Patterns of Cryptosporidium oocyst shedding by eastern grey kangaroos inhabiting an Australian watershed

Zoonotic Cryptosporidium and Giardia in marsupials-an update

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 Impacts of Drought on the Health and Demography of Eastern Grey Kangaroos

Simple Summary

Eastern grey kangaroos, like most wildlife, are facing an increasingly uncertain future under rapid climate change. How individuals and populations cope with extreme climatic events will influence their capacity to adapt and persist. Here, we analyzed how drought impacted eastern grey kangaroo populations by focusing on their body condition, demography, activity rates at water points, and the likelihood of parasitic infections. We found that body condition was lower as environmental conditions became more extreme and that fewer males in the population were observed. The proportion of juveniles within the population increased as more favorable conditions returned. Kangaroos with poor body conditions were more likely to become hosts to ticks, while higher parasite egg burdens in scats occurred in autumn. Our study has shown that the impacts eastern grey kangaroos face during climatic events such as drought can be severe and may have long-term consequences.

Abstract

Extreme climatic events such as droughts and floods are expected to become more intense and severe under climate change, especially in the southern and eastern parts of Australia. We aimed to quantify the relationship between body condition scores (BCS), demography, activity rate, and parasitic infections of eastern grey kangaroos on a large conservation property under different climate extremes by employing camera traps established at artificial water points (AWPs). The survey period included a severe drought, broken by a significant flooding event. Climatic and environmental conditions were documented using remotely sensed indices of moisture availability and vegetation productivity. These conditions were found to affect all health and population parameters measured. BCS, juvenile proportions, and sex ratios were most correlated with 6-month lags in climatic conditions, while the activity rate of kangaroos at AWPs was most correlated with vegetation productivity. Ticks were mostly found on individuals with a poorer BCS, while the concentration of parasitic eggs in feces was higher in autumn than in spring. Our study offers a glimpse into some of the environmental drivers of eastern grey kangaroo populations and their health, information that may become increasingly important in today’s climate. It further emphasizes the importance of this knowledge for wildlife conservation efforts appropriate to managing the impact of climate change alongside other threats.

Microbial Diversity Profiling of Gut Microbiota of Macropus giganteus Using Three Hypervariable Regions of the Bacterial 16S rRNA

Animal faecal contamination of surface waters poses a human health risk, as they may contain pathogenic bacteria or viruses. Of the numerous animal species residing along surface waterways in Australia, macropod species are a top contributor to wild animals’ faecal pollution load. We characterised the gut microbiota of 30 native Australian Eastern Grey Kangaroos from six geographical regions (five kangaroos from each region) within South East Queensland in order to establish their bacterial diversity and identify potential novel species-specific bacteria for the rapid detection of faecal contamination of surface waters by these animals. Using three hypervariable regions (HVRs) of the 16S rRNA gene (i.e., V1–V3, V3–V4, and V5–V6), for their effectiveness in delineating the gut microbial diversity, faecal samples from each region were pooled and microbial genomic DNA was extracted, sequenced, and analysed. Results indicated that V1-V3 yielded a higher taxa richness due to its larger target region (~480 bp); however, higher levels of unassigned taxa were observed using the V1-V3 region. In contrast, the V3–V4 HVR (~569 bp) attained a higher likelihood of a taxonomic hit identity to the bacterial species level, with a 5-fold decrease in unassigned taxa. There were distinct dissimilarities in beta diversity between the regions, with the V1-V3 region displaying the highest number of unique taxa (n = 42), followed by V3–V4 (n = 11) and V5–V6 (n = 8). Variations in the gut microbial diversity profiles of kangaroos from different regions were also observed, which indicates that environmental factors may impact the microbial development and, thus, the composition of the gut microbiome of these animals.

A review of Cryptosporidium spp. and their detection in water

Cryptosporidium spp. are one of the most important waterborne pathogens worldwide and a leading cause of mortality from waterborne gastrointestinal diseases. Detection of Cryptosporidium spp. in water can be very challenging due to their low numbers and the complexity of the water matrix. This review describes the biology of Cryptosporidium spp. and current methods used in their detection with a focus on C. parvum and C. hominis. Among the methods discussed and compared are microscopy, immunology-based methods using monoclonal antibodies, molecular methods including PCR (polymerase chain reaction)-based assays, and emerging aptamer-based methods. These methods have different capabilities and limitations, but one common challenge is the need for better sensitivity and specificity, particularly in the presence of contaminants. The application of DNA aptamers in the detection of Cryptosporidium spp. oocysts shows promise in overcoming these challenges, and there will likely be significant developments in aptamer-based sensors in the near future.

Molecular identification of Cryptosporidium isolates from ill exotic pet animals in Japan including a new subtype in Cryptosporidium fayeri

Cryptosporidium is an obligate intracellular parasite which can cause fatal diarrheal disease in exotic animals. Sugar gliders (Petaurus breviceps), hedgehogs (Atelerix albiventris), chinchillas (Chinchilla lanigera), and common leopard geckos (Eublepharis macularius) are popular exotic animals commonly sold in pet shops in Japan. We herein investigated the species and subtypes of Cryptosporidium in these animals. Cryptosporidium fayeri was detected in a sugar glider in a Japanese animal hospital. Sequence analyses of the 60-kDa glycoprotein (gp60) gene revealed that C. fayeri belonged to subtype family IVh (IVhA13G2T1), which was proposed to be a new subtype. This is the first study to report C. fayeri infection in a sugar glider. In other animals, the Cryptosporidium horse genotype, C. ubiquitum, and C. varanii were detected in two four-toed hedgehogs (A. albiventris), a chinchilla (C. lanigera), and common leopard gecko (E. macularius), respectively. The gp60 subtypes identified were VIbA13 of the horse genotype and XIId of C. ubiquitum. The present results revealed that potentially zoonotic Cryptosporidium is widespread in exotic animals in Japan.

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Cryptosporidium was detected from ill exotic pet animals in Japan.

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Cryptosporidium fayeri was detected for the first time from a sugar glider.

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The new 60-kDa glycoprotein (gp60) subtype family IVh was detected from Cryptosporidium fayeri.

Prevalence and Genotypes of Cryptosporidium in Wildlife Populations Co-Located in a Protected Watershed in the Pacific Northwest, 2013 to 2016

Between October 2013 and May 2016, 506 scat samples were collected from 22 species of wildlife located in a protected watershed of a major municipal water supply in the Pacific Northwest, USA. Overall prevalence of Cryptosporidium in the wildlife scat was 13.8% (70/506), with 15 species of wildlife found positive for Cryptosporidium. Prevalence of Cryptosporidium varied among species of wildlife, with higher prevalences observed in cougars (50.0%), mountain beavers (40.0%), and bobcats (33.3%), but none of these species are riparian-dependent. Genotyping of Cryptosporidium by sequencing PCR amplicons from the 18S rRNA gene were successful for seven species of wildlife, including bobcat, unknown predator, black-tailed deer, deer mouse, snowshoe hare, mountain beaver, and western spotted skunk. BLAST and phylogenetic analyses indicated that multiple species and genotypes of Cryptosporidium were present, with some isolates possibly co-circulating within and between wildlife populations in this protected watershed. Evidence of oocyst exchange between infected prey and their predators was also found. During the study period, several zoonotic Cryptosporidium species and genotypes that are uncommon in humans were detected in bobcat (99.58% identical to Cryptosporidium felis), unknown predator (100% identical to Cryptosporidium canis), snowshoe hare (100% identical to Cryptosporidium sp. skunk genotype), and mountain beaver (100% identical to Cryptosporidium ubiquitum). Novel sequences were also found in mountain beaver. To our knowledge, this is the first published report of a unique genotype or species of Cryptosporidium in mountain beaver (Aplodontia rufa).

Cryptosporidium species and subtypes in animals inhabiting drinking water catchments in three states across Australia

As part of long-term monitoring of Cryptosporidium in water catchments serving Western Australia, New South Wales (Sydney) and Queensland, Australia, we characterised Cryptosporidium in a total of 5774 faecal samples from 17 known host species and 7 unknown bird samples, in 11 water catchment areas over a period of 30 months (July 2013 to December 2015). All samples were initially screened for Cryptosporidium spp. at the 18S rRNA locus using a quantitative PCR (qPCR). Positives samples were then typed by sequence analysis of an 825 bp fragment of the 18S gene and subtyped at the glycoprotein 60 (gp60) locus (832 bp). The overall prevalence of Cryptosporidium across the various hosts sampled was 18.3% (1054/5774; 95% CI, 17.3-19.3). Of these, 873 samples produced clean Sanger sequencing chromatograms, and the remaining 181 samples, which initially produced chromatograms suggesting the presence of multiple different sequences, were re-analysed by Next- Generation Sequencing (NGS) to resolve the presence of Cryptosporidium and the species composition of potential mixed infections. The overall prevalence of confirmed mixed infection was 1.7% (98/5774), and in the remaining 83 samples, NGS only detected one species of Cryptosporidium. Of the 17 Cryptosporidium species and four genotypes detected (Sanger sequencing combined with NGS), 13 are capable of infecting humans; C. parvum, C. hominis, C. ubiquitum, C. cuniculus, C. meleagridis, C. canis, C. felis, C. muris, C. suis, C. scrofarum, C. bovis, C. erinacei and C. fayeri. Oocyst numbers per gram of faeces (g^-1) were also determined using qPCR, with medians varying from 6021-61,064 across the three states. The significant findings were the detection of C. hominis in cattle and kangaroo faeces and the high prevalence of C. parvum in cattle. In addition, two novel C. fayeri subtypes (IVaA11G3T1 and IVgA10G1T1R1) and one novel C. meleagridis subtype (IIIeA18G2R1) were identified. This is also the first report of C. erinacei in Australia. Future work to monitor the prevalence of Cryptosporidium species and subtypes in animals in these catchments is warranted.

Wildlife parasitology in Australia: past, present and future

Wildlife parasitology is a highly diverse area of research encompassing many fields including taxonomy, ecology, pathology and epidemiology, and with participants from extremely disparate scientific fields. In addition, the organisms studied are highly dissimilar, ranging from platyhelminths, nematodes and acanthocephalans to insects, arachnids, crustaceans and protists. This review of the parasites of wildlife in Australia highlights the advances made to date, focussing on the work, interests and major findings of researchers over the years and identifies current significant gaps that exist in our understanding. The review is divided into three sections covering protist, helminth and arthropod parasites. The challenge to document the diversity of parasites in Australia continues at a traditional level but the advent of molecular methods has heightened the significance of this issue. Modern methods are providing an avenue for major advances in documenting and restructuring the phylogeny of protistan parasites in particular, while facilitating the recognition of species complexes in helminth taxa previously defined by traditional morphological methods. The life cycles, ecology and general biology of most parasites of wildlife in Australia are extremely poorly understood. While the phylogenetic origins of the Australian vertebrate fauna are complex, so too are the likely origins of their parasites, which do not necessarily mirror those of their hosts. This aspect of parasite evolution is a continuing area for research in the case of helminths, but remains to be addressed for many other parasitic groups.

Molecular characterization of Cryptosporidium and Giardia from the Tasmanian devil (Sarcophilus harrisii)

The Tasmanian devil (Sarcophilus harrisii) is a carnivorous marsupial found only in the wild in Tasmania, Australia. Tasmanian devils are classified as endangered and are currently threatened by devil facial tumour disease, a lethal transmissible cancer that has decimated the wild population in Tasmania. To prevent extinction of Tasmanian devils, conservation management was implemented in 2003 under the Save the Tasmanian Devil Program. This study aimed to assess if conservation management was altering the interactions between Tasmanian devils and their parasites. Molecular tools were used to investigate the prevalence and diversity of two protozoan parasites, Cryptosporidium and Giardia, in Tasmanian devils. A comparison of parasite prevalence between wild and captive Tasmanian devils showed that both Cryptosporidium and Giardia were significantly more prevalent in wild devils (p < 0.05); Cryptosporidium was identified in 37.9% of wild devils but only 10.7% of captive devils, while Giardia was identified in 24.1% of wild devils but only 0.82% of captive devils. Molecular analysis identified the presence of novel genotypes of both Cryptosporidium and Giardia. The novel Cryptosporidium genotype was 98.1% similar at the 18S rDNA to Cryptosporidium varanii (syn. C. saurophilum) with additional samples identified as C. fayeri, C. muris, and C. galli. Two novel Giardia genotypes, TD genotype 1 and TD genotype 2, were similar to G. duodenalis from dogs (94.4%) and a Giardia assemblage A isolate from humans (86.9%). Giardia duodenalis BIV, a zoonotic genotype of Giardia, was also identified in a single captive Tasmanian devil. These findings suggest that conservation management may be altering host-parasite interactions in the Tasmanian devil, and the presence of G. duodenalis BIV in a captive devil points to possible human-devil parasite transmission.

Zoonotic Cryptosporidium Species in Animals Inhabiting Sydney Water Catchments

Cryptosporidium is one of the most common zoonotic waterborne parasitic diseases worldwide and represents a major public health concern of water utilities in developed nations. As animals in catchments can shed human-infectious Cryptosporidium oocysts, determining the potential role of animals in dissemination of zoonotic Cryptosporidium to drinking water sources is crucial. In the present study, a total of 952 animal faecal samples from four dominant species (kangaroos, rabbits, cattle and sheep) inhabiting Sydney's drinking water catchments were screened for the presence of Cryptosporidium using a quantitative PCR (qPCR) and positives sequenced at multiple loci. Cryptosporidium species were detected in 3.6% (21/576) of kangaroos, 7.0% (10/142) of cattle, 2.3% (3/128) of sheep and 13.2% (14/106) of rabbit samples screened. Sequence analysis of a region of the 18S rRNA locus identified C. macropodum and C. hominis in 4 and 17 isolates from kangaroos respectively, C. hominis and C. parvum in 6 and 4 isolates respectively each from cattle, C. ubiquitum in 3 isolates from sheep and C. cuniculus in 14 isolates from rabbits. All the Cryptosporidium species identified were zoonotic species with the exception of C. macropodum. Subtyping using the 5' half of gp60 identified C. hominis IbA10G2 (n = 12) and IdA15G1 (n = 2) in kangaroo faecal samples; C. hominis IbA10G2 (n = 4) and C. parvum IIaA18G3R1 (n = 4) in cattle faecal samples, C. ubiquitum subtype XIIa (n = 1) in sheep and C. cuniculus VbA23 (n = 9) in rabbits. Additional analysis of a subset of samples using primers targeting conserved regions of the MIC1 gene and the 3' end of gp60 suggests that the C. hominis detected in these animals represent substantial variants that failed to amplify as expected. The significance of this finding requires further investigation but might be reflective of the ability of this C. hominis variant to infect animals. The finding of zoonotic Cryptosporidium species in these animals may have important implications for the management of drinking water catchments to minimize risk to public health.

Cryptosporidium and Giardia taxa in faecal samples from animals in catchments supplying the city of Melbourne with drinking water (2011 to 2015)

BACKGROUND

In a long-term program to monitor pathogens in water catchments serving the City of Melbourne in the State of Victoria in Australia, we detected and genetically characterised Cryptosporidium and Giardia in faecal samples from various animals in nine water reservoir areas over a period of 4 years (July 2011 to November 2015).

METHODS

This work was conducted using PCR-based single-strand conformation polymorphism (SSCP) and phylogenetic analyses of portions of the small subunit of ribosomal RNA (SSU) and 60 kDa glycoprotein (gp60) genes for Cryptosporidium, and triose-phosphate isomerase (tpi) gene for Giardia.

RESULTS

The prevalence of Cryptosporidium was 1.62 % (69 of 4,256 samples); 25 distinct sequence types were defined for pSSU, and six for gp60 which represented C. hominis (genotype Ib - subgenotype IbA10G2), C. cuniculus (genotype Vb - subgenotypes VbA26, and VbA25), and C. canis, C. fayeri, C. macropodum, C. parvum, C. ryanae, Cryptosporidium sp. "duck" genotype, C. suis and C. ubiquitum as well as 12 novel SSU sequence types. The prevalence of Giardia was 0.31 % (13 of 4,256 samples); all three distinct tpi sequence types defined represented assemblage A of G. duodenalis.

CONCLUSIONS

Of the 34 sequence types (genotypes) characterized here, five and one have been recorded previously for Cryptosporidium and Giardia, respectively, from humans. Novel genotypes of Cryptosporidium and Giardia were recorded for SSU (n = 12), gp60 (n = 4) and tpi (n = 1); the zoonotic potential of these novel genotypes is presently unknown. Future work will continue to monitor the prevalence of Cryptosporidium and Giardia genotypes in animals in these catchments, and expand investigations to humans. Nucleotide sequences reported in this paper are available in the GenBank database under accession nos. KU531647-KU531718.

Public health significance of zoonotic Cryptosporidium species in wildlife: Critical insights into better drinking water management

Cryptosporidium is an enteric parasite that is transmitted via the faecal-oral route, water and food. Humans, wildlife and domestic livestock all potentially contribute Cryptosporidium to surface waters. Human encroachment into natural ecosystems has led to an increase in interactions between humans, domestic animals and wildlife populations. Increasing numbers of zoonotic diseases and spill over/back of zoonotic pathogens is a consequence of this anthropogenic disturbance. Drinking water catchments and water reservoir areas have been at the front line of this conflict as they can be easily contaminated by zoonotic waterborne pathogens. Therefore, the epidemiology of zoonotic species of Cryptosporidium in free-ranging and captive wildlife is of increasing importance. This review focuses on zoonotic Cryptosporidium species reported in global wildlife populations to date, and highlights their significance for public health and the water industry.

Characterizing the concentration of Cryptosporidium in Australian surface waters for setting health-based targets for drinking water treatment

It is proposed that the next revision of the Australian Drinking Water Guidelines will include 'health-based targets', where the required level of potable water treatment quantitatively relates to the magnitude of source water pathogen concentrations. To quantify likely Cryptosporidium concentrations in southern Australian surface source waters, the databases for 25 metropolitan water supplies with good historical records, representing a range of catchment sizes, land use and climatic regions were mined. The distributions and uncertainty intervals for Cryptosporidium concentrations were characterized for each site. Then, treatment targets were quantified applying the framework recommended in the World Health Organization Guidelines for Drinking-Water Quality 2011. Based on total oocyst concentrations, and not factoring in genotype or physiological state information as it relates to infectivity for humans, the best estimates of the required level of treatment, expressed as log10 reduction values, ranged among the study sites from 1.4 to 6.1 log10. Challenges associated with relying on historical monitoring data for defining drinking water treatment requirements were identified. In addition, the importance of quantitative microbial risk assessment input assumptions on the quantified treatment targets was investigated, highlighting the need for selection of locally appropriate values.

Cryptosporidium from a free-ranging marsupial host: bandicoots in urban Australia

Expansion of human settlement has increased the interface between people and bandicoots with implications for the emergence and spread of zoonotic parasites. The host status of bandicoots inhabiting suburban areas and their potential role in Cryptosporidium transmission remains unresolved. Our study aimed to determine the prevalence and identity of Cryptosporidium in two sympatric bandicoot species. Cryptosporidium signatures were detected in twelve bandicoot faecal samples (n=98) through amplification of the 18S rRNA. Phylogenetic inference placed the isolates in a clade with Cryptosporidium parvum, a species with a broad host range and zoonotic potential, or loosely related to Cryptosporidium hominis. However, the identity of the bandicoot isolates was not fully resolved and whether they were infected or simply passively transmitting oocysts is unknown. This study revealed that free-ranging bandicoots of northern Sydney were shedding Cryptosporidium oocysts at a prevalence of 12.2% (95% CI [6.76, 20.8]), similar to marsupial species that act as reservoirs for Cryptosporidium. Our findings expand the range of hosts known to shed Cryptosporidium in urban areas.

Cryptosporidiosis and Cryptosporidium species in animals and humans: a thirty colour rainbow?

Parasites of the genus Cryptosporidium (Apicomplexa) cause cryptosporidiosis in humans and animals worldwide. The species names used for Cryptosporidium spp. are confusing for parasitologists and even more so for non-specialists. Here, 30 named species of the genus Cryptosporidium are reviewed and proposed as valid. Molecular and experimental evidence suggests that humans and cattle are the hosts for 14 and 13 out of 30 named species, respectively. Two, four and eight named species are considered of major, moderate and minor public health significance, respectively. There are at least nine named species that are shared between humans and cattle. The aim of this review is to outline available species information together with the most commonly used genetic markers enabling the identification of named Cryptosporidium spp. Currently, 28 of 30 named species can be identified using the complete or partial ssrRNA, serving as a retrospective 'barcode'. Currently, the ssrRNA satisfies the implicit assumption that the reference databases used for comparison are sufficiently complete and applicable across the whole genus. However, due to unreliable annotation in public DNA repositories, the reference nucleotide entries and alignment of named Cryptosporidium spp. has been compiled. Despite its known limitations, ssrRNA remains the optimal marker for species identification.

Zoonotic potential of Giardia

Giardia duodenalis (syn. Giardia lamblia and Giardia intestinalis) is a common intestinal parasite of humans and mammals worldwide. Assessing the zoonotic transmission of the infection requires molecular characterization as there is considerable genetic variation within G. duodenalis. To date eight major genetic groups (assemblages) have been identified, two of which (A and B) are found in both humans and animals, whereas the remaining six (C to H) are host-specific and do not infect humans. Sequence-based surveys of single loci have identified a number of genetic variants (genotypes) within assemblages A and B in animal species, some of which may have zoonotic potential. Multi-locus typing data, however, has shown that in most cases, animals do not share identical multi-locus types with humans. Furthermore, interpretation of genotyping data is complicated by the presence of multiple alleles that generate "double peaks" in sequencing files from PCR products, and by the potential exchange of genetic material among isolates, which may account for the non-concordance in the assignment of isolates to specific assemblages. Therefore, a better understanding of the genetics of this parasite is required to allow the design of more sensitive and variable subtyping tools, that in turn may help unravel the complex epidemiology of this infection.

Molecular-based investigation of Cryptosporidium and Giardia from animals in water catchments in southeastern Australia

There has been no large-scale systematic molecular epidemiological investigation of the waterborne protozoans, Cryptosporidium or Giardia, in southeastern Australia. Here, we explored, for the first time, the genetic composition of these genera in faecal samples from animals in nine Melbourne Water reservoir areas, collected over a period of two-years. We employed PCR-based single-strand conformation polymorphism (SSCP) and phylogenetic analyses of loci (pSSU and pgp60) in the small subunit (SSU) of ribosomal RNA and 60-kDa glycoprotein (gp60) genes to detect and characterise Cryptosporidium, and another locus (ptpi) in the triose-phosphate isomerase (tpi) gene to identify and characterise Giardia. Cryptosporidium was detected in 2.8% of the 2009 samples examined; the analysis of all amplicons defined 14 distinct sequence types for each of pSSU and pgp60, representing Cryptosporidium hominis (genotype Ib - subgenotype IbA10G2R2), Cryptosporidium parvum (genotype IIa - subgenotypes IIaA15G2R1, IIaA19G2R1, IIaA19G3R1, IIaA19G4R1, IIaA20G3R1, IIaA20G4R1, IIaA20G3R2 and IIaA21G3R1), Cryptosporidium cuniculus (genotype Vb - subgenotypes VbA22R4, VbA23R3, VbA24R3, VbA25R4 and VbA26R4), and Cryptosporidium canis, Cryptosporidium fayeri, Cryptosporidium macropodum and Cryptosporidium ubiquitum as well as six new pSSU sequence types. In addition, Giardia was identified in 3.4% of the samples; all 28 distinct ptpi sequence types defined were linked to assemblage A of Giardia duodenalis. Of all 56 sequence types characterised, eight and one have been recorded previously in Cryptosporidium and Giardia, respectively, from humans. In contrast, nothing is known about the zoonotic potential of 35 new genotypes of Cryptosporidium and Giardia recorded here for the first time. Future work aims to focus on estimating the prevalence of Cryptosporidium and Giardia genotypes in humans and a wide range of animals in Victoria and elsewhere in Australia. (Nucleotide sequences reported in this paper are available in the GenBank database under accession nos. KC282952-KC283005).

Cryptosporidium species in Australian wildlife and domestic animals

Cryptosporidium is an important enteric parasite that is transmitted via the fecal-oral route, water and food. Humans, wildlife and domestic livestock all potentially contribute Cryptosporidium to surface waters. Most species of Cryptosporidium are morphologically indistinguishable and can only be identified using molecular tools. Over 24 species have been identified and of these, 7 Cryptosporidium species/genotypes are responsible for most human cryptosporidiosis cases. In Australia, relatively few genotyping studies have been conducted. Six Cryptosporidium species (C. hominis, C. parvum, C. meleagridis, C. fayeri, C. andersoni and C. bovis) have been identified in humans in Australia. However, little is known about the contribution of animal hosts to human pathogenic strains of Cryptosporidium in drinking water catchments. In this review, we focus on the available genotyping data for native, feral and domestic animals inhabiting drinking water catchments in Australia to provide an improved understanding of the public health implications and to identify key research gaps.

Identification of novel Cryptosporidium genotypes in kangaroos from Western Australia

A total of 763 faecal samples were collected from western grey kangaroos (Macropus fuliginosus) in Western Australia and screened for the presence of Cryptosporidium by PCR at the 18S ribosomal RNA (rRNA) locus. Samples that were positive at the 18S locus were also amplified at the actin locus. The overall prevalence was 9.3% (71/763). At the 18S rRNA locus, sequences were obtained for 28 of the 71 positives. Sequence analysis identified four species; Cryptosporidium fayeri in seven isolates, Cryptosporidium marcopodum in four isolates, Cryptosporidium xiaoi in six isolates and a novel genotype (kangaroo genotype I) in eleven isolates. Analysis at the actin locus confirmed the genetic distinctness of the novel genotype. The results of the present study indicate that in addition to C. fayeri and C. marcopodum, kangaroos may be capable of being infected with a wider range of Cryptosporidium species and genotypes including livestock species such as C. xiaoi. The novel genotype identified in the kangaroos most likely represents a cryptic species that requires further analyses to confirm its species status.

Wombats and domestic livestock as potential vectors of Cryptosporidium and Giardia in an agricultural riparian area

Emerging pathogenic diseases are a significant burden on global economies and public health administrators. In Australia, the pathogens Giardia and Cryptosporidium are widespread in riparian areas subject to urban or agricultural contamination. Bare-nosed wombats (Vombatus ursinus) occur at relatively high densities alongside domestic cattle in agricultural riparian areas in south-eastern Australia and may transmit protozoan pathogens. We assessed the distribution of wombat scats and cattle pats on streambanks and screened them for the presence of Giardia and Cryptosporidium. The density of wombat scats declined with increasing distance from water while the cover of cattle pats increased with distance from water, but only at sites subjected to low cattle usage. We were unable to find any Cryptosporidium species or genotypes known to infect humans in either wombat or cattle faeces. One cattle sample contained Cryptosporidium bovis, a cattle-specific organism unlikely to be zoonotic. Giardia duodenalis (Assemblage E), a non-zoonotic pathogen, was detected in four cattle samples, but no wombat samples tested positive for Giardia. Our results suggest that while wombats represent a low-pathogen risk there is a need for consistent monitoring of potentially harmful waterborne and chlorine-resistant Giardia and Cryptosporidium pathogens in drinking-water catchments.

Adaptive management for mitigating Cryptosporidium risk in source water: a case study in an agricultural catchment in South Australia

Water-borne pathogens such as Cryptosporidium pose a significant human health risk and catchments provide the first critical pollution 'barrier' in mitigating risk in drinking water supply. In this paper we apply an adaptive management framework to mitigating Cryptosporidium risk in source water using a case study of the Myponga catchment in South Australia. Firstly, we evaluated the effectiveness of past water quality management programs in relation to the adoption of practices by landholders using a socio-economic survey of land use and management in the catchment. The impact of past management on the mitigation of Cryptosporidium risk in source water was also evaluated based on analysis of water quality monitoring data. Quantitative risk assessment was used in planning the next round of management in the adaptive cycle. Specifically, a pathogen budget model was used to identify the major remaining sources of Cryptosporidium in the catchment and estimate the mitigation impact of 30 alternative catchment management scenarios. Survey results show that earlier programs have resulted in the comprehensive adoption of best management practices by dairy farmers including exclusion of stock from watercourses and effluent management from 2000 to 2007. Whilst median Cryptosporidium concentrations in source water have decreased since 2004 they remain above target levels and put pressure on other barriers to mitigate risk, particularly the treatment plant. Non-dairy calves were identified as the major remaining source of Cryptosporidium in the Myponga catchment. The restriction of watercourse access of non-dairy calves could achieve a further reduction in Cryptosporidium export to the Myponga reservoir of around 90% from current levels. The adaptive management framework applied in this study was useful in guiding learning from past management, and in analysing, planning and refocusing the next round of catchment management strategies to achieve water quality targets.

Taxonomy and species delimitation in Cryptosporidium

Amphibians, reptiles, birds and mammals serve as hosts for 19 species of Cryptosporidium. All 19 species have been confirmed by morphological, biological, and molecular data. Fish serve as hosts for three additional species, all of which lack supporting molecular data. In addition to the named species, gene sequence data from more than 40 isolates from various vertebrate hosts are reported in the scientific literature or are listed in GenBank. These isolates lack taxonomic status and are referred to as genotypes based on the host of origin. Undoubtedly, some will eventually be recognized as species. For them to receive taxonomic status sufficient morphological, biological, and molecular data are required and names must comply with the rules of the International Code for Zoological Nomenclature (ICZN). Because the ICZN rules may be interpreted differently by persons proposing names, original names might be improperly assigned, original literature might be overlooked, or new scientific methods might be applicable to determining taxonomic status, the names of species and higher taxa are not immutable. The rapidly evolving taxonomic status of Cryptosporidium sp. reflects these considerations.

Cryptosporidium fayeri: diversity within the GP60 locus of isolates from different marsupial hosts

The highly polymorphic 60 kDa glycoprotein (GP60) of Cryptosporidium is an important tool for investigating the epidemiology of this parasite. Characterization of the GP60 gene has only been performed for 3 of the 20 known Cryptosporidium species, and has already enabled sub-typing and source tracking of species with human significance. We have characterised a fourth species, Cryptosporidium fayeri, at the GP60 locus using isolates (n=26) from different marsupial hosts to assess the diversity of GP60 within this species. The analysis demonstrated that C. fayeri isolates could be assigned to 6 subtypes which were associated with host species and locality. The intra-species diversity for the host-adapted C. fayeri was less than the diversity for human pathogenic species suggesting that the GP60 locus is under less selective pressure in these than host-adapted species.

Prevalence and genetic characterization of Cryptosporidium isolates from common brushtail possums (Trichosurus vulpecula) adapted to urban settings

The common brushtail possum (Trichosurus vulpecula) is one of the most abundant native marsupials in urban Australia, having successfully adapted to utilize anthropogenic resources. The habituation of possums to food and shelter available in human settlements has facilitated interaction with people, pets, and zoo animals, increasing the potential for transmission of zoonotic Cryptosporidium pathogens. This study sought to examine the identity and prevalence of Cryptosporidium species occurring in possums adapted to urban settings compared to possums inhabiting remote woodlands far from urban areas and to characterize the health of the host in response to oocyst shedding. Findings indicated that both populations were shedding oocysts of the same genotype (brushtail possum 1 [BTP1]) that were genetically and morphologically distinct from zoonotic species and genotypes and most closely related to Cryptosporidium species from marsupials. The urban population was shedding an additional five Cryptosporidium isolates that were genetically distinct from BTP1 and formed a sister clade with Cryptosporidium parvum and Cryptosporidium hominis. Possums that were shedding oocysts showed no evidence of pathogenic changes, including elevated levels of white blood cells, diminished body condition (body mass divided by skeletal body length), or reduced nutritional state, suggesting a stable host-parasite relationship typical of Cryptosporidium species that are adapted to the host. Overall, Cryptosporidium occurred with a higher prevalence in possums from urban habitat (11.3%) than in possums from woodland habitat (5.6%); however, the host-specific nature of the genotypes may limit spillover infection in the urban setting. This study determined that the coexistence of possums with sympatric populations of humans, pets, and zoo animals in the urban Australian environment is unlikely to present a threat to public health safety.

Identification of zoonotic Giardia genotypes in marsupials in Australia

A total of 421 fecal samples from a variety of captive and wild marsupial hosts in Western Australia, Victoria and South Australia were screened for the presence of Giardia species/genotypes using PCR and sequence analysis of a fragment of the 18S rRNA gene. Giardia spp. were identified in 13.4% (28/209) of samples from captive marsupials and 13.7% (29/212) of samples from wild marsupials. Sequence analysis at the 18S locus identified the zoonotic Giardia duodenalis Genotypes A and B in both captive and wild marsupials. Eight isolates were typed as genotype B3 and B4 at the gdh locus, although 7/8 were typed as genotype A at the 18S rRNA locus. The possible reasons for this discordance are discussed. This is the first report of genotype B and only the second report of genotype A in marsupials. As some of the genotype B isolates were identical to human-derived Giardia gdh sequences, these results suggest that marsupials in catchments may pose a public health risk and therefore warrant further investigation.