Genetic characterization of Cryptosporidium parvum from calves by mutation scanning and targeted sequencing--zoonotic implications

Cryptosporidium parvum and gp60 genotype prevalence in dairy calves worldwide: a systematic review and meta-analysis

Cryptosporidium is a significant zoonotic pathogen that often occurs in dairy cattle. We conducted a systematic review and meta-analysis of the prevalence of Cryptosporidium parvum infection in dairy calves worldwide to help improve global animal husbandry and public policy implementation. Published articles were obtained from PubMed and Web of Science from January 1, 2000 to December 31, 2021. The prevalence of C. parvum infection in dairy calves was estimated using a random effects model, and the sources of heterogeneity were explored using meta-regression. In total, 118 datasets were included in the final quantitative analysis. The results showed that the global prevalence of C. parvum in dairy calves was 21.9% (7755/42,890; 95% confidence interval: 19.9-23.9%). C. parvum infection was high in pre-weaned dairy calves (24.9%, 6706/29,753) and diarrhea dairy calves (33.6%, 1637/6077). In countries with low dairy stocking density (<10 cows/farm), the prevalence of C. parvum in dairy calves was also relatively low (15.2%, 1960/16,584). Three subtype families [IIa (72.2%, 2293/3177), IId (27.4%, 872/3177), and IIl (0.4%, 12/3177)] were detected in dairy calves globally from selected studies. C. parvum IIa was the dominant zoonotic subtype. In the IIa subtype family of C. parvum, the proportions of subtypes from high to low (top nine) were IIaA15G2R1 (32.4%, 742/2293), IIaA18G3R1 (11.8%, 271/2293), IIaA13G2R1 (8.2%, 187/2293), IIaA16G1R1 (6.4%, 147/2293), IIaA20G1R1 (3.5%, 81/2293), IIaA16G3R1 (3.4%, 78/2293), IIaA17G2R1 (2.7%, 62/2293), IIaA18G1R1 (2.5%, 58/2293), and IIaA15G1R1 (2.4%, 56/2293). In the IId subtype family of C. parvum, the proportions of subtypes (top four) were IIdA19G1 (36.0%, 314/872), IIdA15G1 (27.3%, 238/872), IIdA20G1 (16.2%, 141/872), and IIdA14G1 (13.0%, 113/872). Furthermore, IId is commonly found in China (771/872). The study results indicated that the IIa subtype family is globally prevalent, while IId is found in Asia, Europe, and Africa and IIl is only found in Europe. Diarrhea in dairy calves is associated with C. parvum infection and a significantly higher prevalence is observed in diarrheic calves. Age and stock density are two significant risk factors in the prevalence of C. parvum in dairy calves. The prevention and control of this zoonosis in dairy calves should receive greater attention, especially in regions with a high degree of intensive dairy farming.

Follow-up investigation into Cryptosporidium prevalence and transmission in Western European dairy farms

Cryptosporidium parvum is an enteric parasite and a major contributor to acute enteritis in calves worldwide, causing an important economic burden for farmers. This parasite poses a major public health threat through transmission between livestock and humans. Our previous pilot study in Western Europe revealed a high prevalence of Cryptosporidium in calves of dairy farms. In the sequel study herein, 936 faecal samples were collected from the same 51 dairy farms across Belgium, France, and the Netherlands. Following DNA extraction, Cryptosporidium screening was carried out using nested-PCR amplification targeting the SSU rRNA gene. All positive samples were sequenced, and phylogenetic analyses were used to identify the Cryptosporidium spp. present. The 60 kDa glycoprotein (gp60) gene was also sequenced to determine the C. parvum subtypes present. Prevalence of Cryptosporidium ranged from 23.3% to 25%, across the three countries surveyed. The parasite was found in most of the farms sampled, with 90.2% testing positive. Cryptosporidium parvum, C. bovis, C. ryanae and C. andersoni were all identified, with the former being the most predominant, representing 71.4% of all infections. Cryptosporidium parvum was associated with pre-weaned calves, while other species were associated with older animals. Subtyping of gp60 gene revealed nine subtypes, eight of which have previously been reported to cause clinical disease in humans. Similarly to the first study, vertical transmission was not a major contributor to Cryptosporidium spread. Our study highlights the need for further investigation into cryptosporidiosis transmission, and future studies will require a One Health approach to reduce the impact of this disease.

High Occurrence of Zoonotic Subtypes of Cryptosporidiumparvum in Cypriot Dairy Farms

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

First identification of Cryptosporidium parvum zoonotic subtype IIaA15G2R1 in diarrheal lambs in France

To date, no information is available about the presence of Cryptosporidium spp. in French sheep, nor their potential role as zoonotic reservoirs. A total of 23 fecal samples were collected from diarrheic lambs (<11 days old) from seven randomly selected farms. Cryptosporidium-oocysts were detected microscopically with Direct Immunofluorescence Assays (DFA) in 23/23 (100%) of fecal samples. PCR-RFLP of the 18S rRNA gene was used to determine species in all samples, and only Cryptosporidium parvum was identified. Isolates were subtyped by sequencing the 60 kDa glycoprotein (gp60) gene. Two zoonotic subtypes within the IIa subtype family were identified, including IIaA15G2R1 (22/23) and IIaA16G3R1 (1/23). This study reports for the first time the identification and genotyping of zoonotic C. parvum subtypes from lambs in France. Sheep could thus play an important role as potential reservoirs for this zoonotic protist.

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.

Occurrence and genotyping of Giardia duodenalis and Cryptosporidium in pre-weaned dairy calves in central Sichuan province, China

Giardia duodenalis and Cryptosporidium spp. are common human and animal pathogens. They have increasingly been reported in dairy calves in recent years; however, multilocus genotyping information for G. duodenalis and Cryptosporidium infecting pre-weaned dairy calves in southwestern China is limited. In the present study, the prevalence of G. duodenalis and Cryptosporidium spp. in pre-weaned dairy calves in central Sichuan province was determined and the pathogens were analyzed molecularly. Of 278 fecal samples from pre-weaned dairy calves, 26 (9.4%) were positive for G. duodenalis and 40 (14.4%) were positive for Cryptosporidium spp. Cryptosporidium bovis (n = 28), Cryptosporidium ryanae (n = 5) and Cryptosporidium parvum (n = 7) were detected. All seven C. parvum isolates were successfully subtyped based on the gp60 gene sequence, and only IIdA15G1 was detected. Multilocus sequence typing of G. duodenalis based on beta-giardin (bg), triose phosphate isomerase (tpi) and glutamate dehydrogenase (gdh) genes revealed 19 different assemblage E multilocus genotypes (two known and 17 unpublished genotypes). Based on eBURST analysis, a high degree of genetic diversity within assemblage E was observed in pre-weaned dairy calves in Sichuan province. To the best of our knowledge, this is the first study using multilocus sequence typing and eBURST analysis to characterize G. duodenalis in pre-weaned dairy calves in southwestern China.

First report of Cryptosporidium parvum in a dromedary camel calf from Western Australia

Cryptosporidium is an important enteric parasite that can contribute large numbers of infectious oocysts to drinking water catchments. As a result of its resistance to disinfectants including chlorine, it has been responsible for numerous waterborne outbreaks of gastroenteritis. Wildlife and livestock play an important role in the transmission of Cryptosporidium in the environment. Studies conducted outside Australia have indicated that camels may also play a role in the transmission of zoonotic species of Cryptosporidium. Despite Australia being home to the world's largest camel herd, nothing is known about the prevalence and species of Cryptosporidium infecting camels in this country. In the present study, C. parvum was identified by PCR amplification and sequencing of a formalin-fixed intestinal tissue specimen from a one-week old dromedary camel (Camelus dromedarius). Subtyping analysis at the glycoprotein 60 (gp60) locus identified C. parvum subtype IIaA17G2R1, which is a common zoonotic subtype reported in humans and animals worldwide. Histopathological findings also confirmed the presence of large numbers of variably-sized (1-3 µm in diameter) circular basophilic protozoa - consistent with Cryptosporidium spp.- adherent to the mucosal surface and occasionally free within the lumen. Further analysis of the prevalence and species of Cryptosporidium in camel populations across Australia are essential to better understand their potential for contamination of drinking water catchments.

Molecular investigation of Cryptosporidium and Giardia in pre- and post-weaned calves in Hubei Province, China

Background

The protistan pathogens Cryptosporidium and Giardia can cause significant intestinal diseases in animals and humans. Cattle, particularly calves, carrying these protists can be significant reservoirs for human infections and disease. However, little is known about the genetic make-up of Cryptosporidium and Giardia populations in cattle and other ruminants in some regions of China.

Results

In the present study, PCR-based tools were used to genetically characterise these protists in faecal samples from a total of 339 pre- and post-weaned calves from four distinct locations in Hubei Province using markers in the large (LSU) or small (SSU) subunits of nuclear ribosomal RNA genes. Cryptosporidium andersoni, C. bovis, C. ryanae and Giardia duodenalis assemblage E were detected in 0.6%, 10.9%, 4.1% and 22.6% of calves, respectively.

Conclusions

This study is the first to report the prevalence of Cryptosporidium and Giardia in pre- and post-weaned calves in Hubei Province, and encourages large-scale molecular studies of animals and humans, in an effort to better understand the epidemiology of these enteric pathogens in China.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2463-3) contains supplementary material, which is available to authorized users.

Cryptosporidium spp. and Giardia spp. in feces and water and the associated exposure factors on dairy farms

The aims of this study were to verify the prevalence of Cryptosporidium spp. and Giardia spp. in animal feces and drinking water on dairy farms and to identify a possible relation between the exposure factors and the presence of these parasites. Fecal samples from cattle and humans and water samples were collected on dairy farms in Paraná, Brazil. Analysis of (oo)cysts in the feces was performed by the modified Ziehl-Neelsen staining and centrifugal flotation in zinc sulfate. Test-positive samples were subjected to nested PCR amplification of the 18SSU ribosomal RNA gene for identification of Cryptosporidium and Giardia and of the gp60 gene for subtyping of Cryptosporidium. Microbiological analysis of water was carried out by the multiple-tube method and by means of a chromogenic substrate, and parasitological analysis was performed on 31 samples by direct immunofluorescence and nested PCR of the genes mentioned above. Identification of the species of Cryptosporidium was performed by sequencing and PCR with analysis of restriction fragment length polymorphisms. The prevalence of Giardia and Cryptosporidium was higher in calves than in adults. Among the samples of cattle feces, Cryptosporidium parvum was identified in 41 (64%), C. ryanae in eight (12.5%), C. bovis in four (6.3%), C. andersoni in five (7.8%), and a mixed infection in 20 samples (31.3%). These parasites were not identified in the samples of human feces. Thermotolerant coliform bacteria were identified in 25 samples of water (45.5%). Giardia duodenalis and C. parvum were identified in three water samples. The gp60 gene analysis of C. parvum isolates revealed the presence of two strains (IIaA20G1R1 and IIaA17G2R2) in the fecal samples and one (IIaA17G2R1) in the water samples. The presence of coliforms was associated with the water source, structure and degradation of springs, rain, and turbidity. The prevalence of protozoa was higher in calves up to six months of age. C. parvum and G. duodenalis were identified in the water of dairy farms, as were thermotolerant coliforms; these findings point to the need for guidance on handling of animals, preservation of water sources, and water treatment.

A perspective on Cryptosporidium and Giardia, with an emphasis on bovines and recent epidemiological findings

Cryptosporidium and Giardia are two common aetiological agents of infectious enteritis in humans and animals worldwide. These parasitic protists are usually transmitted by the faecal-oral route, following the ingestion of infective stages (oocysts or cysts). An essential component of the control of these parasitic infections, from a public health perspective, is an understanding of the sources and routes of transmission in different geographical regions. Bovines are considered potential sources of infection for humans, because species and genotypes of Cryptosporidium and Giardia infecting humans have also been isolated from cattle in molecular parasitological studies. However, species and genotypes of Cryptosporidium and Giardia of bovids, and the extent of zoonotic transmission in different geographical regions in the world, are still relatively poorly understood. The purpose of this article is to (1) provide a brief background on Cryptosporidium and Giardia, (2) review some key aspects of the molecular epidemiology of cryptosporidiosis and giardiasis in animals, with an emphasis on bovines, (3) summarize research of Cryptosporidium and Giardia from cattle and water buffaloes in parts of Australasia and Sri Lanka, considering public health aspects and (4) provide a perspective on future avenues of study. Recent studies reinforce that bovines harbour Cryptosporidium and Giardia that likely pose a human health risk and highlight the need for future investigations of the biology, population genetics and transmission dynamics of Cryptosporidium and Giardia in cattle, water buffaloes and other ruminants in different geographical regions, the fate and transport of infective stages following their release into the environment, as well as for improved strategies for the control and prevention of cryptosporidiosis and giardiasis, guided by molecular epidemiological studies.

Cryptosporidium parvum GP60 subtypes in dairy cattle from Buenos Aires, Argentina

Cryptosporidium parvum from 73 dairy calves less than two months old from Buenos Aires province (Argentina) were molecularly characterized using sequence analysis of the GP60 gene. Seventy-five sequences were obtained, and seven different subtypes were identified, all belonging to the IIa subtype family. The most common subtypes were IIaA20G1R1 (27/75), IIaA22G1R1 (16/75), and IIaA18G1R1 (13/75). Subtypes IIaA21G1R1, IIaA23G1R1, IIaA16G1R1 and IIaA19G1R1 were found sporadically. Two samples contained mixed infections with IIaA21G1R1 and IIaA22G1R1. A significant association was found between subtypes and geographic location, whereas there was no relation between subtypes and presence of diarrhea. Three of the subtypes found in this study (IIaA16G1R1, IIaA18G1R1, and IIaA19G1R1) were previously identified in humans. These findings suggest that cattle could play an important role in the transmission of cryptosporidiosis to humans in Buenos Aires province.

Genetic characterization of selected parasites from people with histories of gastrointestinal disorders using a mutation scanning-coupled approach

A SSCP analysis and targeted sequencing approach was used for the genetic characterization of some major pathogens from a cohort of 227 people with histories of gastrointestinal disorders. Genomic DNAs from fecal samples were subjected to PCR-amplification of regions in the glycoprotein (gp60) or triose phosphate isomerase (tpi) gene, or the second internal transcribed spacer of nuclear ribosomal DNA (ITS-2). Cryptosporidium, Giardia, and strongylid nematodes were detected in 94, 132 and 12 samples. Cryptosporidium hominis subgenotypes IbA10G2, IdA15G1, IgA17, IgA18, and IfA13G1 were identified in 74.6, 16.9, 5.6, 1.4, and 1.4% of 71 samples, respectively. For Cryptosporidium parvum, subgenotypes IIaA17G2R1 (47.6%) and IIaA18G3R1 (23.8%) were identified in 23 samples. Giardia duodenalis assemblage B (78%) was more common than assemblage A (22%). In addition, DNA of the nematodes Ancylostoma ceylanicum (n = 2), Ancylostoma duodenale (4), Necator americanus (5), and Haemonchus contortus (1) was specifically detected. This is the first report of A. ceylanicum in two persons in Australia and, we provide molecular evidence of H. contortus in a child. This SSCP-based approach should provide a useful diagnostic and analytical tool for a wide range of pathogens.

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).

Comparative evaluation of two DNA isolation techniques for PCR-based diagnosis of gastrointestinal nematode infections in sheep

The specific diagnosis of gastrointestinal parasite infections in livestock is central to their control. PCR assays have been developed for routine diagnosis and to overcome limitations of classical methods. Central to the performance of such assays is the effective isolation of the nucleic acids from samples and the elimination of components that are inhibitory to PCR. Here, we directly compared two techniques for the isolation of DNA from strongylid nematode eggs from faecal samples from sheep, and assessed their performance in relation to the sensitivity and specificity of PCR, time required for DNA isolation and ease of use. The results showed differences in the performance of the two isolation techniques, subsequently effecting the PCR results. The main differences related to the time required for DNA isolation, and the elimination of inhibitory substances from the DNA isolated by one technique but not the other.

Genetic characterisation of Cryptosporidium and Giardia from dairy calves: discovery of species/genotypes consistent with those found in humans

Cryptosporidium and Giardia are important genera of parasitic protists that can cause significant diarrhoeal diseases in humans and other animals. Depending on the species/genotype of parasite, human infection may be acquired via anthroponotic or zoonotic transmission routes. Here, we undertook a molecular epidemiological investigation of these two genera of parasites in pre- and post-weaned calves from eight locations in Canterbury, New Zealand, by PCR-coupled sequencing and phylogenetic analysis of sequence data for regions in the 60 kDa glycoprotein (pgp60) gene of Cryptosporidium and/or the triose-phosphate isomerase (ptpi) gene of Giardia. The pgp60 and ptpi regions were specifically amplified from 15 (8.3%) and 11 (6.1%) of the 180 individual faecal samples, respectively. The sequences derived from all of the amplicons were aligned with homologous reference sequences and subjected to phylogenetic analysis by Bayesian inference. For Cryptosporidium, three samples contained Cryptosporidium parvum genotype IIa, subgenotypes IIaA15G3R1, IIaA19G3R1 and IIaA23G4. Twelve samples contained Cryptosporidium hominis genotype Ib, subgenotype IbA10G2R2. While subgenotypes IIaA15G3R1 and IIaA23G4 are new records, IIaA19G3R1 and IbA10G2R2 are commonly found in humans in various countries. For Giardia, two samples contained Giardia duodenalis assemblage A, also common in humans. In contrast, nine samples contained G. duodenalis assemblage E, which is the first report of this assemblage in cattle in New Zealand. Therefore, the present results indicate that dairy calves on the South Island of New Zealand harbour 'zoonotic' genotypes of Cryptosporidium and Giardia, which is likely to have significant public health implications.

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.

Evidence of Cryptosporidium transmission between cattle and humans in northern New South Wales

Cryptosporidium is an enteric parasite of public health significance that causes diarrhoeal illness through faecal oral contamination and via water. Zoonotic transmission is difficult to determine as most species of Cryptosporidium are morphologically identical and can only be differentiated by molecular means. Transmission dynamics of Cryptosporidium in rural populations were investigated through the collection of 196 faecal samples from diarrheic (scouring) calves on 20 farms and 63 faecal samples from humans on 14 of these farms. The overall prevalence of Cryptosporidium in cattle and humans by PCR and sequence analysis of the 18S rRNA was 73.5% (144/196) and 23.8% (15/63), respectively. Three species were identified in cattle; Cryptosporidium parvum, Cryptosporidium bovis and Cryptosporidium ryanae, and from humans, C. parvum and C. bovis. This is only the second report of C. bovis in humans. Subtype analysis at the gp60 locus identified C. parvum subtype IIaA18G3R1 as the most common subtype in calves. Of the seven human C. parvum isolates successfully subtyped, five were IIaA18G3R1, one was IIdA18G2 and one isolate had a mix of IIaA18G3R1 and IIdA19G2. These findings suggest that zoonotic transmission may have occurred but more studies involving extensive sampling of both calves and farm workers are needed for a better understanding of the sources of Cryptosporidium infections in humans from rural areas of Australia.

Longitudinal and spatial distribution of GP60 subtypes in human cryptosporidiosis cases in Ireland

Within Europe, Ireland has one of the highest reported infection rates with the diarrhoeal protozoan pathogen Cryptosporidium. In this study 249 Cryptosporidium parvum isolates collected from Irish patients between 2000 and 2009 were subtyped by sequence analysis of the GP60 locus. A subsample of 127 isolates was also typed at the MS1 and ML1 loci. GP60 subtype IIaA18G3R1 was the predominant subtype in every year and every season throughout the country. Over the 10-year period there was no evidence that host immunity to the predominant subtype caused a shift in its prevalence. Length frequency distributions of the GP60 TCA/TCG repeats compiled from published data, showed distinct patterns for countries with predominantly zoonotic or anthroponotic transmission cycles, respectively. Although considered to be mostly affected by zoonotic cryptosporidiosis, the GP60 fragment length of Irish C. parvum isolates mirrored that of countries with predominantly human-to-human transmission, indicating more complex routes of infection between livestock and humans. Due to their homogeneity, ML1 and MS1 were not considered useful loci for subtyping C. parvum strains in Ireland.

Characteristics of Cryptosporidium transmission in preweaned dairy cattle in Henan, China

To estimate the prevalence and public health significance of cryptosporidiosis in preweaned calves in China, 801 fecal samples from eight farms in seven areas in Henan Province were examined for Cryptosporidium oocysts. The overall infection rate of Cryptosporidium was 21.5%, with the farm in Xinxiang having the highest prevalence (40%). No significant difference in infection rates was observed between seasons. Cryptosporidium spp. were characterized by PCR-restriction fragment length polymorphism (RFLP) analysis of the small subunit (SSU) rRNA gene and DNA sequencing of the 60-kDa glycoprotein (gp60) gene. The SSU rRNA-based PCR identified four Cryptosporidium species, including Cryptosporidium parvum (54/172), C. bovis (65/172), C. ryanae (19/172), and C. andersoni (12/172), and the occurrence of infections with mixed species (22/172). The earliest detection of C. bovis was in calves of 1 week of age, showing that the prepatent period was shorter than the previously stated 10 to 12 days. Infections with C. parvum peaked in summer, whereas C. bovis dominated in autumn and winter. There was no apparent difference in the age of cattle infected with either C. parvum or C. bovis. Sequencing analysis of the gp60 gene showed all 67 C. parvum samples belonged to subtype IIdA19G1. These findings suggested that the transmission of Cryptosporidium spp. in preweaned calves in Henan, China, appeared to be different from other areas both at genotype and subtype levels. Further molecular epidemiologic studies (including samples from both calves and humans) are needed to elucidate the transmission dynamics and public significance of C. parvum in cattle in China.

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).

Genetic richness and diversity in Cryptosporidium hominis and C. parvum reveals major knowledge gaps and a need for the application of "next generation" technologies--research review

Cryptosporidium species (apicomplexan protists) are a major cause of diarrhoeal disease (= cryptosporidiosis) in humans worldwide. The impact of cryptosporidiosis is also compounded by the spread of HIV/AIDS and a lack of cost-effective anti-cryptosporidial chemotherapeutics or vaccines. Mitigation of the impact of cryptosporidiosis in humans needs to focus on prevention and control strategies, built on a sound understanding of the epidemiology of Cryptosporidium species. Refined epidemiological studies rely on the use of molecular tools employing informative genetic markers. Currently, the 60-kDa glycoprotein gene (gp60) is the most suitable and widely used genetic marker for Cryptosporidium species infecting humans. Here, we undertake an analysis of all publicly-available gp60 sequence data and associated literature for C. hominis and C. parvum, and yield useful insights into the richness, diversity and distribution of genetic variants, and link these variants to human cryptosporidiosis. This global analysis reveals that, despite high genetic richness in Cryptosporidium isolates from humans, there is a surprisingly low diversity. It also highlights limited knowledge about the genetics of cryptosporidiosis in developing nations and in many animals that might act as infection sources. Clearly, there is a major need for more comprehensive studies of Cryptosporidium infecting humans and other animals in Africa and Asia. As molecular technologies improve and become affordable, future studies should utilize "next generation" sequencing and bioinformatic platforms to conduct comparative 'genome sequence surveys' to test the validity of current genetic classifications based on gp60 data. Complemented by in vitro and in vivo investigations, these biotechnological advances will also assist significantly in the search for new intervention strategies against human cryptosporidiosis.

Comparative efficacy of conventional primer sets in detection of Cryptosporidium parvum for diagnostic use

In this study, the sensitivity and specificity of different previously described primer sets for Cryptosporidium parvum detection by polymerase chain reaction (PCR) was evaluated. For this purpose, the primer sets defined by Cacciò et al. (FEMS Microbiol Lett 170(1):173-179, 1999) (tub), Widmer et al. (Appl Environ Microbiol 64(11):4477-4481, 1998) (btub) and Rochelle et al. (Appl Environ Microbiol 63:2029-2037, 1997) (cphsp), respectively, were used. Deoxyribonucleic acid (DNA) was isolated from three different sample materials: (1) from the faeces of an experimentally C. parvum-infected calf, (2) from purified C. parvum oocysts, and (3) from C. parvum-infected HCT-8 cell cultures. The DNA samples were subjected to PCR reactions with each of the three given primer sets to investigate sensitivity and suitability for routine use. The primers described by Cacciò et al. (FEMS Microbiol Lett 170(1):173-179, 1999) (TUB) were superior regarding sensitivity and specificity in terms of detection of C. parvum in faeces, in purified oocysts and also in cell culture, and may thus be applied for routine diagnostic use in common sample materials.