Seasonal shedding of multiple Cryptosporidium genotypes in California ground squirrels (Spermophilus beecheyi)

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.

European ground squirrels Spermophilus citellus (Linnaeus) do not share identical Cryptosporidium spp. with North American ground squirrels

Cryptosporidium Tyzzer, 1910 is one of the most common protistan parasites of vertebrates. The results of this study provide the first data on Cryptosporidium diversity in the European ground squirrel Spermophilus citellus (Linnaeus). A total of 128 faecal samples of European ground squirrels from 39 localities in the Czech Republic were analysed for the presence of Cryptosporidium spp. by microscopy and PCR/sequence analysis of small subunit ribosomal RNA (SSU) and the actin gene. While the microscopical examination did not reveal the presence of any Cryptosporidium oocysts, eight samples from six localities were PCR-positive. Phylogenetic analyses revealed the presence of five different Cryptosporidium spp. isolates. Four isolates, designated as Cryptosporidium sp. isolate Sc01-04, detected in wild populations and never recorded before, clustered closely to Cryptosporidium genotypes that have previously been found in North American ground squirrels' species. Cryptosporidium sciurinum Prediger, Ježková, Holubová, Sak, Konečný, Rost, McEvoy, Rajský et Kváč, 2021 was found in an animal sanctuary. Because C. sciurinum had previously been detected in Eurasian red squirrels Sciurus vulgaris Linnaeus at the same facility, it can be concluded that this Cryptosporidium was transmitted from tree squirrels to ground squirrels within the animal sanctuary. The results indicate that populations of European and North American ground squirrels are parasitised by different Cryptosporidium spp. At the same time, this is the first description of the occurrence of C. sciurinum in ground squirrels.

Genotyping and subtyping of Cryptosporidium spp. and Giardia duodenalis isolates from two wild rodent species in Gansu Province, China

Cryptosporidium spp. and Giardia duodenalis are commonly detected intestinal protozoa species in humans and animals, contributing to global gastroenteritis spread. The present study examined the prevalence and zoonotic potential of Cryptosporidium spp. and G. duodenalis in Himalayan marmots and Alashan ground squirrels in China's Qinghai-Tibetan Plateau area (QTPA) for the first time. Four hundred ninety-eight intestinal content samples were collected from five counties of QTPA of Gansu province, China. All samples were examined for Cryptosporidium spp. and G. duodenalis by PCR amplification. The resultant data were statistically analyzed by chi-square, Fisher's test and Bonferroni correction using SPSS software 25. 0. Cryptosporidium positive samples were further subtyped through analysis of the 60-kDa glycoprotein (gp60) gene sequence. A total of 11 and 8 samples were positive for Cryptosporidium spp. and G. duodenalis, respectively. Prevalence of Cryptosporidium spp. and G. duodenalis were 2.5% (10/399) and 1.5% (6/399) in Himalayan marmots, 1.0% (1/99) and 2.0% (2/99) in Alashan ground squirrels, respectively. Sequence analysis confirmed the presence of C. rubeyi (n = 2), ground squirrel genotype II (n = 7), chipmunk genotype V (n = 1) and horse genotype (n = 1). The horse genotype was further subtyped as novel subtype VIbA10. G. duodenalis zoonotic assemblages A (n = 1), B (n = 6), E (n = 1) were identified in the present study. This is the first study to identify Cryptosporidium spp. and G. duodenalis in Himalayan marmots and Alashan ground squirrels, suggesting the potential zoonotic transmission of the two pathogens in QTPA.

Prevalence and Molecular Characterization of the Zoonotic Enteric Protozoans Cryptosporidium spp., Enterocytozoon bieneusi, and Blastocystis from Pallas's Squirrels (Callosciurus erythraeus) in Kanagawa Prefecture, Japan

Pallas's squirrel (Callosciurus erythraeus) was introduced in Japan in the 1930s and has since established itself in several areas across the country. Although wild Sciuridae populations have been demonstrated to be potential reservoirs for zoonotic enteric protozoa, epidemiological studies of such pathogens in Japan are scarce. Here, we examined 423 fecal samples from Pallas's squirrels captured in Kanagawa Prefecture, Japan, using PCR and DNA sequencing to determine the occurrence of Cryptosporidium spp., Enterocytozoon bieneusi, and Blastocystis. The overall prevalence of Cryptosporidium spp., E. bieneusi, and Blastocystis was 4.3% (18/423 samples), 13.0% (55/423 samples), and 44.0% (186/423 samples), respectively. The prevalence of Blastocystis and E. bieneusi was significantly higher in spring (60.1% and 17.4%, respectively) than in winter (27.6% and 8.6%, respectively [P < 0.01]). Sequence analysis of Cryptosporidium spp., targeting the partial small subunit ribosomal RNA gene (SSU rDNA), showed 100% identity (541/541 bp) to Cryptosporidium ubiquitum, and analysis of the gp60 gene showed 99.76% (833/835 bp) identity to C. ubiquitum subtype XIIh. The sequences of the ribosomal internal transcribed spacer region of E. bieneusi and the partial SSU rDNA of Blastocystis were identified as E. bieneusi genotype SCC-2 and Blastocystis subtype 4, respectively. This study confirmed the presence of C. ubiquitum, E. bieneusi, and Blastocystis in Pallas's squirrels in Kanagawa Prefecture. Because Pallas's squirrels inhabit urban areas, living close to humans, the species may serve as a potential source of infection in human populations. IMPORTANCE Pallas's squirrel is designated a "regulated organism" under the Invasive Alien Species Act in Japan, and municipal authorities are introducing control measures to reduce its populations. It has been suggested that wild mammals may play a role in contaminating the environment with zoonotic pathogens. The present study detected the enteric pathogens Cryptosporidium ubiquitum, Enterocytozoon bieneusi, and Blastocystis in the feces of Pallas's squirrels inhabiting Kanagawa Prefecture, Japan. These pathogens persist in the environment and contaminate soils and water, which may potentially infect humans. Because Pallas's squirrels in Kanagawa Prefecture are found in urban areas, where they are in close contact with human populations, continued monitoring of zoonotic diseases among squirrel populations will be important for evaluating the significance of wildlife in pathogen transmission.

Taxonomy and molecular epidemiology of Cryptosporidium and Giardia - a 50 year perspective (1971-2021)

The protozoan parasites Cryptosporidium and Giardia are significant causes of diarrhoea worldwide and are responsible for numerous waterborne and foodborne outbreaks of diseases. Over the last 50 years, the development of improved detection and typing tools has facilitated the expanding range of named species. Currently at least 44 Cryptosporidium spp. and >120 genotypes, and nine Giardia spp., are recognised. Many of these Cryptosporidium genotypes will likely be described as species in the future. The phylogenetic placement of Cryptosporidium at the genus level is still unclear and further research is required to better understand its evolutionary origins. Zoonotic transmission has long been known to play an important role in the epidemiology of cryptosporidiosis and giardiasis, and the development and application of next generation sequencing tools is providing evidence for this. Comparative whole genome sequencing is also providing key information on the genetic mechanisms for host specificity and human infectivity, and will enable One Health management of these zoonotic parasites in the future.

CRYPTOSPORIDIUM SPP. IN PET DWARF WINTER WHITE RUSSIAN HAMSTERS (PHODOPUS SUNGORIS SUNGORIS) IN CHINA

Cryptosporidium spp. have been identified in a wide range of hosts, such as humans and domestic and wild animals, while less information about the prevalence of Cryptosporidium spp. in pet hamsters is documented. A total of 351 dwarf winter white Russian hamsters' fecal specimens were collected from 6 pet markets from the cities of Luzhou and Ziyang in Sichuan province in the southwestern part of China. The prevalence of Cryptosporidium spp. determined with nested-PCR amplification of the partial small-subunit (SSU) rRNA gene was 39.32% (138/351). The highest prevalence of Cryptosporidium spp. was in pet market 5 (79.49%, 62/78), followed by pet market 6 (38.64%, 17/44). The lowest prevalence of Cryptosporidium spp. was observed in pet market 3 (14.89%, 7/47). Statistically significant differences in the prevalence of Cryptosporidium spp. were observed among different pet markets (χ2 = 76.386, df = 5, P < 0.05), and a further post hoc test revealed that only pet market 5 was significantly different from other pet markets. Molecular analysis showed that 4 different Cryptosporidium species or genotypes were identified: Cryptosporidium parvum (n = 127), Cryptosporidium chipmunk genotype III (n = 6), Cryptosporidium andersoni (n = 4), and Cryptosporidium wrairi (n = 1). The identification of Cryptosporidium spp. was further tested with the 60-kDa glycoprotein (GP60) gene, and the positive rate was 29.7% (41/138). This is the first molecular report on Cryptosporidium spp. infection in dwarf winter white Russian hamsters in China. With C. parvum and C. andersoni being identified in both humans and pet hamsters, these findings suggest that pet hamsters may be potential reservoirs of zoonotic Cryptosporidium species and subtypes.

Diverse Genotypes and Species of Cryptosporidium in Wild Rodent Species from the West Coast of the USA and Implications for Raw Produce Safety and Microbial Water Quality

Cryptosporidium spp. are protozoan parasites that infect perhaps all vertebrate animals, with a subset of species and genotypes that function as food- and waterborne pathogens. The objective of this work was to collate the Cryptosporidium species and genotypes from common wild rodents on the west coast of the USA and update the information regarding the zoonotic potential of Cryptosporidium from these ubiquitous wild species. Representative sequences of the 18S rRNA gene for a unique set of Cryptosporidium isolates obtained from deer mice, house mice, mountain beavers, yellow-bellied marmot, long-tailed vole, California ground squirrels, Belding’s ground squirrels, and a golden-mantled ground squirrel in GenBank were selected for phylogenetic analysis. Phylogenetic and BLAST analysis indicated that 4 (18%) of the 22 unique Cryptosporidium sequences from these wild rodent species were 99.75% to 100% identical to known zoonotic species (C. parvum, C. ubiquitum, C. xiaoi), suggesting that a minority of these representative Cryptosporidium isolates could have a public health impact through food and waterborne routes of human exposure. These zoonotic isolates were shed by deer mice and a yellow-bellied marmot from California, and from a mountain beaver trapped in Oregon. In addition, the group of unique Cryptosporidium isolates from deer mice and ground dwelling squirrels exhibited considerable DNA diversity, with multiple isolates appearing to be either host-limited or distributed throughout the various clades within the phylogenetic tree representing the various Cryptosporidium species from host mammals. These results indicate that only a subset of the unique Cryptosporidium genotypes and species obtained from wild rodents on the US west coast are of public health concern; nevertheless, given the geographic ubiquity of many of these host species and often high density at critical locations like municipal watersheds or produce production fields, prudent pest control practices are warranted to minimize the risks of water- and foodborne transmission to humans.

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).

Quantitative Shedding of Multiple Genotypes of Cryptosporidium and Giardia by Deer Mice (Peromyscus maniculatus) in a Major Agricultural Region on the California Central Coast

Deer mice (Peromyscus maniculatus) are abundant and widely distributed rodents in North America that occupy diverse habitats, including agricultural landscapes. Giardia and Cryptosporidium are common parasites in wildlife including deer mice, which may play a role in on-farm contamination of produce. An important step in assessing the risk of produce contamination by Cryptosporidium and Giardia shed by deer mice is to determine the prevalence, levels, and genotypes of (oo)cysts in mouse feces. A total of 63 (30.3%) and 53 (25.5%) of 208 deer mice trapped on 12 farms on the California Central Coast were positive for Cryptosporidium and Giardia, respectively. Of these mice, 41 (19.7%) contained both parasites. The odds of Cryptosporidium shedding were 2.5 to 5 times higher for mice trapped in autumn than for mice trapped in summer or spring. Female mice had a higher prevalence and two- to threefold higher levels of Cryptosporidium and Giardia compared with male mice. Female adults and female juveniles had the highest rates of contamination of the environment with Cryptosporidium and Giardia, respectively. We estimated that 20 infected deer mice inhabiting 1 ha of a typical leafy green produce farm in the study region could shed approximately 5.3 × 108 Cryptosporidium and 10.5 × 108 Giardia, respectively, per day into the environment. The small-subunit rRNA gene loci from a subset of protozoan isolates were sequenced and compared with existing sequences in GenBank. Multiple genotypes of Cryptosporidium and Giardia were found, and BLAST analyses suggest that Giardia and the majority of Cryptosporidium genotypes in deer mice circulate within various rodent populations, but some Cryptosporidium isolates possess zoonotic potential.

Use of aerobic spores as a surrogate for cryptosporidium oocysts in drinking water supplies

Waterborne illnesses are a growing concern among health and regulatory agencies worldwide. The United States Environmental Protection Agency has established several rules to combat the contamination of water supplies by cryptosporidium oocysts, however, the detection and study of cryptosporidium oocysts is hampered by methodological and financial constraints. As a result, numerous surrogates for cryptosporidium oocysts have been proposed by the scientific community and efforts are underway to evaluate many of the proposed surrogates. The purpose of this review is to evaluate the suitability of aerobic bacterial spores to serve as a surrogate for cryptosporidium oocysts in identifying contaminated drinking waters. To accomplish this we present a comparison of the biology and life cycles of aerobic spores and oocysts and compare their physical properties. An analysis of their surface properties is presented along with a review of the literature in regards to the transport, survival, and prevalence of aerobic spores and oocysts in the saturated subsurface environment. Aerobic spores and oocysts share many commonalities with regard to biology and survivability, and the environmental prevalence and ease of detection make aerobic spores a promising surrogate for cryptosporidium oocysts in surface and groundwater. However, the long-term transport and release of aerobic spores still needs to be further studied, and compared with available oocyst information. In addition, the surface properties and environmental interactions of spores are known to be highly dependent on the spore taxa and purification procedures, and additional research is needed to address these issues in the context of transport.

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.

North American tree squirrels and ground squirrels with overlapping ranges host different Cryptosporidium species and genotypes

Wildlife-associated Cryptosporidium are an emerging cause of cryptosporidiosis in humans. The present study was undertaken to determine the extent to which North American tree squirrels and ground squirrels host zoonotic Cryptosporidium species and genotypes. Fragments of the Cryptosporidium 18S rRNA and actin genes were amplified and sequenced from fecal samples obtained from three tree squirrel and three ground squirrel species. In tree squirrels, Cryptosporidium was identified in 40.5% (17/42) of American red squirrels (Tamiasciurus hudsonicus), 40.4% (55/136) of eastern gray squirrels (Sciurus carolinensis), and 28.6% (2/7) of fox squirrels (Sciurus niger). Human-pathogenic Cryptosporidium ubiquitum and Cryptosporidium skunk genotype were the most prevalent species/genotypes in tree squirrels. Because tree squirrels live in close proximity to humans and are frequently infected with potentially zoonotic Cryptosporidium species/genotypes, they may be a significant reservoir of infection in humans. In ground squirrels, Cryptosporidium was detected in 70.2% (33/47) of 13-lined ground squirrels (Ictidomys tridecemlineatus), 35.1% (27/77) of black-tailed prairie dogs (Cynomys ludovicianus), and the only golden-mantled ground squirrel (Callospermophilus lateralis) that was sampled. Cryptosporidium rubeyi and ground squirrel genotypes I, II, and III were identified in isolates from these ground squirrel species. In contrast to the Cryptosporidium infecting tree squirrels, these species/genotypes appear to be specific for ground squirrels and are not associated with human disease.

Cryptosporidium rubeyi n. sp. (Apicomplexa: Cryptosporidiidae) in multiple Spermophilus ground squirrel species

Previously we reported the unique Cryptosporidium sp. "c" genotype (e.g., Sbey03c, Sbey05c, Sbld05c, Sltl05c) from three species of Spermophilus ground squirrel (Spermophilus beecheyi, Spermophilus beldingi, Spermophilus lateralis) located throughout California, USA. This follow-up work characterizes the morphology and animal infectivity of this novel genotype as the final step in proposing it as a new species of Cryptosporidium. Analysis of sequences of 18S rRNA, actin, and HSP70 genes of additional Cryptosporidium isolates from recently sampled California ground squirrels (S. beecheyi) confirms the presence of the unique Sbey-c genotype in S. beecheyi. Phylogenetic and BLAST analysis indicates that the c-genotype in Spermophilus ground squirrels is distinct from Cryptosporidium species/genotypes from other host species currently available in GenBank. We propose to name this c-genotype found in Spermophilus ground squirrels as Cryptosporidium rubeyi n. sp. The mean size of C. rubeyi n. sp. oocysts is 4.67 (4.4-5.0) μm × 4.34 (4.0-5.0) μm, with a length/width index of 1.08 (n = 220). Oocysts of C. rubeyi n. sp. are not infectious to neonatal BALB/c mice and Holstein calves. GenBank accession numbers for C. rubeyi n. sp. are DQ295012, AY462233, and KM010224 for the 18S rRNA gene, KM010227 for the actin gene, and KM010229 for the HSP70 gene.

Elevation and vegetation determine Cryptosporidium oocyst shedding by yellow-bellied marmots (Marmota flaviventris) in the Sierra Nevada Mountains

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Yellow-bellied marmots of Sierra Nevada Mountain shed Cryptosporidium oocysts.

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Oocysts loads are low compared to other mammals in California.

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Shedding of oocysts is associated with altitude and vegetation type.

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Cryptosporidium oocysts were 99.9%–100% match to Cryptosporidium parvum.

Wildlife are increasingly recognized as important biological reservoirs of zoonotic species of Cryptosporidium that might contaminate water and cause human exposure to this protozoal parasite. The habitat range of the yellow-bellied marmot (Marmota flaviventris) overlaps extensively with the watershed boundaries of municipal water supplies for California communities along the foothills of the Sierra Nevada. We conducted a cross-sectional epidemiological study to estimate the fecal shedding of Cryptosporidium oocysts by yellow-bellied marmots and to quantify the environmental loading rate and determine risk factors for Cryptosporidium fecal shedding in this montane wildlife species. The observed proportion of Cryptosporidium positive fecal samples was 14.7% (33/224, positive number relative to total number samples) and the environmental loading rate was estimated to be 10,693 oocysts animal^-1 day^-1. Fecal shedding was associated with the elevation and vegetation status of their habitat. Based on a portion of the 18s rRNA gene sequence of 2 isolates, the Cryptosporidium found in Marmota flaviventris were 99.88%–100% match to multiple isolates of C. parvum in the GenBank.

Prevalence, environmental loading, and molecular characterization of Cryptosporidium and Giardia isolates from domestic and wild animals along the Central California Coast

The risk of disease transmission from waterborne protozoa is often dependent on the origin (e.g., domestic animals versus wildlife), overall parasite load in contaminated waterways, and parasite genotype, with infections being linked to runoff or direct deposition of domestic animal and wildlife feces. Fecal samples collected from domestic animals and wildlife along the central California coast were screened to (i) compare the prevalence and associated risk factors for fecal shedding of Cryptosporidium and Giardia species parasites, (ii) evaluate the relative importance of animal host groups that contribute to pathogen loading in coastal ecosystems, and (iii) characterize zoonotic and host-specific genotypes. Overall, 6% of fecal samples tested during 2007 to 2010 were positive for Cryptosporidium oocysts and 15% were positive for Giardia cysts. Animal host group and age class were significantly associated with detection of Cryptosporidium and Giardia parasites in animal feces. Fecal loading analysis revealed that infected beef cattle potentially contribute the greatest parasite load relative to other host groups, followed by wild canids. Beef cattle, however, shed host-specific, minimally zoonotic Cryptosporidium and Giardia duodenalis genotypes, whereas wild canids shed potentially zoonotic genotypes, including G. duodenalis assemblages A and B. Given that the parasite genotypes detected in cattle were not zoonotic, the public health risk posed by protozoan parasite shedding in cattle feces may be lower than that posed by other animals, such as wild canids, that routinely shed zoonotic genotypes.

Multiple unique Cryptosporidium isolates from three species of ground squirrels (Spermophilus beecheyi, S. beldingi, and S. lateralis) in California

Phylogenetic analyses of the 18S small-subunit (SSU) rRNA and Cryptosporidium oocyst wall protein (COWP) genes indicate that multiple unique Cryptosporidium isolates are shed by separate species of Spermophilus ground squirrels (S. beecheyi, S. beldingi, and S. lateralis) throughout California, despite some squirrel populations' being geographically isolated. The data support our assertion that Spermophilus squirrels shed novel Cryptosporidium species.

Cryptosporidium spp. in wild, laboratory, and pet rodents in china: prevalence and molecular characterization

To understand the prevalence of Cryptosporidium infection in rodents in China and to assess the potential role of rodents as a source for human cryptosporidiosis, 723 specimens from 18 rodent species were collected from four provinces of China and examined between August 2007 and December 2008 by microscopy after using Sheather's sugar flotation and modified acid-fast staining. Cryptosporidium oocysts were detected in 83 specimens, with an overall prevalence of 11.5%. Phodopus sungorus, Phodopus campbelli, and Rattus tanezumi were new reported hosts of Cryptosporidium. The genotypes and subtypes of Cryptosporidium strains in microscopy-positive specimens were further identified by PCR and sequence analysis of the small subunit rRNA and the 60-kDa glycoprotein (gp60) genes. In addition to Cryptosporidium parvum, C. muris, C. andersoni, C. wrairi, ferret genotype, and mouse genotype I, four new Cryptosporidium genotypes were identified, including the hamster genotype, chipmunk genotype III, and rat genotypes II and III. Mixed Cryptosporidium species/genotypes were found in 10.8% of Cryptosporidium-positive specimens. Sequence analysis of the gp60 gene showed that C. parvum strains in pet Siberian chipmunks and hamsters were all of the subtype IIdA15G1, which was found previously in a human isolate in The Netherlands and lambs in Spain. The gp60 sequences of C. wrairi and the Cryptosporidium ferret genotype and mouse genotype I were also obtained. These findings suggest that pet rodents may be potential reservoirs of zoonotic Cryptosporidium species and subtypes.

Cryptosporidium and cryptosporidiosis

Cryptosporidium is one of the most common enteric protozoan parasites of vertebrates with a wide host range that includes humans and domestic animals. It is a significant cause of diarrhoeal disease and an ubiquitous contaminant of water which serves as an excellent vehicle for transmission. A better understanding of the development and life cycle of Cryptosporidium, and new insights into its phylogenetic relationships, have illustrated the need to re-evaluate many aspects of the biology of Cryptosporidium. This has been reinforced by information obtained from the recent successful Cryptosporidium genome sequencing project, which has emphasised the uniqueness of this organism in terms of its parasite life style and evolutionary biology. This chapter provides an up to date review of the biology, biochemistry and host parasite relationships of Cryptosporidium.

Genetic polymorphism in Cryptosporidium species: an update

Cryptosporidia, widely distributed protozoan parasites of vertebrates, have attracted increasing interest due to several serious waterborne outbreaks, the life-threatening nature of infection in immunocompromised patients, and the realization of economic losses caused by these pathogens in livestock. Genetic polymorphism within Cryptosporidium species is being detected at a continuously growing rate, owing to the widespread use of modern molecular techniques. The aim of this paper is to review the current status of taxonomy, genotyping and molecular phylogeny of Cryptosporidium species. To this date, 20 Cryptosporidium species have been recognized. Two named species of Cryptosporidium have been found in fish, 1 in amphibians, 2 in reptiles, 3 in birds, and 12 in mammals. Nearly 61 Cryptosporidium genotypes with uncertain species status have been found based on SSUrRNA sequences. The gp-60 gene showed a high degree of sequence polymorphism among isolates of Cryptosporidium species and several subtype groups and subgenotypes have been identified, of which the Cryptosporidium parvum IIa and IId subtype groups were found to be zoonotic. This review describes considerable progress in the identification, genetic characterization, and strain differentiation of Cryptosporidium over the last 20 years. All the valid species, genotypes and zoonotic subtypes of Cryptosporidium reported in the international literature are included in this paper with respect to the taxonomy, epidemiology, transmission and morphologic-genetic information for each species.

90-kilodalton heat shock protein, Hsp90, as a target for genotyping Cryptosporidium spp. known to infect humans

Small-subunit (SSU) rRNA-based methods have been commonly used in the differentiation of Cryptosporidium species or genotypes. In order to develop a new tool for confirming the genotypes of Cryptosporidium species, parts of the 90-kDa heat shock protein (Hsp90) genes of seven Cryptosporidium species and genotypes known to infect humans (C. hominis, C. parvum, C. meleagridis, C. canis, C. muris, C. suis, and the cervine genotype), together with one from cattle (C. andersoni), were sequenced and analyzed. With the exception of C. felis from cats and C. baileyi from birds, the Hsp90 genes of all tested Cryptosporidium species were amplified. Phylogenetic analysis of the hsp90 sequences from all these species is congruent with previous studies in which the SSU rRNA, 70-kDa heat shock protein, oocyst wall protein, and actin genes were analyzed and showed that gastric and intestinal parasites segregate into two distinct clades. In this study, the secondary products of hsp90 produced after PCR-restriction fragment length digestion with StyI and HphI or with BbsI showed that parasites within the intestinal or gastric clade could be differentiated from each other. These data confirm the utility of the Hsp90 gene as a sensitive, specific, and robust molecular tool for differentiating species and/or genotypes of Cryptosporidium in clinical specimens.

Cryptosporidium in wild placental mammals

Cryptosporidium species are common parasites of wild placental mammals. Recent parasitological studies combined with molecular genotyping techniques have been providing valuable new insight into the host specificity and potential transmission of various Cryptosporidium species/genotypes among animals and between these animals and humans. Although Cryptosporidium in wild animals may possess a potential public health problem due to oocyst contamination in the environment, studies at various regions of the world have indicated a strong host-adaptation by these parasites and a limited potential of cross-species transmission of cryptosporidiosis among placental mammals, suggesting that these animals are probably not a major reservoir for human infection. However, Cryptosporidium species/genotypes in placental animals have been reported occasionally in humans. Therefore, public health significance of some Cryptosporidium species in wild placental mammals, such as the cervine genotype, should not be overlooked and should be further studied.

The molecular epidemiology of Cryptosporidium and Giardia infections in coyotes from Alberta, Canada, and observations on some cohabiting parasites

Coyotes from southern Alberta and Saskatchewan, Canada, were examined for the presence of Giardia and Cryptosporidium and cohabiting helminths. Toxascaris was present in over 90% of the 70 animals examined, and Taenia sp. in 6.5-25% of the two groups of animals studied. Giardia (12.5-21.7%) and Cryptosporidium (0-17.4%) were also common and molecular characterisation revealed both zoonotic and host-adapted genotypes of Giardia, whereas the Cryptosporidium proved to be a variant of the canine species C. canis. The seasonal variation observed in the occurrence of Cryptosporidium may be related to stress-induced shedding of the parasite.

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.

Cryptosporidium genotypes in wildlife from a new york watershed

To identify the animal sources for Cryptosporidium contamination, we genotyped Cryptosporidium spp. in wildlife from the watershed of the New York City drinking water supply, using a small-subunit rRNA gene-based PCR-restriction fragment length polymorphism analysis and DNA sequencing. A total of 541 specimens from 38 species of wildlife were analyzed. One hundred and eleven (20.5%) of the wildlife specimens were PCR positive. Altogether, 21 Cryptosporidium genotypes were found in wildlife samples, 11 of which were previously found in storm runoff in the watershed, and six of these 11 were from storm water genotypes of unknown animal origin. Four new genotypes were found, and the animal hosts for four storm water genotypes were expanded. With the exception of the cervine genotype, most genotypes were found in a limited number of animal species and have no major public health significance.

Capture and retention of Cryptosporidium parvum oocysts by Pseudomonas aeruginosa biofilms

The association of Cryptosporidium oocysts with biofilm communities can influence the propagation of this pathogen through both environmental systems and water treatment systems. We observed the capture and retention of C. parvum oocysts in Pseudomonas aeruginosa biofilms using laboratory flow cells. Biofilms were developed in two different growth media using two different strains of P. aeruginosa, a wild-type strain (PAO1) and a strain that overproduces the exopolysaccharide alginate (PDO300). Confocal laser-scanning microscopy was used in conjunction with image analysis to assess the structure of the biofilms prior to introducing oocysts into the flow cells. More oocysts were captured by the biofilm-coated surfaces than the abiotic glass surface in both media. There was no significant difference in capture across the two strains of P. aeruginosa biofilm, but the fraction of oocysts captured was positively related to biofilm roughness and surface-area-to-volume ratio. Once captured, oocysts were retained in the biofilm for more than 24 h and were not released after a 40-fold increase in the system flow rate. We believe the capture and retention of oocysts by biofilm communities can impact the environmental transmission of C. parvum, and this interaction should be taken into consideration when predicting the migration of pathogens in the environment.

Deposition of Cryptosporidium oocysts in streambeds

The transfer of Cryptosporidium oocysts from the surface water to the sediment beds of streams and rivers influences their migration in surface waters. We used controlled laboratory flume experiments to investigate the deposition of suspended Cryptosporidium parvum oocysts in streambeds. The experimental results demonstrate that hydrodynamic interactions between an overlying flow and a sediment bed cause oocysts to accumulate in the sediments and reduce their concentrations in the surface water. The association of C. parvum with other suspended sediments increased both the oocysts' effective settling velocity and the rate at which oocysts were transferred to the sediment bed. A model for the stream-subsurface exchange of colloidal particles, including physical transport and physicochemical interactions with sediment grains, accurately represented the deposition of both free C. parvum oocysts and oocysts that were attached to suspended sediments. We believe that these pathogen-sediment interactions play an important role in regulating the concentrations of Cryptosporidium in streams and rivers and should be taken into consideration when predicting the fate of pathogens in the environment.

New genotypes and factors associated with Cryptosporidium detection in mussels (Mytilus spp.) along the California coast

A 3 year study was conducted to evaluate mussels as bioindicators of faecal contamination in coastal ecosystems of California. Haemolymph samples from 4680 mussels (Mytilus spp.) were tested for Cryptosporidium genotypes using PCR amplification and DNA sequence analysis. Our hypotheses were that mussels collected from sites near livestock runoff or human sewage outflow would be more likely to contain the faecal pathogen Cryptosporidium than mussels collected distant to these sites, and that the prevalence would be greatest during the wet season when runoff into the nearshore marine environment was highest. To test these hypotheses, 156 batches of sentinel mussels were collected quarterly at nearshore marine sites considered at higher risk for exposure to livestock runoff, higher risk for exposure to human sewage, or lower risk for exposure to both faecal sources. Cryptosporidium genotypes detected in Haemolymph samples from individual mussels included Cryptosporidium parvum, Cryptosporidium felis, Cryptosporidium andersoni, and two novel Cryptosporidium spp. Factors significantly associated with detection of Cryptosporidium spp. in mussel batches were exposure to freshwater outflow and mussel collection within a week following a precipitation event. Detection of Cryptosporidium spp. was not associated with higher or lower risk status for exposure to livestock faeces or human sewage sources. This study showed that mussels can be used to monitor water quality in California and suggests that humans and animals ingesting faecal-contaminated water and shellfish may be exposed to both host-specific and anthropozoonotic Cryptosporidium genotypes of public health significance.

Efficacy of natural grassland buffers for removal of Cryptosporidium parvum in rangeland runoff

Our goal for this project was to estimate the retention efficiency of natural grassland buffers for Cryptosporidium parvum. Three sets of 16 plots (2.0 by 3.0 m) were established at 5, 20, and 35% slopes. Within each set of 16 plots, residual dry vegetation matter treatments of 225, 560, and 900 kg/ha were implemented, along with a noncut control averaging 4,500 kg/ ha. Buffer width treatments were implemented by placing cattle fecal material containing known loads of C. parvum 0.1, 1.1, or 2.1 m up-slope of the runoff collector. Grassland buffers of 1.1 and 2.1 m generated 3.2- to 8.8-log and 3.6- to 8.8-log retention of C. parvum, respectively, across the range of residual dry vegetation matter, land slope, rainfall, and runoff conditions examined during this project. Buffers with an increased percent land slope exhibited improved the retention efficiencies, whereas buffers experiencing larger maximum annual runoff events exhibited reduced retention efficiencies. Water-quality data from the 0.1-m-wide buffer plots (effectively no buffer) demonstrated that the majority of C. parvum oocysts (98 to 99.999%) were retained in the fecal matrix for the duration of the storm season, irrespective of the presence of a vegetated buffer. In conclusion, these results support the assertion that grassland buffers are an effective method for reducing animal agricultural inputs of waterborne C. parvum into drinking and irrigation water supplies.