Prevalence and distribution of Cryptosporidium and Giardia in wastewater and the surface, drinking and ground waters in the Lower Rhine, Germany

Autochthonous and imported giardiasis cases: An analysis of two decades of national surveillance data, Germany, 2002 to 2021

BackgroundGiardia duodenalis is a major cause of gastroenteritis globally, and is the most common food- and waterborne parasitic infection in Europe.AimTo describe the epidemiology of reported acute giardiasis cases in Germany and compare demographic and clinical characteristics between imported and autochthonous cases.MethodsWe conducted a descriptive analysis of giardiasis cases that fulfilled the national case definition and were reported between January 2002 and December 2021. We defined an imported case as having at least one place of exposure abroad in the 3-25 days before symptom onset. We analysed case numbers and incidence by age, sex, month reported and geographic region, both overall and stratified by autochthonous and imported cases.ResultsFrom 2002 to 2021, 72,318 giardiasis cases were reported in Germany, corresponding to a mean annual incidence of 4.4 per 100,000 population. Annual incidence gradually decreased since 2013, declining sharply during the COVID-19 pandemic in 2020-21. Of 69,345 cases reported between 2002 and 2019, 35% were imported. Incidence of autochthonous cases (overall yearly mean: 3.1/100,000) was highest in males and young children (< 5 years); imported cases were predominantly adults aged 20-39 years. We identified seasonal patterns for imported and autochthonous cases.ConclusionsGiardiasis in Germany is typically assumed to be imported. Our data, however, underline the importance of autochthonous giardiasis. Travel advice might reduce imported infections, but prevention strategies for autochthonous infections are less clear. Dietary, behavioural and environmental risk factors need to be further investigated to enhance infection prevention measures for autochthonous giardiasis.

Cryptosporidium and agriculture: A review

Cryptosporidiosis is a significant contributor to global foodborne and waterborne disease burden. It is a widespread cause of diarrheal diseases that affect humans and animals worldwide. Agricultural environments can become a source of contamination with Cryptosporidium species through faecal material derived from humans and animals. This review aims to report the main findings of scientific research on Cryptosporidium species related to various agricultural sectors, and highlights the risks of cryptosporidiosis in agricultural production, the contamination sources, the importance of animal production in transmission, and the role of farmed animals as hosts of the parasites. Agricultural contamination sources can cause water pollution in groundwater and different surface waters used for drinking, recreational purposes, and irrigation. The application of contaminated manure, faecal sludge management, and irrigation with inadequately treated water are the main concerns associated with foodborne and waterborne cryptosporidiosis related to agricultural activities. The review emphasizes the public health implications of agriculture concerning the transmission risk of Cryptosporidium parasites and the urgent need for a new concept in the agriculture sector. Furthermore, the findings of this review provide valuable information for developing appropriate measures and monitoring strategies to minimize the risk of infection.

Occurrence, transmission and risks assessment of pathogens in aquatic environments accessible to humans

Pathogens are ubiquitously detected in various natural and engineered water systems, posing potential threats to public health. However, it remains unclear which human-accessible waters are hotspots for pathogens, how pathogens transmit to these waters, and what level of health risk associated with pathogens in these environments. This review collaboratively focuses and summarizes the contamination levels of pathogens on the 5 water systems accessible to humans (natural water, drinking water, recreational water, wastewater, and reclaimed water). Then, we showcase the pathways, influencing factors and simulation models of pathogens transmission and survival. Further, we compare the health risk levels of various pathogens through Quantitative Microbial Risk Assessment (QMRA), and assess the limitations of water-associated QMRA application. Pathogen levels in wastewater are consistently higher than in other water systems, with no significant variation for Cryptosporidium spp. among five water systems. Hydraulic conditions primarily govern the transmission of pathogens into human-accessible waters, while environmental factors such as temperature impact pathogens survival. The median and mean values of computed public health risk levels posed by pathogens consistently surpass safety thresholds, particularly in the context of recreational waters. Despite the highest pathogens levels found in wastewater, the calculated health risk is significantly lower than in other water systems. Except pathogens concentration, variables like the exposure mode, extent, and frequency are also crucial factors influencing the public health risk in water systems. This review shares valuable insights to the more accurate assessment and comprehensive management of public health risk in human-accessible water environments.

Individual and Community-Level Risk Factors for Giardiasis in Children under Five Years of Age in Pakistan: A Prospective Multi-Regional Study

OBJECTIVES

This study aimed to estimate the prevalence of Giardia lamblia infection and identify associated risk factors at both individual and community levels in a pediatric population in different agroecological zones of Khyber Pakhtunkhwa, Pakistan.

METHODS

A community-based cross-sectional study was conducted from March to December 2022. Using stratified sampling, 1026 households were recruited from nine agroecological zones. Stool samples were collected from 1026 children up to the age of five years and processed for detection of Giardia using a commercial ELISA kit. Data on potential risk factors were collected using a pre-structured questionnaire. A multivariable logistic regression model was used to identify risk factors associated with giardiasis.

RESULTS

The study found that the prevalence of giardiasis in the study area was 3.31%. Children aged 13-24 months were found to be at higher risk for giardiasis. Illiterate mothers and fathers attending daycare institutions/kindergartens, mothers not practicing hand washing during critical times, households with companion animals, and homes where stray dogs/cats enter were identified as predictors of giardiasis at the individual level. Children living in sub-mountain valleys use un-piped water, inadequate domestic water storage vessels, drink un-boiled or unfiltered water, live near rubbish heaps or un-paved streets/pathways, and have unimproved latrine facilities were identified as risk factors of giardiasis at the community level.

CONCLUSIONS

The study highlights the need for integrated intervention approaches at both individual and community levels to reduce the incidence of giardiasis in Khyber Pakhtunkhwa, Pakistan. Interventions aimed at promoting behavioral change and providing safe and adequate water sources, combined with individual-level interventions such as hand washing and awareness of giardiasis prevention methods, would be critical to addressing this health concern. Inter-sectoral collaboration between the health sector and other sectors would also be necessary to achieve meaningful progress in reducing the incidence of giardiasis in resource-limited areas.

Spatially explicit model of the Cryptosporidium and Giardia disease burden from surface and ground waters in urban and rural areas of the Three Gorges Reservoir watershed in Chongqing, China

Cryptosporidium and Giardia (major causes of diarrhea) are widely distributed in Chinese source waters and threaten human health. A new spatially explicit GloWPa-TGR-Crypt-Giar C1 model is presented to simultaneously estimate mean monthly (oo)cyst concentrations in surface and ground waters in the Three Gorges Reservoir (TGR) watershed. A quantitative risk assessment of protozoal infections considered different source waters, transmission pathways, regions, susceptible subpopulations, and drinking water treatments. Monthly mean Cryptosporidium oocyst and Giardia cyst concentrations ranged between 0.5-19.3 oocysts/10 L and 0.2-5.0 cysts/10 L in surface water, respectively, and 0.007-0.3 oocysts/10 L and 0.002-0. 2 cysts/10 L in groundwater. The cumulative disease burdens attributable to cryptosporidiosis and giardiasis were, respectively, 5.77×10-5 DALYs (disability-adjusted life years/person/year) and 4.63×10-6 DALYs in urban areas, and 6.35×10-4 DALYs and 8.84×10-5 DALYs in rural areas, which were much higher than the reference risk level recommended by the World Health Organization ([Formula: see text] DALYs). The annual burden associated with consuming surface water was calculated to be 3.84×10-4 DALYs for Cryptosporidium and [Formula: see text] DALYs for Giardia, whereas consuming groundwater entailed the lower burdens (1.26×10-5 and 3.50×10-6 DALYs, respectively). Most DALYs were a consequence of consumption of directly supplied surface water. Fifty percent of the health burden was carried by immunodeficiency with HIV. Children (0-4 years) were more likely to have an individual disease burden than adults (15-64 years). Males were more susceptible than females. Improving sanitation through adequate ozone and microfiltration treatment should be considered when attempting to reduce disease burden. Sensitivity analysis highlighted the importance of reducing (oo)cyst loads to protect the watershed. The methodology and results described will help in evaluating and reducing the burden of protozoal infection associated with surface and ground waters in the TGR and similar watersheds.

Microbiological quality of irrigation water for cultivation of fruits and vegetables: An overview of available guidelines, water testing strategies and some factors that influence compliance

Contaminated irrigation water is among many potential vehicles of human pathogens to food plants, constituting significant public health risks especially for the fresh produce category. This review discusses some available guidelines or regulations for microbiological safety of irrigation water, and provides a summary of some common methods used for characterizing microbial contamination. The goal of such exploration is to understand some of the considerations that influence formulation of water testing guidelines, describe priority microbial parameters particularly with respect to food safety risks, and attempt to determine what methods are most suitable for their screening. Furthermore, the review discusses factors that influence the potential for microbiologically polluted irrigation water to pose substantial risks of pathogenic contamination to produce items. Some of these factors include type of water source exploited, irrigation methods, other agro ecosystem features/practices, as well as pathogen traits such as die-off rates. Additionally, the review examines factors such as food safety knowledge, other farmer attitudes or inclinations, level of social exposure and financial circumstances that influence adherence to water testing guidelines and other safe water application practices. A thorough understanding of relevant risk metrics for the application and management of irrigation water is necessary for the development of water testing criteria. To determine sampling and analytical approach for water testing, factors such as agricultural practices (which differ among farms and regionally), as well as environmental factors that modulate how water quality may affect the microbiological safety of produce should be considered. Research and technological advancements that can improve testing approach and the determination of target levels for hazard characterization or description for the many different pollution contexts as well as farmer adherence to testing requirements, are desirable.

Probabilistic fecal pollution source profiling and microbial source tracking for an urban river catchment

We developed an innovative approach to estimate the occurrence and extent of fecal pollution sources for urban river catchments. The methodology consists of 1) catchment surveys complemented by literature data where needed for probabilistic estimates of daily produced fecal indicator (FIBs, E. coli, enterococci) and zoonotic reference pathogen numbers (Campylobacter, Cryptosporidium and Giardia) excreted by human and animal sources in a river catchment, 2) generating a hypothesis about the dominant sources of fecal pollution and selecting a source targeted monitoring design, and 3) verifying the results by comparing measured concentrations of the informed choice of parameters (i.e. chemical tracers, C. perfringensspores, and host-associated genetic microbial source tracking (MST) markers) in the river, and by multi-parametric correlation analysis. We tested the approach at a study area in Vienna, Austria. The daily produced microbial particle numbers according to the probabilistic estimates indicated that, for the dry weather scenario, the discharge of treated wastewater (WWTP) was the primary contributor to fecal pollution. For the wet weather scenario, 80-99 % of the daily produced FIBs and pathogens resulted from combined sewer overflows (CSOs) according to the probabilistic estimates. When testing our hypothesis in the river, the measured concentrations of the human genetic fecal marker were log₁₀ 4 higher than for selected animal genetic fecal markers. Our analyses showed for the first-time statistical relationships between C. perfringens spores (used as conservative microbial tracer for communal sewage) and a human genetic fecal marker (i.e. HF183/BacR287) with the reference pathogen Giardia in river water (Spearman rank correlation: 0.78-0.83, p < 0.05. The developed approach facilitates urban water safety management and provides a robust basis for microbial fate and transport models and microbial infection risk assessment.

Removal of protozoan (oo)cysts and bacteria during microalgae harvesting: Outcomes from a lab-scale experiment

The efficiency of microalgae harvesting on the removal of Giardia spp. cysts, Cryptosporidium spp. oocysts, total coliforms, Escherichia coli, Enterococcus spp. and Clostridium spp. was assessed in lab-scale experiments (Jartest and Flotatest) using effluent from a flat panel photobioreactor used for Chlorella sorokiniana cultivation. Three harvesting methods were evaluated: (1) flocculation induced by pH modulation followed by sedimentation (pH-SED), (2) flocculation induced by pH modulation followed by dissolved air flotation (pH-DAF), and (3) coagulation using an organic coagulant (Tanfloc SG) followed by dissolved air flotation (Coag-DAF). The results indicated that the three harvesting methods were efficient in removing protozoan (oo)cysts and bacteria, achieving percentages of removal higher than 97% for all the analyzed pathogens. Among the three methods, pH-SED showed the best removal performance: 99.60% (2.5 log) for Giardia spp. cysts, 100% (>6.3 log) for total coliforms, 100% (>4.6 log) for Escherichia coli, 100% (>5.8 log) for Enterococcus spp. and 99.96% (3.6 log) for Clostridium spp. Clostridium spp. seemed to be more tolerant to the harvesting methods than the other groups of bacteria analyzed in the study, and its presence was positively correlated to the presence of Giardia spp. cysts.

Analytical challenges and perspectives of assessing viability of Giardia muris cysts and Cryptosporidium parvum oocysts by live/dead simultaneous staining

Giardia and Cryptosporidium are pathogenic protozoa often present in the environment in their infective form(cysts and oocysts). These parasites are very resistant to disinfection, which makes them important target organisms in environmental quality monitoring and sanitation. Viability assessment provides an interpretation of cell inactivation, and it can be evaluated by membrane integrity as well as enzyme activity, using different staining methods. These are straightforward and adequate to laboratories that lack infrastructure for molecular-based technologies or animal infectivity tests. This study investigated simultaneous staining by a commercial live/dead kit, in order to assess viability of Cryptosporidium parvum oocysts and Giardia muris cysts, comparing it to propidium iodide (PI) incorporation, a common stain applied in viability estimation. Results suggested that, although the central hypothesis of one-panel visualization (α = 0.05) was met, simultaneous staining impaired (oo)cyst detection by immunofluorescence assay (IFA), which was found to be essential to enumeration, as the live/dead test led to poor (oo)cyst labelling or a 10-fold lower recovery when carried out concomitantly to IFA. As for the viability assessment itself, although red dye uptake occurred as expected by dead or weakened organisms, neither live G. muris cysts or C. parvum oocysts present any green fluorescence by esterase metabolism. This may have been caused by low enzyme activity in the infective form and/or wall thickness of these parasites. The results do not exclude the possibility of simultaneous fluorescence staining for protozoa, but it is a starting point for a broader analysis, that may consider, for instance, different incubation conditions.

RT qLAMP-Direct Detection of SARS-CoV-2 in Raw Sewage

A highly efficient, selective, and sensitive method for analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in raw sewage was developed and tested to illustrate basic characteristics of the procedure. The method uses reverse transcriptase (RT) loop mediated isothermal amplification (LAMP) in a quantitative application, RT qLAMP. The applicability of this procedure to detection of SARS-CoV-2 in clinical samples has been documented in many reports since early 2020. Basic LAMP characteristics depending on the multiple primer design that produce highly selective and sensitive target amplification virtually free of interferences in complex sample media make it ideal for application to target recognition in raw sewage. Three previously described primer sets targeting ORF1a, E- and N-gene regions were selected and tested to define method performance characteristics and performance for SARS-CoV-2 detection in raw sewage samples from a municipal sewage system serving > 600 000, between July and October, 2020. The virus was detected in all samples from each of three independent interceptors near their treatment terminus. Virus quantities varied significantly between samples and between primer targets within samples. Sewage sampling dates corresponded to relatively low COVID-19 incidence rates reported by the local service area health department. The limited number of samples and aggregating downstream sampling locations did not permit resolving concentration differences. The most significant finding was the ability of the RT qLAMP method to detect SARS-CoV-2 in the raw sewage samples directly without preprocessing to isolate or concentrate the virus or to extract and concentrate viral RNA.

Blue mussel (Mytilus edulis)-A bioindicator of marine water contamination by protozoa: Laboratory and in situ approaches

AIMS

The protozoan parasites Cryptosporidium spp., Giardia duodenalis and Toxoplasma gondii are identified as public health priorities and are present in a wide variety of environments including the marine ecosystem. The objective of this study was to demonstrate that the marine bivalve blue mussel (Mytilus edulis) can be used as a tool to monitor the contamination of marine waters by the three protozoa over time.

METHODS AND RESULTS

In order to achieve a proof of concept, mussels were exposed to three concentrations of G. duodenalis cysts and Cryptosporidium parvum/T. gondii oocysts for 21 days, followed by 21 days of depuration in clear water. Then, natural contamination by these protozoa was sought for in wild marine blue mussels along the northwest coast of France to validate their relevance as bioindicators in the field. Our results highlighted that: (a) blue mussels bioaccumulated the parasites for 21 days, according to the conditions of exposure, and parasites could still be detected during the depuration period (until 21 days); (b) the percentage of protozoa-positive M. edulis varied under the degree of protozoan contamination in water; (c) mussel samples from eight out of nine in situ sites were positive for at least one of the protozoa.

CONCLUSIONS

The blue mussel M. edulis can bioaccumulate protozoan parasites over long time periods, according to the degree of contamination of waters they are inhabiting, and can highlight recent but also past contaminations (at least 21 days).

SIGNIFICANCE AND IMPACT OF THE STUDY

Mytilus edulis is a relevant bioaccumulators of protozoan (oo)cysts in laboratory and field conditions, hence its potential use for monitoring parasite contamination in marine waters.

Evaluation of pathogen risks using QMRA to explore wastewater reuse options: A case study from New Delhi in India

Selecting appropriate reuse for treated wastewater is a challenge. The current investigation outlines the utilization of quantitative microbial risk assessment (QMRA) to assist Effluent Treatment Plant (ETP) management to determine the best-possible reuse of treated wastewater from 11 ETPs in Delhi. Four representative pathogens: pathogenic Escherichia coli spp., Salmonella spp., Cryptosporidium spp. and Giardia spp. were selected to characterize microbial water quality. Reuse options selected based on the survey and interaction with ETP managers include crop irrigation, garden irrigation, toilet flush and industrial applications. The probability of infection was characterized for two exposure groups: workers and children. Water quality monitoring indicates the occurrence of pathogenic E. coli spp. (100%), Salmonella spp. (63%), Cryptosporidium spp. (81%) and Giardia spp. (45%) in the treated wastewater. QMRA reveals the annual median-probability of infection above acceptable limits for pathogenic E. coli spp., Cryptosporidium spp. and Salmonella spp. The probabilities of Giardia-associated infections were low. Adults showed a 1.24 times higher probability of infection compared to children. Sensitivity analysis indicated pathogen concentration as the most critical factor. The study highlights that the existing plans for chlorination-based treatment technology may prove insufficient in reducing the risk for selected reuse options; but, alternate on-site control measures and up-grading water reuse protocol may be effective.

Wastewater-based epidemiology-surveillance and early detection of waterborne pathogens with a focus on SARS-CoV-2, Cryptosporidium and Giardia

Waterborne diseases are a major global problem, resulting in high morbidity and mortality, and massive economic costs. The ability to rapidly and reliably detect and monitor the spread of waterborne diseases is vital for early intervention and preventing more widespread disease outbreaks. Pathogens are, however, difficult to detect in water and are not practicably detectable at acceptable concentrations that need to be achieved in treated drinking water (which are of the order one per million litre). Furthermore, current clinical-based surveillance methods have many limitations such as the invasive nature of the testing and the challenges in testing large numbers of people. Wastewater-based epidemiology (WBE), which is based on the analysis of wastewater to monitor the emergence and spread of infectious disease at a population level, has received renewed attention in light of the current coronavirus disease 2019 (COVID-19) pandemic. The present review will focus on the application of WBE for the detection and surveillance of pathogens with a focus on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the waterborne protozoan parasites Cryptosporidium and Giardia. The review highlights the benefits and challenges of WBE and the future of this tool for community-wide infectious disease surveillance.

Prevalence of Cryptosporidium and Giardia in vegetables in Iran: a nineteen-years meta-analysis review

Cryptosporidium and Giardia are two major protozoa reported from vegetables and environment. The prevalence of these parasites supposes to be different regarding the climate zones. This review aimed to evaluate the prevalence of Cryptosporidium and Giardia in vegetables according to the major climate zones in Iran. The results showed pooled prevalence 7% (95% CI: 2%, 14%) and 4% (95% CI: 3%, 6%) for Cryptosporidium spp., and Giardia spp., respectively. The prevalence of Giardia spp. in mountain, desert and semi-desert, and Mediterranean regions was 4% (95% CI: 2%, 6%), 5% (95% CI: 3%, 8%) and 7% (95% CI: 1%, 18%), respectively. Cryptosporidium spp. was reported 8% (95% CI: 0%, 65%), 6% (95% CI: 0%, 18%) and 4% (95% CI: 0%, 77%) from mountain, desert and semi-desert, and Mediterranean climate zones, respectively. This review suggests the higher prevalence of Giardia and Cryptosporidium in Mediterranean and mountain regions, respectively.

Cryptosporidium sp. skunk genotype in wild raccoons (Procyon lotor) naturally infected with Baylisascaris procyonis from Central Germany

Cryptosporidium spp. are apicomplexan parasites of public health concern. They are one of the main causes of intestinal diseases in humans and animals. Contaminated water is among the main sources of infection for humans and mammals. Raccoons are an introduced species in Germany. They are anthropogenic adapters with a natural affinity for water bodies. We collected samples from wild raccoons in the Federal States of Saxony and Thuringia, Central Germany. Through molecular genotyping, we found Cryptosporidium sp. skunk genotype in one raccoon from Saxony (1/24) and in one animal from Thuringia (1/27). Both raccoons were also infected with the zoonotic nematode Baylisascaris procyonis. This is the first report of co-infection with these two parasites in raccoons from Germany. Our study highlights the potential of these animals as carriers of zoonotic pathogens. Since raccoons can thrive in human settlements, this study provides data that can be used as a baseline for preventive programs.

Waterborne protozoan pathogens in environmental aquatic biofilms: Implications for water quality assessment strategies

Biofilms containing pathogenic organisms from the water supply are a potential source of protozoan parasite outbreaks and a significant public health concern. The aim of the present study was to demonstrate the simultaneous and multi-spatial occurrence of waterborne protozoan pathogens (WBPP) in substrate-associated biofilms (SAB) and compare it to surface water (SW) and sediments with bottom water (BW) counterparts using manual filtration and elution from low-volume samples. For scenario purposes, simulated environmental biofilm contamination was created from in-situ grown one-month-old SAB (OM-SAB) that were spiked with Cryptosporidium parvum oocysts. Samples were collected from the largest freshwater reservoirs in Luzon, Philippines and a University Lake in Thailand. A total of 69 samples (23 SAB, 23 SW, and 23 BW) were evaluated using traditional staining techniques for Cryptosporidium, and Immunofluorescence staining for the simultaneous detection of Cryptosporidium and Giardia. WBPP were found in 43% SAB, 39% SW, and 39% BW of the samples tested in the present study with SAB results reflecting SW and BW results. Further highlights were demonstrated in the potential of using low-volume samples for the detection of parasites in source water. Scanning electron microscopy of OM-SAB samples revealed a naturally-associated testate amoeba shell, while Cryptosporidium oocysts spiked samples provided a visual profile of what can be expected from naturally contaminated biofilms. This study provides the first evidence for the simultaneous and multi-spatial occurrence of waterborne protozoan pathogens in low-volume aquatic matrices and further warrants SAB testing along with SW and BW matrices for improved water quality assessment strategies (iWQAS).

Cryptosporidium and Giardia in urban wastewater: A challenge to overcome

This study aimed to quantify Giardia and Cryptosporidium in disinfected water reuse samples from two Wastewater Treatment Plants (A and B), which were quantified by USEPA 1693/2014 Method. Giardia was found in 35.8% of the total samples (<0.03 to 16 cysts/L) while Cryptosporidium in 30.2% (<0.03 to 25.8 oocysts/L). This study highlights the presence of both parasites in water for reuse despite treatment processes for their removal, which means there is a challenge to overcome. Their presence is preoccupant even though in low concentrations because the infectivity dose is low coupled with high prevalence in the global population. The practice of water recycling is valuable for sustainable water management and it is in line with Sustainable Developments Goals but should not threaten human health. Tackling this issue is more critical in developing countries because treatment processes are often more limited, the monitoring data from water reuse are not always available, the lack of regulation for water reuse quality and the lack of planning for its sustainable usage.

Precipitation effects on parasite, indicator bacteria, and wastewater micropollutant loads from a water resource recovery facility influent and effluent

The variability of fecal microorganisms and wastewater micropollutants (WWMPs) loads in relation to influent flow rates was evaluated for a water resource recovery facility (WRRF) in support of a vulnerability assessment of a drinking water source. Incomplete treatment and bypass discharges often occur following intense precipitation events that represent conditions that deviate from normal operation. Parasites, fecal indicator bacteria, and WWMPs concentrations and flow rate were measured at the WRRF influent and effluent during dry and wet weather periods. Influent concentrations were measured to characterize potential bypass concentrations that occur during wet weather. Maximum influent Giardia and C. perfringens loads and maximum effluent Escherichia coli and C. perfringens loads were observed during wet weather. Influent median loads of Cryptosporidium and Giardia were 6.8 log oocysts/day and 7.9 log cysts/day per 1,000 people. Effluent median loads were 3.9 log oocysts/day and 6.3 log cysts/day per 1,000 people. High loads of microbial contaminants can occur during WRRF bypasses following wet weather and increase with increasing flow rates; thus, short-term infrequent events such as bypasses should be considered in vulnerability assessments of drinking water sources in addition to the increased effluent loads during normal operation following wet weather.

High serological response to Cryptosporidium-specific antigens in the Czech Republic and its association with water supply

A survey was conducted in the Czech Republic to determine whether serological responses to the 15/17-kDa and 27-kDa Cryptosporidium antigens had changed since the end of the communist era and if these responses were associated with drinking water sources. Sera from 301 blood donors residing in six areas served by various sources of drinking water were analysed by Western Blot (mini-immunoblots) to measure the IgG response. The intensity of response and percentage of persons with a strong response to the 27-kDa, but not the 15/17-kDa, antigen were higher than found 20 years earlier. A strong response to both the 15/17- and 27-kDa-antigens was higher than reported in other countries, and the probability of persons having a strong response was greater in areas with surface water sources than river-bank infiltration. Few cases of cryptosporidiosis were reported in spite of these high responses to Cryptosporidium antigens. These responses suggest a chronic low-level exposure from several sources that may be affording protection against symptoms and illness. Although strong serological responses were associated with surface water sources, drinking water is not likely to be the most important exposure for Cryptosporidium in the Czech Republic.

Cryptosporidium Incidence and Surface Water Influence of Groundwater Supplying Public Water Systems in Minnesota, USA

Regulations for public water systems (PWS) in the U.S. consider Cryptosporidium a microbial contaminant of surface water supplies. Groundwater is assumed free of Cryptosporidium unless surface water is entering supply wells. We determined the incidence of Cryptosporidium in PWS wells varying in surface water influence. Community and noncommunity PWS wells ( n = 145) were sampled ( n = 964) and analyzed for Cryptosporidium by qPCR and immunofluorescence assay (IFA). Surface water influence was assessed by stable isotopes and the expert judgment of hydrogeologists using site-specific data. Fifty-eight wells (40%) and 107 samples (11%) were Cryptosporidium-positive by qPCR, and of these samples 67 were positive by IFA. Cryptosporidium concentrations measured by qPCR and IFA were significantly correlated ( p < 0.001). Cryptosporidium incidence was not associated with surface water influence as assessed by stable isotopes or expert judgment. We successfully sequenced 45 of the 107 positive samples to identify species, including C. parvum (41), C. andersoni (2), and C. hominis (2), and the predominant subtype was C. parvum IIa A17G2R1. Assuming USA regulations for surface water-supplied PWS were applicable to the study wells, wells positive for Cryptosporidium by IFA would likely be required to add treatment. Cryptosporidium is not uncommon in groundwater, even when surface water influence is absent.

Temporal variability of parasites, bacterial indicators, and wastewater micropollutants in a water resource recovery facility under various weather conditions

Wastewater discharges lead to the deterioration of receiving waters through treated effluents and by-passes, combined and sanitary sewer overflows, and cross-connections to storm sewers. The influence of weather conditions on fecal indicator bacteria, pathogens and wastewater micropollutants on raw and treated sewage concentrations has not been extensively characterized. However, such data are needed to understand the effects of by-pass discharges and incomplete treatment on receiving waters. A water resource recovery facility was monitored for pathogenic parasites (Cryptosporidium oocysts, Giardia cysts), fecal indicator bacteria (Escherichia coli, Clostridium perfringens), and wastewater micropollutants (caffeine, carbamazepine, 2-hydroxycarbamazepine, acesulfame, sucralose, and aspartame) during 6 events under different weather conditions (snowmelt and trace to 32 mm 2-day cumulative precipitation). Greater intra- and inter-event variability was observed for Giardia, E. coli and C. perfringens than for studied WWMPs. Even with the addition of inflow and infiltration, daily variations dominated concentration trends. Thus, afternoon and early evening were identified as critical times with regards to high concentrations and flows for potential by-pass discharges. Peak concentrations of Giardia were observed during the June wet weather event (1010 cysts/L), with the highest flowrates relative to the mean monthly flowrate. Overall, Giardia, E. coli and C. perfringens concentrations were positively correlated with flowrate (R > 0.32, p < 0.05). In raw sewage samples collected under high precipitation conditions, caffeine, carbamazepine and its metabolite 2-OH-carbamazepine were significantly correlated (p < 0.05) with Giardia, E. coli, and C. perfringens demonstrating that they are useful markers for untreated sewage discharges. Data from the study are needed for estimating peak concentrations discharged from wastewater sources in relation to precipitation or snowmelt events.

Profiling the diversity of Cryptosporidium species and genotypes in wastewater treatment plants in Australia using next generation sequencing

Wastewater recycling is an increasingly popular option in worldwide to reduce pressure on water supplies due to population growth and climate change. Cryptosporidium spp. are among the most common parasites found in wastewater and understanding the prevalence of human-infectious species is essential for accurate quantitative microbial risk assessment (QMRA) and cost-effective management of wastewater. The present study conducted next generation sequencing (NGS) to determine the prevalence and diversity of Cryptosporidium species in 730 raw influent samples from 25 Australian wastewater treatment plants (WWTPs) across three states: New South Wales (NSW), Queensland (QLD) and Western Australia (WA), between 2014 and 2015. All samples were screened for the presence of Cryptosporidium at the 18S rRNA (18S) locus using quantitative PCR (qPCR), oocyst numbers were determined directly from the qPCR data using DNA standards calibrated by droplet digital PCR, and positives were characterized using NGS of 18S amplicons. Positives were also screened using C. parvum and C. hominis specific qPCRs. The overall Cryptosporidium prevalence was 11.4% (83/730): 14.3% (3/21) in NSW; 10.8% (51/470) in QLD; and 12.1% (29/239) in WA. A total of 17 Cryptosporidium species and six genotypes were detected by NGS. In NSW, C. hominis and Cryptosporidium rat genotype III were the most prevalent species (9.5% each). In QLD, C. galli, C. muris and C. parvum were the three most prevalent species (7.7%, 5.7%, and 4.5%, respectively), while in WA, C. meleagridis was the most prevalent species (6.3%). The oocyst load/Litre ranged from 70 to 18,055 oocysts/L (overall mean of 3426 oocysts/L: 4746 oocysts/L in NSW; 3578 oocysts/L in QLD; and 3292 oocysts/L in WA). NGS-based profiling demonstrated that Cryptosporidium is prevalent in the raw influent across Australia and revealed a large diversity of Cryptosporidium species and genotypes, which indicates the potential contribution of livestock, wildlife and birds to wastewater contamination.

Cryptosporidium and Giardia in Wastewater and Surface Water Environments

and spp. are significant contributors to the global waterborne disease burden. Waterways used as sources of drinking water and for recreational activity can become contaminated through the introduction of fecal materials derived from humans and animals. Multiple studies have reported the occurence or concentrations of these pathogens in the environment. However, this information has not been comprehensively reviewed. Quantitative microbial risk assessment (QMRA) for and can be beneficial, but it often relies on the concentrations in environmental sources reported from the literature. A thorough literature review was conducted to develop an inventory of reported and concentrations in wastewater and surface water available in the literature. This information can be used to develop QMRA inputs. and (oo)cyst concentrations in untreated wastewater were up to 60,000 oocysts L and 100,000 cysts L, respectively. The maximum reported concentrations for and in surface water were 8400 oocysts L and 1000 cysts L, respectively. A summary of the factors for interpretation of concentration information including common quantification methods, survival and persistence, biofilm interactions, genotyping, and treatment removal is provided in this review. This information can help in identifying assumptions implicit in various QMRA parameters, thus providing the context and rationale to guide model formulation and application. Additionally, it can provide valuable information for water quality practitioners striving to meet the recreational water quality or treatment criteria. The goal is for the information provided in the current review to aid in developing source water protection and monitoring strategies that will minimize public health risks.

Temporal Variability of Faecal Contamination from On-Site Sanitation Systems in the Groundwater of Northern Thailand

We investigated the impacts of on-site sanitation systems to local groundwater. In this year-long study, we monitored the response of faecal contamination levels to hydroclimatological factors including rainfall and groundwater table. Concentration of faecal indicators-E. coli (ESC), Enterococcus (ENT), nitrate-in thirteen pairs of shallow and deep wells were determined every 7-14 days. All samples from shallow wells were tested positive for faecal contamination (ESC and ENT > 1 MPN/100 mL) but concentration varies. A maximum of 24,000 MPN/100 mL were recorded in some shallow wells. Water from deep wells showed lower susceptibility to contamination with only 4 and 23% of samples tested positive for ESC and ENT, respectively. Concentrations of ESC and ENT were lower too, with a maximum of 5 MPN/100 mL and 28 MPN/100 mL, respectively. Fluctuation in contamination among the wells was described by four archetypal responses to hydroclimatological forcing: (i) flushing during the onset of wet season, (ii) dilution over the course of the wet season, (iii) concentration during the dry season, and (iv) synoptic response to storms. Previous studies attempting to link the prevalence of faecal/waterborne diseases and temporal factors (e.g., dry vs wet season) have produced differing outcomes. Our study may help explain the relevant hydrological mechanisms leading to these varying observations. Presently, most communities in Thailand have access to 'improved' sanitation systems. However, due to the unsustainable implementation of these systems, the otherwise viable drinking-water resources in the form of the abundant local groundwater has become a genuine health hazard.

On the use of total aerobic spore bacteria to make treatment decisions due to Cryptosporidium risk at public water system wells

Spore reduction can be used as a surrogate measure of Cryptosporidium natural filtration efficiency. Estimates of log10 (log) reduction were derived from spore measurements in paired surface and well water samples in Casper Wyoming and Kearney Nebraska. We found that these data were suitable for testing the hypothesis (H₀) that the average reduction at each site was 2 log or less, using a one-sided Student's t-test. After establishing data quality objectives for the test (expressed as tolerable Type I and Type II error rates), we evaluated the test's performance as a function of the (a) true log reduction, (b) number of paired samples assayed and (c) variance of observed log reductions. We found that 36 paired spore samples are sufficient to achieve the objectives over a wide range of variance, including the variances observed in the two data sets. We also explored the feasibility of using smaller numbers of paired spore samples to supplement bioparticle counts for screening purposes in alluvial aquifers, to differentiate wells with large volume surface water induced recharge from wells with negligible surface water induced recharge. With key assumptions, we propose a normal statistical test of the same hypothesis (H₀), but with different performance objectives. As few as six paired spore samples appear adequate as a screening metric to supplement bioparticle counts to differentiate wells in alluvial aquifers with large volume surface water induced recharge. For the case when all available information (including failure to reject H₀ based on the limited paired spore data) leads to the conclusion that wells have large surface water induced recharge, we recommend further evaluation using additional paired biweekly spore samples.

Occurrence and removal efficiency of parasitic protozoa in Swedish wastewater treatment plants

Giardia intestinalis, Cryptosporidium spp., Entamoeba histolytica and Dientamoeba fragilis are parasitic protozoa and causative agents of gastroenteritis in humans. G. intestinalis and Cryptosporidium spp. in particular are the most common protozoa associated with waterborne outbreaks in high-income countries. Surveillance of protozoan prevalence in wastewater and evaluation of wastewater treatment removal efficiencies of protozoan pathogens is therefore imperative for assessment of human health risk. In this study, influent and effluent wastewater samples from three wastewater treatment plants in Sweden were collected over nearly one year and assessed for prevalence of parasitic protozoa. Quantitative real-time PCR using primers specific for the selected protozoa Cryptosporidium spp., G. intestinalis, E. histolytica, Entamoeba dispar and D. fragilis was used for protozoan DNA detection and assessment of wastewater treatment removal efficiencies. Occurrence of G. intestinalis, E. dispar and D. fragilis DNA was assessed in both influent (44, 30 and 39 out of 51 samples respectively) and effluent wastewater (14, 9 and 33 out of 51 samples respectively) in all three wastewater treatment plants. Mean removal efficiencies of G. intestinalis, E. dispar and D. fragilis DNA quantities, based on all three wastewater treatment plants studied varied between 67 and 87%, 37-75% and 20-34% respectively. Neither E. histolytica nor Cryptosporidium spp. were detected in any samples. Overall, higher quantities of protozoan DNA were observed from February to June 2012. The high prevalence of protozoa in influent wastewater indicates the need for continued monitoring of these pathogens in wastewater-associated aquatic environments to minimise the potential risk for human infection.

Giardia duodenalis and Cryptosporidium spp. as contaminant protozoa of the main rivers of western Romania: genetic characterization and public health potential of the isolates

The objective of this study was to establish the prevalence, contamination level, and public health significance of Giardia duodenalis and Cryptosporidium spp. in the primary rivers of western Romania. A total of 53 sampling points in the 24 most important western Romanian rivers in four counties (Arad, Bihor, Caraș-Severin, and Timiș) were investigated from March to September 2016. Surface water samples were collected by microfiber filtration. Cryptosporidium and Giardia (oo)cysts were isolated using immunomagnetic separation (IMS) according to the USEPA 1623 method and, after staining with fluorescently labeled (FITC) monoclonal antibodies, were identified and counted under a microscope. The Cryptosporidium and Giardia (oo)cysts were identified to species and assemblage/sub-assemblage level through the nested PCR-RFLP procedure targeting the 18S ribosomal RNA and gdh genes, respectively. PCR-based techniques were utilized for all water samples. Overall, 22 samples (41.5%) were determined to be positive for Giardia cysts (ranging from 0.05 to 300 cysts per liter), and four samples (7.5%) tested positive for Cryptosporidium oocysts (0.17-48 oocysts/l). G. duodenalis was molecularly identified in 13 water samples (24.5%), indicating the presence of the sub-assemblage A-II (n = 12) and assemblage E (n = 1). PCR-RFLP showed that two samples (3.8%) contained Cryptosporidium DNA, and the identified species were Cryptosporidium parvum and Cryptosporidium canis. All positive results were successfully confirmed by DNA sequencing. Subtyping of the zoonotic C. parvum isolate based on sequence analysis of the GP60 gene revealed the occurrence of the IIaA16G1R1 subtype. The results of this study highlight considerable contamination of river waters with pathogenic Giardia spp. and Cryptosporidium spp., suggesting a potential risk for the public and animal health. This report presents the first extended published description of the presence of Giardia spp. and Cryptosporidium spp. in the aquatic environment in Romania.

Human cryptosporidiosis in Iran: a systematic review and meta-analysis

Cryptosporidiosis caused by Cryptosporidium spp. is an important parasitic disease that can be life-threatening for children and immunocompromised patients. This systematic review and meta-analysis was designed to determine the prevalence rate of Cryptosporidium infection and related risk factors among the Iranian general population. We searched electronic databases including Google Scholar, PubMed, Science Direct, Scopus and Proquest for articles in English and SID, Magiran, IranMedex, and IranDoc for articles in Persian. Out of 4816 studies identified in the electronic search, 94 articles were eligible for inclusion in the systematic review and meta-analysis. The prevalence rate of cryptosporidiosis by using the random effect model among children, healthy people, and gastroenteritis and immunocompromised patients in Iran was estimated as 3.65, 2.94, 1.29, and 4.54%, respectively. Findings of a phylogenetic analysis inferred by gp60 and 18S ribosomal RNA markers indicated that most of the infection rate belonged to C. parvum (particularly subtype IIaA15G2R1) and C. hominis among understudied groups. The present study is the first systematic review and meta-analysis providing a comprehensive view of the prevalence of human cryptosporidiosis and its related risk factors in Iran. It seems that the awareness of Cryptosporidium prevalence, risk factors, and disease complications may be required for developing effective strategies to prevent infection.

Bioaccumulation of Toxoplasma and Cryptosporidium by the freshwater crustacean Gammarus fossarum: Involvement in biomonitoring surveys and trophic transfer

The protozoa Toxoplasma gondii and Cryptosporidium parvum are public health priorities because their oocysts can persist in recreational, surface, drinking, river, and sea water sources for a long time. To evaluate the capacity of the freshwater crustacean Gammarus fossarum to accumulate T. gondii and C. parvum oocysts, gammarids were exposed to 200, 2000 or 20,000 oocysts per gammarid and per day for 21 days followed by 5 days of depuration. C. parvum DNA was detected by qPCR in G. fossarum in only one out of four pools for the highest concentration and after 14 days of exposure, and T. gondii DNA was detected after 7 days of exposure to the two highest concentrations. Our results document the capacity of G. fossarum to accumulate T. gondii in its tissues proportionally to the ambient concentration; the maximum number of oocysts was detected in gammarid tissues after exposure to 20,000 oocysts per day. Mean values of 3.26 (±3), 21.71 (±15.18), and 17.41 (±10.89) oocysts were detected in gammarids after 7, 14, and 21 days, respectively, and after 5 days of depuration, T. gondii oocysts were still present in gammarid tissues. These results show for the first time that a freshwater crustacean can bioaccumulate T. gondii oocysts, suggesting that G. fossarum is a potential effective bioindicator of protozoan contamination in biomonitoring studies. Moreover, due to its key position in freshwater food webs, G. fossarum could also play a role in the trophic transfer of protozoa.

The River Ruhr - an urban river under particular interest for recreational use and as a raw water source for drinking water: The collaborative research project "Safe Ruhr" - microbiological aspects

Along the intense industrialization of the Ruhr valley (Germany), the River Ruhr became increasingly polluted. Over time, using it for recreational purposes became a serious health hazard and bathing was banned due to chemical and microbiological risks. The purpose of the collaborative project "Safe Ruhr" was to verify the current status and to provide a scientific basis for lifting the bathing ban. As the river also provides a raw water source for drinking water production, it was investigated how well the treatment procedures control possible hygienic risks. As study area, the barrier Lake Baldeney was chosen as it embraces earlier bathing sites and tributes to river bank filtration water for drinking water treatment plants. The hygienic condition of the river water was determined over 18 months by measuring general physical, chemical and microbiological water quality parameters including fecal indicators, bacterial obligate and facultative pathogens, parasitic protozoa, enteric viruses and schistosome parasites (Trichobilharzia). Samples were taken at eight locations including sites before and after receiving the discharge of stormwater and treated wastewater, potential future bathing sites and a raw water abstraction point for potable water production. In summary, for all investigated physico-chemical parameters no significant difference between the eight investigated sampling locations on a distinct sampling date were observed. This study focused on hygienically relevant bacteria and parasitic protozoa. Fecal indicators, Escherichia coli, intestinal enterococci and Clostridium perfringens as well as coliform bacteria were detected in 94-100% of the water samples. Enteric pathogens, including Campylobacter spp. and Salmonella enterica, were isolated from 33% and 28% of the samples, respectively, in relatively low concentrations. Among the environmental facultative pathogens, P. aeruginosa was detected at a high frequency of 82% of all samples, but in low numbers, while Aeromonas spp. were found in all water samples in relative high concentrations. The levels of all target organisms were not clearly associated with sources of pollution, with the exception of slightly enhanced numbers of coliform bacteria and E. coli downstream of a sewage discharge point from a wastewater treatment plant. Seasonal variations were observed with higher detection rates of Campylobacter spp. in winter and S. enterica in autumn and winter in contrast to the other bacterial groups, which showed no significant fluctuations throughout the year. Precipitation within two days prior to sampling resulted in a trend of enhanced numbers of coliform bacteria, E. coli, intestinal enterococci and Aeromonas. Sampling and analysis of parasitic protozoa was carried out in accordance to the European bathing water guideline and the ISO 15553 method. Characteristics of the river (flow, vegetation, birds protection zone, bathing of people, sewage etc.) were compared to the number of organisms detected. All in all 184 samples were investigated for Cryptosporidium spp. and Giardia spp. 80% of the samples were positive for Giardia spp. with a mean of 5cysts/100l (0.1-157.9). Highest values were achieved in autumn and winter, lowest values during the assumed bathing season. There seemed to be a trend to lower values in and after a reservoir in the river course, but with no statistical significance. A statistical significance could be shown for higher concentrations after heavy rainfall that led to discharge of combined sewage overflows in the city of Essen. Only 29% of the samples were positive for Cryptosporidium spp. with a single maximum value of 27.7 and all other concentrations below 5 oocysts/100l. On a low level there seemed to be slightly higher findings during summer and bathing season than in autumn and winter. No correlation to heavy rainfall could be found. The findings correspond to earlier results from the River Rhine (Germany). The influence of sewage on the water quality of the Ruhr could be shown from the correlation of Giardia load and activity of combined sewage overflows after heavy rainfall. The rare and low findings of Cryptosporidium spp. lead to the same conclusion, that microbial water quality in the investigation area is rather influenced from sewage water than from diffuse water sources into the River Ruhr.

Giardia and Cryptosporidium spp. dissemination during wastewater treatment and comparative detection via immunofluorescence assay (IFA), nested polymerase chain reaction (nested PCR) and loop mediated isothermal amplification (LAMP)

Environmental water samples from the Lower Rhine area in Germany were investigated via immunofluorescence assays (IFAs), nested polymerase chain reaction (nested PCR) and loop-mediated isothermal amplification (LAMP) to detect the presence of Giardia spp. (n=185) and Cryptosporidium spp. (n=227). The samples were concentrated through filtration or flocculation, and oocysts were purified via centrifugation through a sucrose density gradient. For all samples, IFA was performed first, followed by DNA extraction for the nested PCR and LAMP assays. Giardia cysts were detected in 105 samples (56.8%) by IFA, 62 samples (33.5%) by nested PCR and 79 samples (42.7%) by LAMP. Cryptosporidium spp. were detected in 69 samples (30.4%) by IFA, 95 samples (41.9%) by nested PCR and 99 samples (43.6%) by LAMP. According to these results, the three detection methods are complementary for monitoring Giardia and Cryptosporidium in environmental waters.

Removal of Cryptosporidium by wastewater treatment processes: a review

Cryptosporidium is a protozoan parasite that infects humans and various animal species. The environmental stability and the low infectious dose of Cryptosporidium facilitate its transmission by water and food. Discharge of untreated wastewater may result in waterborne or foodborne Cryptosporidium outbreaks, therefore a suitable treatment may prevent its dissemination. Most studies on the prevalence of Cryptosporidium oocysts in wastewater have reported a concentration range between 10 and 200 oocysts/L and a prevalence of 6 to 100%. Activated sludge has been found to be ineffective for the removal of Cryptosporidium oocysts. Stabilization ponds and constructed wetlands are efficient for the reduction of Cryptosporidium from wastewater, especially when the retention time is longer than 20 days at suitable sunlight and temperature. High rate filtration and chlorine disinfection are inefficient for the reduction of Cryptosporidium from effluents, whereas ultrafiltration and UV irradiation were found to be very efficient for the reduction of Cryptosporidium oocysts. Adequate tertiary treatment may result in high quality effluent with low risk of Cryptosporidium for unrestricted irrigation and other non-potable applications.

Assessment of molecular methods as a tool for detecting pathogenic protozoa isolated from water bodies

Several species belong to the Cryptosporidium and Giardia genus, the main parasitic protozoa occurring in water, but only some of them are infectious to humans. We investigated the occurrence of Cryptosporidium and Giardia and identified their species in the water samples collected from natural water bodies in north-western Poland. A total of 600 samples from water bodies used for bathing, sewage discharge, as drinking water sources and watering places for animals were screened. The samples were collected during a 3-year period in each of the four seasons and filtered using Filta-Max (IDEXX Laboratories, USA). Genomic DNA was extracted from all samples and used as a target sequence for polymerase chain reaction (PCR) and TaqMan real-time PCR, as well as for reverse line blotting (RLB) methods. PCR methods seem to be more sensitive to detect Giardia and Cryptosporidium DNA in water samples than RLB methods. All PCR products were sequenced and three were identified as C. parvum and four as G. intestinalis. The overall prevalence of C. parvum (0.5%) and G. intestinalis (0.6%) in the samples suggests that the risk of Cryptosporidium and Giardia infections in north-western Poland is minimal.

Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir

Background: The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Methods: Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Results: Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. Conclusion: This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

Assessment of Toxoplasma gondii levels in zebra mussel (Dreissena polymorpha) by real-time PCR: an organotropism study

Water quality is a public health concern that calls for relevant biomonitoring programs. Molecular tools such as polymerase chain reaction (PCR) are progressively becoming more sensitive and more specific than conventional techniques to detect pathogens in environmental samples such as water and organisms. The zebra mussel (Dreissena polymorpha) has already been demonstrated to accumulate and concentrate various human waterborne pathogens. In this study, first, a spiking experiment to evaluate detection levels of Toxoplasma gondii DNA in zebra mussel organs using real-time PCR was conducted. Overall, lower DNA levels in the hemolymph, digestive gland, and remaining tissues (gonad and foot) were detected compared to mantle, muscle, and gills. Second, an in vivo experiment with 1000 T. gondii oocysts per mussel and per day for 21 consecutive days, followed by 14 days of depuration time in protozoa-free water was performed. T. gondii DNA was detected in all organs, but greatest concentrations were observed in hemolymph and mantle tissues compared to the others organs at the end of the depuration period. These results suggest that (i) the zebra mussel is a potential new tool for measuring T. gondii concentrations and (ii) real-time PCR is a suitable method for pathogen detection in complex matrices such as tissues.

Evaluation of Cryptosporidium oocyst and Giardia cyst removal efficiency from urban and slaughterhouse wastewater treatment plants and assessment of cyst viability in wastewater effluent samples from Tehran, Iran

Five municipal and domestic wastewater treatment plants, most of which had secondary treatment systems formed by activated sludge, were studied during 2013–2014 in Tehran. The study was done in order to evaluate their efficiency in terms of removal of Cryptosporidium and Giardia by (oo)cyst recovery in effluent samples using immunofluorescence with monoclonal antibodies. Results showed that mean concentrations of cysts in the influent samples always outnumbered mean concentrations of oocysts (883.3 ± 4,16.7–3,191.7 ± 1,067.2 versus 4.8 ± 6.2–83.8 ± 77.3 (oo)cysts/L), and that lower concentrations of (oo)cysts were recorded in summer, and higher levels in autumn, and that the difference was statistically significant (t-test, P &lt;0.05) only in wastewater from slaughterhouses. Results for removal percentages of all the plants ranged from 76.7 to 92.1% for cysts and from 48.9 to 90.8% for oocysts. There was more reduction of (oo)cysts at the urban treatment plant by activated sludge-A2O-sand filtration than at plants with conventional activated sludge and activated sludge-trickling filter, however, this difference was not statistically significant for cysts and oocysts (ANOVA, P &gt; 0.05). Infections in mice inoculated with cysts obtained from urban wastewater effluent demonstrated presence of infectious Giardia cysts. Results demonstrate limited efficiency of conventional wastewater treatment processes at physico-chemical removal of (oo)cysts.

Occurrence of Cryptosporidium and Giardia in recycled waters used for irrigation and first description of Cryptosporidium parvum and C. muris in Greece

Here, we present the first time findings regarding the occurrence of Cryptosporidium and Giardia in sewage waters and the first molecular characterization of Cryptosporidium species in Greece. Biological treatment plants from three regions in Greece have been investigated. The detection of Cryptosporidium oocysts was by modified Ziehl-Neelsen acid fast (MZN-AF) and by immunofluorescence microscopy (IFT) for Cryptosporidium and Giardia (oo)cysts, whereas nested PCR based on the SSU rDNA assay was used for molecular detection of Cryptosporidium followed by sequencing for the genetic characterization of the species. In total, 73 samples (37 raw sewage samples and 38 of treated water samples) were collected and analyzed. Of the 73 water samples, 4 samples were Cryptosporidium-positive by IFT and staining, 12 samples were Cryptosporidium-positive by nested PCR; 9 samples were Giardia-positive by IFT. We showed that Cryptosporidium cysts are found both in the input and the discharge of the biological treatment plants. Molecular characterization of Cryptosporidium based on the small subunit ribosomal DNA gene resulted in the determination of Cryptosporidium parvum and Cryptosporidium muris Greek isolates. This is the first report of Cryptosporidium and Giardia occurrence in wastewaters and the first molecular identification of Cryptosporidium species in Greek environments. As the treated water is used for irrigation, or it is discharged into the sea, our findings indicate that biological treatment facilities constitute a possible risk for public health because the related species are prevalent in humans; the results invite for further epidemiological investigations to evaluate the real public health risk in Greece.

Large outbreak of Cryptosporidium hominis infection transmitted through the public water supply, Sweden

In November 2010, ≈27,000 (≈45%) inhabitants of Östersund, Sweden, were affected by a waterborne outbreak of cryptosporidiosis. The outbreak was characterized by a rapid onset and high attack rate, especially among young and middle-aged persons. Young age, number of infected family members, amount of water consumed daily, and gluten intolerance were identified as risk factors for acquiring cryptosporidiosis. Also, chronic intestinal disease and young age were significantly associated with prolonged diarrhea. Identification of Cryptosporidium hominis subtype IbA10G2 in human and environmental samples and consistently low numbers of oocysts in drinking water confirmed insufficient reduction of parasites by the municipal water treatment plant. The current outbreak shows that use of inadequate microbial barriers at water treatment plants can have serious consequences for public health. This risk can be minimized by optimizing control of raw water quality and employing multiple barriers that remove or inactivate all groups of pathogens.

Molecular identification of Giardia and Cryptosporidium from dogs and cats

The aim of the present study was to diagnose the presence of Giardia cysts and Cryptosporidium oocysts in household animals using nested polymerase chain reaction (PCR) and sequence analysis. One hundred faecal samples obtained from 81 dogs and 19 cats were investigated. The Cryptosporidium genotypes were determined by sequencing a fragment of the small subunit (SSU) rRNA gene, while the Giardia Assemblages were determined through analysis of the glutamate dehydrogenase (GDH) locus. Isolates from five dogs and two cats were positive by PCR for the presence of Giardia, and their sequences matched the zoonotic Assemblage A of Giardia. Cryptosporidium spp. isolated from one dog and one cat were both found to be C. parvum. One dog isolate harboured a mixed infection of C. parvum and Giardia Assemblage A. These findings support the growing evidence that household animals are potential reservoirs of the zoonotic pathogens Giardia spp. and Cryptosporidium spp. for infections in humans.