Occurrence and molecular characterization of Cryptosporidium spp. in mammals and reptiles at the Lisbon Zoo

Minimal zoonotic risk of cryptosporidiosis and giardiasis from frogs and reptiles

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.

A review of the diversity of Cryptosporidium in Rattus norvegicus, R. rattus and Mus musculus: What we know and challenges for the future

The aim of this paper is to review the diversity of Cryptosporidium species and genotypes infecting synantropic rodents. A total of 27 papers published between 1990 and 2020 assed the presence of Cryptosporidium in these rodents worldwide and described 17 different species and genotypes of Cryptosporidium. A great variation in the prevalence values were observed (0-63%). The most frequent species/genotypes were Rat genotype I and IV for R. norvegicus and Rat genotype II and III R. rattus, while C. tyzzeri was for M. musculus. Cryptosporidium parvum, the second most common species after C. hominis involved in human cryptosporidiosis cases, was the third most detected Cryptosporidium species in R, norvergicus (9.4% of the positive samples) and the 3 rodent species are common host for C. muris, also recognized as zoonotic. Besides, these synanthopic rodents can harbor Cryptosporidium species whose natural hosts are cattle, bovids, pigs, other rodent species, birds and a broad range of mammals. Considering the diversity described so far, it would have a great epidemiological impact to know how the variation of Cryptosporidium species composition along urban-rural gradients is like, including synanthropic rodents, wild and domestic animals and environmental samples, and to analyze the causal factors of such variation.

Exploration of Zoo felids in North-East China for the prevalence and molecular identification of Cryptosporidium spp

Cryptosporidium spp. is a protozoan having the potential to cause zoonosis in humans and animals. Despite the zoonotic importance of this protozoan parasite, limited data are available about its prevalence in zoo felids in North-Eastern China. Hence, the current study was designed to determine the occurrence and molecular characterization of Cryptosporidium spp. from the fecal samples of captive zoo felids. Fecal samples (N = 244) were collected from different felids from five different zoos of North-Eastern China. 18S rRNA gene was amplified from the genomic DNA using species specific primers in nested polymerase chain reaction (nPCR) and Cryptosporidium parvum and Cryptosporidium spp. was found. The overall prevalence of Cryptosporidium was 9.43% (23/244). The 18S rRNA gene similarity analysis showed that 6 Cryptosporidium isolates were Cryptosporidium parvum and the remaining 17 Cryptosporidium isolates were resembling to a Cryptosporidium spp., which is similar to Cryptosporidium NEV10. Phylogenetic tree was constructed based on 18S rRNA of Cryptosporidium spp. The similarity of Cryptosporidium parvum was with its other isolates in China, India, Iran, Iraq, Turkey, Czech Republic, Spain and USA while Cryptosporidium NEV10 alike had a close relationship with Turkish isolates. In conclusion, Cryptosporidium was prevailing in feline animals of China zoo and zoo officials are directed to consider their control policy as it can be a cause of zoonosis.

Occurrence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis among captive mammals in the Bangladesh National Zoo

Cryptosporidium and Giardia are protozoan parasites capable of causing gastrointestinal illness in humans and animals. The purpose of this research was to determine the occurrence, genetic characteristics, and zoonotic potential of Cryptosporidium spp. and Giardia duodenalis in captive mammals at the Bangladesh National Zoo. A total of 200 fresh fecal samples from 32 mammalian species were collected and examined for Cryptosporidium spp. using nested polymerase chain reaction (PCR) targeting the small subunit (SSU) rRNA gene and G. duodenalis targeting the β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes. The overall infection rates of Cryptosporidium and G. duodenalis among captive mammals in the zoo were 3.5% (7/200) and 5.5% (11/200), respectively. Five species/genotypes of Cryptosporidium (C. hominis, C. andersoni, C. muris, C. felis, and Cryptosporidium deer genotype) were identified. C. hominis was subtyped as IbA12G3 by sequence analysis of the glycoprotein 60 (gp60) gene. Multilocus genotyping of G. duodenalis revealed assemblages A, B, and D. Mixed infections of assemblages B and D and A and B were found in an Asiatic jackal and a Nilgiri langur, respectively. To our knowledge, this is the first report on the occurrence and genetic identity of the two parasites among zoo animals in Bangladesh. The results suggest that zoonotic Cryptosporidium spp. and G. duodenalis are maintained in and transmitted between captive mammals. Therefore, washing, cleaning, and disinfection measures should be implemented to reduce the spread of Cryptosporidium and G. duodenalis infections.

Detection of Cryptosporidium parvum in a Red-Eared Slider Turtle (Trachemys scripta elegans), a Noted Invasive Alien Species, Captured in a Rural Aquatic Ecosystem in Eastern Poland

Purpose

Little is known about cryptosporidiosis in turtles of invasive alien species (IAS) inhabiting European bodies of fresh water. In this article, we report an occurrence of Cryptosporidium parvum in a red-eared slider turtle (Trachemys scripta elegans) captured in a rural aquatic ecosystem in eastern Poland.

Methods

A pair of samples consisting of feces and scrapings of intestinal mucosa (taken during necropsy) were collected from 104 animals representing the four IAS turtle species red-eared slider, yellow-bellied slider, false map and Cumberland slider. The animals were trapped in running and standing freshwater ecosystems across the Lublin province. Parasite genomic DNA was extracted from samples using a modified alkali wash and a heat-lysis method and identification of the Cryptosporidium species was performed at the 18SSU rRNA and COWP loci.

Results

The presence of Cryptosporidium DNA was only detected in one sample of intestinal scraping collected from a red-eared slider. A phylogenetic analysis of a 18SSU rRNA gene fragment showed 100% sequence identity between the C. parvum strain isolated from the turtle and other C. parvum strains previously detected in cattle from the Lublin province.

Conclusions

There was no clinical evidence that the red-eared slider turtle was truly infected rather than being merely a mechanical parasite carrier. Sporadic detection of this protozoan parasite in the studied population of IAS turtles could be associated with low natural occurrence of Cryptosporidium infections in this animal species. The results provide evidence for possible transmission of zoonotic Cryptosporidium species by IAS turtles.

The first report of Cryptosporidium testudinis in Chinese alligators (Alligator sinensis) in China

Several Cryptosporidium species that infect reptiles, especially squamates, are well described, but there is limited data about Cryptosporidium species infecting crocodilians. In this study, we assess the occurrence of intestinal parasites using traditional microscopic examination and describe the prevalence and Cryptosporidium species in the captive-bred Chinese alligators (Alligator sinensis) in eastern China using molecular methods. The results of microscopic examination showed that no intestinal parasites were detected among the 491 fecal samples examined from the Chinese alligators. The overall prevalence for Cryptosporidium was 0.41% (2/491) by PCR detection using the SSU rRNA locus. Sequence and phylogenetic analysis of the SSU rRNA, COWP, and actin genes revealed the presence of Cryptosporidium testudinis, which has been isolated primarily from chelonians. This is the first detection of the specific DNA of C. testudinis in the feces of the Chinese alligator. This study expands our knowledge of the Cryptosporidium species involved in crocodiles, and more extensive studies are necessary to confirm the validity of C. testudinis in crocodiles.

Cryptosporidium infections in terrestrial ungulates with focus on livestock: a systematic review and meta-analysis

Background

Cryptosporidium spp. are causative agents of gastrointestinal diseases in a wide variety of vertebrate hosts. Mortality resulting from the disease is low in livestock, although severe cryptosporidiosis has been associated with fatality in young animals.

Methods

The goal of this systematic review and meta-analysis was to review the prevalence and molecular data on Cryptosporidium infections in selected terrestrial domestic and wild ungulates of the families Bovidae (bison, buffalo, cattle, goat, impala, mouflon sheep, sheep, yak), Cervidae (red deer, roe deer, white-tailed deer), Camelidae (alpaca, camel), Suidae (boar, pig), Giraffidae (giraffes) and Equidae (horses). Data collection was carried out using PubMed, Scopus, Science Direct and Cochran databases, with 429 papers being included in this systematic analysis.

Results

The results show that overall 18.9% of ungulates from the investigated species were infected with Cryptosporidium spp. Considering livestock species (cattle, sheep, goats, pigs, horses and buffaloes), analysis revealed higher Cryptosporidium infection prevalence in ungulates of the Cetartiodactyla than in those of the Perissodactyla, with cattle (29%) being the most commonly infected farm animal.

Conclusions

Overall, the investigated domestic ungulates are considered potential sources of Cryptosporidium contamination in the environment. Control measures should be developed to reduce the occurrence of Cryptosporidium infection in these animals. Furthermore, literature on wild populations of the named ungulate species revealed a widespread presence and potential reservoir function of wildlife.

Cryptosporidium testudinis sp. n., Cryptosporidium ducismarci Traversa, 2010 and Cryptosporidium tortoise genotype III (Apicomplexa: Cryptosporidiidae) in tortoises

Understanding of the diversity of species of Cryptosporidium Tyzzer, 1910 in tortoises remains incomplete due to the limited number of studies on these hosts. The aim of the present study was to characterise the genetic diversity and biology of cryptosporidia in tortoises of the family Testudinidae Batsch. Faecal samples were individually collected immediately after defecation and were screened for presence of cryptosporidia by microscopy using aniline-carbol-methyl violet staining, and by PCR amplification and sequence analysis targeting the small subunit rRNA (SSU), Cryptosporidium oocyst wall protein (COWP) and actin genes. Out of 387 faecal samples from 16 tortoise species belonging to 11 genera, 10 and 46 were positive for cryptosporidia by microscopy and PCR, respectively. All samples positive by microscopy were also PCR positive. Sequence analysis of amplified genes revealed the presence of the Cryptosporidium tortoise genotype I (n = 22), C. ducismarci Traversa, 2010 (n = 23) and tortoise genotype III (n = 1). Phylogenetic analyses of SSU, COWP and actin gene sequences revealed that Cryptosporidium tortoise genotype I and C. ducismarci are genetically distinct from previously described species of Cryptosporidium. Oocysts of Cryptosporidium tortoise genotype I, measuring 5.8-6.9 µm × 5.3-6.5 µm, are morphologically distinguishable from C. ducismarci, measuring 4.4-5.4 µm × 4.3-5.3 µm. Oocysts of Cryptosporidium tortoise genotype I and C. ducismarci obtained from naturally infected Russian tortoises (Testudo horsfieldii Gray) were infectious for the same tortoise but not for Reeve's turtles (Mauremys reevesii [Gray]), common garter snake (Thamnophis sirtalis [Linnaeus]), zebra finches (Taeniopygia guttata [Vieillot]) and SCID mice (Mus musculus Linnaeus). The prepatent period was 11 and 6 days post infection (DPI) for Cryptosporidium tortoise genotype I and C. ducismarci, respectively; the patent period was longer than 200 days for both cryptosporidia. Naturally or experimentally infected tortoises showed no clinical signs of disease. Our morphological, genetic, and biological data support the establishment of Cryptosporidium tortoise genotype I as a new species, Cryptosporidium testudinis sp. n., and confirm the validity of C. ducismarci as a separate species of the genus Cryptosporidium.

Molecular Characterization of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in Captive Wildlife at Zhengzhou Zoo, China

Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi are common gastrointestinal protists in humans and animals. Two hundred and three fecal specimens from 80 wildlife species were collected in Zhengzhou Zoo and their genomic DNA extracted. Three intestinal pathogens were characterized with a DNA sequence analysis of different loci. Cryptosporidium felis, C. baileyi, and avian genotype III were identified in three specimens (1.5%), the manul, red-crowned crane, and cockatiel, respectively. Giardia duodenalis was also found in five specimens (2.5%) firstly: assemblage B in a white-cheeked gibbon and beaver, and assemblage F in a Chinese leopard and two Siberian tigers, respectively. Thirteen genotypes of E. bieneusi (seven previously reported genotypes and six new genotypes) were detected in 32 specimens (15.8%), of which most were reported for the first time. A phylogenetic analysis of E. bieneusi showed that five genotypes (three known and two new) clustered in group 1; three known genotypes clustered in group 2; one known genotype clustered in group 4; and the remaining four genotypes clustered in a new group. In conclusion, zoonotic Cryptosporidium spp., G. duodenalis, and E. bieneusi are maintained in wildlife and transmitted between them. Zoonotic disease outbreaks of these infectious agents possibly originate in wildlife reservoirs.

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.

Prevalence and molecular characterization of Cryptosporidium in giant panda (Ailuropoda melanoleuca) in Sichuan province, China

Background

Cryptosporidium spp. have been extensively reported to cause significant diarrheal disease in humans and domestic animals. On the contrary, little information is available on the prevalence and characterization of Cryptosporidium in wild animals in China, especially in giant pandas. The aim of the present study was to detect Cryptosporidium infections and identify Cryptosporidium species at the molecular level in both captive and wild giant pandas in Sichuan province, China.

Findings

Using a PCR approach, we amplified and sequenced the 18S rRNA gene from 322 giant pandas fecal samples (122 from 122 captive individuals and 200 collected from four habitats) in Sichuan province, China. The Cryptosporidium species/genotypes were identified via a BLAST comparison against published Cryptosporidium sequences available in GenBank followed by phylogenetic analysis. The results revealed that both captive and wild giant pandas were infected with a single Cryptosporidium species, C. andersoni, at a prevalence of 15.6 % (19/122) and 0.5 % (1/200) in captive and wild giant pandas, respectively.

Conclusions

The present study revealed the existence of C. andersoni in both captive and wild giant panda fecal samples for the first time, and also provided useful fundamental data for further research on the molecular epidemiology and control of Cryptosporidium infection in giant pandas.

Emerging infectious diseases of chelonians

Various new diseases have emerged in captive and wild populations of turtles and tortoises. Several of these seem to be on the rise and have the potential to cause widespread disease. This article reviews the current literature and authors' experience with intranuclear coccidiosis, cryptosporidium, iridovirus, and adenovirus. The biology, epidemiology, clinical signs, diagnosis, treatment, and pathologic changes are described for each disease.

Cryptosporidium tyzzeri n. sp. (Apicomplexa: Cryptosporidiidae) in domestic mice (Mus musculus)

The Cryptosporidium in the small intestine of domestic mice (Mus musculus) was initially described as Cryptosporidium parvum. Recent genetic and biologic characterization of Cryptosporidium isolates indicate that domestic mice are infected with several morphologically indistinguishable intestinal Cryptosporidium parasites with different host specificities, including C. parvum sensu stricto, mouse genotype I, and mouse genotype II. In this study, the morphological, biological, and genetic characteristics of the Cryptosporidium mouse genotype I are described. As a full re-description of C. parvum was made in 1985 for isolates from calves and humans and the name C. parvum has been widely used for the parasite that is infectious to both ruminants and humans, the mouse genotype I is named as Cryptosporidium tyzzeri. Oocysts of the new species (4.64±0.05 μm ×4.19±0.06 μm, with a mean shape index of 1.11±0.02; n=69) are slightly smaller than those of the re-described C. parvum. The prepatent period was six and seven days, and the patent period was 24-28 and 28-29 days in neonatal and adult mice, respectively. Oocysts were not infectious to lambs and calves. Light, transmission electron and scanning electron microscopy studies of the new species showed the presence of developmental stages in the microvillar brush border of the jejunum and ileum of experimentally infected mice, with the infection most intensive in the ileum. It had nucleotide sequences significantly different from C. parvum at the small subunit rRNA, 70 kDa heat shock protein, oocyst wall protein, actin, and the 60 kDa glycoprotein genes. Based on the morphological, genetic, and biological data and in compliance of established Cryptosporidium species naming criteria, this geographically widespread parasite is named as a new species in honor of Ernest Edward Tyzzer, who pioneered Cryptosporidium research.

Gastrointestinal parasites in mammals of two Italian zoological gardens

The prevalence of gastrointestinal parasites was investigated in mammals housed in two of the main Italian zoological gardens: the Zoo Safari of Fasano (province of Bindisi, Apulia, Italy) and the Giardino Zoologico of Pistoia (Tuscany, Italy). In November 2007, fecal samples were collected at the Zoo Safari of Fasano (n = 96) and at the Giardino Zoologico of Pistoia (n = 60), from primates, carnivores, perissodactyls, artiodactyls and proboscideans. In most of the cases, the same animal species or genera were considered in both the zoos. One or more intestinal parasites were detected in 61.5% of the examined samples. However, very different percentages of protozoa- and helminth-positive samples were obtained in the animals from the two zoos, with an overall gastrointestinal parasitic infection of 77.1% in the Zoo Safari of Fasano and 36.7% in the Giardino Zoologico of Pistoia. Overall, 10% (Cryptosporidium sp.) and 43.3% (Toxocara cati, Strongyloides stercoralis, Toxascaris leonina, and hookworms) of carnivores, 66.7% (Cryptosporidium spp.) and 100% (Trichuris spp. and Strongyloides fülleborni) of primates, 25.0% (Eimeria spp., Cryptosporidium spp.), and 57.1% (Trichuris sp., Toxocara [Neoascaris] vitulorum, gastrointestinal strongyles, and Paramphistomidae) of artiodactyls were infected with protozoa and helminthes parasites, respectively. Only gastrointestinal strongyles were diagnosed in 16.7% of proboscideans and in 50.0% of perissodactyls examined. The results of this study suggest that zoonotic protozoans and gastrointestinal helminths are common in zoo mammals and that these animals may serve as a potential reservoir and transmit these parasites to humans. The different animal management in the two zoos indicates that the regular monitoring of parasitic diseases and the use of selective treatments can represent effective measures for the control of several gastrointestinal infections in zoological gardens.

Molecular detection of Cryptosporidium cuniculus in rabbits in Australia

In the United Kingdom, rabbits have been reported to harbour genotypes of Cryptosporidium (now recognized as C. cuniculus) identical to those from human patients exhibiting symptoms of cryptosporidiosis. The high density of rabbits in many regions of Australia, including both rural and urban as well as natural water catchments areas, and the absence of any information on Cryptosporidium from lagomorphs in this country stimulated the present study. We undertook an epidemiological study that genetically characterized Cryptosporidium from rabbits from four locations in Victoria by PCR-coupled sequencing and phylogenetic analysis of sequence data for loci within the small subunit of nuclear ribosomal RNA (SSU; for specific identification) and the 60kDa glycoprotein gene (gp60; for genotypic/subgenotypic identification). Cryptosporidium was detected in 12 (6.8%) of 176 individual faecal samples. For SSU, all 12 sequences were identical to each other and to that of C. cuniculus. For pgp60, all corresponding sequences matched the known genotype Vb, and were classified as subgenotype VbA23R3 (n=11) and VbA26R4 (n=1), which are both new records. Present evidence indicates that genotype Vb is limited to rabbits; however, it would be premature to conclude that this genotype is not zoonotic. Future studies should focus on the zoonotic potential of C. cuniculus from rabbits and a wide range of yet unstudied animals. (Nucleotide sequences reported in this paper are available in the GenBank database under accession nos. HM852431-HM852433).

Evidence for a new species of Cryptosporidium infecting tortoises: Cryptosporidium ducismarci

Cryptosporidiosis affects the gastrointestinal and respiratory tract of humans as well as of a wide range of companion, farm, laboratory and wild animals. In the past few years, three independent studies have provided strong evidence for the existence of a distinct Cryptosporidium species affecting tortoises and likely circulating in other reptile species as well. A new Cryptosporidium genotype was firstly detected and genetically characterized in a marginated tortoise in Italy in 2007 and named Cryptosporidium sp. ex Testudo marginata CrIT-20. The phylogenetic analysis of this isolate indicated that this Cryptosporidium was unique and belonged to the intestinal clade. These findings were later on confirmed by the detection of genetic homologies of isolates from a python and a chameleon from Spain and by recent research in the United States. The latter study presented both the occurrence of intestinal lesions in a pancake tortoise and a Russian tortoise and the genetic characterization of the isolates, together with the first pictures of the endogenous stages of Cryptosporidium CrIT-20. Phylogenetic inference based on the sequences representing small subunit of the nuclear ribosomal RNA gene (SSU) of these isolates confirmed the pathological findings because this Cryptosporidium was related to the intestinal group and supported previous results in T. marginata from Italy. The present scientific data on the Cryptosporidium CrIT-20 support its classification as a new species of Cryptosporidium causing intestinal diseases in tortoises. Although further morphological (i.e. exogenous stages) and biological aspects (i.e. complete host range) are yet to be elucidated, it is proposed that this Cryptosporidium is designated Cryptosporidium ducismarci.

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.

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.

Occurrence and molecular characterization of Cryptosporidium and Giardia in captive wild ruminants in Belgium

Both Cryptosporidium and Giardia are frequently found in the stool of domestic ruminants, especially young animals. Wild ruminants are also host to these protozoa, but the prevalence of these parasites in both free-ranging and captive nondomesticated ruminants needs to be further investigated. Moreover, the role of wild ruminants serving as reservoirs for these zoonotic parasites remains unclear. Therefore, a cross-sectional survey was conducted to estimate the occurrence of Cryptosporidium and Giardia in captive wild ruminants younger than 6 mo and to determine the potential of these animals to serve as reservoirs for these zoonotic parasites. A total of 67 captive wild ruminants belonging to 21 different animal species at the Antwerp Zoo (Belgium), along with 82 American bison (Bison bison) on a commercial breeding farm, were sampled for the detection of Cryptosporidium and Giardia, using a commercial immunofluoresence assay (Merifluor Cryptosporidium/Giardia IFA). The Cryptosporidium prevalence was 7.5% in the Antwerp Zoo animals and 3.7% in the bison from the breeding farm. All but two of the Cryptosporidium-positive animals were younger than 1 mo of age. Molecular characterization by amplification of the 70-kDa heat-shock protein and the 18S ribosomal DNA gene identified Cryptosporidium parvum in four animals of the Antwerp Zoo. The prevalence of Giardia was 8.9% in the Antwerp Zoo animals and 23.2% in the bison calves. Most Giardia-positive animals were older than 1 mo of age. Molecular characterization on the beta-giardin gene and the triose phosphate isomerase gene identified Giardia duodenalis assemblage A in the Antwerp Zoo and both G. duodenalis assemblage A and assemblage E in the bison calves. These findings indicate that both protozoan parasites are prevalent in captive wild ruminants and that these animals can serve as a potential reservoir for zoonotic transmission.

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.

Novel Cryptosporidium genotype in wild Australian mice (Mus domesticus)

A total of 250 mouse fecal specimens collected from crop farms in Queensland, Australia, were screened for the presence of Cryptosporidium spp. using PCR. Of these, 19 positives were detected and characterized at a number of loci, including the 18S rRNA gene, the acetyl coenzyme A gene, and the actin gene. Sequence and phylogenetic analyses identified two genotypes: mouse genotype I and a novel genotype (mouse genotype II), which is likely to be a valid species. Cryptosporidium parvum, which is zoonotic, was not detected. The results of the study indicate that wild Australian mice that are not in close contact with livestock are probably not an important reservoir of Cryptosporidium infection for humans and other animals.

Molecular characterization of Cryptosporidium from animal sources in Qinghai province of China

The presence of Cryptosporidium oocysts in 20 zoo animals of the Xining Zoo, 16 farm yaks and 42 farm goats in Qinghai province, China was investigated by an immunofluorescence test (IFT). The species and/or genotypes were determined by nested polymerase chain reaction (PCR) and sequence analysis of a fragment of the small subunit (SSU) rRNA gene. Cryptosporidium oocysts were found in 16 zoo animals, 2 yaks, and 15 goats by IFT. The IFT positive samples were further investigated by PCR, and 16 of them were found to be positive by that method also. Sequence analysis of the PCR products derived from Cryptosporidium oocysts from Black leopard (Panthera pardus), Heijing He (Grus nigricollis), Barbary sheep (Ammotragus lervia), Takin (Budorcas taxicolor), Lesser panda (Ailurus fulgens), and White-eared pheasant (Crossoptilon crossoptilon) fecal samples matched that of Cryptosporidium parvum mouse genotype. Sequence analyses of other PCR products were consistent with cervine genotype Cryptosporidium from Ibex (Capra ibex), a novel Cryptosporidium genotype from a wild yak (Bos mutus), C. bovis-like genotype from one goat sample and also a novel Cryptosporidium genotype from one other separate goat sample. The present work reports the first data on Cryptosporidium infections in animals from the Qinghai province of mountainous central western China and the first findings of the 'cervine' genotype in Capra ibex, C. bovis-like genotype and the new Cryptosporidium spp. in farm goat and in wild yak.