and meta-analysis

Recreational water quality guidelines protect the public from health risks associated with water recreation by helping to prevent unacceptable concentrations of pathogenic organisms in ambient water. However, illness risk is associated with both the concentration of pathogens in the water and the degree of contact with those pathogens. Different recreational activities can result in different levels of contact with ambient water containing water-borne pathogens. We conducted a systematic literature review and meta-analysis to evaluate risks of illness associated with different recreational activities and different levels of contact to ambient surface waters. We screened 8,618 potentially relevant studies for quantitative measures of risk using inclusion/exclusion criteria established in advance. We categorized recreational activities as swimming, sports-related contact, minimal contact, and sand contact. We combined relative risks using a random effects meta-analysis for adverse health outcome categories representing gastrointestinal illness, respiratory illness, skin, eye, ear, nose, throat, and cold/flu illness. We identified 92 studies meeting our inclusion criteria. Pooled risk estimates indicate significant elevation of gastrointestinal illness with the recreational activity categories swimming (2.19, 95% CI: 1.82, 2.63) and sports-related contact (2.69, 95% CI: 1.04, 6.92), and nonsignificant elevation of gastrointestinal illness with minimal contact (1.27, 95% CI: 0.74, 2.16). We also found a significant elevation of respiratory illness with swimming (1.78, 95% CI: 1.38, 2.29) and sports-related contact (1.49, 95% CI: 1.00, 2.24), and no elevation of respiratory illness with minimal contact (0.90, 95% CI: 0.71, 1.14). This study suggests that exposures associated with different types of recreational activities are important characteristics of the exposure pathway when assessing illness risk associated with recreation in ambient surface waters.

Risk factors for developing acute gastrointestinal, skin or respiratory infections following obstacle and mud run participation, the Netherlands, 2017

BackgroundIn the Netherlands, obstacle, mud and survival runs are increasingly popular. Although outbreaks of gastroenteritis have been reported following these events, associated health risks have not been systematically assessed.AimTo investigate the incidence of acute gastrointestinal infections (AGI), skin infections (SI) and respiratory infections (RI) among obstacle run participants, as well as risk factors.MethodsBetween April and October 2017, we conducted a retrospective cohort study among 2,900 participants of 17 obstacle runs in the Netherlands. Demographic, symptomatic and behavioural data were collected from participants via an online questionnaire 1 week after participation in an obstacle run. Stool specimens were obtained from respondents for microbiological tests. Adjusted relative risks (aRR) and 95% confidence intervals (CI) using multilevel binomial regression analysis were calculated.ResultsOf 2,646 respondents (median age: 33 years; 53% male), 76 had AGI after the obstacle run; ingesting mud was associated with AGI (aRR: 1.7; 95% CI: 1.2-4.9) and 38 respondents had AGI during or in the week before the obstacle run. Overall, 103 respondents reported SI and 163 RI. Rinsing off in a hot tub was associated with SI (aRR: 2.2; 95% CI: 1.7-2.8). Of 111 stool specimens, 13 tested positive for six different pathogens. No clusters were found.ConclusionThe reported incidence of AGI, SI and RI was low. Risk of these infections could be decreased by informing participants on preventive measures, e.g. showering vs rinsing in the hot tub, avoiding ingesting mud and not participating with symptoms of AGI.

Norovirus and human adenovirus occurrence and diversity in recreational water in a karst aquifer in the Yucatan Peninsula, Mexico

AIMS

To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico.

METHODS AND RESULTS

Hollow fibre ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real-time quantitative polymerase chain reaction assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1600 genome copies per litre (GC l^-1 ). The NoV genogroup II (GII) was detected in 30 and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l^-1 . During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l^-1 . Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16 and GII.P17, and HAdV F serotypes 40 and 41.

CONCLUSIONS

These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is one of the few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations and diversity of NoVs and HadVs in these particular environments.

A spatial and temporal analysis of risk factors associated with sporadic Shiga toxin-producing Escherichia coli O157 infection in England between 2009 and 2015

Infection with STEC O157 is relatively rare but has potentially serious sequelae, particularly for children. Large outbreaks have prompted considerable efforts designed to reduce transmission primarily from food and direct animal contact. Despite these interventions, numbers of infections have remained constant for many years and the mechanisms leading to many sporadic infections remain unclear.Here, we show that two-thirds of all cases reported in England between 2009 and 2015 were sporadic. Crude rates of infection differed geographically and were highest in rural areas during the summer months. Living in rural areas with high densities of cattle, sheep or pigs and those served by private water supplies were associated with increased risk. Living in an area of lower deprivation contributed to increased risk but this appeared to be associated with reported travel abroad. Fresh water coverage and residential proximity to the coast were not risk factors.To reduce the overall burden of infection in England, interventions designed to reduce the number of sporadic infections with STEC should focus on the residents of rural areas with high densities of livestock and the effective management of non-municipal water supplies. The role of sheep as a reservoir and potential source of infection in humans should not be overlooked.

Infection risks of city canal swimming events in the Netherlands in 2016

Introduction

Swimming events in city canals are gaining popularity in the Netherlands, even though canal water is usually not officially designated for recreational use. Knowledge regarding the risk of infection after swimming in canals is limited. An outbreak was reported in 2015 following a canal swimming event in Utrecht, the Netherlands. Local governments were concerned about the health risks of such events. In order to assess the safety of canal swimming, the Public Health Service (PHS) prospectively investigated two city canal swimming events in 2015. In 2016, we repeated this study, aiming to prospectively determine the risks of infection during two urban swimming events, the Utrecht SingelSwim 2016 (USS) and the Amsterdam City Swim 2016 (ACS).

Methods

We sent online questionnaires to 271 USS participants and 2697 ACS participants, concerning personal characteristics, symptoms, and exposure. Participants were asked to forward the questionnaire to three relatives, i.e., non-exposed. We analyzed water samples from the USS venue taken during the event, as well as stool samples of USS participants with acute gastrointestinal illness (AGI). AGI was defined as diarrhea and/or vomiting within seven days after the event. We calculated adjusted risk ratios (RR) for AGI in the exposed group compared with non-exposed respondents, using binomial regression models.

Results

The questionnaire was returned by 160 USS participants (exposed) (59%) and 40 non-exposed relatives. Five percent of the exposed (n = 17) and 3% of non-exposed (n = 1) reported AGI (RR = 1.69; 95% CI: 0.23–12.46). Norovirus genogroup II was detected in two of six USS water samples and in none of the three stool samples. In one of three stool samples, rotavirus was detected.

The questionnaire was returned by 1169 ACS participants (exposed) (43%) and 410 non-exposed relatives. Six percent of the exposed (n = 71) and 1% of non-exposed (n = 5) reported AGI (RR 4.86; 95% CI: 1.98–11.97).

Conclusion

Results of the ACS event showed a higher risk for AGI among the exposed, indicating that participants of events in urban canals in the Netherlands could be at a higher risk for AGI than those not participating. The inconclusive results from the USS are likely due to the small sample size. Swimming in non-monitored open water can bring health risks and more knowledge about environmental and human risk factors helps reduce the risk by being able to more specifically advise organizations and governments.

Waterborne outbreak of gastroenteritis on the KwaZulu-Natal Coast, South Africa, December 2016/January 2017

An unexpected increase in gastroenteritis cases was reported by healthcare workers on the KwaZulu-Natal Coast, South Africa, January 2017 with >600 cases seen over a 3-week period. A case-control study was conducted to identify the source and risk factors associated with the outbreak so as to recommend control and prevention measures. Record review identified cases and controls and structured-telephonic interviews were conducted to obtain exposure history. Stool specimens were collected from 20 cases along with environmental samples and both screened for enteric pathogens. A total of 126 cases and 62 controls were included in the analysis. The odds of developing gastroenteritis were 6.0 times greater among holiday makers than residents (95% confidence interval (CI) 2.0-17.7). Swimming in the lagoon increased the odds of developing gastroenteritis by 3.3 times (95% CI 1.06-10.38). Lagoon water samples tested positive for norovirus (NoV) GI.6, GII.3 and GII.6, astrovirus and rotavirus. Eleven (55%) stool specimens were positive for NoV with eight genotyped as GI.1 (n = 2), GI.5 (n = 3), GI.6 (n = 2), and GI.7 (n = 1). A reported sewage contamination event impacting the lagoon was the likely source with person-to-person spread perpetuating the outbreak. Restriction to swimming in the lagoon was apparently ineffective at preventing the outbreak, possibly due to inadequate enforcement, communication and signage strategies.