Giardia is the most common protozoan cause of diarrhoeal illness in humans worldwide. Despite this, our understanding of the zoonotic transmission of Giardia, and in particular the role of cattle as a zoonotic reservoir, is not well understood, due to the limitations of current typing systems and a recent taxonomic revision of the genus. Newly improved multilocus sequencing typing tools are not yet widely used and are not applicable to all species. However, data generated to date suggest that zoonotic transmission of Giardia of bovine origin is limited. Carefully designed epidemiological investigations using improved typing tools are essential to understand the extent of zoonotic transmission from cattle. Improved on-farm biosecurity measures are also needed to control the transmission of zoonotic Giardia in cattle.

Introduction:Cryptosporidium hominis is the dominant Cryptosporidium species infecting humans, but most advances in developing robust in vitro culturing platforms for Cryptosporidium have utilised C. parvum. Consequently, there is relatively little available information specific to the biology and life cycle of C. hominis. The present study utilised a pumpless and tubeless gut-on-chip to generate a physiologically relevant in vitro environment by applying a constant fluid shear stress of 0.02 dyn cm-2 to HCT-8 cells. Methods:Gut-on-chips were fabricated using standard soft lithography. C. hominis oocysts isolated from human pathology samples were used to infect the human ileocecal colorectal adenocarcinoma (HCT-8) cell line under a constant fluid shear stress of 0.02 dyn cm-2. Parasite growth was assessed using a C. hominis-specific quantitative PCR, a Cryptosporidium genus-specific immunofluorescence assay, and scanning electron microscopy. Differences in the HCT-8 transcriptome with and without fluid shear stress, and the host-parasite interaction, were both assessed using bulk transcriptomics. Results:Transcriptomic analysis of the HCT-8 cell line cultured within the gut-on-chip demonstrated a metabolic shift towards oxidative phosphorylation when compared to the same cell line cultured under static conditions. Extended C. hominis (subtype IdA15G1) cultures were sustained for up to 10 days within the gut-on-chip as shown by a C. hominis-specific qPCR and a Cryptosporidium genus-specific immunofluorescence assay, which demonstrated ~30-fold amplification in the gut-on-chip over the duration of the experiment. Scanning electron microscopy of infected monolayers identified trophozoites, meronts, merozoites, macrogamonts, microgamonts, and possible gamont-like stages at 48 h post-infection. The potential role of gamonts in the Cryptosporidium life cycle remains unclear and warrants further investigation. Transcriptomes of HCT-8 cells infected with C hominis revealed upregulation of biological processes associated with cell cycle regulation and cell signalling in C. hominis-infected cells under fluid shear stress compared to static culture. Conclusions:These data demonstrate that bioengineered gut-on-chip models support extended C. hominis growth and can be used to interrogate responses of host cells to infection. Owing to its relative simplicity, the pumpless and tubeless gut-on-chip can be accessible to most laboratories with established HCT-8 infection models for Cryptosporidium culture.

Cattle infected with Cryptosporidium can shed large quantities of the environmentally resistant oocysts, which can cause significant diarrhoeal disease, particularly in neonatal calves and in susceptible human populations worldwide. More than ten species of Cryptosporidium have been reported in cattle; however, C. parvum dominates in young calves in many countries, with C. ryanae, C. bovis and C. andersoni prevalent in older animals. Cryptosporidium hominis and C. parvum are the main species infecting humans. In most countries, zoonotic cryptosporidiosis is primarily caused by C. parvum IIa subtypes, which also dominates in calves, but in China, C. parvum infections in cattle are exclusively caused by IId subtypes. Outbreak investigations and molecular epidemiological studies support calves as a major source of zoonotic cryptosporidiosis. The zoonotic significance of increasing reports of C. hominis in cattle requires further investigation. Epidemiological investigations designed to better understand the sources and transmission dynamics using improved typing tools are required before better control strategies can be implemented.

Cryptosporidium species are an important cause of diarrhoeal disease worldwide. Many countries reported declines in cryptosporidiosis incidence during COVID-19 restrictions, followed by marked increases post-COVID. A similar pattern has been observed in Australia, with record-high case numbers reported across multiple states in 2024-2025, including Western Australia (WA), where an outbreak occurred in 2025. Between 1st January - 30th June 2025, WA reported a statewide total of 1110 human cryptosporidiosis cases, which is substantially higher than the previous years. In the present study, a subset of WA cases from 2025 was investigated using contact tracing and molecular typing and compared with subtypes circulating in 2023 and 2024. Sequence analysis of the 18S rRNA and gp60 loci identified three Cryptosporidium species: C. hominis (91.5 %, 108/118), C. parvum (6.8 %, 8/118), and C. meleagridis (1.7 %, 2/118), comprising 13 distinct subtypes, over the three years. Notably, a previously rare C. hominis subtype, IeA11G3T3, emerged in 2023 and by 2025 had become the dominant subtype (92.1 %, 70/76) of samples typed. Multi-locus sequence typing (MLST) of a representative subset of IeA11G3T3 isolates (n = 13) showed that all sequences were identical, except for one isolate from 2024, which contained three insertions: an 18-bp repeat in the cp-47 gene and both a 12-bp and a 6-bp repeat in the dz-hrgp gene. The C. hominis IeA11G3T3 subtype has also recently emerged as a dominant subtype in several other countries, although the factors driving its emergence remain unclear.

Background:The enteric parasite Cryptosporidium remains a treatment challenge for drinking water utilities globally due to its resistance to chlorine disinfection. However, the lack of an in vitro culture system for Cryptosporidium that is both cost-effective and reliable remains a key bottleneck in Cryptosporidium research. Methods:Here we report that the microfluidic culture of human ileocecal colorectal adenocarcinoma (HCT-8) cells under fluid shear stress enables the extended development of Cryptosporidium parvum. Specifically, the growth of C. parvum in a user-friendly pumpless microfluidic device was assessed using immunofluorescence assays, scanning electron microscopy, and quantitative polymerase chain reaction, which revealed that development continued for 10 days in total. Results:Oocysts produced within the microfluidic device were infective to fresh HCT-8 monolayers; however, these oocysts were only present at low levels. Conclusions:We anticipate that such microfluidic approaches will facilitate a wide range of in vitro studies on Cryptosporidium and may have the potential to be further developed as a routine infectivity assessment tool for the water industry.

Marsupials, inhabiting diverse ecosystems, including urban and peri-urban regions in Australasia and the Americas, intersect with human activities, leading to zoonotic spill-over and anthroponotic spill-back of pathogens, including Cryptosporidium and Giardia. This review assesses the current knowledge on the diversity of Cryptosporidium and Giardia species in marsupials, focusing on the potential zoonotic risks. Cryptosporidium fayeri and C. macropodum are the dominant species in marsupials, while in possums, the host-specific possum genotype dominates. Of these three species/genotypes, only C. fayeri has been identified in two humans and the zoonotic risk is considered low. Generally, oocyst shedding in marsupials is low, further supporting a low transmission risk. However, there is some evidence of spill-back of C. hominis into kangaroo populations, which requires continued monitoring. Although C. hominis does not appear to be established in small marsupials like possums, comprehensive screening and analysis are essential for a better understanding of the prevalence and potential establishment of zoonotic Cryptosporidium species in small marsupials. Both host-specific and zoonotic Giardia species have been identified in marsupials. The dominance of zoonotic G. duodenalis assemblages A and B in marsupials may result from spill-back from livestock and humans and it is not yet understood if these are transient or established infections. Future studies using multilocus typing tools and whole-genome sequencing are required for a better understanding of the zoonotic risk from Giardia infections in marsupials. Moreover, much more extensive screening of a wider range of marsupial species, particularly in peri-urban areas, is required to provide a clearer understanding of the zoonotic risk of Cryptosporidium and Giardia in marsupials.

The zoonotic potential of the protist parasites Cryptosporidium spp. and Giardia duodenalis in amphibians and reptiles raises public health concerns due to their growing popularity as pets. This review examines the prevalence and diversity of these parasites in wild and captive amphibians and reptiles to better understand the zoonotic risk. Research on Giardia in both groups is limited, and zoonotic forms of Cryptosporidium or Giardia have not been reported in amphibians. Host-adapted Cryptosporidium species dominate in reptiles, albeit some reptiles have been found to carry zoonotic (C. hominis and C. parvum) and rodent-associated (C. tyzzeri, C. muris and C. andersoni) species, primarily through mechanical carriage. Similarly, the limited reports of Giardia duodenalis (assemblages A, B and E) in reptiles may also be due to mechanical carriage. Thus, the available evidence indicates minimal zoonotic risk associated with these organisms in wild and captive frogs and reptiles. The exact transmission routes for these infections within reptile populations remain poorly understood, particularly regarding the importance of mechanical carriage. Although the risk appears minimal, continued research and surveillance efforts are necessary to gain a more comprehensive understanding of the transmission dynamics and ultimately improve our ability to safeguard human and animal health.

Rabbits are highly abundant in many countries and can serve as reservoirs of diseases for a diversity of pathogens including the enteric protozoan parasites, Cryptosporidium and Giardia. Both parasites shed environmentally robust environmental stages (oo/cysts) and have been responsible for numerous waterborne outbreaks of diseases. Cryptosporidium hominis and C. parvum are responsible for most infections in humans, while Giardia duodenalis assemblages A and B, cause most human cases of giardiasis. Cryptosporidium cuniculus, the dominant species infecting rabbits, is the only spceies other than C. hominis and C. parvum to have caused a waterborne outbreak of gastritis, which occurred in the United Kingdom in 2008. This review examines the prevalence of Cryptosporidium and Giardia species in rabbits to better understand the public health risks of contamination of water sources with Cryptosporidium and Giardia oo/cysts from rabbits. Despite the abundance of C. cuniculus in rabbits, reports in humans are relatively rare, with the exception of the United Kingdom and New Zealand, and reports of C. cuniculus in humans from the United Kingdom have declined substantially since the 2008 outbreak. Subtyping of C. cuniculus has supported the potential for zoonotic transmission. Relatively few studies have been conducted on Giardia, but assemblage B dominates. However, improved typing methods are required to better understand the transmission dynamics of Giardia assemblages in rabbits. Similarly, it is not well understood if pet rabbits or contaminated water are the main source of C. cuniculus infections in humans. Well-planned studies using high-resolution typing tools are required to understand the transmission dynamics better and quantify the public health risk of Cryptosporidium and Giardia from rabbits.

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.

Contamination by wastewater has been traditionally assessed by measuring faecal coliforms, such as E. coli and entereococci. However, using micropollutants to track wastewater input is gaining interest. In this study, we identified nine micropollutant indicators that could be used to characterize water quality and wastewater treatment efficiency in pond-based wastewater treatment plants (WWTPs) of varying configuration. Of 232 micropollutants tested, nine micropollutants were detected in treated wastewater at concentrations and frequencies suitable to be considered as indicators for treated wastewater. The nine indicators were then classified as stable (carbamazepine, sucralose, benzotriazole, 4+5-methylbenzotriazole), labile (atorvastatin, naproxen, galaxolide) or intermediate/uncertain (gemfibrozil, tris(chloropropyl)phosphate isomers) based on observed removals in the pond-based WWTPs and correlations between micropollutant and dissolved organic carbon removal. The utility of the selected indicators was evaluated by assessing the wastewater quality in different stages of wastewater treatment in three pond-based WWTPs, as well as selected groundwater bores near one WWTP, where treated wastewater was used to irrigate a nearby golf course. Ratios of labile to stable indicators provided insight into the treatment efficiency of different facultative and maturation ponds and highlighted the seasonal variability in treatment efficiency for some pond-based WWTPs. Additionally, indicator ratios of labile to stable indicators identified potential unintended release of untreated wastewater to groundwater, even with the presence of micropollutants in other groundwater bores related to approved reuse of treated wastewater.

Bats are known to harbour various pathogens and are increasingly recognised as potential reservoirs for zoonotic diseases. This paper reviews the genetic diversity and zoonotic potential of Cryptosporidium and Giardia in bats. The risk of zoonotic transmission of Cryptosporidium from bats to humans appears low, with bat-specific Cryptosporidium genotypes accounting for 91.5% of Cryptosporidium-positive samples genotyped from bats worldwide, and C. parvum and C. hominis accounting for 3.4% each of typed positives, respectively. To date, there have only been sporadic detections of Giardia in bats, with no genetic characterisation of the parasite to species or assemblage level. Therefore, the role bats play as reservoirs of zoonotic Giardia spp. is unknown. To mitigate potential risks of zoonotic transmission and their public health implications, comprehensive research on Cryptosporidium and Giardia in bats is imperative. Future studies should encompass additional locations across the globe and a broader spectrum of bat species, with a focus on those adapted to urban environments.

The horse genotype is one of three common Cryptosporidium spp. in equine animals and has been identified in some human cases. The species status of Cryptosporidium horse genotype remains unclear due to the lack of extensive morphological, biological, and genetic data. In the present study, we have conducted biological and whole genome sequence analyses of an isolate of the genotype from hedgehogs and proposed to name it Cryptosporidium equi n. sp. to reflect its common occurrence in equine animals. Oocysts of C. equi measured 5.12 ± 0.36 μm × 4.46 ± 0.21 μm with a shape index of 1.15 ± 0.08 (n = 50). Cryptosporidium equi was infectious to 3-week-old four-toed hedgehogs (Atelerix albiventris) and mice, with a prepatent period of 2-9 days and a patent period of 30-40 days in hedgehogs. It was not infectious to rats and rabbits. Phylogenetic analyses of small subunit rRNA, 70 kDa heat shock protein, actin, 60 kDa glycoprotein and 100 other orthologous genes revealed that C. equi is genetically distinct from other known Cryptosporidium species and genotypes. The sequence identity between C. equi and Cryptosporidium parvum genomes is 97.9%. Compared with C. parvum, C. equi has lost two MEDLE genes and one insulinase-like protease gene and gained one SKSR gene. In addition, 60 genes have highly divergent sequences (sequence differences ≥ 5.0%), including those encoding mucin-like glycoproteins, insulinase-like peptidases, and MEDLE and SKSR proteins. The genetic uniqueness of C. equi supports its increasing host range and the naming of it as a valid Cryptosporidium species. This is the first known use of whole genome sequence data in delineating new Cryptosporidium species.

Due to the close bond between humans and companion animals, a thorough understanding of the diversity of Cryptosporidium species and Giardia assemblages in cats and dogs is essential to determine the potential zoonotic risks. Analysis of molecular studies shows that C. felis and C. canis are the main species infecting cats and dogs, respectively. These species are largely host-specific, as despite intense association with humans, prevalence of C. felis and C. canis in humans is low and predominantly in immunocompromised individuals and low-income countries. There have been reports of C. parvum in cats and dogs and two reports of C. hominis in dogs. In most studies conducted to date, however, the prevalence of zoonotic species was low and may be associated with coprophagy and or/spillback, but this remains to be determined. Results of subtyping studies suggest that for C. felis and C. canis, some zoonotic transmission may occur but host-adapted subtypes also exist. Giardia duodenalis assemblages C and D are commonly reported in dogs, with assemblages F and A most common in cats. Assemblages C, D and F are largely host-specific as there are only a handful of reports of them in humans. Reports of assemblage A and B in cats and dogs may be due to coprophagy or spillback from owners. Despite the extent of pet ownership and the close contact between humans and companion animals worldwide, the overall risk of zoonotic transmission from cats and dogs to humans is uncertain but thought to be low due to C. canis, C. felis and G. duodenalis assemblages C, D and F being predominantly host-specific, the relatively low prevalence of C. parvum (and C. hominis) in cats and dogs (which may be due to mechanical carriage), and low oo/cyst shedding. Carefully designed epidemiological studies of cats and dogs and their owners using subtyping tools are essential to better quantify the extent of spillover and spillback of Cryptosporidium and Giardia between pets and their owners.

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.

Cryptosporidium is a major cause of diarrhoeal disease and mortality in young children in resource-poor countries, for which no vaccines or adequate therapeutic options are available. Infection in humans is primarily caused by two species: C. hominis and C. parvum . Despite C. hominis being the dominant species infecting humans in most countries, very little is known about its growth characteristics and life cycle in vitro, given that the majority of our knowledge of the in vitro development of Cryptosporidium has been based on C. parvum . In the present study, the growth and development of two C. parvum isolates (subtypes Iowa-IIaA17G2R1 and IIaA18G3R1) and one C. hominis isolate (subtype IdA15G1) in HCT-8 cells were examined and compared at 24 h and 48 h using morphological data acquired with scanning electron microscopy. Our data indicated no significant differences in the proportion of meronts or merozoites between species or subtypes at either time-point. Sexual development was observed at the 48-h time-point across both species through observations of both microgamonts and macrogamonts, with a higher frequency of macrogamont observations in C. hominis (IdA15G1) cultures at 48-h post-infection compared to both C. parvum subtypes. This corresponded to differences in the proportion of trophozoites observed at the same time point. No differences in proportion of microgamonts were observed between the three subtypes, which were rarely observed across all cultures. In summary, our data indicate that asexual development of C. hominis is similar to that of C. parvum, while sexual development is accelerated in C. hominis. This study provides new insights into differences in the in vitro growth characteristics of C. hominis when compared to C. parvum , which will facilitate our understanding of the sexual development of both species.

Cryptosporidium bovis and Cryptosporidium ryanae are common species causing cryptosporidiosis in cattle. Data accumulated thus far indicate that the infection patterns of the two species could be different between areas with and without Cryptosporidium parvum. To better understand the infection dynamics of these two species, cross-sectional and longitudinal studies of Cryptosporidium spp. were conducted using genotyping and subtyping tools. In the cross-sectional survey, analysis of 634 faecal samples from two farms identified only C. bovis and C. ryanae in pre-weaned calves. Two birth cohorts of 61 and 78 calves were followed longitudinally over a 12 month period, which revealed the shedding of C. bovis oocysts started at 1-2 weeks of age and peaked initially at 6-8 weeks of age. Altogether calves experienced four infections by six subtype families of C. bovis, with each infection caused by different subtype families. In contrast, the shedding of C. ryanae oocysts started at 2-4 weeks of age, and the two infections were caused by different subtype families. The cumulative incidence of C. bovis infection was 100% (58/58, 32/32) on both farms, compared with 84.4-98.3% (27/32 and 57/58) for C. ryanae infection. Overall, the mean duration of oocyst shedding in the cohort studies was 3.8-4.0 weeks for C. bovis compared with 2.1 weeks for C. ryanae. The oocyst shedding intensity was high (mean oocysts per gram of faeces was over 105) during the first infection with each species but became significantly lower in the later infections. Cryptosporidium ryanae was associated with the occurrence of diarrhea on one farm, while C. bovis was not. The data indicate that there is an early occurrence of C. bovis and C. ryanae in pre-weaned calves with high infection intensity in the absence of C. parvum. Calves infected with the same Cryptosporidium sp. multiple times could be associated with the presence of subtype-specific immunity.

Animal farming has intensified significantly in recent decades, with the emergence of concentrated animal feeding operations (CAFOs) in industrialized nations. The congregation of susceptible animals in CAFOs can lead to heavy environmental contamination with pathogens, promoting the emergence of hyper-transmissible, and virulent pathogens. As a result, CAFOs have been associated with emergence of highly pathogenic avian influenza viruses, hepatitis E virus, Escherichia coli O157:H7, Streptococcus suis, livestock-associated methicillin-resistant Staphylococcus aureus, and Cryptosporidium parvum in farm animals. This has led to increased transmission of zoonotic pathogens in humans and changes in disease patterns in general communities. They are exemplified by the common occurrence of outbreaks of illnesses through direct and indirect contact with farm animals, and wide occurrence of similar serotypes or subtypes in both humans and farm animals in industrialized nations. Therefore, control measures should be developed to slow down the dispersal of zoonotic pathogens associated with CAFOs and prevent the emergence of new pathogens of epidemic and pandemic potential.

Cryptosporidium spp. and Giardia duodenalis are important protozoan parasites which are associated with diarrheal diseases in humans and animals worldwide. Relatively little is known about the molecular epidemiology of Cryptosporidium spp. and Giardia duodenalis in the Middle East Countries and North Africa (MENA region). Therefore, this review aimed to inspect published genotyping and subtyping studies on Cryptosporidium spp. and Giardia duodenalis in the MENA region. These studies indicate that both anthroponotic and zoonotic transmission of Cryptosporidium occurs with the predominance of zoonotic transmission in most countries. Seven Cryptosporidium species were identified in humans (C. parvum, C. hominis, Cryptosporidium meleagridis, C. felis, Cryptosporidium muris, C. canis and C. bovis), with C. parvum by far being the most prevalent species (reported in 95.4% of the retrieved studies). Among C. parvum gp60 subtype families, IIa and IId predominated, suggesting potential zoonotic transmission. However, in four MENA countries (Lebanon, Israel, Egypt and Tunisia), C. hominis was the predominant species with five subtype families reported including Ia, Ib, Id, If and Ie, all of which are usually anthroponotically transmitted between humans. In animals, the majority of studies were conducted mainly on livestock and poultry, 15 species were identified (C. parvum, C. hominis, C. muris, Cryptosporidium cuniculus, C. andersoni, C. bovis, C. meleagridis, C. baileyi, C. erinacei, C. ryanae, C. felis, C. suis, Cryptosporidium galli, C. xiaoi and C. ubiquitum) with C. parvum (IIa and IId subtypes) the dominant species in livestock and C. meleagridis and C. baileyi the dominant species in poultry. With G. duodenalis, five assemblages (A, B, C, E and F) were identified in humans and six (A, B, C, E, D and F) in animals in MENA countries with assemblages A and B commonly reported in humans, and assemblages A and E dominant in livestock. This review also identified a major knowledge gap in the lack of Cryptosporidium spp. and Giardia duodenalis typing studies in water and food sources in the MENA region. Of the few studies conducted on water sources (including drinking and tap water), ten Cryptosporidium species and four genotypes were identified, highlighting the potential role of water as the major route of Cryptosporidium spp. transmission in the region. In addition, three G. duodenalis assemblages (A, B and E) were detected in different water sources with AI, AII and BIV being the main sub-assemblages reported. More research is required in order to better understand the molecular diversity and transmission dynamics of Cryptsporidum spp. and Giardia duodenalis in humans, animals, water and food sources in MENA region.

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.