Critical processes affecting Cryptosporidium oocyst survival in the environment

Cryptosporidium spp. in captive snakes from 26 provinces in China: Prevalence, molecular characterization, and symptoms

Snakes are sometimes regarded as pets and are used in traditional Chinese medicine. Cryptosporidium spp. are frequently identified in snakes, representing an important pathogen and causing gastrointestinal diseases. Current data indicate that risk factors for infection and patterns of clinical symptom presentation may differ among Cryptosporidium spp. To better understand the infection status by Cryptosporidium spp., fecal samples were collected from 603 asymptomatic and 147 symptomatic snakes in 26 provinces of China. These samples came from Elaphe guttata, Elaphe obsoleta, Pituophis melanoleucus, Thamnophis sirtalis, Lampropeltis getulus, and Heterodon nasicus. The partial small subunit (SSU) rRNA gene was amplified using nested polymerase chain reaction (PCR) to investigate the infection rate of Cryptosporidium spp., and to assess evolutionary relationships and genetic characterization. A prevalence of 20% was recorded in asymptomatic snakes, with age identified as a significant risk factor. In contrast, 70% of symptomatic snakes were positive for Cryptosporidium spp., with Cryptosporidium serpentis and Cryptosporidium varanii (syn. C. saurophilum). Further analysis revealed a potential association between C. serpentis and regurgitation, and C. varanii and diarrhea, while neither species was linked to flatulence. To our knowledge, this is the first study to report Cryptosporidium spp. and associated clinical signs in symptomatic snakes in China. This study aims to enhance the understanding of Cryptosporidium infections, risk factors, and clinical manifestations in snakes, providing data crucial for the control and prevention of cryptosporidiosis.

Investigating the relationship between extreme weather and cryptosporidiosis and giardiasis in Colorado: A multi-decade study using distributed-lag nonlinear models

Environmentally-mediated protozoan diseases like cryptosporidiosis and giardiasis are likely to be highly impacted by extreme weather, as climate-related conditions like temperature and precipitation have been linked to their survival, distribution, and overall transmission success. Our aim was to investigate the relationship between extreme temperature and precipitation and cryptosporidiosis and giardiasis infection using monthly weather data and case reports from Colorado counties over a twenty-one year period. Data on reportable diseases and weather among Colorado counties were collected using the Colorado Electronic Disease Reporting System (CEDRS) and the Daily Surface Weather and Climatological Summaries (Daymet) Version 3 dataset, respectively. We used a conditional Poisson distributed-lag nonlinear modeling approach to estimate the lagged association (between 0 and 12-months) between relative temperature and precipitation extremes and the risk of cryptosporidiosis and giardiasis infection in Colorado counties between 1997 and 2017, relative to the risk found at average values of temperature and precipitation for a given county and month. We found distinctly different patterns in the associations between temperature extremes and cryptosporidiosis, versus temperature extremes and giardiasis. When maximum or minimum temperatures were high (90th percentile) or very high (95th percentile), we found a significant increase in cryptosporidiosis risk, but a significant decrease in giardiasis risk, relative to risk at the county and calendar-month mean. Conversely, we found very similar relationships between precipitation extremes and both cryptosporidiosis and giardiasis, which highlighted the prominent role of long-term (>8 months) lags. Our study presents novel insights on the influence that extreme temperature and precipitation can have on parasitic disease transmission in real-world settings. Additionally, we present preliminary evidence that the standard lag periods that are typically used in epidemiological studies to assess the impacts of extreme weather on cryptosporidiosis and giardiasis may not be capturing the entire relevant period.

Evaluation of molecular-based methods for the detection and quantification of Cryptosporidium spp. in wastewater

Cryptosporidium poses significant public health risks as a cause of waterborne disease worldwide. Clinical surveillance of cryptosporidiosis is largely underreported due to the asymptomatic and mildly symptomatic infections, clinical misdiagnoses, and barriers to access testing. Wastewater surveillance overcomes these limitations and could serve as an effective tool for identifying cryptosporidiosis at the population level. Despite its potential, the lack of standardized wastewater surveillance methods for Cryptosporidium spp. challenges implementation design and the comparability between studies. Thus, this study compared and contrasted Cryptosporidium wastewater surveillance methods for concentrating wastewater oocysts, extracting oocyst DNA, and detecting Cryptosporidium genetic markers. The evaluated concentration methods included electronegative membrane filtration, Envirocheck HV capsule filtration, centrifugation, and Nanotrap Microbiome Particles, with and without additional immunomagnetic separation purification (except for the Nanotrap Microbiome Particles). Oocyst DNA extraction by either the DNeasy Powersoil Pro kit and the QIAamp DNA Mini kit were evaluated and the impact of bead beating and freeze-thaw pretreatments on DNA recoveries was assessed. Genetic detection via qPCR assays targeting either the Cryptosporidium 18S rRNA gene or the Cryptosporidium oocyst wall protein gene were tested. Oocyst recovery percentages were highest for centrifugation (39-77 %), followed by the Nanotrap Microbiome Particles (24 %), electronegative filtration with a PBST elution (22 %), and Envirocheck HV capsule filtration (13 %). Immunomagnetic separation purification was found to be unsuitable due to interference from the wastewater matrix. Bead-beating pretreatment enhanced DNA recoveries from both the DNeasy Powersoil Pro kit (314 gc/μL DNA) and the QIAamp DNA Mini kit (238 gc/μL DNA). In contrast, freeze-thaw pretreatment reduced DNA recoveries to under 92 gc/μL DNA, likely through DNA degradation. Finally, while both qPCR assays were specific to Cryptosporidium spp., the 18S rRNA assay had a 5-fold lower detection limit and could detect a wider range of Cryptosporidium spp. than the Cryptosporidium oocyst wall protein assay.

Critters and contamination: Zoonotic protozoans in urban rodents and water quality

Rodents represent the single largest group within mammals and host a diverse array of zoonotic pathogens. Urbanisation impacts wild mammals, including rodents, leading to habitat loss but also providing new resources. Urban-adapted (synanthropic) rodents, such as the brown rat (R. norvegicus), black rat (R. rattus), and house mouse (Mus musculus), have long successfully adapted to living close to humans and are known carriers of zoonotic pathogens. Two important enteric, zoonotic protozoan parasites, carried by rodents, include Cryptosporidium and Giardia. Their environmental stages (oocysts/cysts), released in faeces, can contaminate surface and wastewaters, are resistant to common drinking water disinfectants and can cause water-borne related gastritis outbreaks. At least 48 species of Cryptosporidium have been described, with C. hominis and C. parvum responsible for the majority of human infections, while Giardia duodenalis assemblages A and B are the main human-infectious assemblages. Molecular characterisation is crucial to assess the public health risk linked to rodent-related water contamination due to morphological overlap between species. This review explores the global molecular diversity of these parasites in rodents, with a focus on evaluating the zoonotic risk from contamination of water and wasterwater with Cryptosporidium and Giardia oocysts/cysts from synanthropic rodents. Analysis indicates that while zoonotic Cryptosporidium and Giardia are prevalent in farmed and pet rodents, host-specific Cryptosporidium and Giardia species dominate in urban adapted rodents, and therefore the risks posed by these rodents in the transmission of zoonotic Cryptosporidium and Giardia are relatively low. Many knowledge gaps remain however, and therefore understanding the intricate dynamics of these parasites in rodent populations is essential for managing their impact on human health and water quality. This knowledge can inform strategies to reduce disease transmission and ensure safe drinking water in urban and peri‑urban areas.

The risk of wild birds contaminating source water with zoonotic Cryptosporidium and Giardia is probably overestimated

Cryptosporidium and Giardia are important waterborne protozoan parasites that are resistant to disinfectants commonly used for drinking water. Wild birds, especially wild migratory birds, are often implicated in the contamination of source and wastewater with zoonotic diseases, due to their abundance near water and in urban areas and their ability to spread enteric pathogens over long distances. This review summarises the diversity of Cryptosporidium and Giardia in birds, with a focus on zoonotic species, particularly in wild and migratory birds, which is critical for understanding zoonotic risks. The analysis revealed that both avian-adapted and zoonotic Cryptosporidium species have been identified in birds but that avian-adapted Cryptosporidium species dominate in wild migratory birds. Few studies have examined Giardia species and assemblages in birds, but the non-zoonotic Giardia psittaci and Giardia ardeae are the most commonly reported species. The identification of zoonotic Cryptosporidium and Giardia in birds, particularly C. parvum and G. duodenalis assemblages A and B in wild migratory birds, is likely due to mechanical carriage or spillback from birds co-grazing pastures contaminated with C. parvum from livestock. Therefore, the role of wild migratory birds in the transmission of zoonotic Cryptosporidium and Giardia to source water is likely overestimated. To address knowledge gaps, it is important to conduct more extensive studies on the prevalence of Cryptosporidium and Giardia in a broader range of migratory wild birds. There is also a need to investigate the extent to which zoonotic infections with C. hominis/C. parvum and G. duodenalis assemblages A and B are mechanical and/or transient, and to assess the load and viability of zoonotic oo/cysts shed in avian faeces. Understanding the contribution of birds to zoonoses is essential for effective disease surveillance, prevention, and control.

Fate of Cryptosporidium and Giardia through conventional and compact drinking water treatment plants

Over the past three decades, a notable rise in the occurrence of enteric protozoan pathogens, especially Giardia and Cryptosporidium spp., in drinking water sources has been observed. This rise could be attributed not only to an actual increase in water contamination but also to improvements in detection methods. These waterborne pathogens have played a pivotal role in disease outbreaks and the overall escalation of disease rates in both developed and developing nations worldwide. Consequently, the control of waterborne diseases has become a vital component of public health policies and a primary objective of drinking water treatment plants (DWTPs). Limited studies applied real-time PCR (qPCR) and/or immunofluorescence assay (IFA) for monitoring Giardia and Cryptosporidium spp., particularly in developing countries like Egypt. Water samples from two conventional drinking water treatment plants and two compact units (CUs) were analyzed using both IFA and qPCR methods to detect Giardia and Cryptosporidium. Using qPCR and IFA, the conventional DWTPs showed complete removal of Giardia and Cryptosporidium, whereas Mansheyat Alqanater and Niklah CUs achieved only partial removal. Specifically, Cryptosporidium gene copies removal rates were 33.33% and 60% for Mansheyat Alqanater and Niklah CUs, respectively. Niklah CU also removed 50% of Giardia gene copies, but no Giardia gene copies were removed by Mansheyat Alqanater CU. Using IFA, both Mansheyat Alqanater and Niklah CUs showed a similar removal rate of 50% for Giardia cysts. Additionally, Niklah CU achieved a 50% removal of Cryptosporidium oocysts, whereas Mansheyat Alqanater CU did not show any removal of Cryptosporidium oocysts. Conventional DWTPs were more effective than CUs in removing enteric protozoa. The contamination of drinking water by enteric pathogenic protozoa remains a significant issue globally, leading to increased disease rates. Infectious disease surveillance in drinking water is an important epidemiological tool to monitor the health of a population.

Molecular Detection and Epidemiology of Potentially Zoonotic Cryptosporidium spp. and Giardia duodenalis in Wild Boar (Sus scrofa) from Eastern Spain

The protozoans Giardia duodenalis and Cryptosporidium spp. are common causes of gastrointestinal disease in humans and animals. While both are commonly documented in domestic animals, few studies have analysed their presence in wildlife. To assess the prevalence of both parasites in wild boar (Sus scrofa) in the Valencian Community (eastern Spain), 498 wild boar faecal samples were collected from 2018 to 2022. Cryptosporidium spp. was detected by performing a nested PCR targeting a 578 bp sequence of the small subunit ribosomal RNA gene (SSU rRNA), followed by sequencing and phylogenetic analysis. For G. duodenalis, a qPCR amplifying a fragment of 62 bp from the SSU rRNA was employed. Positive samples were genotyped for glutamate dehydrogenase and β-giardin genes. Different epidemiological factors were considered potential modulating variables in the transmission of both parasites. G. duodenalis prevalence was 1.20%, while Cryptosporidium spp. prevalence reached 21.7%. Coinfection was observed in 0.2%. Genotyping of G. duodenalis isolates only detected genotype E. Two species of Cryptosporidium spp. were identified: Cryptosporidium scrofarum and Cryptosporidium suis. The results of this study demonstrate that the exposure to Cryptosporidium spp. in wild boars is high, particularly among young individuals belonging to the Typical Mediterranean climate. Moreover, the probability of infection is dependent on both the season and the density of wild boars. On the other side, exposure to G. duodenalis seems scarce and is influenced, in turn, by the climate. Both Cryptosporidium species detected in the present study have been reported in humans. Due to wild boar increasing in number and their colonisation of urban and peri-urban areas, this could represent an inherent health risk for the human population.

Plastic pollution and fungal, protozoan, and helminth pathogens - A neglected environmental and public health issue?

Plastic waste is ubiquitous in the environment and can become colonised by distinct microbial biofilm communities, known collectively as the 'plastisphere.' The plastisphere can facilitate the increased survival and dissemination of human pathogenic prokaryotes (e.g., bacteria); however, our understanding of the potential for plastics to harbour and disseminate eukaryotic pathogens is lacking. Eukaryotic microorganisms are abundant in natural environments and represent some of the most important disease-causing agents, collectively responsible for tens of millions of infections, and millions of deaths worldwide. While prokaryotic plastisphere communities in terrestrial, freshwater, and marine environments are relatively well characterised, such biofilms will also contain eukaryotic species. Here, we critically review the potential for fungal, protozoan, and helminth pathogens to associate with the plastisphere, and consider the regulation and mechanisms of this interaction. As the volume of plastics in the environment continues to rise there is an urgent need to understand the role of the plastisphere for the survival, virulence, dissemination, and transfer of eukaryotic pathogens, and the effect this can have on environmental and human health.

Infectious Disease Sensitivity to Climate and Other Driver-Pressure Changes: Research Effort and Gaps for Lyme Disease and Cryptosporidiosis

Climate sensitivity of infectious diseases is discussed in many studies. A quantitative basis for distinguishing and predicting the disease impacts of climate and other environmental and anthropogenic driver-pressure changes, however, is often lacking. To assess research effort and identify possible key gaps that can guide further research, we here apply a scoping review approach to two widespread infectious diseases: Lyme disease (LD) as a vector-borne and cryptosporidiosis as a water-borne disease. Based on the emerging publication data, we further structure and quantitatively assess the driver-pressure foci and interlinkages considered in the published research so far. This shows important research gaps for the roles of rarely investigated water-related and socioeconomic factors for LD, and land-related factors for cryptosporidiosis. For both diseases, the interactions of host and parasite communities with climate and other driver-pressure factors are understudied, as are also important world regions relative to the disease geographies; in particular, Asia and Africa emerge as main geographic gaps for LD and cryptosporidiosis research, respectively. The scoping approach developed and gaps identified in this study should be useful for further assessment and guidance of research on infectious disease sensitivity to climate and other environmental and anthropogenic changes around the world.

Environmental Factors Associated with Cryptosporidium and Giardia

Environmental factors significantly influence the transmission of intestinal protozoan diseases. Cryptosporidiosis and giardiasis are important zoonotic diseases characterized by diarrhea, and are mainly water or foodborne diseases caused by fecal-borne oocysts. The One Health approach effectively addresses environmentally influenced zoonotic diseases. However, the impact of environmental factors on the survival of Cryptosporidium/Giardia (oo)cysts or disease transmission is mostly uncharacterized. Associations between cryptosporidiosis and giardiasis incidence and environmental variables (e.g., climatic conditions, soil characteristics, and water characteristics) have been reported; however, the identified relationships are not consistently reported. Whether these are country-specific or global observations is unclear. Herein, we review the evidence for the influence of environmental factors on Cryptosporidium/Giardia and corresponding diseases from three perspectives: climatic, soil, and water characteristics. The (oo)cyst concentration or survival of Cryptosporidium/Giardia and the incidence of corresponding diseases are related to environmental variables. The associations identified varied among studies and have different levels of importance and lag times in different locations. This review summarizes the influence of relevant environmental factors on Cryptosporidium/Giardia from the One Health perspective and provides recommendations for future research, monitoring, and response.

A systematic review and meta-analysis of pathogen reduction in onsite sanitation systems

The safe management of fecal sludge from the 3.4 billion people worldwide that use onsite sanitation systems can greatly reduce the global infectious disease burden. However, there is limited knowledge about the role of design, operational, and environmental factors on pathogen survival in pit latrines, urine diverting desiccation toilets, and other types of onsite toilets. We conducted a systematic literature review and meta-analysis to characterize pathogen reduction rates in fecal sludge, feces, and human excreta with respect to pH, temperature, moisture content, and the use of additives for desiccation, alkalinization, or disinfection. A meta-analysis of 1,382 data points extracted from 243 experiments described in 26 articles revealed significant differences between the decay rates and T₉₉ values of pathogens and indicators from different microbial groups. The overall median T₉₉ values were 4.8 days, 29 days, >341 days, and 429 days for bacteria, viruses, protozoan (oo)cysts, and Ascaris eggs, respectively. As expected, higher pH values, higher temperatures, and the application of lime all significantly predicted greater pathogen reduction rates but the use of lime by itself was more effective for bacteria and viruses than for Ascaris eggs, unless urea was also added. In multiple lab-scale experiments, the application of urea with enough lime or ash to reach a pH of 10 - 12 and a sustained concentration of 2,000 - 6,000 mg/L of non-protonated NH_3-N reduced Ascaris eggs more rapidly than without urea. In general, the storage of fecal sludge for 6 months adequately controls hazards from viruses and bacteria, but much longer storage times or alkaline treatment with urea and low moisture or heat is needed to control hazards from protozoa and helminths. More research is needed to demonstrate the efficacy of lime, ash, and urea in the field. More studies of protozoan pathogens are also needed, as very few qualifying experiments were found for this group.

First report of Cryptosporidium andersoni and risk factors associated with the occurrence of Cryptosporidium spp. in pre-weaned native Korean calves with diarrhea

Cryptosporidium spp. are important enteric protozoan parasites that infect humans and other animals throughout the world. Cryptosporidium infection in cattle industry leads to substantial economic losses due to diarrhea, growth retardation, weight loss, and possibly death. Most studies have focused on C. parvum, and studies on other Cryptosporidium spp. and calf diarrhea are limited. Therefore, this study aimed to investigate the occurrence of Cryptosporidium spp. in pre-weaned calves, to determine the risk factors for Cryptosporidium spp. infection such as age and season, and to identify subtypes of C. parvum circulating in the Republic of Korea (ROK). A total of 510 fecal samples were collected from calves with diarrhea and divided by age and season. Cryptosporidium spp. were first screened using PCR targeting the small subunit (SSU) rRNA gene and further the 60-kDa glycoprotein gene for subtyping of C. parvum. Out of 510 fecal samples, 71 (13.9%) were positive for Cryptosporidium spp. in pre-weaned calves with diarrhea. C. andersoni (2.8%), C. bovis (30.9%), C. parvum (29.6%), and C. ryanae (36.6%) were identified. C. ryanae was the most predominant in calves in the ROK. Calf age was a significant risk factor for C. bovis (χ² = 13.83, P = 0.001), C. parvum (χ² = 7.57, P = 0.023), and C. ryanae (χ² = 20.18, P = 0.000) occurrence. Additionally, C. parvum was detected 3.1-fold more frequently in pre-weaned calves with diarrhea in fall (95% CI: 1.23-7.81; P = 0.016) than in spring, whereas C. ryanae was 8.9-fold more frequently detected in summer (95% CI: 1.65-48.68; P = 0.011) than in spring. Three subtypes (IIaA17G4R1, IIaA18G3R1, and IIaA20G3R1) of C. parvum were identified. Of them, IIaA17G4R1 was the most common, whereas IIaA20G3R1 was not previously detected in calves in the ROK. To our knowledge, this is the first report of C. andersoni in pre-weaned calves in the ROK. The occurrence of Cryptosporidium spp. appears to be age-dependent in calves. Season had a significant effect on the occurrence of C. parvum and C. ryanae. Taken together, C. bovis and C. ryanae along with C. parvum are detected in pre-weaned calves with diarrhea and these two pathogens should not be overlooked in the diagnosis of calf diarrhea.

Performance of sewage treatment technologies for the removal of Cryptosporidium sp. and Giardia sp.: Toward water circularity

Cryptosporidium sp. and Giardia sp. are parasites that cause diseases in the population. Most of parasite diseases regarding the consumption of drinking water polluted with sewage are caused by Cryptosporidium sp. or Giardia sp. it is because of the incomplete disinfection of the wastewater treatment. Therefore, in this work the removal or inactivation efficiency of different treatment technologies presented by around 40 scientific studies was evaluated, with a view to water circularity. For Cryptosporidium sp., we conclude that the most efficient secondary technologies are aerobic technologies, which remove between 0.00 and 2.17 log units (Ulog), with activated sludge presenting the greatest efficiency, and that the tertiary technologies with the greatest removal are those that use ultrasound, which reach removal values of 3.17 Ulog. In the case of Giardia sp., the secondary technologies with the greatest removal are anaerobic technologies, with values between 0.00 and 3.80 Ulog, and the tertiary technologies with the greatest removal are those that combine filtration with UV or a chemical disinfection agent. Despite the removal values obtained, the greatest concern remains detecting and quantifying the infectious forms of both parasites in effluents; therefore, although the technologies perform adequately, discharge effluents must be monitored with more sensitive techniques, above all aiming for circularity of the treated water in a context of the water scarcity that affects some parts of the world.

Review of generic screening level assumptions for quantitative microbial risk assessment (QMRA) for estimating public health risks from Australian drinking water sources contaminated with Cryptosporidium by recreational activities

As urban communities continue to grow, demand for recreational access (including swimming) in drinking water sources have increased, yet relatively little is understood about the public health implications this poses for drinking water consumers. Preventative risk-based approaches to catchment management, informed by quantitative microbial risk assessment (QMRA), requires accurate input data to effectively model risks. A sound understanding of the knowledge gaps is also important to comprehend levels of uncertainty and help prioritise research needs. Cryptosporidium is one of the most important causes of waterborne outbreaks of gastroenteritis globally due to its resistance to chlorine. This review was undertaken by Water Research Australia to provide the most up-to-date information on current Cryptosporidium epidemiological data and underlying assumptions for exposure assessment, dose response and risk assessment for generic components of QMRA for Cryptosporidium and highlights priorities for common research. Key interim recommendations and guidelines for numerical values for relatively simple screening level QMRA modelling are provided to help support prospective studies of risks to drinking water consumers from Cryptosporidium due to body-contact recreation in source water. The review does not cover site-specific considerations, such as the levels of activity in the source water, the influence of dilution and inactivation in reservoirs, or water treatment. Although the focus is Australia, the recommendations and numerical values developed in this review, and the highlighted research priorities, are broadly applicable across all drinking source water sources that allow recreational activities.

Occurrence of Cryptosporidium spp. and Giardia spp. Infection in Humans in Latvia: Evidence of Underdiagnosed and Underreported Cases

Background and Objectives: Protozoan parasites—Cryptosporidium and Giardia—are important causes of diarrhea with an underestimated short-term burden on childhood growth and wellbeing in children under five years of age. The main transmission routes for both parasites are food and drinking water; transmission from person to person; and, due to their zoonotic nature, from domestic or wild animals to humans. The aims of the present study were to summarize the officially reported human cases of cryptosporidiosis and giardiasis in Latvia and to assess the occurrence of Cryptosporidium and Giardia in children within a prospective prevalence study. Materials and Methods: The number of officially reported cases of cryptosporidiosis and giardiasis in the time period of 2000–2020 was collected from the Centre for Disease Prevention and Control of Latvia. Data from a clinical diagnostic laboratory were included in the study in the period from 1 January 2008 to 31 December 2018. Additionally, a prospective study was performed, and fecal samples were collected from unique 0–17-year-old patients from January to February 2021 and tested using fluorescent microscopy. Results: Overall, during the 20-year period, 71 cases (mean per year = 9) of cryptosporidiosis and 1020 (mean per year = 34) cases of giardiasis were officially reported in Latvia. Meanwhile, within the prospective study, we found 35 (6.0%; 95%CI 4.3–8.1) Cryptosporidium and 42 (7.2%; 95%CI 5.3–9.6) Giardia cases. Conclusions: Here, we provide clear proof that both Cryptosporidium and Giardia are underdiagnosed in Latvia, which could also be true for neighboring Baltic and European countries, where a low number of cases are officially reported. Therefore, we highlight the hypothesis that the actual number of cryptosporidiosis and giardiasis human cases in the Baltic states is higher than that officially reported, including in Latvia.

Cryptosporidiosis

Cryptosporidiosis is a common cause of diarrhea among preweaned dairy calves. In the United States, the most common species of Cryptosporidium found in dairy calves is Cryptosporidium parvum, an important zoonotic species. Cryptosporidiosis is spread by fecal-oral transmission. Calves begin shedding the oocysts as early as 2 days of age, with peak shedding occurring at 14 days of age. Diarrhea generally starts 3 to 4 days after ingestion of the oocysts. Risk factors for the disease include large dairy farms, summer months, feeding of milk replacer, and early feeding of starter grain. Concrete flooring and appropriate cleaning of feeding utensils decreases the risk of disease.

High Occurrence of Zoonotic Subtypes of Cryptosporidiumparvum in Cypriot Dairy Farms

Cryptosporidium parvum is one of the major causes of neonatal calf diarrhoea resulting in reduced farm productivity and compromised animal welfare worldwide. Livestock act as a major reservoir of this parasite, which can be transmitted to humans directly and/or indirectly, posing a public health risk. Research reports on the prevalence of Cryptosporidium in ruminants from east Mediterranean countries, including Cyprus, are limited. This study is the first to explore the occurrence of Cryptosporidium spp. in cattle up to 24 months old on the island of Cyprus. A total of 242 faecal samples were collected from 10 dairy cattle farms in Cyprus, all of which were screened for Cryptosporidium spp. using nested-PCR amplification targeting the small subunit of the ribosomal RNA (18S rRNA) gene. The 60 kDa glycoprotein (gp60) gene was also sequenced for the samples identified as Cryptosporidium parvum-positive to determine the subtypes present. The occurrence of Cryptosporidium was 43.8% (106/242) with at least one positive isolate in each farm sampled. Cryptosporidium bovis, Cryptosporidium ryanae and C. parvum were the only species identified, while the prevalence per farm ranged from 20–64%. Amongst these, the latter was the predominant species, representing 51.8% of all positive samples, followed by C. bovis (21.7%) and C. ryanae (31.1%). Five C. parvum subtypes were identified, four of which are zoonotic—IIaA14G1R1, IIaA15G1R1, IIaA15G2R1 and IIaA18G2R1. IIaA14G1R1 was the most abundant, representing 48.2% of all C. parvum positive samples, and was also the most widespread. This is the first report of zoonotic subtypes of C. parvum circulating in Cyprus. These results highlight the need for further research into the parasite focusing on its diversity, prevalence, host range and transmission dynamics on the island.

A review of the current status of Cryptosporidium in fish

Species of the genus Cryptosporidium (phylum Apicomplexa) infect the epithelium of the gastrointestinal tract of several vertebrate hosts, including humans and domestic and wild animals. In the past 20 years, several studies have focused on Cryptosporidium in fish. To date, a total of four piscine-host-specific species (Cryptosporidium molnari, Cryptosporidium huwi, Cryptosporidium bollandi and Cryptosporidium abrahamseni), nine piscine genotypes and more than 29 unnamed genotypes have been described in fish hosts. In addition, Cryptosporidium species and genotypes typical of other groups of vertebrates have also been identified. This review summarizes the history, biology, pathology and clinical manifestations, as well as the transmission, prevalence and molecular epidemiology of Cryptosporidium in wild, cultured and ornamental fish from both marine and freshwater environments. Finally, the potential role of piscine hosts as a reservoir of zoonotic Cryptosporidium species is also discussed.

An Update on Zoonotic Cryptosporidium Species and Genotypes in Humans

The enteric parasite, Cryptosporidium is a major cause of diarrhoeal illness in humans and animals worldwide. No effective therapeutics or vaccines are available and therefore control is dependent on understanding transmission dynamics. The development of molecular detection and typing tools has resulted in the identification of a large number of cryptic species and genotypes and facilitated our understanding of their potential for zoonotic transmission. Of the 44 recognised Cryptosporidium species and >120 genotypes, 19 species, and four genotypes have been reported in humans with C. hominis, C. parvum, C. meleagridis, C. canis and C. felis being the most prevalent. The development of typing tools that are still lacking some zoonotic species and genotypes and more extensive molecular epidemiological studies in countries where the potential for transmission is highest are required to further our understanding of this important zoonotic pathogen. Similarly, whole-genome sequencing (WGS) and amplicon next-generation sequencing (NGS) are important for more accurately tracking transmission and understanding the mechanisms behind host specificity.

Bayesian spatio-temporal modelling to assess the role of extreme weather, land use change and socio-economic trends on cryptosporidiosis in Australia, 2001-2018

BACKGROUND

Intensification of land use threatens to increase the emergence and prevalence of zoonotic diseases, with an adverse impact on human wellbeing. Understanding how the interaction between agriculture, natural systems, climate and socioeconomic drivers influence zoonotic disease distribution is crucial to inform policy planning and management to limit the emergence of new infections.

OBJECTIVES

Here we assess the relative contribution of environmental, climatic and socioeconomic factors influencing reported cryptosporidiosis across Australia from 2001 to 2018.

METHODS

We apply a Bayesian spatio-temporal analysis using Integrated Nested Laplace Approximation (INLA).

RESULTS

We find that area-level risk of reported disease are associated with the proportions of the population under 5 and over 65 years of age, socioeconomic disadvantage, annual rainfall anomaly, and the proportion of natural habitat remaining. This combination of multiple factors influencing cryptosporidiosis highlights the benefits of a sophisticated spatio-temporal statistical approach. Two key findings from our model include: an estimated 4.6% increase in the risk of reported cryptosporidiosis associated with 22.8% higher percentage of postal area covered with original habitat; and an estimated 1.8% increase in disease risk associated with a 77.99 mm increase in annual rainfall anomaly at the postal area level.

DISCUSSION

These results provide novel insights regarding the predictive effects of extreme rainfall and the proportion of remaining natural habitat, which add unique explanatory power to the model alongside the variance associated with other predictive variables and spatiotemporal variation in reported disease. This demonstrates the importance of including perspectives from land and water management experts for policy making and public health responses to manage environmentally mediated diseases, including cryptosporidiosis.

Application of QMRA to prioritise water supplies for Cryptosporidium risk in New South Wales, Australia

A Quantitative Microbial Risk Assessment (QMRA) framework was applied to assess 312 drinking water supply systems across regional New South Wales (NSW). The framework was needed to support the implementation of a recommendation in the Australian Drinking Water Guidelines (ADWG) for appropriate treatment barriers to be operating in systems 'at risk' for Cryptosporidium. The objective was to prioritise systems so that those with the highest risk could be identified and addressed first. The framework was developed in a pilot study of 30 systems, selected to represent the range of water supplies across regional NSW. From these, source water categories were defined to represent local conditions with reference to the literature and Cryptosporidium risk factors. Values for Cryptosporidium oocyst concentration were assigned to the categories to allow quantification of the health risk from those water sources. The framework was then used to assess the risks in all 312 regional drinking water supply systems. Combining the disciplined approach of QMRA with simple catchment and treatment information and categorical risk outputs provided a useful and transparent method for prioritising systems for further investigation and potential risk management intervention. The risk rankings for drinking water supplies from this QMRA process have been used to set priorities for a large State Government funding program.

Cryptosporidium spp. infections in livestock and wild animals in Azerbaijan territory

Cryptosporidium is an intracellular protozoan parasite, globally distributed and capable of infecting various vertebrate species, including humans as well as domestic and wild animals. Cryptosporidium is increasingly gaining attention as a human and an animal pathogen mainly due to its dominant involvement in worldwide waterborne outbreaks. The present paper reviews the current knowledge and understanding of Cryptosporidium spp. in terrestrial and water animals in Azerbaijan.

Current pharmacotherapy of cryptosporidiosis: an update of the state-of-the-art

Introduction: Cryptosporidiosis has emerged as a major cause of diarrheal disease worldwide. It has especially serious health consequences for young, malnourished children living in endemic areas and for individuals with highly impaired T-cell function, such as HIV-positive individuals with low CD4 counts or immunosuppressed solid-organ transplant recipients.Areas covered: A selective literature search using PubMed was performed to review the available therapeutics to treat cryptosporidiosis, as well as related advances in drug development.Expert opinion: The only FDA-approved antiparasitic treatment in immunocompetent patients is nitazoxanide; however, it has failed to demonstrate convincing effectiveness among HIV-positive patients, immunosuppressed individuals and malnourished children. Thus, restoring HIV-positive patients' cellular immune response through effective antiretroviral therapy (ART), or reducing or changing immunosuppressive drugs, is important. Several new targets have been identified for chemotherapy, and the development of drugs for these targets has progressed, including parasite kinases, nucleic acid synthesis and processing, proteases and lipid metabolism. Candidate drugs that have been shown to be effective and safe in a neonatal calf model will most likely constitute the next advance for clinical trials in humans. However, developing an effective and inexpensive vaccination, as well as complementing structural preventive measures, would most decisively reduce the global cryptosporidiosis burden.

Global projections of temperature-attributable mortality due to enteric infections: a modelling study

BACKGROUND

Mortality due to enteric infections is projected to increase because of global warming; however, the different temperature sensitivities of major enteric pathogens have not yet been considered in projections on a global scale. We aimed to project global temperature-attributable enteric infection mortality under various future scenarios of sociodemographic development and climate change.

METHODS

In this modelling study, we generated global projections in two stages. First, we forecasted baseline mortality from ten enteropathogens (non-typhoidal salmonella, Shigella, Campylobacter, cholera, enteropathogenic Escherichia coli, enterotoxigenic E coli, typhoid, rotavirus, norovirus, and Cryptosporidium) under several future sociodemographic development and health investment scenarios (ie, pessimistic, intermediate, and optimistic). We then estimated the mortality change from baseline attributable to global warming using the product of projected annual temperature anomalies and pathogen-specific temperature sensitivities.

FINDINGS

We estimated that in the period 2080-95, the global mean number of temperature-attributable deaths due to enteric infections could be as low as 6599 (95% empirical CI 5441-7757) under the optimistic sociodemographic development and climate change scenario, or as high as 83 888 (67 760-100 015) under the pessimistic scenario. Most of the projected temperature-attributable deaths were from shigellosis, cryptosporidiosis, and typhoid fever in sub-Saharan Africa and South Asia. Considerable reductions in the number of attributable deaths were from viral infections, such as rotaviral and noroviral enteritis, which resulted in net reductions in attributable enteric infection mortality under optimistic scenarios for Latin America and the Caribbean and East Asia and the Pacific.

INTERPRETATION

Temperature-attributable mortality could increase under warmer climate and unfavourable sociodemographic conditions. Mitigation policies for limiting global warming and sociodemographic development policies for low-income and middle-income countries might help reduce mortality from enteric infections in the future.

FUNDING

Japan Society for the Promotion of Science, Japan Science and Technology Agency, and Spanish Ministry of Economy, Industry, and Competitiveness.

Cryptosporidium and waterborne outbreaks - A mini review

Cryptosporidium spp. is one of the prime agents of infectious diarrhea. Cryptosporidium spp. has been gaining awareness as a pathogen of public health importance in India and other developing countries. Owing to the nature of multiple transmission routes such as person-to-person, animal-to-person, waterborne and foodborne, the epidemiology of cryptosporidiosis in humans is not well known. A deeper understanding of the pathogenesis may lead to better diagnosis and better treatment of the condition. Asymptomatic human and animal transmission illustrates that the spread of infection through the environment is a more plausible explanation, waterborne transmission in particular. The disease burden is underestimated and its global impact is yet to be quantified due to the lack of country-specific estimates. Assessment of the disease itself has been crucial since the morphological indistinguishability, differences in distribution and transmission, and variations in the genotypes.

Prevalence of Cryptosporidium spp. in water: a global systematic review and meta-analysis

Cryptosporidium spp., as a genus of protozoan intestinal parasites, is recognized as responsible for cryptosporidiosis. The present study was conducted to provide an overview of the prevalence of Cryptosporidium based on water. In this regard, some databases such as Scopus, PubMed, Embase, and Web of Science were screened in order to retrieve the related citations from 1 January 1983 to 10 September 2019. The pooled prevalence of Cryptosporidium spp. was calculated by using a random effect model (REM) based on defined subgroups, including countries, water type, treatment conditions (treated and untreated), economic condition, World Health Organization (WHO) regions, and method of detection. In contrast, this index for treated and untreated water was 25.7% and 40.1%, respectively. Also, the overall prevalence of Cryptosporidium spp. among all water types was defined as 36 (95% CI: 31.4-40.7). The rank order of prevalence of Cryptosporidium spp. based on water type was wastewater (46.9%) > surface water (45.3%) > raw water (31.6%) > drinking water (25.5%) > reservoirs water (24.5%) > groundwater (18.8%) > swimming pool water (7.5%) > marine water (0.20%). Identifying the key contributing factors to Cryptosporidium spp. survival can help provide solutions at both local and global scales.

Private Wells and Rural Health: Groundwater Contaminants of Emerging Concern

PURPOSE OF REVIEW

Approximately 12% of the population in the US and Canada rely on federally unregulated private wells, which are common in rural areas and may be susceptible to microbiological and chemical contamination. This review identifies and summarizes recent findings on contaminants of emerging concern in well water across the US and Canada.

RECENT FINDINGS

Private well water quality modeling is complicated by the substantial variability in contamination sources, well construction, well depth, and the hydrogeology of the environment surrounding the well. Temporal variation in contaminant levels in wells suggests the need for monitoring efforts with greater spatial and temporal coverage. More extensive private well monitoring will help identify wells at greater risk of contamination, and in turn, public health efforts can focus on education and outreach to improve monitoring, maintaining, and treating private wells in these communities. Community interventions need to be coupled with stricter regulations and financing mechanisms that can support and protect private well owners.

Influence of weather and climate on cryptosporidiosis-A review

Studies have shown that climatic factors can significantly influence transmission of many waterborne diseases. However, knowledge of the impact of climate variability on cryptosporidiosis is much less certain. Associations between the incidence of cryptosporidiosis and climatic variables have been reported in several countries. Given that the identified relationships were not consistently reported across studies, it is not known whether these were country-specific observations or can be considered more globally. Variation in the disease risk in both low- and middle-income countries and high-income countries presents new challenges and opportunities to enact responsive changes in research and public health policies. Available epidemiological evidence of the influence of weather and climate on cryptosporidiosis is reviewed. Fourteen studies met the inclusion criteria, and most studies showed that the incidence of cryptosporidiosis is highly sensitive to climatic conditions, especially temperature, rainfall and relative humidity. The identified associations varied across studies, with different conditions of importance and lag times across different locations. Therefore, there is a need for countries at risk to assess Cryptosporidium transmission routes based on the spatiotemporal patterns of the disease and what role climate and other socio-ecological changes play in the transmission. Information gathering will then allow us to provide information for evidence-based control strategies and mitigation of transmission. This review offers new perspectives on the role of climate variability on Cryptosporidium transmission. It highlights different epidemiological approaches adopted and provides the potential for future research and surveillance to reduce the disease burden. By evaluating the epidemiological transmission of this organism in high-income countries, all mitigation strategies, for example filtration and water catchment management, can be used as exemplars of preventing infection in low- to middle-income countries.

Shedding light on environmentally transmitted parasites: lighter conditions within lakes restrict epidemic size

Parasite fitness depends on a successful journey from one host to another. For parasites that are transmitted environmentally, abiotic conditions might modulate the success of this journey. Here we evaluate how light, a key abiotic factor, influences spatiotemporal patterns of zooplankton disease where light varies seasonally, across lakes, and with depth in a lake. In an in situ experiment using those three sources of variation, we tested sensitivity of spores of two parasites to ambient light. Infectivity of both parasites was lower when exposed to ambient light in comparison to parasites exposed to otherwise similar conditions in the dark. The more sensitive parasite (the fungus, Metschnikowia) was damaged even under lower ambient light during late fall (November). With this differential sensitivity established, we evaluated links between light environment and natural outbreaks in lakes. Consistent with the incubations, epidemics of the less sensitive parasite (the bacterium, Pasteuria) started earlier in the fall (under higher ambient light), and both parasites had smaller outbreaks in more transparent lakes. Overall, light environment may impact the timing and size of disease outbreaks. Outbreaks could thus become exacerbated by human activities that darken waters, including lake browning associated with climate change and eutrophication.

Cryptosporidium spp. in groundwater supplies intended for human consumption - A descriptive review of global prevalence, risk factors and knowledge gaps

Cryptosporidiosis is one of the leading causes of diarrhoeal illness and mortality induced by protozoan pathogens worldwide. As a largely waterborne disease, emphasis has been given to the study of Cryptosporidium spp. in surface waters, readily susceptible to pathogenic contamination. Conversely, the status of Cryptosporidium in potable groundwater sources, generally regarded as a pristine and "safe" drinking-water supply owing to (sub)-soil protection, remains largely unknown. As such, this investigation presents the first literature review aimed to ascertain the global prevalence of Cryptosporidium in groundwater supply sources intended for human consumption. Thirty-seven peer-reviewed studies were identified and included in the review. Groundwater sample and supply detection rates (estimated 10-20%) indicate Cryptosporidium is frequently present in domestic groundwater sources, representing a latent health concern for groundwater consumers. Specifically, sample (10.4%) and source (19.1%) detection rates deriving from comprehensive "temporal" investigations are put forward as representative of a contamination 'baseline' for Cryptosporidium in 'domestic' groundwater supplies. Proposed 'baseline' prevalence figures are largely applicable in preventive risk-based catchment and groundwater quality management including the formulation of Quantitative Microbial Risk Assessment (QMRA). Notwithstanding, a large geographical disparity in available investigations and lack of standardized reporting restrict the transferability of research findings. Overall, the mechanisms responsible for Cryptosporidium transport and ingress into groundwater supplies remain ambiguous, representing a critical knowledge gap, and denoting a distinctive lack of integration between groundwater and public-health sub-disciplines among investigations. Key recommendations and guidelines are provided for prospective studies directed at more integrative and multi-disciplinary research.

Bayesian risk assessment model of human cryptosporidiosis cases following consumption of raw Eastern oysters (Crassostrea virginica) contaminated with Cryptosporidium oocysts in the Hillsborough River system in Prince Edward Island, Canada

Cryptosporidium spp. has been associated with foodborne infectious disease outbreaks; however, it is unclear to what extent raw oyster consumption poses a risk to public health. Control of Cryptosporidium in shellfish harvest seawater in Canada is not mandatory and, despite relay/depuration processes, the parasite can remain viable in oysters for at least a month (depending on initial loads and seawater characteristics). Risks of human infection and illness from exposure to oysters contaminated with Cryptosporidium oocysts were assessed in a Bayesian framework. Two data sets were used: counts of oocysts in oysters harvested in Approved, Restricted, and Prohibited zones of the Hillsborough River system; and oocyst elimination rate from oysters exposed to oocysts in laboratory experiments. A total of 20 scenarios were assessed according to number of oysters consumed in a single serving (1, 10 and 30) and different relay times. The median probability of infection and developing cryptosporidiosis (e.g. illness) due to the consumption of raw oysters in Prince Edward Island was zero for all scenarios. However, the 95th percentiles ranged from 2% to 81% and from 1% to 59% for probability of infection and illness, respectively. When relay times were extended from 14 to 30 days and 10 oysters were consumed in one serving from the Restricted zones, these probabilities were reduced from 35% to 16% and from 15% to 7%, respectively. The 14-day relay period established by Canadian authorities for harvesting in Restricted zones seems prudent, though insufficient, as this relay period has been shown to be enough to eliminate fecal coliforms but not Cryptosporidium oocysts, which can remain viable in the oyster for over a month. Extending relay periods of 14 and 21 days for oysters harvested in Restricted zones to 30 days is likely insufficient to substantially decrease the probability of infection and illness. The highest risk was found for oysters that originated in Prohibited zones. Our findings suggest that Cryptosporidium oocysts are a potential cause of foodborne infection and illness when consuming raw oysters from Hillsborough River, one of the most important oyster production bays on Prince Edward Island. We discuss data gaps and limitations of this work in order to identify future research that can be used to reduce the uncertainties in predicted risks.

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Risk of infection and illness of cryptosporidiosis in humans by consuming raw oysters from PEI is likely to be negligible.

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Depuration time of 14 days might not be enough to reduce Cryptosporidium oocysts contamination in oysters in bays of PEI.

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More field data need to be obtained to reduce uncertainties in predicted risks.

Biological HRPs in wastewater

Biological high-risk pollutants (HRPs) have become a serious threat to human health worldwide, and wastewater is one of the major sources of them in a natural environment. Despite the long history of wastewater research, comprehensive understanding of the role and behavior of HRPs during wastewater treatment is still limited owing to the complexity of the community. In recent decades, the rapid development of molecular tools, especially the wide application of next generation sequencing technologies, helps to unravel the community composition, structure, and dynamic variation in wastewater. Overall, this chapter mainly focuses on biological HRPs, including bacteria, viruses, protozoa, helminth, biotoxins, antibiotic resistance genes and antibiotic resistant bacteria in wastewater. The characteristics, classification, fates, functions, and health implications of these HRPs are introduced in detail. Moreover, the biogeography of HRPs is a research hotspot in recent years, and available information is also summarized in this chapter. Finally, we also propose the future research needs of HRPs in wastewater after the comprehensive summary of the existing research reports. This chapter is wished to be helpful for beginners to quickly understand the biological HRPs in wastewater.

Micromanipulation System for Isolating a Single Cryptosporidium Oocyst

In this paper, an integrated system for contact micromanipulation of Cryptosporidium oocysts is presented. The system integrates five actuators and a partially automated control system and contacts the oocyst using a drawn glass end effector with tip dimensions of 1 μ m. The system is intended to allow single cell analysis (SCA) of Cryptosporidium-a very harmful parasite found in water supplies-by isolating the parasite oocyst of 5 μ m diameter in a new environment. By allowing this form of analysis, the source of Cryptosporidium can be found and potential harm to humans can be reduced. The system must overcome the challenges of locating the oocysts and end effector in 3D space and contact adhesion forces between them, which are prominent over inertial forces on this scale. An automated alignment method is presented, using the Prewitt operator to give feedback on the level of focus and this system is tested, demonstrating alignment accuracy of <2 μ m. Moreover, to overcome the challenge of adhesion forces, use of dry and liquid environments are investigated and a strategy is developed to capture the oocyst in the dry environment and release in the liquid environment. An experiment is conducted on the reliability of the system for isolating a Cryptosporidium oocyst from its culture, demonstrating a success rate of 98%.

Direct Sequencing of Cryptosporidium in Stool Samples for Public Health

The protozoan parasite Cryptosporidium is an important cause of diarrheal disease (cryptosporidiosis) in humans and animals, with significant morbidity and mortality especially in severely immunocompromised people and in young children in low-resource settings. Due to the sexual life cycle of the parasite, transmission is complex. There are no restrictions on sexual recombination between sub-populations, meaning that large-scale genetic recombination may occur within a host, potentially confounding epidemiological analysis. To clarify the relationships between infections in different hosts, it is first necessary to correctly identify species and genotypes, but these differentiations are not made by standard diagnostic tests and more sophisticated molecular methods have been developed. For instance, multilocus genotyping has been utilized to differentiate isolates within the major human pathogens, Cryptosporidium parvum and Cryptosporidium hominis. This has allowed mixed populations with multiple alleles to be identified: recombination events are considered to be the driving force of increased variation and the emergence of new subtypes. As yet, whole genome sequencing (WGS) is having limited impact on public health investigations, due in part to insufficient numbers of oocysts and purity of DNA derived from clinical samples. Moreover, because public health agencies have not prioritized parasites, validation has not been performed on user-friendly data analysis pipelines suitable for public health practitioners. Nonetheless, since the first whole genome assembly in 2004 there are now numerous genomes of human and animal-derived cryptosporidia publically available, spanning nine species. It has also been demonstrated that WGS from very low numbers of oocysts is possible, through the use of amplification procedures. These data and approaches are providing new insights into host-adapted infectivity, the presence and frequency of multiple sub-populations of Cryptosporidium spp. within single clinical samples, and transmission of infection. Analyses show that although whole genome sequences do indeed contain many alleles, they are invariably dominated by a single highly abundant allele. These insights are helping to better understand population structures within hosts, which will be important to develop novel prevention strategies in the fight against cryptosporidiosis.

Antiprotozoal activity of silver nanoparticles against Cryptosporidium parvum oocysts: New insights on their feasibility as a water disinfectant

Cryptosporidium is a protozoan of extremely medical and veterinary impact; whose oocysts donate a considerable resistant to the water treatment processes. Therefore, this study aimed to explore the impacts of silver nanoparticles (AgNPs) on count and viability of the Cryptosporidium parvum (CP) isolated from different tap water samples. The oocysts were exposed to AgNPs at different dosages of 0.05, 0.1 and 1 ppm for several contact times (30 min to 4 h). The results showed a significant decrease in oocyst count and viability in a dose-dependent manner. Additionally, AgNPs at a conc. of 1 ppm for 30 min and 0.1 ppm for 1 h reduced the oocysts by 97.2 and 94.4%, respectively. Comparatively, there was a noticeable increase in the oocyst's viability at 2 and 4 h, which emphasized that the time of contact between AgNPs and CP was not a major influencing factor for successful application of AgNPs in the nano-water treatment.

Calcium-Mediated Biophysical Binding of Cryptosporidium parvum Oocysts to Surfaces Is Sensitive to Oocyst Age

Cryptosporidium parvum causes potentially life-threatening gastrointestinal disease in humans and may not be effectively removed from drinking water via conventional methods. Prior research has shown that environmental biofilms immobilize oocysts from the water column, but the biophysical mechanisms driving this attraction are still under investigation. This study investigates the affinity of C. parvum oocysts to silanized surfaces. Surfaces were prepared with hydroxyl, amine, and carboxyl moieties. Binding forces between the oocysts and these engineered substrates were analyzed, with and without divalent ions, using atomic force microscopy. Binding forces were measured over several weeks to investigate the influence of age on adhesion. C. parvum oocysts bind most strongly to carboxylic acid functional groups, with rupture forces greater than that required to break noncovalent molecular bonds, regardless of oocyst age. This adhesion is shown to be due to divalent cation bridging mechanisms. In addition, the binding strength increases over a 5-week period as the oocysts age, followed by a decrease in the binding strength, which may be related to structural or biochemical changes in the outer wall-bound glycosylated proteins. This study sheds new light on the biochemical parameters that influence C. parvum oocyst binding to surfaces. Increased understanding of how age and water chemistry influence the binding strength of oocysts may inform future developments in environmental detection and drinking water treatment, such as with the development of oocyst-specific sensors that allow for more frequent tracking of oocysts in the environment.IMPORTANCE The mechanisms by which pathogens bind to surfaces are of interest to a wide variety of scientific communities, as these mechanisms drive infectivity, fate, and transport of the pathogenic organisms. This study begins to reveal the mechanism of direct binding of Cryptosporidium parvum to surfaces containing both carboxylic acid and amine moieties, in an attempt to understand how much of the binding ability is due to long-range electrostatic forces versus other mechanisms (specific or nonspecific) of bonding. In addition to improving the scientific understanding of fate and transport of oocysts, an expanded understanding of the binding mechanisms may aid in the development of new tools and sensors designed to detect and track oocysts in waterways. Furthermore, the methods used to examine binding in this study could be translated to other waterborne pathogens of interest.

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.

Public health risks associated with food-borne parasites

Parasites are important food‐borne pathogens. Their complex lifecycles, varied transmission routes, and prolonged periods between infection and symptoms mean that the public health burden and relative importance of different transmission routes are often difficult to assess. Furthermore, there are challenges in detection and diagnostics, and variations in reporting. A Europe‐focused ranking exercise, using multicriteria decision analysis, identified potentially food‐borne parasites of importance, and that are currently not routinely controlled in food. These are Cryptosporidium spp., Toxoplasma gondii and Echinococcus spp. Infection with these parasites in humans and animals, or their occurrence in food, is not notifiable in all Member States. This Opinion reviews current methods for detection, identification and tracing of these parasites in relevant foods, reviews literature on food‐borne pathways, examines information on their occurrence and persistence in foods, and investigates possible control measures along the food chain. The differences between these three parasites are substantial, but for all there is a paucity of well‐established, standardised, validated methods that can be applied across the range of relevant foods. Furthermore, the prolonged period between infection and clinical symptoms (from several days for Cryptosporidium to years for Echinococcus spp.) means that source attribution studies are very difficult. Nevertheless, our knowledge of the domestic animal lifecycle (involving dogs and livestock) for Echinoccocus granulosus means that this parasite is controllable. For Echinococcus multilocularis, for which the lifecycle involves wildlife (foxes and rodents), control would be expensive and complicated, but could be achieved in targeted areas with sufficient commitment and resources. Quantitative risk assessments have been described for Toxoplasma in meat. However, for T. gondii and Cryptosporidium as faecal contaminants, development of validated detection methods, including survival/infectivity assays and consensus molecular typing protocols, are required for the development of quantitative risk assessments and efficient control measures.

Use of ultrasound irradiation to inactivate Cryptosporidium parvum oocysts in effluents from municipal wastewater treatment plants

Water reuse is currently considered an innovative way to addressing water shortage that can provide significant economic, social and environmental benefits, particularly -but not exclusively- in water deficient areas. The potential transmission of infectious diseases is the most common concern in relation to water reclamation. Cryptosporidium is an important genus of protozoan enteropathogens that infect a wide range of vertebrate hosts, including humans. The infective form (oocyst) is highly resistant to the environmental conditions and disinfection treatments. Consequently, Cryptosporidium is the most common etiological agent identified in waterborne outbreaks attributed to parasitic protozoa worldwide. The present study evaluates the efficacy of ultrasound disinfection, at three power levels (60, 80 and 100 W), pulsed at 50% or in continuous mode, for inactivating the waterborne protozoan parasite Cryptosporidium parvum in simulated and real effluents from municipal wastewater treatment plants (MWTPs). Overall interpretation of the results shows that the application of ultrasound irradiation at 80 W power in continuous mode for an exposure time of 10 min drastically reduced the viability of C. parvum. Thus, oocyst viabilities of 4.16 ± 1.93%; 1.29 ± 0.86%; 3.16 ± 0.69%; and 3.15 ± 0.87% were obtained in distilled water, simulated, real and filtered MWTP effluents, respectively (vs 98.57 ± 0.01%, initial oocyst viability), as determined using inclusion/exclusion of the fluorogenic vital dye propidium iodide, an indicator of the integrity of the oocyst wall. Independently of the mode used (pulsed/continuous) and at 80 W power, higher level of oocyst inactivation was detected in MWTP effluents than in distilled water used as a control solution, may be due to the differences in the chemical composition of the samples. Comparison of the results obtained in both modes showed that use of the continuous mode yielded significantly lower oocyst viability. However, when the Dose parameter was considered (energy per volume unit), no statistically significant differences in oocyst viability were observed in relation to the type of mode used. The results demonstrate that ultrasound technology represents a promising alternative to the disinfection methods (ultraviolet irradiation and chlorine products) currently used in water reclamation as it drastically reduces the survival of Cryptosporidium oocysts, without changing the chemical composition of the water or producing toxic by-products.

Selective electrohydrodynamic concentration of waterborne parasites on a chip

Concentrating diluted samples is a key step to improve detection capabilities. The wise use of scaling laws shows the advantages of working with sub-microliter-sized samples. Rapid progress in MEMS technologies has driven the design of integrated platforms performing many biochemical operations. Here we report a new concentrator device based on electro-hydrodynamic forces which can be easily integrated into electrowetting-on-dielectric (EWOD) platforms. This approach is label-free and applicable to a wide range of micro-objects. The detection and analysis of two common waterborne parasites, Cryptosporidium and Giardia, is a perfect test case due to their global health relevance. By fully controlling the interplay of the various forces acting on the micron-sized Cryptosporidium parvum and Cryptosporidium muris oocysts, we show that it is possible to concentrate them on the side of a 10 μL initial drop and then extract them efficiently from a droplet of a few hundred nanoliters. We performed a finite element modeling of the forces acting on the parasites' oocysts to optimize the electrodes' shapes. We obtained state-of-the-art concentration factors of 12 ± 0.4 times and 2 to 4 times in the sub-region of the drop and the extracted droplet, respectively, with an efficiency of 70 ± 6%. Furthermore, this device had the ability to selectively concentrate parasites of different species out of a mix. We demonstrated this by segregating C. parvum oocysts from either Giardia lamblia cysts or its related species, C. muris oocysts.

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.

Understanding human infectious Cryptosporidium risk in drinking water supply catchments

Treating drinking water appropriately depends, in part, on the robustness of source water quality risk assessments, however quantifying the proportion of infectious, human pathogenic Cryptosporidium oocysts remains a significant challenge. We analysed 962 source water samples across nine locations to profile the occurrence, rate and timing of infectious, human pathogenic Cryptosporidium in surface waters entering drinking water reservoirs during rainfall-runoff conditions. At the catchment level, average infectivity over the four-year study period reached 18%; however, most locations averaged <5%. The maximum recorded infectivity fraction within a single rainfall runoff event was 65.4%, and was dominated by C. parvum. Twenty-two Cryptosporidium species and genotypes were identified using PCR-based molecular techniques; the most common being C. parvum, detected in 23% of water samples. Associations between landuse and livestock stocking characteristics with Cryptosporidium were determined using a linear mixed-effects model. The concentration of pathogens in water were significantly influenced by flow and dominance of land-use by commercial grazing properties (as opposed to lifestyle properties) in the catchment (p < 0.01). Inclusion of measured infectivity and human pathogenicity data into a quantitative microbial risk assessment (QMRA) could reduce the source water treatment requirements by up to 2.67 log removal values, depending on the catchment, and demonstrated the potential benefit of collating such data for QMRAs.

Foodborne cryptosporidiosis

Foodborne illness, the majority of which is caused by enteric infectious agents, costs global economies billions of dollars each year. The protozoan parasite Cryptosporidium is particularly suited to foodborne transmission and is responsible for >8 million cases of foodborne illness annually. Procedures have been developed for sensitive detection of Cryptosporidium oocysts on fresh produce and molecular diagnostic assays have been widely used in case linkages and infection source tracking, especially during outbreak investigations. The integrated use of advanced diagnostic techniques with conventional epidemiological studies is essential to improve our understanding of the occurrence, source and epidemiology of foodborne cryptosporidiosis. The implementation of food safety management tools such as Good Hygienic Practices (GHP), Hazard Analysis and Critical Control Points (HACCP), and Quantitative Microbial Risk Assessment (QMRA) in industrialised nations and Water, Sanitation, and Hygiene (WASH) in developing countries is central for prevention and control and foodborne cryptosporidiosis in the future.

Analysis of Parasitic Protozoa at the Single-cell Level using Microfluidic Impedance Cytometry

At present, there are few technologies which enable the detection, identification and viability analysis of protozoan pathogens including Cryptosporidium and/or Giardia at the single (oo)cyst level. We report the use of Microfluidic Impedance Cytometry (MIC) to characterise the AC electrical (impedance) properties of single parasites and demonstrate rapid discrimination based on viability and species. Specifically, MIC was used to identify live and inactive C. parvum oocysts with over 90% certainty, whilst also detecting damaged and/or excysted oocysts. Furthermore, discrimination of Cryptosporidium parvum, Cryptosporidium muris and Giardia lamblia, with over 92% certainty was achieved. Enumeration and identification of (oo)cysts can be achieved in a few minutes, which offers a reduction in identification time and labour demands when compared to existing detection methods.

Cryptosporidium Attenuation across the Wastewater Treatment Train: Recycled Water Fit for Purpose

Compliance with guideline removal targets for Cryptosporidium which do not provide any credit for the inactivation of oocysts through wastewater treatment processes can considerably increase the cost of providing recycled water. Here we present the application of an integrated assay to quantify both oocyst numbers and infectivity levels after various treatment stages at three Victorian and two South Australian (SA) wastewater treatment plants (WWTPs). Oocyst density in the raw sewage was commensurate with community disease burden, with early rounds of sampling capturing a widespread cryptosporidiosis outbreak in Victoria. The level of infectivity of oocysts in sewage was stable throughout the year but was significantly lower at the SA WWTPs. Removals across secondary treatment processes were seasonal, with poorer removals associated with inflow variability; however, no decrease in the oocyst infectivity was identified. For SA WWTPs, those oocysts remaining within the secondary treatment-clarified effluent were proportionally more infectious than those in raw sewage. Lagoon systems demonstrated significant inactivation or removal of oocysts, with attenuation being seasonal. Examination of a UV system emphasized its efficacy as a disinfectant barrier but conversely confirmed the importance of a multibarrier approach with the detection of infectious oocysts postdisinfection. The ability to characterize risk from infectious oocysts revealed that the risk from Cryptosporidium is significantly lower than previously thought and that its inclusion in quantitative risk assessments of reuse systems will more accurately direct the selection of treatment strategies and capital expenditure, influencing the sustainability of such schemes.IMPORTANCE Here we present the application of a recently developed integrated assay not only to quantify the removal of Cryptosporidium oocysts but also to quantify their infectivity across various treatment stages at five wastewater treatment plants (WWTPs), thereby better measuring the "true effect" of the treatment train on oocyst risk reduction. For a number of the WWTPs analyzed in this study the risk, is significantly lower than previously thought. Therefore, the inclusion of oocyst infectivity in guideline values and in quantitative microbial risk assessment (QMRA) has the potential to affect future treatment directions and capital expenditure.