Cryptosporidium in farmed animals: the detection of a novel isolate in sheep

Prevalence and Characterization of Cryptosporidium Species and Genotypes in Four Farmed Deer Species in the Northeast of China

Cryptosporidiosis is a major public health problem in humans and animals. Information on the prevalence and molecular diversity of Cryptosporidium in farmed deer in northeastern China is limited. In this study, the prevalence of these parasites was investigated in four farmed deer species, including 125 reindeer, 109 red deer, 86 sika deer, and 18 Siberian roe deer by nested PCR amplification of the partial small subunit of ribosomal RNA (SSU rRNA) gene. C. ubiquitum isolates were subtyped using nested PCR and sequence analysis of the 60-kDa glycoprotein (gp60) gene. The overall prevalence of Cryptosporidium was 7.1%, with 15.1% for sika deer, 4.0% for reindeer, 4.6% for red deer, and 5.6% for roe deer. C. ubiquitum (n = 4), C. xiaoi (n = 2), and Cryptosporidium deer genotype (n = 18) were identified. All four C. ubiquitum isolates belonged to the XIIa subtype (n = 4). This study confirms that Cryptosporidium deer genotype is widely occurring in deer in the investigated areas. Presence of zoonotic C. ubiquitum XIIa subtype indicates that farmed deer represent potential source of zoonotic cryptosporidia and might pose a threat to human health.

Cryptosporidium and Giardia in Ruminants

Cryptosporidium and Giardia are ubiquitous protozoan parasites that infect a broad range of vertebrate hosts, including domestic and wild animals as well as humans. Both parasites are of medical and veterinary importance. Infections with Cryptosporidium and Giardia in ruminants are associated with diarrhea outbreaks, mainly in young animals. Ruminants are potential sources of infection for humans because some species of Cryptosporidium and assemblages of Giardia duodenalis have been isolated from both ruminants and humans. Knowledge of these parasites has greatly expanded in the last 2 decades from simple microscopic observations of organisms to the knowledge acquired from molecular tools.

First report of Cryptosporidium sp. infection in sheep population of Ladakh, India

Ladakh is the high altitude (11,184 ft above sea level) cold desert region in the state of Jammu & Kashmir (India), where winter temperature goes below - 35 °C. A total of 37 faecal samples were collected from local Changthangi and Russian merino sheep of the Leh region of Ladakh, having the history of diarrhoea and emaciation, followed by death. Of the 37 samples collected, 20 (54.05%) showed presence of Cryptosporidium sp. infection on faecal smear examination after Ziehl-Neelsen staining. The number of samples positive for Cryptosporidium sp. infection on faecal smear examination was 7 and 13 for Russian Merino and local Changthangi sheep, respectively. The occurrence of Cryptosporidium sp. infection was similar in both sexes, 11/20 (55%) in females and 9/20 (45%) for males. The Age-wise occurrence of Cryptosporidium sp. infection in different age groups was found to be: 50% in less than 2 year age group and 50% in more than 2 year age group. To the best of our knowledge, this is the first report of Cryptosporidium sp. infection in adult sheep from India. The survival of the parasite at such freezing temperature gives the insight about its cold-resistant nature.

Distribution of Cryptosporidium parvum gp60 subtypes in calf herds of Saxony, Germany

Cryptosporidiosis is a common protozoan parasitic infection that causes diarrhoea in neonatal calves. The high shedding of environmentally resistant oocysts facilitates outbreaks of cryptosporidiosis in humans. In total, 58 farms (512 calves) in Germany (Saxony and Brandenburg) were visited three times each. Faecal samples of pre-weaned calves were microscopically examined for oocysts of Cryptosporidium spp. using Heine staining and were scored with regard to their consistency. Overall, 88.9% of calves tested microscopically positive for Cryptosporidium spp. in at least one sample, and the excretion of oocysts was significantly (P < 0.01) associated with a higher faecal score (diarrhoea). After DNA extraction from pooled farm isolates, 47 samples were successfully subtyped by sequence analysis of the 60 kDa glycoprotein gene (gp60). All isolates belonged to subtype family IIa. IIaA15G2R1 was the most common subtype (present on 66% of the farms), followed by IIaA16G3R1 (13%). Subtypes IIaA14G1R1, IIaA14G2R1, IIaA1612R1, IIaA16G2R1, IIaA17G1R1, IIaA17G2R1, IIaA17G4R1 and IIaA19G2R1 were found sporadically. This is the first description of gp60 subtype IIaA17G4R1 in cattle in Germany.

Sheep as a Potential Source of Zoonotic Cryptosporidiosis in China

In this study, we assessed the prevalence and genetic characteristics of Cryptosporidium in sheep from 10 provinces in China. Fecal samples from 1,035 sheep originating from 16 farms were collected, and 295 (28.5%) were found to be Cryptosporidium positive by nested PCR. Cryptosporidium was detected at all farms, with infection rates between 5.7% and 50.0%. Three Cryptosporidium species were identified, including Cryptosporidium xiaoi (73.2%, 216/295), Cryptosporidium ubiquitum (21.7%, 64/295), and Cryptosporidium parvum (5.1%, 15/295). The distribution of Cryptosporidium species differed by province and by farm. All three species were detected in lambs and adult sheep but the highest infection rate was found in postweaned lambs. All three species were detected in all four seasons, with the highest prevalence found in autumn. Four C. parvum subtypes (IIaA15G2R1, IIaA17G2R1, IIdA18G1, and IIdA19G1) and one C. ubiquitum subtype (XIIa) were identified. For most provinces in this study, we are not aware of a previously published description or molecular characterization of Cryptosporidium infections in sheep. This information will improve our knowledge and understanding of the epidemiology of cryptosporidiosis in China.IMPORTANCECryptosporidium is an important zoonotic parasite that causes diarrhea in humans and animals worldwide. Previous studies suggested geographic differences in the distribution of Cryptosporidium species in sheep. However, molecular characterization studies of Cryptosporidium species in sheep have been carried out in only a few provinces in China, and the limited data available do not reflect the real situation. In this study, five districts, covering most areas where sheep are bred in China, were selected for examination of Cryptosporidium species, and Cryptosporidium infections were detected at all farms assessed, suggesting that Cryptosporidium is widespread in sheep in China. We also found geographic differences in the distribution of Cryptosporidium species but did not detect any differences between sheep age groups or seasons. Subtyping analyses showed that all of the subtypes identified in this study have been reported in humans, suggesting that sheep may be a potential source of zoonotic cryptosporidiosis.

Cryptosporidium species and Cryptosporidium parvum subtypes in dairy calves and goat kids reared under traditional farming systems in Turkey

Molecular characterizations of Cryptosporidium spp. in ruminants reared under traditional animal management systems are scarce and studies conducted thus far have revealed largely an absence of the pathogenic and zoonotic species Cryptosporidium parvum in pre-weaned animals. In this study, we examined Cryptosporidium species and subtype distribution in free-range pre-weaned dairy calves and goat kids with diarrhea. Cryptosporidium-positive specimens from pre-weaned calves on 10 farms and goat kids on 4 farms in Ankara, Balikesir, Corum, Kirikkale, and Kirsehir Provinces, Turkey were genotyped by PCR-restriction length polymorphism analysis of the small subunit rRNA gene, which identified C. parvum in 27 calves and 9 goat kids and Cryptosporidium ryanae in 1 calf. Among the C. parvum isolates successfully subtyped by DNA sequence analysis of the 60 kDa glycoprotein gene, three subtypes were detected in calves, including IIaA13G2R1 (20/23), IIdA18G1 (2/23), and IIdA20G1b (1/23), and four subtypes were detected in goat kids, including IIaA13G2R1 (3/8), IIaA15G1R1 (2/8), IIdA22G1 (2/8), and IIdA18G1 (1/8). Data of the study suggest that dairy calves reared in a traditional cow-calf system in Turkey are mainly infected with a C. parvum subtype rarely seen elsewhere, whereas goat kids are infected with diverse subtypes. As all five C. parvum subtypes found in this study are known human pathogens, pre-weaned farm animals could play a potential role in the transmission of human cryptosporidiosis.

Prevalence of Cryptosporidium in small ruminants from Veracruz, Mexico

BACKGROUND

Cryptosporidiosis is a zoonotic disease caused by the protozoan parasite Cryptosporidium spp. that can affect domestic animal and human populations. In newborn ruminants, cryptosporidiosis is characterized by outbreaks of diarrhea, which can result in high morbidity and economic impact. The aim of the present study was to determine the prevalence of Cryptosporidium spp. in small ruminants from the Perote municipality in Veracruz State, Mexico. One hundred and sixty small ruminants (80 sheep and 80 goats) from eight farms located in four towns of the Perote municipality were examined following a cross-sectional study design. Stool samples were analyzed by a modification of the Faust centrifugation method, and the presence of Cryptosporidium spp. oocysts was examined using a modification of the Ziehl-Neelsen staining procedure. Bivariate and multivariate analyses were used to assess the association of Cryptosporidium infection and the general characteristics of the animals studied.

RESULTS

Overall, 112 (70%, 95% CI: 62.3-76.9) of the 160 small ruminants sampled were infected with Cryptosporidium spp. The prevalence of Cryptosporidium spp. infection in goats was 72.5% (95% CI: 61.4-81.9) and in sheep 67.5% (95% CI: 56.1-77.6). Small ruminants aged 1 month old had the highest (88.2%; 95% CI: 63.6-98.5) prevalence of infection. Prevalence varied from 60% to 85% among herds. Animal species, age, sex, breed, farm, town or cohabitation with cattle did not influence the prevalence of Cryptosporidium infection.

CONCLUSIONS

A high prevalence of infection with Cryptosporidium spp. was observed in small ruminants from the Perote municipality in Veracruz, Mexico. Infection was widely distributed among sheep and goats regardless of their age, breed or farm location. Further research is required to identify risk factors for, and to assess the veterinary public health significance of Cryptosporidium infection among sheep and goats in the Mexican state of Veracruz.

Description of a novel viral tool to identify and quantify ovine faecal pollution in the environment

Farmed animals such as sheep, cattle, swine and poultry play an important role in microbial contamination of water, crops and food, and introduce large quantities of pathogens into the environment. The ability to determine the origin of faecal pollution in water resources is essential when establishing a robust and efficient water management system. Animal-specific viruses have previously been suggested as microbial source tracking tools, but specific ovine viral markers have not been reported before now. Previous studies have shown that polyomaviruses are host-specific, highly prevalent and are commonly excreted in urine. Furthermore, they have been reported to infect several vertebrate species but not sheep. That situation encouraged the study of a new putative ovine polyomavirus (OPyV) and its use to determine whether faecal pollution originates from ovine faecal/urine contamination. Putative OPyV DNA was amplified from ovine urine and faecal samples using a broad-spectrum nested PCR (nPCR). Specific nested PCR and quantitative PCR assays were developed and applied to faecal and environmental samples, including sheep slurries, slaughterhouse wastewater effluents, urban sewage and river water samples. Successful amplification by PCR was achieved in sheep urine samples, sheep slaughterhouse wastewater and downstream sewage effluents. The assay was specific and was negative in samples of human, bovine, goat, swine and chicken origin. Ovine faecal pollution was detected in river water samples by applying the designed methods. These results provide a quantitative tool for the analysis of OPyV as a suitable viral indicator of sheep faecal contamination that may be present in the environment.

Genetic diversity of Cryptosporidium spp. within a remote population of Soay Sheep on St. Kilda Islands, Scotland

This is the first report to characterize the genotypes and subtypes of Cryptosporidium species infecting a geographically isolated population of feral Soay sheep (Ovis aries) on Hirta, St. Kilda, Scotland, during two distinct periods: (i) prior to a population crash and (ii) as host numbers increased. Cryptosporidium DNA was extracted by freeze-thawing of immunomagnetically separated (IMS) bead-oocyst complexes, and species were identified following nested-PCR-restriction fragment length polymorphism (RFLP)/PCR sequencing at two Cryptosporidium 18S rRNA loci. Two hundred fifty-five samples were analyzed, and the prevalent Cryptosporidium species in single infections were identified as C. hominis (11.4% of all samples tested), C. parvum (9%), C. xiaoi (12.5%), and C. ubiquitum (6.7%). Cryptosporidium parvum was also present with other Cryptosporidium species in 27.1% of all samples tested. Cryptosporidium parvum- and C. hominis-positive isolates were genotyped using two nested-PCR assays that amplify the Cryptosporidium glycoprotein 60 gene (GP60). GP60 gene analysis showed the presence of two Cryptosporidium genotypes, namely, C. parvum IIaA19G1R1 and C. hominis IbA10G2. This study reveals a higher diversity of Cryptosporidium species/genotypes than was previously expected. We suggest reasons for the high diversity of Cryptosporidium parasites within this isolated population and discuss the implications for our understanding of cryptosporidiosis.

Identification of Cryptosporidium xiaoi in diarrhoeic goat kids (Capra hircus) in Spain

Faecal specimens from five diarrhoeic goat kids (Capra hircus) younger than 21 days were collected in a goat farm in Galicia (NW Spain) and examined for the presence of Cryptosporidium oocysts. Two Cryptosporidium-positive isolates were detected and selected for molecular examination. A banding pattern indicative of Cryptosporidium bovis was obtained after restriction analyses of PCR products from small-subunit rRNA genes. However, both positive isolates were identified as Cryptosporidium xiaoi by sequence analyses of SSU rRNA and actin genes. Our results demonstrate that domestic goats are a host for C. xiaoi and suggest that this parasite species may be involved in the aetiology of neonatal diarrhoeic outbreaks in goat farms. This is the first published description of C. xiaoi in goat kids in Spain.

Cryptosporidium ubiquitum n. sp. in animals and humans

A new species, Cryptosporidium ubiquitum, previously identified as the Cryptosporidium cervine genotype and infrequently as the cervid, W4 or genotype 3 genotype, is described. In published studies this genotype was reported in wild and domesticated ruminants, rodents, carnivores and primates including humans. In the present study oocysts were found in feces from a captive prehensile-tailed porcupine and her infant. Oocysts from the porcupine were transmitted to 4 boer goats. Oocysts from the goats were transmitted to a calf (calf 1) and oocysts from calf 1 were transmitted to gerbils and BALB/c mouse pups. Calf 2 housed near calf 1 became contaminated and excreted oocysts of C. ubiquitum. Oocysts collected from calf 2 were transmitted to a calf 3. When calf 2 stopped excreting C. ubiquitum oocysts it was challenged with oocysts of C. parvum and became infected, indicating a lack of cross-species immunity. Oocysts of C. ubiquitum from calf 1 measured 4.71-5.32 microm x 4.33-4.98 microm (mean=5.04 microm x4.66 microm) with a length/width shape index of 1.08 (n=50). Purified PCR products of the SSU rRNA, actin and COWP genes were sequenced and analysis of the 3 unlinked loci demonstrated the new species to be distinct from all other species and also demonstrated a lack of recombination, providing further evidence of species status. Based on morphological, molecular and biological data, this geographically widespread parasite infectious for a wide range of mammalian hosts is recognized as a new species and is named C. ubiquitum.

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.

Cryptosporidium xiaoi n. sp. (Apicomplexa: Cryptosporidiidae) in sheep (Ovis aries)

A new species, Cryptosporidium xiaoi, is described from sheep. Oocysts of C. xiaoi, previously identified as the Cryptosporidium bovis-like genotype or as C. bovis from sheep in Spain, Tunisia, United Kingdom, and the United States are recorded as such in GenBank (EU408314-EU408317, EU327318-EU327320, EF362478, EF514234, DQ991389, and EF158461). Oocysts obtained from naturally infected sheep were infectious for a lamb and oocysts from that lamb were infectious for three other lambs. The prepatent period for C. xiaoi in these four Cryptosporidium-naive lambs was 7-8 days and the patent period was 13-15 days. Oocysts are similar to those of C. bovis but slightly smaller, measuring 2.94-4.41 microm x 2.94-4.41 microm (mean=3.94 microm x 3.44 microm) with a length/width shape index of 1.15 (n=25). Oocysts of C. xioai were not infectious for BALB/c mice, Bos taurus calves, or Capra aegagrus hircus kids. Fragments of the SSU-rDNA, HSP-70, and actin genes were amplified by PCR, purified, and PCR products were sequenced. The new species was distinct from all other Cryptosporidium species as demonstrated by multi-locus analysis of the 3 unlinked loci. Based on morphological, molecular and biological data, this geographically widespread parasite found in Ovis aries is recognized as a new species and is named C. xiaoi.

Microbiological surveillance of private water supplies in England: the impact of environmental and climate factors on water quality

A passive surveillance system captured information on 34,904 microbiological samples from 11,233 private drinking water supplies within England as well as the associated constructional, climatic and environmental variables. Escherichia coli was detected in 6588 (18.87%) of samples and at least one positive sample was detected from 3638 (32.39%) of sites. However, this estimate of supplies failing to meet the European drinking water E. coli standard was probably an underestimate as the more samples taken per supply, the more likely the supply was to fail. A multivariable model of private water supplies data showed a strong seasonal impact, with samples between January and May being significantly less contaminated with E. coli than samples between June and December. Samples from springs (OR 2.5, CI 2.0-3.1) or surface waters (OR 2.4, CI 0.8-7.0) were more likely to fail than groundwater sources, as were supplies with no effective treatment (OR1.8, CI 1.5-2.3). Commercial supplies were less likely to fail than domestic supplies (OR 0.63, CI 0.48-0.83) and the probability of failure was linearly associated with the density of sheep in the area and rainfall on the previous day. A Monte Carlo modelling approach was used to estimate that, had sufficient samples been taken, 54% (95% confidence intervals 49-59%) of all private water supplies in England were likely to be unsatisfactory. These findings will be able to inform risk assessments of private water supplies prior to microbiological results being available.

GiardiaandCryptosporidiuminfections in sheep and goats: a review of the potential for transmission to humans via environmental contamination

The public health significance of giardiasis and cryptosporidiosis in sheep is currently unclear. Some research suggests that they are probably not an important zoonotic reservoir, whilst other research indicates this potential exists, and some outbreaks have also been associated with infections in sheep. Actions to limit water supply contamination by sheep have sometimes been severe, occasionally creating problems between farming and public health communities. Here our knowledge on these parasites in both sheep and goats is reviewed; although direct evidence of transmission to humans via water supply contamination is limited, the data accrued indicate that this is a real possibility. As cryptosporidiosis in sheep is generally more prevalent than giardiasis, and species/genotypes ofCryptosporidiuminfections in sheep are likely to be infectious to humans, this parasite may be considered the greater threat. Nevertheless, geographical variation in prevalence and genotypic distribution is extensive and as measures to limit sheep grazing can have a highly negative impact, it is important that cases are judged individually. If water contamination from a particular population of sheep/goats is suspected, then suitable investigations should be instigated, investigating both prevalence and species/genotype, before precautionary measures are imposed.

Analysis of the genetic diversity within Cryptosporidium hominis and Cryptosporidium parvum from imported and autochtonous cases of human cryptosporidiosis by mutation scanning

The present study investigated sequence variation in part of the 60 kilodalton glycoprotein (pgp60) gene among Cryptosporidium hominis and Cryptosporidium parvum isolates (n=115) from citizens of the UK inferred to have been infected whilst travelling abroad (to 25 countries) or in the UK. The genomic DNA samples from these isolates were subjected to PCR-coupled single-strand conformation polymorphism analysis, followed by targeted sequencing of pgp60. Individual samples were classified to the genotypic and subgenotypic levels based on phylogenetic analysis (Bayesian inference) of pgp60 data, including published sequences for comparison. Based on this analysis, five C. hominis (Ia-If) and four C. parvum (IIa, IIc-IIe) genotypes were identified, equating to 16 and 10 subgenotypes, respectively. Of these genotypes, C. hominis Ib was predominant (n=82). Interestingly, one subgenotype (C. hominis Ib A10G2R2) accounted for the majority of the samples examined and was identified in travellers to 14 countries; the examination of published records suggested that C. hominis Ib A10G2R2 has a global distribution. Numerous new and seemingly rare subgenotypes (eight for C. hominis and six for C. parvum) were also discovered. In conclusion, the present study revealed substantial genetic variation in pgp60 within both C. hominis and C. parvum and emphasizes the need to undertake investigations of human and animal populations in countries for which there is no information on the genetic make-up of Cryptosporidium infecting humans.

Cryptosporidium genotypes and subtypes in lambs and goat kids in Spain

To provide information on the transmission dynamics of cryptosporidial infections in domestic small ruminants and the potential role of sheep and goats as a source for human cryptosporidiosis, Cryptosporidium-positive isolates from 137 diarrheic lambs and 17 goat kids younger than 21 days of age were examined by using genotyping and subtyping techniques. Fecal specimens were collected between 2004 and 2006 from 71 sheep and 7 goat farms distributed throughout Aragón (northeastern Spain). Cryptosporidium parvum was the only species identified by restriction analyses of PCR products from small-subunit rRNA genes from all 154 microscopy-positive isolates and the sequencing of a subset of 50 isolates. Sequence analyses of the glycoprotein (GP60) gene revealed extensive genetic diversity within the C. parvum strains in a limited geographical area, in which the isolates from lambs exhibited 11 subtypes in two subtype families (IId and IIa) and those from goat kids displayed four subtypes within the family IId. Most isolates (98%) belonged to the subtype family IId, whereas only three isolates belonged to the most widely distributed family, IIa. Three of the four most prevalent subtypes (IIdA17G1a, IIdA19G1, and IIdA18G1) were previously identified in humans, and five subtypes (IIdA14G1, IIdA15G1, IIdA24G1, IIdA25G1, and IIdA26G1) were novel subtypes. All IId subtypes were identical to each other in the nonrepeat region, except for subtypes IIdA17G1b and IIdA22G1, which differed by a single nucleotide polymorphism downstream of the trinucleotide repeats. These findings suggest that lambs and goat kids are an important reservoir of the zoonotic C. parvum subtype family IId for humans.

Distribution of Cryptosporidium species in sheep in the UK

There have been few studies of the distribution of Cryptosporidium species and genotypes in sheep, and the anthropozoonotic potential has been questioned since one of the major human pathogens, Cryptosporidium parvum, is not always found. To investigate the situation in the UK we undertook three studies: a reactive sampling programme of flocks identified as exposures for human cases of cryptosporidiosis; investigation of neonatal cryptosporidiosis in lambs; and a screening programme of lambs at an open farm. C. parvum was the only species found in neonatal lambs with cryptosporidiosis and predominated in flocks sampled reactively to a human case of cryptosporidiosis. C. bovis was also found in the latter study but at a lower frequency than C. parvum. C. bovis and the cervine genotype were found in the orphan lambs under the screening programme. The results of these studies show that C. parvum is important in neonatal lamb diarrhoea and is widespread in sheep flocks in the UK, but that other Cryptosporidium species and genotypes are also present. Sheep, and young lambs in particular, must still be considered as a source of C. parvum infection for humans.

Serological responses to Cryptosporidium in human populations living in areas reporting high and low incidences of symptomatic cryptosporidiosis

One approach to investigating differences in the reported incidence of disease is to measure the extent of exposure to the organism in question by testing for a specific antibody response. IgG responses to Cryptosporidium sporozoite antigens of low molecular size in adults have been shown to be consistent and of sufficient intensity to act as reliable markers of exposure. This study used a western blot procedure to investigate the relative intensity of IgG antibody responses to the 15/17-kDa Cryptosporidium sporozoite antigen complex and the 27-kDa antigen in sera from two cities in north-west England: Liverpool (low numbers of clinical cases reported) and Preston (high numbers reported). The intensity of antibody response to the 15/17-kDa antigen complex was significantly greater in the Liverpool sera, but there was no significant difference in intensity of response to the 27-kDa antigen. The relationship between diagnosed and reported cryptosporidiosis infections and infections identified by serological testing is complex, but could indicate a protective effect resulting from either exposure to non-pathogenic strains or from repeated low-level exposure to pathogenic strains.

Prevalence and molecular characterization of Cryptosporidium and Giardia species and genotypes in sheep in Maryland

In the United Kingdom and Australia sheep have been implicated as sources of Cryptosporidium and Giardia that infect humans, but no such studies have been conducted in North America. Therefore, a study was undertaken to investigate the prevalence of these parasites in sheep on a farm in Maryland. Feces were collected from 32 pregnant ewes 1, 2, and 3 days after parturition and from each of their lambs 7, 14, and 21 days after birth. The presence of Cryptosporidium oocysts and Giardia cysts was determined by both immunofluorescence microscopy and PCR/gene sequence analysis. PCR was consistently more sensitive than microscopy. The prevalence, by PCR, of Cryptosporidium in ewes and lambs was 25 and 77.4%, respectively. Three species/genotypes of Cryptosporidium were identified: C. parvum, a novel C. bovis-like genotype, and Cryptosporidium cervine genotype. Cryptosporidium parvum and the cervine genotype have been reported worldwide in human infections. The novel C. bovis-like genotype is reported here for the first time. The prevalence of Giardia in ewes and lambs was 12 and 4%, respectively. Most infections were Assemblage E which is not zoonotic; however, one ewe was infected with zoonotic Assemblage A. The identification of only two lambs infected with C. parvum and one ewe infected with G. duodenalis Assemblage A suggests a low prevalence of these zoonoses. However, the high prevalence of the zoonotic cervine genotype indicates that sheep should be considered a potential environmental source of this human pathogen.

Investigation of potential zooanthroponotic transmission of cryptosporidiosis and giardiasis through agricultural use of reclaimed wastewater

A field study in the Juarez Valley of Mexico was performed to investigate the potential transmission of Cryptosporidium and Giardia to sheep livestock grazing on forage irrigated with reclaimed wastewater, and the potential for disease transmission back to humans. United States Environmental Protection Agency Method 1623 immunofluorescent assay (IFA) revealed high levels of pathogens in reclaimed wastewater, with 183 to >7000 Giardia cysts and 9 - 762 Cryptosporidium oocysts detected per litre. Infectious Cryptosporidium were detected in the reclaimed wastewater using the cell culture focus detection method (FDM). Polymerase chain reaction (PCR) analyses revealed reclaimed wastewater contained the C. parvum bovine (zoonotic) genotype, human-specific C. hominis subgenotypes, and G. lamblia (syn. G. duodenalis, G. intestinalis) Assemblage A genotypes (A2 and A3). Despite high levels of Cryptosporidium and Giardia in the reclaimed wastewater, these pathogens were rarely found on the forage plants, possibly due to environmental attenuation. Sheep fecal specimens were positive for only livestock-associated G. lamblia Assemblage E genotypes. Therefore, in this field study, there was no evidence of zooanthroponotic transmission of Cryptosporidium or Giardia.

Sheep may not be an important zoonotic reservoir for Cryptosporidium and Giardia parasites

Little is known of the prevalence of Cryptosporidium and Giardia parasites in sheep and the genotypes that they harbor, although potentially sheep may contribute significantly to contamination of watersheds. In the present study, conducted in Western Australia, a total of 1,647 sheep fecal samples were screened for the presence of Cryptosporidium and Giardia spp. using microscopy, and a subset (n = 500) were screened by PCR and genotyped. Analysis revealed that although both parasites were detected in a high proportion of samples by PCR (44% and 26% for Giardia and Cryptosporidium spp., respectively), with the exception of one Cryptosporidium hominis isolate, the majority of isolates genotyped are not commonly found in humans. These results suggest that the public health risk of sheep-derived Cryptosporidium and Giardia spp. in catchment areas and effluent may be overestimated and warrant further investigation.

Direct comparison of selected methods for genetic categorisation of Cryptosporidium parvum and Cryptosporidium hominis species

A study was undertaken to compare the performance of five different molecular methods (available in four different laboratories) for the identification of Cryptosporidium parvum and Cryptosporidium hominis and the detection of genetic variation within each of these species. The same panel of oocyst DNA samples derived from faeces (n=54; coded blindly) was sent for analysis by: (i) DNA sequence analysis of a fragment of the HSP70 gene; (ii) DNA sequence analysis and the ssrRNA gene in laboratory 1; (iii) single-strand conformation polymorphism analysis of part of the ssrRNA; (iv) SSCP analysis of the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA region in laboratory 2; (v) 60 kDa glycoprotein (gp60) gene sequencing with prior species determination using PCR with restriction fragment length polymorphism analysis of the ssrRNA gene in laboratory 3; and (vi) multilocus genotyping at three microsatellite markers in laboratory 4. For detecting variation within C. parvum and C. hominis, SSCP analysis of ITS-2 was considered to have superior utility and determined 'subgenotypes' in samples containing DNA from both species. SSCP was also most cost effective in terms of time, cost and consumables. Sequence analysis of gp60 and microsatellite markers ML1, ML2 and 'gp15' provided good comparators for the SSCP of ITS-2. However, applicability of these methods to other Cryptosporidium species or genotypes and to environmental samples needs to be evaluated. This trial provided, for the first time, a direct comparison of multiple methods for the genetic characterisation of C. parvum and C. hominis samples. A protocol has been established for the international distribution of samples for the characterisation of Cryptosporidium. This can be applied in further evaluation of molecular methods by investigation of a larger number of unrelated samples to establish sensitivity, typability, reproducibility and discriminatory power based on internationally accepted methods for evaluation of microbial typing schemes.

Failed attempt of Cryptosporidium andersoni infection in lambs

Four lambs 4 months old were inoculated with Cryptosporidium andersoni oocysts (bovine isolate) in a dose of 5 x 10(6) per animal followed later by 1 x 10(7) oocysts per animal. No animal shed Cryptosporidium oocysts during 56 days post infection, no lamb showed clinical symptoms of cryptosporidiosis and no macroscopic changes were detected in the abomasum immediately after autopsy. Histological examinations did not demonstrate the occurrence of Cryptosporidium in the abomasum and other selected organs.

An improved ‘cold SSCP’ method for the genotypic and subgenotypic characterization of Cryptosporidium

A simple, non-isotopic PCR-based single-strand conformation polymorphism ('cold SSCP') method is described which allows the efficient detection of genetic variation among and within genotypes of Cryptosporidium parvum. This low cost approach has important advantages over other 'genotyping' methods and is applicable to a wide range of genetic loci and organisms.

Phylogenetic analysis of the hypervariable region of the 18S rRNA gene of Cryptosporidium oocysts in feces of Canada geese (Branta canadensis): evidence for five novel genotypes

To assess genetic diversity in Cryptosporidium oocysts from Canada geese, 161 fecal samples from Canada geese in the United States were analyzed. Eleven (6.8%) were positive for Cryptosporidium spp. following nested PCR amplification of the hypervariable region of the 18S rRNA gene. Nine PCR products from geese were cloned and sequenced, and all nine diverged from previously reported Cryptosporidium 18S rRNA gene sequences. Five sequences were very similar or identical to each other but genetically distinct from that of Cryptosporidium baileyi; two were most closely related to, but genetically distinct from, the first five; and two were distinct from any other sequence analyzed. One additional sequence in the hypervariable region of the 18S rRNA gene isolated from a cormorant was identical to that of C. baileyi. Phylogenetic analysis provided evidence for new genotypes of Cryptosporidium species in Canada geese. Results of this study suggest that the taxonomy of Cryptosporidium species in geese is complex and that a more complete understanding of genetic diversity among these parasites will facilitate our understanding of oocyst sources and species in the environment.

Cryptosporidium taxonomy: recent advances and implications for public health

There has been an explosion of descriptions of new species of Cryptosporidium during the last two decades. This has been accompanied by confusion regarding the criteria for species designation, largely because of the lack of distinct morphologic differences and strict host specificity among Cryptosporidium spp. A review of the biologic species concept, the International Code of Zoological Nomenclature (ICZN), and current practices for Cryptosporidium species designation calls for the establishment of guidelines for naming Cryptosporidium species. All reports of new Cryptosporidium species should include at least four basic components: oocyst morphology, natural host specificity, genetic characterizations, and compliance with the ICZN. Altogether, 13 Cryptosporidium spp. are currently recognized: C. muris, C. andersoni, C. parvum, C. hominis, C. wrairi, C. felis, and C. cannis in mammals; C. baïleyi, C. meleagridis, and C. galli in birds; C. serpentis and C. saurophilum in reptiles; and C. molnari in fish. With the establishment of a framework for naming Cryptosporidium species and the availability of new taxonomic tools, there should be less confusion associated with the taxonomy of the genus Cryptosporidium. The clarification of Cryptosporidium taxonomy is also useful for understanding the biology of Cryptosporidium spp., assessing the public health significance of Cryptosporidium spp. in animals and the environment, characterizing transmission dynamics, and tracking infection and contamination sources.

Multilocus genotyping of Cryptosporidium parvum Type 2: population genetics and sub-structuring

Cryptosporidium parvum is an intracellular protozoan parasite that infects the gastrointestinal tract of humans and other mammals. It has significant economic importance as a pathogen of livestock and, as there is no effective treatment or vaccine available, understanding transmission routes and identifying sources of infection is key to preventing future outbreaks and controlling this disease. In this study we have determined the multilocus genotype (MLG) of 240 C. parvum Type 2 (bovine) isolates using a combination of seven micro- and minisatellite markers. These isolates were collected over a period of 19 months and are from three different geographical locations within Scotland and three different host species. The results of this study have enabled us to address questions concerning C. parvum population genetics in relation to host, temporal and geographical sub-structuring. We identified 48 multilocus genotypes within the Type 2 C. parvum isolates and found no evidence to support geographic or temporal sub-structuring of the populations. However host sub-structuring was identified within the human Type 2 population highlighting the potential use of such a typing system in understanding the epidemiology of this parasite in addition to raising interesting questions with regard to its population genetic structure. We also isolated two C. parvum 'monkey type' isolates from two separate human cases indicating that this genotype is not restricted to monkey hosts with the multilocus genotypes of these isolates distinguishing them from all other isolates.

Cryptosporidium and Giardia-zoonoses: fact or fiction?

Giardia and Cryptosporidium are enteric protozoan parasites that infect a wide range of vertebrate hosts. Both are transmitted either by direct faecal/oral contact or by the ingestion of contaminated food or water. The discovery of morphologically similar organisms infecting humans and a variety of mammals and birds has led to the proposal that both Cryptosporidium and Giardia are zoonotic (i.e. transmitted in nature between humans and animals). Transmission between humans and animals has been supported by cross-infection studies. However, closer examination of many of these studies reveals limitations in the methodologies utilised. More recent molecular genetic studies have demonstrated considerable genetic diversity among isolates of the same species of Giardia and Cryptosporidium, suggesting that these species are in fact species complexes and that some of these novel species may be host-specific. This paper will critically examine the evidence for the zoonotic transmission of these parasites.

Survey of Cryptosporidium parvum genotypes in humans from the UK by mutation scanning analysis of a heat shock protein gene region

A mutation scanning-selective sequencing approach was employed for the genotypic identification and differentiation of Cryptosporidium parvum isolates. Genomic DNA samples (n=158) from Cryptosporidium oocysts from humans with clinical cryptosporidiosis (following recent foreign travel or during different outbreaks) in the UK were subjected to PCR-based single-strand conformation polymorphism (SSCP) analysis of a heat shock protein 70 gene region (p-hsp70; 448 bp). Samples representing different SSCP profiles were then subjected to sequencing. The analysis allowed the classification of 149 of the 158 samples as type-1 ( approximately 49%) or type-2 ( approximately 46%); amplicons from the remaining nine samples were consistent in size with p-hsp70 but represented non-specific, faecal contaminants. The percentages reflected those of a previous study in the UK for autochtonous, sporadic cases of cryptosporidiosis ( approximately 49% for type-1 and approximately 47% for type-2; n approximately 4000), but contrasted another survey of sporadic cases where type-2 dominated ( approximately 62%; n approximately 1000). The ability of the present SSCP-sequencing approach to accurately screen for C. parvum genotypes and to reliably discern erroneous amplicons has significant implications for the accurate diagnosis and monitoring of cryptosporidiosis and for population genetic studies.

Roles of tyrosine-rich precursor glycoproteins and dityrosine- and 3,4-dihydroxyphenylalanine-mediated protein cross-linking in development of the oocyst wall in the coccidian parasite Eimeria maxima

The oocyst wall of apicomplexan parasites protects them from the harsh external environment, preserving their survival prior to transmission to the next host. If oocyst wall formation could be disrupted, then logically, the cycle of disease transmission could be stopped, and strategies to control infection by several organisms of medical and veterinary importance such as Eimeria, Plasmodium, Toxoplasma, Cyclospora, and Neospora could be developed. Here, we show that two tyrosine-rich precursor glycoproteins, gam56 and gam82, found in specialized organelles (wall-forming bodies) in the sexual stage (macrogamete) of Eimeria maxima are proteolytically processed into smaller glycoproteins, which are then incorporated into the developing oocyst wall. The identification of high concentrations of dityrosine and 3,4-dihydroxyphenylalanine (DOPA) in oocyst extracts by high-pressure liquid chromatography, together with the detection of a UV autofluorescence in intact oocysts, implicates dityrosine- and possibly DOPA-protein cross-links in oocyst wall hardening. In addition, the identification of peroxidase activity in the wall-forming bodies of macrogametes supports the hypothesis that dityrosine- and DOPA-mediated cross-linking might be an enzyme-catalyzed event. As such, the mechanism of oocyst wall formation in Eimeria, is analogous to the underlying mechanisms involved in the stabilization of extracellular matrices in a number of organisms, widely distributed in nature, including insect resilin, nematode cuticles, yeast cell walls, mussel byssal threads, and sea urchin fertilization membranes.

Electrophoretic analysis of genetic variability within Cryptosporidium parvum from imported and autochthonous cases of human cryptosporidiosis in the United Kingdom

Cryptosporidium parvum oocyst DNA samples (n = 184) from humans with cryptosporidiosis contracted during foreign travel or during outbreaks in the United Kingdom were characterized genetically and categorized by single-strand conformation polymorphism (SSCP)-based analysis of the small-subunit gene (pSSU) (approximately 300 bp) and second internal transcribed spacer (pITS-2) (approximately 230 bp) of nuclear ribosomal DNA. The two recognized genotypes (types 1 and 2) of C. parvum could be readily differentiated by a distinct electrophoretic shift in the pSSU SSCP profile, associated with a nucleotide difference of approximately 1.3 to 1.7%. Of the 102 samples from cases contracted during foreign travel, 88 (86.3%) were identified as C. parvum type 1 and 14 (13.7%) were identified as type 2. For outbreak samples, unequivocal differentiation between type 1 (n = 20; one child nursery outbreak) and type 2 (n = 62; two waterborne outbreaks) was also achieved. Nucleotide variation in pITS-2 (both within and among samples representing each genotype) was substantially greater (10 to 13 different profiles for each genotype, relating to sequence differences of approximately 1 to 42%) than that in pSSU. SSCP analysis of pITS-2 for all samples revealed that some profiles had a broad geographical distribution whereas others were restricted to particular locations, suggesting a link between some subgenotypes and the geographical origin or source. Comparative denaturing polyacrylamide gel electrophoretic analysis revealed the same genotypic identification and a similar subgenotypic classification of samples as SSCP analysis. The findings of this study, particularly the detection of intragenotypic variation by SSCP, should have significant diagnostic implications for investigating transmission patterns and the monitoring of outbreaks.

Cryptosporidium oocysts in a water supply associated with a cryptosporidiosis outbreak

An outbreak of cryptosporidiosis occurred in and around Clitheroe, Lancashire, in northwest England, during March 2000. Fifty-eight cases of diarrhea with Cryptosporidium identified in stool specimens were reported. Cryptosporidium oocysts were identified in samples from the water treatment works as well as domestic taps. Descriptive epidemiology suggested that drinking unboiled tap water in a single water zone was the common factor linking cases. Environmental investigation suggested that contamination with animal feces was the likely source of the outbreak. This outbreak was unusual in that hydrodynamic modeling was used to give a good estimate of the peak oocyst count at the time of the contamination incident. The oocysts' persistence in the water distribution system after switching to another water source was also unusual. This persistence may have been due to oocysts being entrapped within biofilm. Despite the continued presence of oocysts, epidemiologic evidence suggested that no one became ill after the water source was changed.