Zoonotic transmission of Cryptosporidium parvum: Implications for water-borne cryptosporidiosis

The Gut-Wrenching Effects of Cryptosporidiosis and Giardiasis in Children

Cryptosporidium species and Giardia duodenalis are infectious intestinal protozoan pathogens that cause alarming rates of morbidity and mortality worldwide. Children are more likely to have clinical symptoms due to their less developed immune systems and factors such as undernutrition, especially in low- and middle-income countries. The severity of the symptoms and clinical manifestations in children may vary from asymptomatic to life-threatening depending on the Cryptosporidium species/G. duodenalis strains and the resulting complex stepwise interactions between the parasite, the host nutritional and immunologic status, and the gut microbiome profile. Structural damages inflicted by both parasites to epithelial cells in the large and small intestines could severely impair children's gut health, including the ability to absorb nutrients, resulting in stunted growth, diminished neurocognitive development, and other long-term effects. Clinically approved cryptosporidiosis and giardiasis drugs have broad antimicrobial effects that have incomprehensible impacts on growing children's gut health.

Occurrence of Cryptosporidium oocysts in commercial oysters in southern Thailand

The enteric parasite Cryptosporidium is spread through the fecal-oral pathway, most commonly by the consumption of contaminated water but also through food. Because eating raw or barely cooked shellfish might put consumers at risk for cryptosporidiosis, identifying the parasite in oysters is important for public health. A total of 240 oysters, collected from two shellfish aquaculture sites in Thailand's Gulf coast, Nakhon Si Thammarat and Surat Thani, were tested for the presence of Cryptosporidium. Escherichia coli, enterococci, and thermotolerant coliform total levels were measured to assess seawater quality in the shellfish production regions. Oocysts of Cryptosporidium spp. were detected in 13.8% of the samples processed by immunofluorescence analyses. The detection of Cryptosporidium spp. oocysts in oysters obtained from Surat Thani (17.5%) was higher than in those obtained from Nakhon Si Thammarat (9.2%). The difference in detection of positive samples obtained from Nakhon Si Thammarat and those obtained from Surat Thani may be attributed to the effects of physical, ecological, and anthropogenic conditions, resulting in an increased level of marine water contamination by Cryptosporidium spp. oocysts. These findings demonstrate that native commercial oysters obtained from Thailand's southern Gulf coast contained Cryptosporidium spp. oocysts which might serve as a source of human infection. Consequently, these findings pose a serious public health concern and suggest that more quality control measures need to be implemented by the oyster aquaculture business to ensure the safety of seafood.

Gut Fungal Microbiome Responses to Natural Cryptosporidium Infection in Horses

It is critical to characterize changes in the structure and composition of the host fungal community in natural Cryptosporidium infection, because it gives the possible overview of gut microbiome in host homeostasis and disease progression. A total of 168 rectal fecal samples were collected and examined using nPCR. The positive samples were double-checked using 18S rDNA high-throughput sequencing. After confirmation, ITS high-throughput sequencing was utilized to investigate the fungal community’s response to natural Cryptosporidium infection. Results showed that a total of three positive samples (1.79%) were identified with an increased abundance of fungi associated with health hazards, such as class Dothideomycetes, families, i.e., Cladosporiaceae, Glomerellaceae, and genera, i.e., Wickerhamomyces, Talaromyces, Cladosporium, Dactylonectria, and Colletotrichum. On the contrary, taxa associated with favorable physiological effects on the host were shown to have the reverse impact, such as families, i.e., Psathyrellaceae, Pseudeurotiaceae and genera (Beauveria, Nigrospora, and Diversispora). For the first time, we evaluated the condition of natural Cryptosporidium infection in horses in Wuhan, China, and discovered distinct variations in the fungal microbiome in response to natural infection. It might prompt a therapy or prevention strategy to apply specific fungal microorganisms that are probably responsible for decreased susceptibility or increased resistance to infection.

Distribution of different species of metacercariae in two freshwater fishes: Haludaria fasciata (Teleostei: Cyprinidae) and Pseudosphromenus cupanus (Teleostei: Osphromenidae)

Information on the distribution and abundance patterns of trematodes are essential to reveal the ecology of host-parasite interactions. The Western Ghats of India, a biodiversity hotspot, is rich in freshwater fish diversity and endemism. Though there are several studies on various other aspects of fish ecology, studies on their parasitic fauna is meager. The objective of the present study is to explore the distribution and infection patterns of metacercariae of five species of trematodes in the freshwater fishes, Haludaria fasciata and Pseudosphromenus cupanus. The infection parameters were analyzed for each host and CART model was applied to analyze the environmental factors affecting parasite distribution patterns. All species of metacercariae showed an over-dispersed aggregate distributions. The classification tree models indicated that among the environmental factors considered, differences in host locality was the most influential factor in both fishes, followed at a greater distance by the factor seasonality. The parasite communities exhibited temporal and spatial differences in the infection pattern in response to seasonal and locational variations.

Seasonal and Age-Associated Pathogen Distribution in Newborn Calves with Diarrhea Admitted to ICU

Calf mortality constitutes a substantial loss for agriculture economy-based countries and is also a significant herd problem in developed countries. However, the occurrence and frequency of responsible gastro-intestinal (GI) pathogens in severe newborn diarrhea is still not well known. We aimed to determine the seasonal and age-associated pathogen distribution of severe diarrhea in newborn calves admitted to the intensive care unit (ICU) of Erciyes University animal hospital over a year. Fecal samples were collected during the ICU admissions, and specimens were subjected to a diarrheal pathogen screening panel that included bovine coronavirus (BCoV), Cryptosporidium spp., ETEC K99+, and bovine rotavirus, using RT-PCR and conventional PCR methods. Further isolation experiments were performed with permissive cell cultures and bacterial enrichment methods to identify the clinical importance of infectious pathogen shedding in the ICU. Among the hospitalized calves aged less than 45 days old, the majority of calves originated from small farms (85.9%). The pathogen that most frequently occurred was Cryptosporidium spp. (61.5%) followed by rotavirus (56.4%). The frequency of animal admission to ICU and GI pathogen identification was higher during the winter season (44.9%) when compared to other seasons. Most calves included in the study were 1-6 days old (44.9%). Lastly, co-infection with rotavirus and Cryptosporidium spp. occurred more frequently than other dual or multi-infection events. This study was the first to define severe diarrhea-causing GI pathogens from ICU admitted newborn calves in Turkey.

First report of the prevalence and genetic characterization of Giardia duodenalis and Cryptosporidium spp. in Yunling cattle in Yunnan Province, southwestern China

Yunling cattle is an unique cattle breed distributed in Yunnan Province, southwestern China. It is yet to know whether Yunling cattle are infected with Giardia duodenalis and Cryptosporidium spp.. The objectives of the present study were to investigate the prevalence and characterize the assemblages of G. duodenalis and species of Cryptosporidium spp. in Yunling cattle in Yunnan province. The overall prevalence of G. duodenalis and Cryptosporidium spp. were 10.49% (41/391) and 0.77% (3/391), respectively. The age was considered as the risk factor for Yunling cattle infection with G. duodenalis (χ² = 8.082, OR = 2.56, P = 0.004). Two assemblages of G. duodenalis, assemblage A (n = 1) and assemblage E (n = 40), were identified by amplification of the β-giardin (bg) and glutamate dehydrogenase (gdh) gene loci using the nested PCR methods. Furthermore, Cryptosporidium andersoni (n = 1) and Cryptosporidium ryanae (n = 2) were detected by nested PCR targeting the small subunit (SSU) rRNA gene. This is the first report of G. duodenalis and Cryptosporidium spp. in Yunling cattle in China, which provided baseline date for further studies of the prevalence, genetic identity, and public health potential of these parasites in Yunling cattle.

Molecular study and genotyping of Cryptosporidium baileyi and Cryptosporidium parvum from free-range and commercial broiler chickens in Guilan province, Iran

Cryptosporidiosis acutely impacts the digestive and/or respiratory tract of the birds in many species of various orders. More importantly, it is also well known as a significant zoonotic disease, which can lead to diarrhea in humans and livestock. Regarding increasing demand for free-range products and increasing the number of free-range poultry farms, the present paper evaluated histopathological and molecular detection of Cryptosporidium baileyi and Cryptosporidium parvum in free-range and commercial broiler chickens in the north part of Iran. For this purpose, 100 fecal and tissue samples of the chickens in Guilan province were collected. After microscopic examination using Ziehl-Neelsen staining, molecular analyses of the fecal samples were processed by Nested-PCR targeting the 18S rRNA gene followed by sequencing of the amplicons and phylogenetic analyses. Eventually, the tissue samples were studied for histological lesions. Findings demonstrated the presence of Cryptosporidium baileyi and Cryptosporidium parvum in 6 % and 2 % of fecal samples, respectively. This is the first identification of C.parvum in avian hosts in Iran, and for the first time, C.baileyi and C.parvum are shown in native free-range chickens in Iran. All of the PCR positive birds with clinical symptoms showed gross lesions of respiratory infections. There was no significant difference between infection rate in free-range and commercial broiler chickens; however, the infection rate was significantly higher in chickens <25 days old. To conclude, we present here a notable Cryptosporidium infection rate in the free-range chicks in Iran, which notify the role of this host as a reservoir and should be more noted due to the economic and zoonotic importance.

Cryptosporidium and giardia species in newly and previously habituated gorillas and nearby water sources in Bwindi Impenetrable National Park, Uganda

Introduction

cryptosporidium and giardia are of great one health significance and major cause of protozoan diarrhea in humans and primates; they are found in the faecal matter of animals and humans and also in contaminated water and soil as well. Therefore, we aimed at establishing the prevalence and shedding intensity of faecal Cryptosporidium and giardia in the Newly Habituated Mountain Gorillas (NHMG) and Previously Habituated Mountain Gorillas (PHMG) and in selected water sources within the gorilla home ranges in the month of January 2018.

Methods

we conducted a cross sectional study in the southern sector of Bwindi Impenetrable National Park where a total of 56 faecal samples from both NHMG (34) and PHMG (22) and 30 water samples were purposively collected. Faecal and water samples were transported in a cooler box at 4ºC to Makerere University Parasitology Laboratory for analysis. The samples were analyzed using modified Ziehl-Neelsen technique and Ether concentration method for Cryptosporidium and giardia respectively.

Results

the prevalence of cryptosporidium was established as 13 (59.1%), 15 (44.1%) and 7 (23.3%) in PHMG, NHMG and water respectively. The mean concentration of the oocysts per gram was 222±52.9 in PHMG, 174±41.5 in NHMG and 31±13.2 in water. The prevalence of giardia was 3 (13.6%), 4 (11.8%) and 3 (10%) in PHMG, NHMG and water respectively. The mean concentration of the oocysts per gram was 34±19.9 in PHMG, 25±12.4 in NHMG and 5±2.9 in water. There was no significant difference in both the prevalence of cryptosporidium (p>0.05) and giardia (p>0.05) in the PHMG and NHMG. This indicates that there is high risk of cross infection among the gorillas within the forest sharing similar home ranges.

Conclusion

the park authorities should ensure that procedures for proper waste disposal while in the forest are properly followed, water drawn for drinking from the forest should be avoided. Further research should be carried out to identify whether the strains of the parasites found in water or other animals in the forest are the same with strains in gorilla dung in order to confirm cross infection.

Infection dynamics of Cryptosporidium bovis and Cryptosporidium ryanae in a Swedish dairy herd

In order to investigate the infection dynamics of Cryptosporidium bovis and Cryptosporidium ryanae, a Swedish dairy farm known to be free of C. parvum was recruited for a one-year study. Fecal samples were collected every four weeks (a total of 13 occasions) from 20 randomly selected calves younger than 65 days. A total of 238 feces samples were collected directly from the rectum and then examined with immunofluorescence microscopy; those positive for Cryptosporidium spp. oocysts were further processed by molecular species determination. Oocysts were found in 92 samples, and in 72 of these the species was successfully determined: 87.5% C. bovis, 9.7% C. ryanae and 2.8% a mix of both species. No C. parvum was found. The prevalence of shedding calves was highest at ages 4 and 5 weeks; however, the feces with the highest oocyst per gram (OPG) were registered at 2-4 weeks of age. This is earlier than what has been found in most other studies, indicating that the infection dynamics of C. bovis/C. ryanae may be affected by the presence of C. parvum. The OPG for the positive calves ranged from 200 to 1.1 × 10⁶ (geometric mean 6.88 × 10³). The youngest calf in which C. bovis was identified was 5 days old, and the youngest calf in which C. ryanae was identified was 15 days old. Calves' housing type and seasonality were not associated with differences in the shedding of oocysts. Furthermore, there was no association between the presence of diarrhea and oocyst shedding.

Molecular diagnosis and characterization of Cryptosporidium spp. in turkeys and chickens in Germany reveals evidence for previously undetected parasite species

A total of 256 fecal specimens were randomly collected from farmed poultry in Germany and screened for the presence of Cryptosporidium spp. by PCR and further characterized by direct automated DNA sequencing. Using a nested PCR amplifying approximately 830 bp 18S rDNA fragment, 7.03% (n = 18) of the samples were Cryptosporidium-positive. In detail, Cryptosporidium was detected in 9.3% (8/86) of turkeys, 5.7% (9/158) of broilers and 8.3% (1/12) of layers. After DNA sequencing, Cryptosporidium parvum the most frequently observed species was identified in 5.1% (13/256) of all poultry species, including 8.1% (7/86) of turkeys, 3.2% (5/158) of broilers and 8.3% (1/12) of layers. Cryptosporidium baileyi was detected in 1.3% (2/256) of the broilers only. Three novel unclassified Cryptosporidium spp. were detected in 1.2% (1/86) of turkeys and 1.3% (2/158) of broilers. The infection rate was high in 13-20 week old turkeys, 1-6 weeks old broilers and >20 weeks old layers but differences between age groups were not significant. This is the first study in Germany uses molecular methods for the detection of Cryptosporidium in poultry. The results indicate that Cryptosporidium parasites are common among broilers and turkeys in Germany. Considering the large size of the poultry industry, the large amount of poultry meat that is consumed and the fact that C. parvum is also the most common Cryptosporidium parasite in humans, poultry might also be a source of human infections.

Balancing ecosystem function, services and disservices resulting from expanding goose populations

As goose populations increase in abundance, their influence on ecological processes is increasing. We review the evidence for key ecological functions of wild goose populations in Eurasia and North America, including aquatic invertebrate and plant propagule transport, nutrient deposition in terrestrial and aquatic ecosystems, the influence of goose populations on vegetation biomass, carbon storage and methane emission, species diversity and disease transmission. To estimate the implications of their growing abundance for humans, we explore how these functions contribute to the provision of ecosystem services and disservices. We assess the weight, extent and trends among such impacts, as well as the balance of their value to society. We examine key unresolved issues to enable a more balanced assessment of the economic costs or benefits of migratory geese along their flyways, including the spatial and temporal variation in services and their contrasting value to different user groups. Many ecological functions of geese are concluded to provide neither services nor disservices and, ecosystem disservices currently appear to outweigh services, although this varies between regions. We consider an improved quantification of ecosystem services and disservices, and how these vary along population flyways with respect to variation in valuing certain cultural services, and under different management scenarios aimed at reducing their disservices, essential for a more balanced management of goose populations.

Common occurrence of Cryptosporidium hominis in horses and donkeys

Extensive genetic variation is observed within the genus Cryptosporidium and the distribution of Cryptosporidium species/genotypes in humans and animals appears to vary by geography and host species. To better understand the genetic diversity of Cryptosporidium spp. in horses and donkeys, we characterized five horse-derived and 82 donkey-derived Cryptosporidium isolates from five provinces or autonomous regions (Sichuan, Gansu, Henan, Inner Mongolia and Shandong) in China at the species/genotype and subtype levels. Three Cryptosporidium species/genotypes were identified based on the analysis of the SSU rRNA gene, including Cryptosporidium parvum (n=22), the Cryptosporidium horse genotype (n=4), and Cryptosporidium hominis (n=61). The identification of C. hominis was confirmed by sequence analysis of the HSP70 and actin genes. Subtyping using sequence analysis of the 60kDa glycoprotein gene identified 21 C. parvum isolates as subtype IIdA19G1, the four horse genotype isolates as subtypes VIaA15G4 (n=2) and VIaA11G3 (n=2), and the 61 C. hominis isolates as IkA16G1 (n=59) and IkA16 (n=2). The common finding of C. hominis reaffirms the heterogeneity of Cryptosporidium spp. in horses and donkeys and is possibly a reflection of endemic transmission of C. hominis in these animals. Data of the study suggest that horses and donkeys as companion animals may potentially transmit Cryptosporidium infections to humans.

Assessment of molecular methods as a tool for detecting pathogenic protozoa isolated from water bodies

Several species belong to the Cryptosporidium and Giardia genus, the main parasitic protozoa occurring in water, but only some of them are infectious to humans. We investigated the occurrence of Cryptosporidium and Giardia and identified their species in the water samples collected from natural water bodies in north-western Poland. A total of 600 samples from water bodies used for bathing, sewage discharge, as drinking water sources and watering places for animals were screened. The samples were collected during a 3-year period in each of the four seasons and filtered using Filta-Max (IDEXX Laboratories, USA). Genomic DNA was extracted from all samples and used as a target sequence for polymerase chain reaction (PCR) and TaqMan real-time PCR, as well as for reverse line blotting (RLB) methods. PCR methods seem to be more sensitive to detect Giardia and Cryptosporidium DNA in water samples than RLB methods. All PCR products were sequenced and three were identified as C. parvum and four as G. intestinalis. The overall prevalence of C. parvum (0.5%) and G. intestinalis (0.6%) in the samples suggests that the risk of Cryptosporidium and Giardia infections in north-western Poland is minimal.

Household Socioeconomic and Demographic Correlates of Cryptosporidium Seropositivity in the United States

BACKGROUND

Cryptosporidium are parasitic protozoa that infect humans, domestic animals, and wildlife globally. In the United States, cryptosporidiosis occurs in an estimated 750,000 persons annually, and is primarily caused by either of the Cryptosporidium parvum genotypes 1 and 2, exposure to which occurs through ingestion of food or water contaminated with oocytes shed from infected hosts. Although most cryptosporidiosis cases are caused by genotype 1 and are of human origin, the zoonotic sources of genotype 2, such as livestock, are increasingly recognized as important for understanding human disease patterns. Social inequality could mediate patterns of human exposure and infection by placing individuals in environments where food or water contamination and livestock contact is high or through reducing the availability of educational and sanitary resources required to avoid exposure.

METHODOLOGY/PRINCIPAL FINDINGS

We here analyzed data from the National Health and Nutritional Examination Survey (NHANES) between 1999 and 2000, and related seropositivity to Cryptosporidium parvum to correlates of social inequality at the household and individual scale. After accounting for the complex sampling design of NHANES and confounding by individual demographics and household conditions, we found impaired household food adequacy was associated with greater odds of Cryptosporidium seropositivity. Additionally, we identified individuals of non-white race and ethnicity and those born outside the United States as having significantly greater risk than white, domestic-born counterparts. Furthermore, we provide suggestive evidence for direct effects of family wealth on Cryptosporidium seropositivity, in that persons from low-income households and from families close to the poverty threshold had elevated odds of seropositivity relative to those in high-income families and in households far above the poverty line.

CONCLUSIONS/SIGNIFICANCE

These results refute assertions that cryptosporidiosis in the United States is independent of social marginalization and poverty, and carry implications for targeted public health interventions for Cryptosporidium infection in resource-poor groups. Future longitudinal and multilevel studies are necessary to elucidate the complex interactions between ecological factors, social inequality, and Cryptosporidium dynamics.

Genotyping and subtyping Cryptosporidium parvum and Giardia duodenalis carried by flies on dairy farms in Henan, China

Background

Cryptosporidium and Giardia are important causes of diarrhea diseases in humans and animals worldwide, and both of them are transmitted by the fecal–oral route, either by direct contact or by the ingestion of contaminated food or water. The role of flies in the mechanical transmission of Cryptosporidium and Giardia has been receiving increasing attention. To date, no information is available in China about the occurrence of Cryptosporidium and Giardia in flies. We here investigated Cryptosporidium and Giardia in flies on dairy farms in Henan Province, China, at the genotype and subtype levels.

Methods

Eight hundred flies were randomly collected from two dairy farms from July 2010 to September 2010 and were divided evenly into 40 batches. The fly samples were screened for the presence of Cryptosporidium and Giardia with nested PCR. Cryptosporidium was genotyped and subtyped by analyzing the DNA sequences of small subunit rRNA (SSU rRNA) and 60-kDa glycoprotein (gp60) genes, respectively. The identity of Giardia was determined by sequence analyzing of the triosephosphate isomerase (tpi), glutamate dehydrogenase (gdh), and β-giardin (bg) genes.

Results

Forty batches of flies had 10% of contamination with Cryptosporidium or Giardia, with a mixed infection of the two parasites in one batch of flies. The Cryptosporidium isolates were identified as C. parvum at the SSU rRNA locus, and all belonged to subtype IIdA19G1 at the gp60 locus. The Giardia isolates were all identified as assemblage E of G. duodenalis at the tpi, gdh, and bg loci. One novel subtype of assemblage E was identified based on the gdh and bg loci.

Conclusions

This is the first molecular study of Cryptosporidium and Giardia in flies identified at both genotype and subtype levels. SSU rRNA and gp60 sequences of C. parvum in flies was 100% homologous with those derived from humans, suggesting flies act as an epidemiological vector of zoonotic cryptosporidiosis. The variable PCR efficiencies observed in the analysis of Giardia at different loci suggest that we should use the multilocus genotyping tool in future studies to increase the detection rate, and importantly, to obtain more complete genetic information on Giardia isolates.

Climate change is likely to worsen the public health threat of diarrheal disease in Botswana

Diarrheal disease is an important health challenge, accounting for the majority of childhood deaths globally. Climate change is expected to increase the global burden of diarrheal disease but little is known regarding climate drivers, particularly in Africa. Using health data from Botswana spanning a 30-year period (1974–2003), we evaluated monthly reports of diarrheal disease among patients presenting to Botswana health facilities and compared this to climatic variables. Diarrheal case incidence presents with a bimodal cyclical pattern with peaks in March (ANOVA p < 0.001) and October (ANOVA p < 0.001) in the wet and dry season, respectively. There is a strong positive autocorrelation (p < 0.001) in the number of reported diarrhea cases at the one-month lag level. Climatic variables (rainfall, minimum temperature, and vapor pressure) predicted seasonal diarrheal with a one-month lag in variables (p < 0.001). Diarrheal case incidence was highest in the dry season after accounting for other variables, exhibiting on average a 20% increase over the yearly mean (p < 0.001). Our analysis suggests that forecasted climate change increases in temperature and decreases in precipitation may increase dry season diarrheal disease incidence with hot, dry conditions starting earlier and lasting longer. Diarrheal disease incidence in the wet season is likely to decline. Our results identify significant health-climate interactions, highlighting the need for an escalated public health focus on controlling diarrheal disease in Botswana. Study findings have application to other arid countries in Africa where diarrheal disease is a persistent public health problem.

Assessment of sources of human pathogens and fecal contamination in a Florida freshwater lake

We investigated the potential for a variety of environmental reservoirs to harbor or contribute fecal indicator bacteria (FIB), DNA markers of human fecal contamination, and human pathogens to a freshwater lake. We hypothesized that submerged aquatic vegetation (SAV), sediments, and stormwater act as reservoirs and/or provide inputs of FIB and human pathogens to this inland water. Analysis included microbial source tracking (MST) markers of sewage contamination (Enterococcus faecium esp gene, human-associated Bacteroides HF183, and human polyomaviruses), pathogens (Salmonella, Cryptosporidium, Giardia, and enteric viruses), and FIB (fecal coliforms, Escherichia coli, and enterococci). Bayesian analysis was used to assess relationships among microbial and physicochemical variables. FIB in the water were correlated with concentrations in SAV and sediment. Furthermore, the correlation of antecedent rainfall and major rain events with FIB concentrations and detection of human markers and pathogens points toward multiple reservoirs for microbial contaminants in this system. Although pathogens and human-source markers were detected in 55% and 21% of samples, respectively, markers rarely coincided with pathogen detection. Bayesian analysis revealed that low concentrations (<45 CFU × 100 ml(-1)) of fecal coliforms were associated with 93% probability that pathogens would not be detected; furthermore the Bayes net model showed associations between elevated temperature and rainfall with fecal coliform and enterococci concentrations, but not E. coli. These data indicate that many under-studied matrices (e.g. SAV, sediment, stormwater) are important reservoirs for FIB and potentially human pathogens and demonstrate the usefulness of Bayes net analysis for water quality assessment.

Prevalence of Cryptosporidium spp. and Giardia duodenalis in pigs in Lusaka, Zambia

This study was aimed at determining the prevalence of Cryptosporidium spp. and Giardia duodenalis in pigs which were being raised in intensive management systems. Faecal samples were collected from pigs of all age groups from three different piggery units. Samples were collected directly from the rectum for piglets and weaners and from the floor within 2 min - 5 min of excretion for sows and boars. At the time of collection, faecal consistency was noted as being normal, pasty or diarrhoeic. Samples were analysed further using the Merifluor® Cryptosporidium/Giardia immunofluorescence assay. All piggeries had at least one pig infected with either parasite. From a total 217 samples collected, 96 (44.2%; confidence interval [CI] = 37.6% - 50.9%) were positive for Cryptosporidium spp., whilst 26 (12%; CI = 7.6% - 16.3%) had G. duodenalis parasites. Of all the pigs, 6.9% (15/217) harboured both parasites. With regard to Cryptosporidium spp. infection, statistically significant differences were observed amongst the three units (p = 0.001), whereas no significant differences were observed for G. duodenalis infection (p = 0.13). Prevalence was higher in weaners as compared to other pig classes for both parasites, with significant differences being observed for G. duodenalis infection (p = 0.013). There was, however, no difference in infection between male and female pigs for both parasites. Furthermore, most infections were asymptomatic. From the study results it was clear that Cryptosporidium spp. and G. duodenalis infections were prevalent amongst pigs in the piggeries evaluated and, as such, may act as a source of infection for persons who come into contact with them.

Prevalence and molecular characterization of Cryptosporidium spp. in dairy cattle from farms in China

Fecal samples of 2,056 dairy cattle from 14 farms were collected in three geographical regions of China and stained using a modified acid-fast staining technique to identify Cryptosporidium oocysts. A total of 387 (18.82%) positive samples were identified and further analyzed by polymerase chain reaction (PCR) using primers designed to amplify DNA fragments from the small subunit ribosomal RNA. The PCR products were sequenced and the sequences were deposited in the GenBank database under accession numbers EU369377-84 and GU070730-33. Phylogenetic analysis was performed and a distances matrix generated from these sequences confirmed the existence of Cryptosporidium (C.) parvum 'mouse' genotype, C. bovis, C. andersoni, C. hominis, and C. serpentis in cattle. These results represent the first report on the prevalence and genetic identification of Cryptosporidium species, and may contribute to a better understanding of the epidemiology of Cryptosporidium in cattle in China.

Novel and promising compounds to treat Cryptosporidium parvum infections

No fully effective approved drug therapy exists for Cryptosporidium infections of immunocompetent and immunocompromised patients. Here, we investigated 11 benzimidazole derivatives carrying substituted thioalkyl and thiobenzyl groups at position 2 of benzimidazole nucleus and additional substituents at the benzene part of benzimidazole for inhibition of the in vitro growth of the intestinal protozoan parasite, Cryptosporidium parvum. Three of them, i.e., 5-carboxy-2-(4-nitrobenzylthio)-1H-benzimidazole, 5,6-dichloro-2-(4-nitrobenzylthio)-1H-benzimidazole, and 4,6-dichloro-2-(4-nitrobenzylthio)-1H-benzimidazole, (compounds 5, 7, and 8) were the most active (IC(50) 28-31 μM). The concentration of compounds 5, 7, and 8 that caused 50% growth inhibition in human enterocytic HCT-8 cells by a quantitative alkaline phosphatase immunoassay was comparable with those obtained for paromomycin.

A role of some food arthropods as vectors of human enteric infections

Arthropods are very important organisms in the environment in relation to transmission of pathogenic infections to humans. The information on transmission of pathogenic infections to people by commercially offered food arthropods is scant. Consumption of seafood is a very popular dietary habit around the world. Whereas shrimp are the most commonly consumed seafood item, crabmeat has recently become a very popular commercial product, specifically for a majority of European countries. The transmission of waterborne protozoan parasites is facilitated by consumption of seafood harvested from contaminated waters, drinking water or via contact with recreational and surface waters, and remains common throughout the developing as well as the developed world. Protozoan infections pose a significant health risk for immunocompetent individuals, and may cause life-threatening diseases among immunocompromised and immunosuppressed individuals. The transmissive stages of human protozoan parasites are small in size and are shed in large numbers in feces of infected people and animals. These pathogens are resistant to environmental stressors (sometimes even to chlorine disinfection), and only a few of them (e.g., Cryptosporidium oocysts, Giardia cysts, or Vibrio bacteria) are able to cause infection in seafood consumers.

Cryptosporidium recovered from Musca domestica, Musca sorbens and mango juice accessed by synanthropic flies in Bahirdar, Ethiopia

The study was conducted to determine the role of house flies, Musca domestica and Musca sorbens to carry Cryptosporidium species in natural environment and filth flies potential for contamination of food item they visited using acid-fast stain technique. Cryptosporidium was identified from flies collected in dairy cow barns, butchery, market and defecating grounds. Musca domestica captured from dairy cow barns and M. sorbens from defecating ground were found carrying more oocyst of Cryptosporidium parvum. Oocyst load per fly for M. domestica and M. sorbens was 5.84 and 3.42, respectively. Flies' population dynamics in each month had little relation to the monthly oocyst frequency, r = 0.06 and 0.02 for M. domestica and M. sorbens, respectively. Cryptosporidium species oocysts were isolated from frozen mango juice, which filth flies visited in dairy farm barn. Load of oocysts in the mango juice was dependent on time contact of flies with mango juice and more oocysts were recovered (P < 0.05) in mango juice samples accessed by filth flies for longer period. Role of filth flies to carry and deposit Cryptosporidium species oocyst for development of food-borne cryptosporidiosis is signified.

Temporal and spatial dynamics of Cryptosporidium parvum infection on dairy farms in the New York City Watershed: a cluster analysis based on crude and Bayesian risk estimates

BACKGROUND

Cryptosporidium parvum is one of the most important biological contaminants in drinking water that produces life threatening infection in people with compromised immune systems. Dairy calves are thought to be the primary source of C. parvum contamination in watersheds. Understanding the spatial and temporal variation in the risk of C. parvum infection in dairy cattle is essential for designing cost-effective watershed management strategies to protect drinking water sources. Crude and Bayesian seasonal risk estimates for Cryptosporidium in dairy calves were used to investigate the spatio-temporal dynamics of C. parvum infection on dairy farms in the New York City watershed.

RESULTS

Both global (Global Moran's I) and specific (SaTScan) cluster analysis methods revealed a significant (p < 0.05) elliptical spatial cluster in the winter with a relative risk of 5.8, but not in other seasons. There was a two-fold increase in the risk of C. parvum infection in all herds in the summer (p = 0.002), compared to the rest of the year. Bayesian estimates did not show significant spatial autocorrelation in any season.

CONCLUSIONS

Although we were not able to identify seasonal clusters using Bayesian approach, crude estimates highlighted both temporal and spatial clusters of C. parvum infection in dairy herds in a major watershed. We recommend that further studies focus on the factors that may lead to the presence of C. parvum clusters within the watershed, so that monitoring and prevention practices such as stream monitoring, riparian buffers, fencing and manure management can be prioritized and improved, to protect drinking water supplies and public health.

Propagation of human enteropathogens in constructed horizontal wetlands used for tertiary wastewater treatment

Constructed subsurface flow (SSF) and free-surface flow (FSF) wetlands are being increasingly implemented worldwide into wastewater treatments in response to the growing need for microbiologically safe reclaimed waters, which is driven by an exponential increase in the human population and limited water resources. Wastewater samples from four SSF and FSF wetlands in northwestern Ireland were tested qualitatively and quantitatively for Cryptosporidium spp., Giardia duodenalis, and human-pathogenic microsporidia, with assessment of their viability. Overall, seven species of human enteropathogens were detected in wetland influents, vegetated areas, and effluents: Cryptosporidium parvum, C. hominis, C. meleagridis, C. muris, G. duodenalis, Encephalitozoon hellem, and Enterocytozoon bieneusi. SSF wetland had the highest pathogen removal rate (i.e., Cryptosporidium, 97.4%; G. duodenalis, 95.4%); however, most of these values for FSF were in the negative area (mean, -84.0%), meaning that more pathogens were discharged by FSF wetlands than were delivered to wetlands with incoming wastewater. We demonstrate here that (i) the composition of human enteropathogens in wastewater entering and leaving SSF and FSF wetlands is highly complex and dynamic, (ii) the removal and inactivation of human-pathogenic microorganisms were significantly higher at the SSF wetland, (iii) FSF wetlands may not always provide sufficient remediation for human enteropathogens, (iv) wildlife can contribute a substantial load of human zoonotic pathogens to wetlands, (v) most of the pathogens discharged by wetlands were viable, (vi) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat, and (vii) even with the best pathogen removal rates achieved by SSF wetland, the reduction of pathogens was not enough for a safety reuse of the reclaimed water. To our knowledge, this is the first report of C. meleagridis from Ireland.

Human zoonotic enteropathogens in a constructed free-surface flow wetland

Effluents from a small-scale free-surface flow constructed wetland, used for polishing of secondary treated wastewater, contained significantly higher concentrations of potentially viable Giardia duodenalis cysts and Enterocytozoon bieneusi spores than did wetland influents consisting of secondary treated wastewater. Zoonotic Assemblage A of G. duodenalis cysts was identified in wetland inflows, while Assemblage A and two nonhuman infective Assemblages (i.e., C, and E) were present in wetland effluents. E. bieneusi spores represented genotype K based on DNA sequencing analysis of internal transcribed spacer. The study demonstrated that: (1) free-surface flow small-scale constructed wetlands may not provide sufficient remediation for human zoonotic protozoa and fungi present in secondary treated wastewater; (2) dogs and livestock can substantially contribute human-pathogenic protozoan and fungal microorganisms to engineered vegetated wetland systems; and (3) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat.

Synanthropic flies as vectors of Cryptosporidium and Giardia among livestock and wildlife in a multispecies agricultural complex

The capacity of synanthropic flies belonging to the families Calliphoridae, Sarcophagidae, and Muscidae to serve as mechanical vectors of Cryptosporidium and Giardia among livestock and wildlife in a multispecies agricultural complex in northwest Georgia (USA) was studied using fluorescent in situ hybridization (FISH) and immunofluorescent antibody (IFA) techniques. Flies from all three families were carrying viable Cryptosporidium oocysts and Giardia cysts internally and externally, and deposited them on trap surfaces. Furthermore, the contaminated flies and trap surfaces occurred in association with each of the four domestic animal units (beef, dairy, equine, and sheep), and in wildlife areas dominated by deer (Odocoileus virginianus) and Canada Geese (Branta canadensis). Cryptosporidium was isolated from 55.56% of the fly samples, whereas Giardia was isolated from only 7.94%. The highest numbers of Cryptosporidium were associated with cattle and wildlife areas, while Giardia occurred in greatest numbers in the sheep area. Cryptosporidium was isolated comparably from exoskeletal elutants and fly homogenates, but Giardia was isolated primarily from homogenates, indicating primarily internal transport in the latter. Surfaces visited by the flies (i.e., traps) became contaminated by both Cryptosporidium (18.89%) and Giardia (1.11%). In conclusion, these flies can serve as mechanical vectors of both Cryptosporidium and Giardia in all of these settings, and undoubtedly play a role in movement of these pathogens among the various host species.

Occurrence of Cryptosporidium and Giardia in sewage sludge and solid waste landfill leachate and quantitative comparative analysis of sanitization treatments on pathogen inactivation

Circulation of Cryptosporidum and Giardia in the environment can be facilitated by spreading of sewage sludge on agricultural or livestock grazing lands or depositing in landfills. Solid waste landfill leachate and sewage sludge samples were quantitatively tested for C. parvum and C. hominis oocysts, and G. lamblia cysts by the combined multiplexed fluorescence in situ hybridization (FISH) and immunofluorescent antibody (IFA) method. Subsequently, the effects of four sanitization treatments (i.e., ultrasound and microwave energy disintegrations, and quicklime and top-soil stabilization) on inactivation of these pathogens were determined. The landfill leachate samples were positive for Giardia, and sewage sludge samples for both Cryptosporididium and Giardia. The overall concentration of G. lamblia cysts (mean; 24.2/g) was significantly higher (P<0.01) than the concentration of C. parvum and C. hominis oocysts (mean; 14.0/g). Sonication reduced the load of G. lamblia cysts to non-detectable levels in 12 of 21 samples (57.1%), and in 5 of 6 samples (83.3%) for C. parvum and C. hominis. Quicklime stabilization treatment was 100% effective in inactivation of Cryptosporidium and Giardia, and microwave energy disintegration lacked the efficacy. Top-soil stabilization treatment reduced gradually the load of both pathogens which was consistent with the serial dilution of sewage sludge with the soil substrate. This study demonstrated that sewage sludge and landfill leachate contained high numbers of potentially viable, human-virulent species of Cryptosporidium and Giardia, and that sonication and quicklime stabilization were the most effective treatments for sanitization of sewage sludge and solid waste landfill leachates.

The role of birds in dissemination of human waterborne enteropathogens

Cryptosporidiosis, giardiasis and microsporidiosis are serious human diseases of waterborne origin; their etiologic agents and a substantial fecal coliform load can enter surface, drinking and recreational water resources from aquatic birds. The aim of this article is to present interactions between waterfowl and these waters that imply a negative public health impact, reinforcing the need for either better water-quality indicators or for water monitoring specifically for Cryptosporidium, Giardia and microsporidia. Where justifiable, the presence of waterfowl should be supported; however, management of drinking and recreational water resources needs to be improved by incorporating effective protection measures for pathogens linked to these birds.

Maximizing recovery and detection of Cryptosporidium parvum oocysts from spiked eastern oyster (Crassostrea virginica) tissue samples

Numerous studies have documented the presence of Cryptosporidium parvum, an anthropozoonotic enteric parasite, in molluscan shellfish harvested for commercial purposes. Getting accurate estimates of Cryptosporidium contamination levels in molluscan shellfish is difficult because recovery efficiencies are dependent on the isolation method used. Such estimates are important for determining the human health risks posed by consumption of contaminated shellfish. In the present study, oocyst recovery was compared for multiple methods used to isolate Cryptosporidium parvum oocysts from oysters (Crassostrea virginica) after exposure to contaminated water for 24 h. The immunomagnetic separation (IMS) and immunofluorescent antibody procedures from Environmental Protection Agency method 1623 were adapted for these purposes. Recovery efficiencies for the different methods were also determined using oyster tissue homogenate and hemolymph spiked with oocysts. There were significant differences in recovery efficiency among the different treatment groups (P < 0.05). We observed the highest recovery efficiency (i.e., 51%) from spiked samples when hemolymph was kept separate during the homogenization of the whole oyster meat but was then added to the pellet following diethyl ether extraction of the homogenate, prior to IMS. Using this processing method, as few as 10 oocysts could be detected in a spiked homogenate sample by nested PCR. In the absence of water quality indicators that correlate with Cryptosporidium contamination levels, assessment of shellfish safety may rely on accurate quantification of oocyst loads, necessitating the use of processing methods that maximize oocyst recovery. The results from this study have important implications for regulatory agencies charged with determining the safety of molluscan shellfish for human consumption.

Human waterborne trematode and protozoan infections

Waterborne trematode and protozoan infections inflict considerable morbidity on healthy, i.e., immunocompetent people, and may cause life-threatening diseases among immunocompromised and immunosuppressed populations. These infections are common, easily transmissible, and maintain a worldwide distribution, although waterborne trematode infections remain predominantly confined to the developing countries. Waterborne transmission of trematodes is enhanced by cultural practices of eating raw or inadequately cooked food, socio-economical factors, and wide zoonotic and sylvatic reservoirs of these helminths. Waterborne protozoan infections remain common in both developed and developing countries (although better statistics exist for developed countries), and their transmission is facilitated via contacts with recreational and surface waters, or via consumption of contaminated drinking water. The transmissive stages of human protozoan parasites are small, shed in large numbers in feces of infected people or animals, resistant to environmental stressors while in the environment, and few are (e.g., Cryptosporidium oocysts) able to resist standard disinfection applied to drinking water.

Risk of handling as a route of exposure to infectious waterborne Cryptosporidium parvum oocysts via Atlantic blue crabs (Callinectes sapidus)

Commercial Atlantic blue crabs (Callinectes sapidus) were exposed to 2.0x10(4) infectious waterborne oocysts of Cryptosporidium parvum. The study demonstrated that blue crabs can transfer C. parvum oocysts to persons involved in handling or preparing crabs and that they may contaminate other surfaces or products during storage.

Human enteropathogen load in activated sewage sludge and corresponding sewage sludge end products

This study demonstrated a significant reduction in the concentrations of Cryptosporidium parvum and Cryptosporidium hominis oocysts, Giardia lamblia cysts, and spores of human-virulent microsporidia in dewatered and biologically stabilized sewage sludge cake end products compared to those of the respective pathogens in the corresponding samples collected during the sludge activation process.

Fluorescent in situ hybridization as a tool to retrospectively identify Cryptosporidium parvum and Giardia lamblia in samples from terrestrial mammalian wildlife

Fecal samples of five terrestrial mammalian wildlife species stored at 4 degrees C or at -20 degrees C for up to 36 months have been tested for human zoonotic enteric parasites (i.e., Cryptosporidium parvum and Giardia lamblia) using combined fluorescent in situ hybridization (FISH) and direct fluorescent antibody techniques. The prevalence of C. parvum and G. lamblia varied from 20 to 63% (mean, 45.8%) and from 13 to 100% (mean, 53.2%), respectively. The prevalence of C. parvum and G. lamblia infections was higher in small rodents (mean, 68.5%) than in other wildlife (mean, 21%). Overall, 31.1% of animals were coinfected, and coinfections were more prevalent in small rodents (mean, 52%) than in other wildlife species (mean, 13.2%). The present study has shown that the FISH assay can be retrospectively applied to fecal samples for the identification of C. parvum oocysts, but is less suitable for the identification of G. lamblia cysts in such samples. Terrestrial mammalian wildlife, particularly small rodents, can contribute to watershed contamination with C. parvum oocysts and G. lamblia cysts. To control contamination, the management of pristine watersheds used for drinking water purposes should incorporate control measures for terrestrial wildlife, especially field rodents residing within such watersheds.

Quantitative assessment of viable Cryptosporidium parvum load in commercial oysters (Crassostrea virginica) in the Chesapeake Bay

The epidemiological importance of increasing reports worldwide on Cryptosporidium contamination of oysters remains unknown in relation to foodborne cryptosporidiosis. Thirty market-size oysters (Crassostrea virginica), collected from each of 53 commercial harvesting sites in Chesapeake Bay, MD, were quantitatively tested in groups of six for Cryptosporidium sp. oocysts by immunofluorescent antibody (IFA). After IFA analysis, the samples were retrospectively retested for viable Cryptosporidium parvum oocysts by combined fluorescent in situ hybridization (FISH) and IFA. The mean cumulative numbers of Cryptosporidium sp. oocysts in six oysters (overall, 42.1+/-4.1) were significantly higher than in the numbers of viable C. parvum oocysts (overall, 28.0+/-2.9). Of 265 oyster groups, 221 (83.4%) contained viable C. parvum oocysts, and overall, from 10-32% (mean, 23%) of the total viable oocysts were identified in the hemolymph as distinct from gill washings. The amount of viable C. parvum oocysts was not related to oyster size or to the level of fecal coliforms at the sampling site. This study demonstrated that, although oysters are frequently contaminated with oocysts, the levels of viable oocysts may be too low to cause infection in healthy individuals. FISH assay for identification can be retrospectively applied to properly stored samples.

Recovery, bioaccumulation, and inactivation of human waterborne pathogens by the Chesapeake Bay nonnative oyster, Crassostrea ariakensis

The introduction of nonnative oysters (i.e., Crassostrea ariakensis) into the Chesapeake Bay has been proposed as necessary for the restoration of the oyster industry; however, nothing is known about the public health risks related to contamination of these oysters with human pathogens. Commercial market-size C. ariakensis triploids were maintained in large marine tanks with water of low (8-ppt), medium (12-ppt), and high (20-ppt) salinities spiked with 1.0 x 10(5) transmissive stages of the following human pathogens: Cryptosporidium parvum oocysts, Giardia lamblia cysts, and microsporidian spores (i.e., Encephalitozoon intestinalis, Encephalitozoon hellem, and Enterocytozoon bieneusi). Viable oocysts and spores were still detected in oysters on day 33 post-water inoculation (pwi), and cysts were detected on day 14 pwi. The recovery, bioaccumulation, depuration, and inactivation rates of human waterborne pathogens by C. ariakensis triploids were driven by salinity and were optimal in medium- and high-salinity water. The concentration of human pathogens from ambient water by C. ariakensis and the retention of these pathogens without (or with minimal) inactivation and a very low depuration rate provide evidence that these oysters may present a public health threat upon entering the human food chain, if harvested from polluted water. This conclusion is reinforced by the concentration of waterborne pathogens used in the present study, which was representative of levels of infectious agents in surface waters, including the Chesapeake Bay. Aquacultures of nonnative oysters in the Chesapeake Bay will provide excellent ecological services in regard to efficient cleaning of human-infectious agents from the estuarine waters.

Cryptosporidiumparvum oocysts in seawater clams (Chameleagallina) in Italy

Bivalves filter large volumes of water and can concentrate organisms which are pathogenic for humans and animals. Our aim was to evaluate the presence of Cryptosporidium spp. in clams from the Adriatic coast (Abruzzo region) and genetically characterize the oocysts isolated from the clams. From March to July 2003, 960 specimens of clams (Chamelea gallina) present in nature were collected at 500 m from the Tordino, Tronto, Vibrata and Vomano river mouths on the Adriatic sea. The haemolymph and tissues were extracted from the specimens (240 per river mouth) after the specimens had been identified, measured and weighed (live weight). Immunofluorescence tests (IFA) were performed on pools (n = 32) of samples and oocysts of Cryptosporidium spp. were detected in 23 pools of C. gallina. To identify the Cryptosporidium species, all the pools IFA-positive were tested by a PCR assay specific for the Cryptosporidium outer wall protein (COWP) gene. Positive amplicons then were sequenced and analysed. Two pools of clams were positive for Cryptosporidium parvum Genotype 2 (the "bovine" i.e. zoonotic genotype). This is the first time that C. parvum was found in clams from the Adriatic sea in Italy and the case might be of public health importance.

Mechanical transmission of human protozoan parasites by insects

The filthy breeding habits, feeding mechanisms, and indiscriminate travel between filth and food make some groups of synanthropic insects such as nonbiting flies and cockroaches efficient vectors of human enteric protozoan parasites. Twenty-one species of filth flies have been listed by regulatory agencies concerned with sanitation and public health as causative agents of gastrointestinal diseases based on synanthropy, endophily, communicative behavior, and strong attraction to filth and human food. Outbreaks and cases of food-borne diarrheal diseases in urban and rural areas are closely related to the seasonal increase in abundance of filth flies, and enforced fly control is closely related to reductions in the occurrence of such diseases. Mechanical transmission of human parasites by nonbiting flies and epidemiological involvement of other synanthropic insects in human food-borne diseases have not received adequate scientific attention.

Human cryptosporidiosis: an update with special emphasis on the situation in Europe

The genus Cryptosporidium consists of different species and genotypes which infect a wide range of hosts, including humans. The parasite is ubiquitous and lack of differentiation between the species and strains has made it difficult to track down sources of human and animal infections. Genetic analysis of strains and isolates has led to the redescription of Cryptosporidium with special consideration of the host specificity and possible ways of transmission to humans. Infection with the small oocysts usually occurs directly by faecal-oral transmission, water- or food-borne. In Europe water from different sources is frequently contaminated with oocysts. Generally, humans are most frequently infected with C. hominis in an anthroponotic cycle (especially in cases of infections imported from highly endemic (sub-) tropical regions) and the animal genotype (type II) of C. parvum in a zoonotic cycle which seems to play a major role in autochthonous infections in Switzerland, the UK and probably other European countries. Other species (such as C. felis or the avian species C. meleagridis and C. baileyi) and genotypes are rare in humans and mostly restricted to immunocompromised individuals who are highly susceptible to serious opportunistic cryptosporidial infections.

Fecal-oral transmission of the cyst form of Blastocystis hominis in rats

The infectivity of two Blastocystis hominis strains, RN94-9 and NIH:1295:1, was examined in 3-week-old SPF Wistar rats. The NIH:1295:1 strain, originally isolated from a guinea pig, was only able to infect rats via intracecal inoculation of the cultured organisms, while the RN94-9 strain, originally isolated from a laboratory rat, was able to infect rats by oral inoculation of the cultures due to the presence of a cystic form in the in vitro culture. Since many cysts were discharged in the feces of the infected rats, the infectivity of the concentrated cysts was compared between the two strains. Successful oral infection was observed in rats inoculated with 1 x 10(2)-1 x 10(6) cysts of the RN94-9 and NIH:1295:1 strains. The infectivity of the ten cysts varied in the three experiments of ten rats, being 20-100% and 30-100% in the RN94-9 and NIH:1295:1 strains, respectively. When an uninfected normal rat was housed with five experimentally inoculated rats, the normal rat became infected, demonstrating the fecal-oral transmission of the cyst form of this parasite. These results show that the Wistar rat is an ideal host for the propagation of strains RN94-9 and NIH:1295:1 of B. hominis, and demonstrate that the cyst form is the only transmissible form of this parasite.

Infection of human and bovine epithelial cells with Cryptosporidium andersoni induces apoptosis and disrupts tight junctional ZO-1: effects of epidermal growth factor

The effects of Cryptosporidium andersoni on human or bovine epithelia are poorly defined. Epidermal growth factor inhibits colonisation of the gastrointestinal epithelium with bacteria and the enteric protozoan parasite Giardia lamblia. This study characterised whether C. andersoni infects human or bovine epithelial cells in vitro, assessed its impact on apoptosis and tight junctional Zonula-Occludens-1, and determined whether these effects may be altered by epidermal growth factor. Monolayers of human colonic CaCo(2) cells, SCBN (non-malignant small intestinal epithelial cells), and Madin Darby bovine kidney epithelial cell lines (MDBK and NBL-1) were grown to confluency in Dulbecco's Modified Eagle Medium. Monolayers were assigned to one of three experimental groups-(1) control: exposed to culture medium alone; (2) untreated: exposed to 10(3) live C. andersoni oocysts or (3) epidermal growth factor-treated: apically pre-treated with recombinant human epidermal growth factor and then exposed to Cryptosporidium. Oocyst viability, infection with Cryptosporidium, apoptosis, and integrity of tight junctional Zonula-Occludens-1 were assessed. In addition, live Cryptosporidium oocysts were incubated with epidermal growth factor to assess whether epidermal growth factor had cryptosporicidial activity. Cryptosporidium andersoni oocysts infected all human and bovine monolayers, increased nuclear fragmentation, and disrupted Zonula-Occludens-1. Apical epidermal growth factor significantly reduced infection with C. andersoni in all cell lines and inhibited the Cryptosporidium-induced apoptosis and disruption of Zonula-Occludens-1. Epidermal growth factor did not affect oocyst viability.

Biology of Cryptosporidium parvum in pigs: from weaning to market

Cryptosporidium parvum is commonly identified as infecting domestic livestock and humans. Prevalence of C. parvum in pigs has been reported, however, the duration and infection pattern of naturally acquired Cryptosporidium infections in pigs has not been reported. This study was undertaken to investigate the age of oocyst shedding and duration of natural Cryptosporidium parvum infections in pigs from weaning to market weight. Fecal samples were collected from weaned Yorkshire-Landrace piglets (n=33) twice per week until Cryptosporidium oocysts were detected. Upon oocyst detection, fecal samples were collected three times per week and pigs were monitored throughout the study for diarrhea and examined after concentration and immunofluroescent staining. Cryptosporidium isolates were genotyped by polymerase chain reaction to amplify the HSP70 gene which was subsequently sequence analyzed. All 33 pigs shed oocysts some time during the study. The mean age of initial oocyst detection was 45.2 days post-weaning with the mean duration of infection 28.7 days. Mean number of Cryptosporidium oocysts was low and declined to zero prior to study completion. Episodes of diarrhea were not associated with oocyst excretion. Genetic sequences were obtained for 10 of the pigs. All of the 10 isolates aligned as the Cryptosporidium parvum 'pig' genotype. This study demonstrates that the age and duration of oocyst shedding in pigs infected with C. parvum porcine genotype is different from other livestock species.

Occurrence of Cryptosporidium sp. oocysts in fecal and water samples in Austria

Oocysts of Cryptosporidium spp. were detected and differentiated by a modular arranged gene amplification procedure in various samples, mostly human stool, feces of herpetotaxa, and water, in different locations of South and Eastern Austria. Cryptosporidium parvum was found in stool samples of immunocompromised persons, in reptile feces, and in water samples. The presence of Cryptosporidium in an area is probably associated with high human population densities since water from protected sources in sparsely inhabited areas is rarely contaminated.

Efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves

The efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves was evaluated in a multicentre, control versus placebo, randomised, double-blind clinical trial. Seventy-eight six- to 48-hour-old calves were treated daily with 120 microg/kg bodyweight of halofuginone lactate administered orally for seven consecutive days, while 80 calves received a placebo. Faecal samples were collected on the first day of dosing and four, seven, 14 and 21 days later, and Cryptosporidium parvum oocysts were counted and faecal indices for diarrhoea were determined after a clinical examination. An analysis of variance for repeated measurements showed a highly significant difference in favour of halofuginone lactate for both the oocyst counts (P=0.0002) and the faecal diarrhoea indices (P=0.0001) throughout the trial. The difference was greatest after seven days, when the mean oocyst count of the placebo group was 2.5 times and its mean faecal index was twice the mean of the halofuginone lactate group. One day after the end of the treatment the calves which received halofuginone lactate excreted 44 per cent fewer C parvum oocysts and 44 per cent fewer of them had diarrhoea. The reduction was even greater (65 per cent) when liquid diarrhoea was assessed, with 32.5 per cent of the calves in the placebo group having liquid diarrhoea compared with 11.5 per cent in the halofuginone lactate group. The treatment was well tolerated and easily administered.

Foodborne infections vectored by molluscan shellfish

Foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5000 deaths each year in the United States. The authors present and analyze information derived from epidemiologic investigations and surveillance systems on foodborne infections caused by consumption of molluscan shellfish. This review focuses on the bias in reporting of shellfish-vectored illness, prevention and control of such infections, the origin of recognized viral and bacterial etiologic agents, and a new potential public health threat of a food-and-waterborne protozoan contaminant, Cryptosporidium parvum.

Viability and infectivity of two Cryptosporidium parvum bovine isolates from different geographical location

The viability of two Cryptosporidium parvum bovine isolates from Spain and Colombia was evaluated by in vitro excystation, inclusion/exclusion of two fluorogenic vital dyes (DAPI and PI) and infectivity assay in a suckling murine model. Excystation percentages were similar for both Spain and Colombia isolates (83% and 87%, respectively). The total viability of the Spain isolate, measured by inclusion/exclusion of two fluorogenic vital dyes, was 71% in comparison with that detected for oocysts of the Colombia isolate, 32.3%. The bovine C. parvum oocysts of both isolates were viable and infectious for suckling Swiss CD-1 mice. However, infectivity percentage and the mean intensity of infection were consistently higher in the Spain isolate than those from Colombia isolate. It was not possible to obtain a good correlation between in vitro excystation, inclusion/exclusion of vital dyes and in vivo infectivity for the Colombia isolate, while data obtained with the Spain isolate indicated that there was an apparent strong correlation between excystation efficiency, total viability and the infectivity. Although a comparative analysis of genetic variation among these isolates from different geographical location is necessary, variations observed between the both isolates seemed to be a result of parasite adaptation to environmental stresses such as temperature which appears to have a direct effect on the permeability of the oocysts.