Survival of Cryptosporidium parvum oocysts under various environmental pressures

Zootechnical wastewater reuse: constructed wetland as a challenge for protozoan parasite removal

Samples of soil, well water, and wastewater from a zootechnical farm, water after phytodepuration and maize plants (Zea mays) grown on soils irrigated with these different kinds of water were analysed for indicator bacteria and the protozoa Giardia and Cryptosporidium. Protozoa and bacterial indicators, except coliforms, were not recovered from well water samples. In the effluent from the zootechnical farm, high parasitological concentrations were observed, whilst water after the phytodepuration process showed a concentration reduction of two orders of magnitude. The high numbers of Giardia and Cryptosporidium in the zootechnical effluent could represent a potential risk for the spread of the pathogens. Nevertheless the environmental spread is minimized when data on soils and plants are observed. From the study, it emerges that this water treatment system could represent an alternative option to other conventional wastewater treatments and an economic and environmental advantage.

Two-year monitoring of Cryptosporidium parvum and Giardia lamblia occurrence in a recreational and drinking water reservoir using standard microscopic and molecular biology techniques

Starting in 2006, a monitoring of Giardia lamblia and Cryptosporidium parvum occurrence was conducted for 2 years in the largest drinking water reservoir of Luxembourg (Esch-sur-Sûre reservoir) using microscopy and qPCR techniques. Parasite analyses were performed on water samples collected from three sites: site A located at the inlet of the reservoir, site B located 18 km downstream site A, at the inlet of the drinking water treatment plant near the dam of the reservoir and site C where the finished drinking water is injected in the distribution network. Results show that both parasites are present in the reservoir throughout the year with a higher occurrence of G. lamblia cysts compared to C. parvum oocysts. According to our results, only 25% of the samples positive by microscopy were confirmed by qPCR. (Oo)cyst concentrations were 10 to 100 times higher at site A compared to site B and they were positively correlated to the water turbidity and negatively correlated to the temperature. Highest (oo)cyst concentrations were observed in winter. In contrast, no relationship between the concentrations of (oo)cysts in the reservoir and rain events could be established. Though a correlation has been observed between both parasites and faecal indicators in the reservoir, some discrepancies highlight that the latter do not represent a reliable tool to predict the presence/absence of these pathogenic protozoa. In summer 2007, the maximal risk of parasite infection per exposure event for swimmers in the reservoir was estimated to be 0.0015% for C. parvum and 0.56% for G. lamblia. Finally, no (oo)cysts could be detected in large volumes of finished drinking water.

Detection of viable Cryptosporidium parvum in soil by reverse transcription-real-time PCR targeting hsp70 mRNA

Extraction of high-quality mRNA from Cryptosporidium parvum is a key step in PCR detection of viable oocysts in environmental samples. Current methods for monitoring oocysts are limited to water samples; therefore, the goal of this study was to develop a rapid and sensitive procedure for Cryptosporidium detection in soil samples. The efficiencies of five RNA extraction methods were compared (mRNA extraction with the Dynabeads mRNA Direct kit after chemical and physical sample treatments, and total RNA extraction methods using the FastRNA Pro Soil-Direct, PowerSoil Total RNA, E.Z.N.A. soil RNA, and Norgen soil RNA purification kits) for the direct detection of Cryptosporidium with oocyst-spiked sandy, loamy, and clay soils by using TaqMan reverse transcription-PCR. The study also evaluated the presence of inhibitors by synthesis and incorporation of an internal positive control (IPC) RNA into reverse transcription amplifications, used different facilitators (bovine serum albumin, yeast RNA, salmon DNA, skim milk powder, casein, polyvinylpyrrolidone, sodium hexametaphosphate, and Salmonella enterica serovar Typhi) to mitigate RNA binding on soil components, and applied various treatments (β-mercaptoethanol and bead beating) to inactivate RNase and ensure the complete lysis of oocysts. The results of spiking studies showed that Salmonella cells most efficiently relieved binding of RNA. With the inclusion of Salmonella during extraction, the most efficient mRNA method was Dynabeads, with a detection limit of 6 × 10(2) oocysts g(-1) of sandy soil. The most efficient total RNA method was PowerSoil, with detection limits of 1.5 × 10(2), 1.5 × 10(3), and 1.5 × 10(4) C. parvum oocysts g(-1) soil for sandy, loamy, and clay samples, respectively.

Cryptosporidium and Giardia associated with reduced lamb carcase productivity

On two extensive sheep farms in southern Western Australia, 111 (Farm A) and 124 (Farm B) female crossbred lambs (2-6 weeks old) were randomly selected and individually identified using ear tags (a numbered tag and radio-frequency tag) at marking. On five separate occasions, faecal samples were collected and live weight, body condition score (BCS), faecal consistency score (FCS), breech fleece faecal soiling score and faecal dry matter percentage (DM%) were recorded. Lamb hot carcase weight (HCW) and dressing percentage were measured at slaughter. Faecal samples were screened by PCR for Cryptosporidium (18S rRNA, actin and 60 kDa glycoprotein [gp60] loci), Giardia duodenalis (glutamate dehydrogenase [gdh] and triosephosphate isomerise [tpi]) and Campylobacter jejuni (16S rRNA). Observation of Eimeria oocysts and faecal worm egg counts (WECs) were performed using a modified McMaster technique. The WECs were adjusted for FCS for analyses. Faecal samples were screened for patent strongylid infections using PCR (specifically ITS-2 nuclear ribosomal DNA for Teladorsagia circumcincta, Trichostrongylus spp. and Haemonchus contortus). Lambs positive for Cryptosporidium at least once had lighter HCWs by 1.25 kg (6.6%) (P=0.029) and 1.46 kg (9.7%) (P<0.001) compared to lambs never positive for Cryptosporidium for Farms A and B respectively. Similarly, dressing percentages were 1.7% (P=0.022) and 1.9% (P<0.001) lower in Cryptosporidium-positive lambs on Farms A and B respectively. Lambs positive for Giardia at least once had 0.69 kg (P<0.001) lighter HCWs and 1.7% (P<0.001) lower dressing percentages compared to lambs never positive for Giardia on Farm B only. Cryptosporidium-positive lambs at the second sampling were 4.72 (P=0.010) and 3.84 (P=0.002) times more likely to have non-pelleted faeces compared to Cryptosporidium-negative lambs for Farms A and B respectively. Breech fleece faecal soiling scores of Cryptosporidium-positive lambs were 3.36 (P=0.026) and 2.96 (P=0.047) times more likely to be moderate to severe (scores 3-5), compared to negative lambs at the second sampling for Farms A and B respectively. Live weight, growth rate and BCS were inconsistently associated with protozoa detection across different samplings and farms. Adjusted WEC was correlated positively with FCS and negatively with faecal DM%, differing between sampling occasions and farms. Campylobacter jejuni prevalence was very low (<1%). Adjusted WEC were not correlated with carcase attributes, growth rates or live weights. This study is the first to quantify productivity consequences of naturally acquired protozoa infections in lambs managed under extensive farming conditions.

Biogeographical region and host trophic level determine carnivore endoparasite richness in the Iberian Peninsula

We address the question of whether host and/or environmental factors might affect endoparasite richness and distribution, using carnivores as a model. We reviewed studies published in international peer-reviewed journals (34 areas in the Iberian Peninsula), describing parasite prevalence and richness in carnivores, and collected information on site location, host bio-ecology, climate and detected taxa (Helminths, Protozoa andMycobacteriumspp.). Three hypotheses were tested (i) host based, (ii) environmentally based, and (iii) hybrid (combination of environmental and host). Multicollinearity reduced candidate variable number for modelling to 5: host weight, phylogenetic independent contrasts (host weight), mean annual temperature, host trophic level and biogeographical region. General Linear Mixed Modelling was used and the best model was a hybrid model that included biogeographical region and host trophic level. Results revealed that endoparasite richness is higher in Mediterranean areas, especially for the top predators. We suggest that the detected parasites may benefit from mild environmental conditions that occur in southern regions. Top predators have larger home ranges and are likely to be subjected to cascading effects throughout the food web, resulting in more infestation opportunities and potentially higher endoparasite richness. This study suggests that richness may be more affected by historical and regional processes (including climate) than by host ecological processes.

Efficacy of amine-based disinfectant KENO™COX on the infectivity of Cryptosporidium parvum oocysts

Cryptosporidium parvum is a zoonotic protozoan parasite that may cause severe neonatal diarrhoea or even mortality in newborn ruminants: its oocysts are extremely resistant to normal environmental conditions and to most common disinfectants. KENO™COX, a patent pending amine-based formula, was tested for its ability to inactivate C. parvum oocysts. The Daugschies assay (2002), a standardized assay for chemical disinfection initially described for Eimeria spp., was adapted for C. parvum oocysts. KENO™COX diluted in water at 2% and 3% concentration and incubated with oocyst suspensions for 2h, allowed a significant reduction in viability, lysing 89% and 91% of oocysts respectively. Infectivity of the remaining C. parvum oocysts was assessed by inoculation to C57 Bl/6 neonatal mice. Each mouse received 2.5 μl of a suspension initially containing 500,000 oocysts before contact with KENO™COX. Six days post inoculation, the intestinal parasite load was significantly reduced by 97.5% with KENO™COX 2% compared to that of the mice inoculated with untreated parasites. KENO™COX 3% completely eliminated infectivity of oocysts. The number of oocysts remaining infectious in the inoculum treated with KENO™COX 2% was calculated from an inoculated dose-response curve: it was estimated at about 48.6 oocysts among the 500,000 oocysts initially treated corresponding to 99.99% of inhibition. These results demonstrate the high efficacy of KENO™COX against C. parvum oocysts. Combined with an appropriate method of cleaning, the application of KENO™COX may be a useful tool to reduce cryptosporidial infectious load on farm level.

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.

The prevalence of Cryptosporidium spp. oocysts in wild mammals in the Kruger National Park, South Africa

This study determined the prevalence of Cryptosporidium spp. oocysts in faecal samples from elephant (Loxodonta africana), buffalo (Syncerus caffer) and impala (Aepyceros melampus) in the Kruger National Park (KNP) and an adjacent game reserve in South Africa. Two of the study areas were in close proximity to rural communities on the western KNP boundary and the third study area was located in the centre of the KNP. Fresh stool samples (n=445) were collected and tested using an immunofluorescent antibody test (IFA) for Cryptosporidium parvum. A total of 278 of these were randomly selected (approximately 90 samples per wildlife species) and tested with the modified Ziehl Neelsen staining technique (ZN) for Cryptosporidium spp. The prevalence of Cryptosporidium spp. was highest in elephants (25.8% [95% confidence interval: 17.3, 35.9]), compared to buffalo (5.5% [1.8, 12.4]) and impala (4.3% [1.2, 10.5]). C. parvum showed similar patterns, being most prevalent in elephants (4.2% [1.5, 8.8]), compared to buffalo (1.4% [0.2, 5.1]) and impala (1.9% [0.4, 5.3]). 29 samples, including ZN positive and IFA positive samples, were retested using a real time PCR (rtPCR) technique. Of the 28 ZN-positive samples, 14 (50%) were positive with rtPCR and of the 9 IFA-positive samples 6 (67%) were confirmed positive by rtPCR. The prevalence of Cryptosporidium oocysts was significantly higher in both of the two study areas adjacent to the western KNP boundary compared to the area in the centre of the KNP (OR=3.2 [1.2, 9.0]; P=0.024). Our study demonstrates for the first time the presence of Cryptosporidium spp. in wildlife in South Africa. The transmission of this parasite between wildlife, domestic animals and humans is a plausible hypothesis and represents a potential risk for immunodeficient human populations.

Presence of Bacteroidales as a predictor of pathogens in surface waters of the central California coast

The value of Bacteroidales genetic markers and fecal indicator bacteria (FIB) to predict the occurrence of waterborne pathogens was evaluated in ambient waters along the central California coast. Bacteroidales host-specific quantitative PCR (qPCR) was used to quantify fecal bacteria in water and provide insights into contributing host fecal sources. Over 140 surface water samples from 10 major rivers and estuaries within the Monterey Bay region were tested over 14 months with four Bacteroidales-specific assays (universal, human, dog, and cow), three FIB (total coliforms, fecal coliforms, and enterococci), two protozoal pathogens (Cryptosporidium and Giardia spp.), and four bacterial pathogens (Campylobacter spp., Escherichia coli O157:H7, Salmonella spp., and Vibrio spp.). Indicator and pathogen distribution was widespread, and detection was not highly seasonal. Vibrio cholerae was detected most frequently, followed by Giardia, Cryptosporidium, Salmonella, and Campylobacter spp. Bayesian conditional probability analysis was used to characterize the Bacteroidales performance assays, and the ratios of concentrations determined using host-specific and universal assays were used to show that fecal contamination from human sources was more common than livestock or dog sources in coastal study sites. Correlations were seen between some, but not all, indicator-pathogen combinations. The ability to predict pathogen occurrence in relation to indicator threshold cutoff levels was evaluated using a weighted measure that showed the universal Bacteroidales genetic marker to have a comparable or higher mean predictive potential than standard FIB. This predictive ability, in addition to the Bacteroidales assays providing information on contributing host fecal sources, supports using Bacteroidales assays in water quality monitoring programs.

Effects of Preservatives on Viability of Cryptosporidium parvum Oocysts

Potassium dichromate and formalin reduced the viability of Cryptosporidium parvum oocysts as assessed by inclusion or exclusion of 4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) and excystation. Some formalin-treated oocysts containing dead sporozoites excluded PI; that this fluorogenic assay relies not solely upon exclusion of PI but also upon highlighting of sporozoite nuclei by DAPI is reiterated.

Significance of wall structure, macromolecular composition, and surface polymers to the survival and transport of Cryptosporidium parvum oocysts

The structure and composition of the oocyst wall are primary factors determining the survival and hydrologic transport of Cryptosporidium parvum oocysts outside the host. Microscopic and biochemical analyses of whole oocysts and purified oocyst walls were undertaken to better understand the inactivation kinetics and hydrologic transport of oocysts in terrestrial and aquatic environments. Results of microscopy showed an outer electron-dense layer, a translucent middle layer, two inner electron-dense layers, and a suture structure embedded in the inner electron-dense layers. Freeze-substitution showed an expanded glycocalyx layer external to the outer bilayer, and Alcian Blue staining confirmed its presence on some but not all oocysts. Biochemical analyses of purified oocyst walls revealed carbohydrate components, medium- and long-chain fatty acids, and aliphatic hydrocarbons. Purified walls contained 7.5% total protein (by the Lowry assay), with five major bands in SDS-PAGE gels. Staining of purified oocyst walls with magnesium anilinonaphthalene-8-sulfonic acid indicated the presence of hydrophobic proteins. These structural and biochemical analyses support a model of the oocyst wall that is variably impermeable and resistant to many environmental pressures. The strength and flexibility of oocyst walls appear to depend on an inner layer of glycoprotein. The temperature-dependent permeability of oocyst walls may be associated with waxy hydrocarbons in the electron-translucent layer. The complex chemistry of these layers may explain the known acid-fast staining properties of oocysts, as well as some of the survival characteristics of oocysts in terrestrial and aquatic environments. The outer glycocalyx surface layer provides immunogenicity and attachment possibilities, and its ephemeral nature may explain the variable surface properties noted in oocyst hydrologic transport studies.

Effect of daily temperature fluctuation during the cool season on the infectivity of Cryptosporidium parvum

The present work calculated the rate of inactivation of Cryptosporidium parvum oocysts attributable to daily oscillations of low ambient temperatures. The relationship between air temperature and the internal temperature of bovine feces on commercial operations was measured, and three representative 24-h thermal regimens in the approximately 15 degrees C, approximately 25 degrees C, and approximately 35 degrees C ranges were chosen and emulated using a thermocycler. C. parvum oocysts suspended in deionized water were exposed to the temperature cycles, and their infectivity in mice was tested. Oral inoculation of 10(3) treated oocysts per neonatal BALB/c mouse (approximately 14 times the 50% infective dose) resulted in time- and temperature-dependent reductions in the proportion of infected mice. Oocysts were completely noninfectious after 14 24-h cycles with the 30 degrees C regimen and after 70 24-h cycles with the 20 degrees C regimen. In contrast, oocysts remained infectious after 90 24-h cycles with the 10 degrees C regimens. The estimated numbers of days needed for a 1-log(10) reduction in C. parvum oocyst infectivity were 4.9, 28.7, and 71.5 days for the 30, 20, and 10 degrees C thermal regimens, respectively. The loss of infectivity of oocysts induced by these thermal regimens was due in part to partial or complete in vitro excystation.

Effect of tillage and rainfall on transport of manure-applied Cryptosporidium parvum oocysts through soil

Most waterborne outbreaks of cryptosporidiosis have been attributed to agricultural sources due to the high prevalence of Cryptosporidium oocysts in animal wastes and manure spreading on farmlands. No-till, an effective conservation practice, often results in soil having higher water infiltration and percolation rates than conventional tillage. We treated six undisturbed no-till and six tilled soil blocks (30 by 30 by 30 cm) with 1 L liquid dairy manure containing 10(5) C. parvum oocysts per milliliter to test the effect of tillage and rainfall on oocyst transport. The blocks were subjected to rainfall treatments consisting of 5 mm or 30 mm in 30 min. Leachate was collected from the base of the blocks in 35-mL increments using a 64-cell grid lysimeter. Even before any rain was applied, approximately 300 mL of water from the liquid manure (30% of that applied) was transported through the no-till soil, but none through the tilled blocks. After rain was applied, a greater number and percentage of first leachate samples from the no-till soil blocks compared to the tilled blocks tested positive for Cryptosporidium oocysts. In contrast to leachate, greater numbers of oocysts were recovered from the tilled soil, itself, than from the no-till soil. Although tillage was the most important factor affecting oocyst transport, rainfall timing and intensity were also important. To minimize transport of Cryptosporidium in no-till fields, manure should be applied at least 48 h before heavy rainfall is anticipated or methods of disrupting the direct linkage of surface soil to drains, via macropores, need to be used.

Cryptosporidium: detection in water and food

Water and food are major environmental transmission routes for Cryptosporidium, but our ability to identify the spectrum of oocyst contributions in current performance-based methods is limited. Determining risks in water and foodstuffs, and the importance of zoonotic transmission, requires the use of molecular methods, which add value to performance-based morphologic methods. Multi-locus approaches increase the accuracy of identification, as many signatures detected in water originate from species/genotypes that are not infectious to humans. Method optimisation is necessary for detecting small numbers of oocysts in environmental samples consistently, and further work is required to (i) optimise IMS recovery efficiency, (ii) quality assure performance-based methods, (iii) maximise DNA extraction and purification, (iv) adopt standardised and validated loci and primers, (v) determine the species and subspecies range in samples containing mixtures, and standardising storage and transport matrices for validating genetic loci, primer sets and DNA sequences.

Evaluation of two methods for quantification of hsp70 mRNA from the waterborne pathogen Cryptosporidium parvum by reverse transcription real-time PCR in environmental samples

We optimized and evaluated two mRNA extraction methods to quantify induced hsp70 mRNA from viable and injured Cryptosporidium parvum oocysts by reverse transcription quantitative real-time PCR (RT-qPCR) in raw and treated manure. Methods based on guanidinium isothiocyanate/phenol/chloroform (GITC-PC) purification and direct mRNA extraction with magnetic oligo(dT)25-coated beads were evaluated for applicability and sensitivity. Both methods proved to be suitable for processing manure samples. With washed manure samples and oocyst disruption by bead beating for 165 s in time intervals with cumulative pooling of the lysate fractions, optimum RT-qPCR results were achieved. On average, 2.6 times more hsp70 mRNA was detected with the oligo(dT)25 method in comparison to the GITC-PC based method using fresh oocysts, whereas less mRNA was detected in aged oocysts. For fresh oocysts, analytical and method detection limits for the oligo(dT)25 based method were 1.7 cDNA copies/qPCR reaction and 5150 oocysts/mL manure, and for the GITC-PC based method 17 cDNA copies/qPCR reaction and 4950 oocysts/mL, respectively. In 12 months old oocysts with reduced viability, mRNA was occasionally detected only by the GITC-PC based method. Failure of or reduced detection with the oligo(dT)25 based method was apparently a result of weakened oocyst walls leading to quicker release of mRNA and therefore mRNA shredding by bead beating in the relatively long stretch between the capture sequence and the RT-qPCR target sites.

In-situ monitoring of Cryptosporidium parvum oocyst surface adhesion using ATR-FTIR spectroscopy

Surface chemistry and molecular interaction mechanisms of Cryptosporidium parvum oocysts with a ZnSe internal reflection element (IRE) surface were investigated as a function of pH and ionic strength in NaCl and CaCl(2) background electrolyte using in-situ ATR-FTIR spectroscopy. Since the surface properties of oocysts play an important role in adhesion behavior, the effects of surface modifications that are commonly employed to inactivate the pathogen for laboratory studies, including viable (control), formalin-, and heat-inactivation, were also examined. The ATR-FTIR spectra of oocyst surfaces exhibit amide, carboxylate, phosphate, and polysaccharide functional groups. Results indicate that changes in solution chemistry strongly impact oocyst adhesion behavior in aqueous systems. Increasing ionic strength from 1 to 100 mM or decreasing pH from 9.0 to 3.0 resulted in an increase in oocyst adhesion to the IRE surface as measured by IR absorbance. For equivalent ionic strength, the adhesion rate was found to be independent of CaCl(2) versus NaCl electrolyte solution, but was increased following formalin and heat treatments. This latter effect correlated with molecular changes reflected in spectral data. The ratio of amide I:amide II band intensities increased, and sugar ring vibrations at 1023 cm(-1) became sharper and more intense following formalin treatment. Similar changes in the polysaccharide region were observed following heat treatment, and protein secondary structure was also altered from mainly parallel beta-sheet to anti-parallel beta-sheet conformation.

Recent advances in the microbial safety of fresh fruits and vegetables

Foodborne illness outbreaks linked to fresh produce are becoming more frequent and widespread. High impact outbreaks, such as that associated with spinach contaminated with Escherichia coli O157:H7, resulted in almost 200 cases of foodborne illness across North America and >$300 m market losses. Over the last decade there has been intensive research into gaining an understanding on the interactions of human pathogens with plants and how microbiological safety of fresh produce can be improved. The following review will provide an update on the food safety issues linked to fresh produce. An overview of recent foodborne illness outbreaks linked to fresh produce. The types of human pathogens encountered will be described and how they can be transferred from their normal animal or human host to fresh produce. The interaction of human pathogens with growing plants will be discussed, in addition to novel intervention methods to enhance the microbiological safety of fresh produce.

Effect of storage media, temperature, and time on preservation of Cryptosporidium parvum oocysts for PCR analysis

The effect of storage media, temperature, and time on suitability of oocysts for use in subsequent molecular studies was examined. Cryptosporidium parvum oocysts were stored for 3, 6, 9, or 12 months in sterile dH(2)O, 70 or 95% ethanol, (room temperature [RT], 4, -20, and -70 degrees C), 10% formalin (RT and 4 degrees C), PBS, TE buffer, antibiotic-antimycotic (A-A) solution (4, -20 and -70 degrees C), 2% sulphuric acid, 2.5% potassium dichromate (4 degrees C), and gDNA from 10(4) oocysts was extracted in triplicate and subjected to PCR. To determine the effect of storage media on PCR sensitivity, gDNA from 10(4), 10(2), and 10(0) oocysts stored for 15 months in the media listed above at RT or 4 degrees C was also extracted in triplicate and subjected to PCR. At RT, ethanol was suitable for up to 15 months, while gDNA from oocysts stored in dH(2)O amplified inconsistently after 3 months. At 4 degrees C, all tested media except dH(2)O and formalin were suitable for storage of 10(4) oocysts up to 15 months, but only 70% ethanol, A-A solution, 2% sulphuric acid and 2.5% potassium dichromate supported amplification of gDNA from fewer than 100 oocysts. At -20 degrees C, 95% ethanol, PBS, or TE were suitable for up to 9 months, while 70% ethanol and A-A solution were effective up to 12 months, and gDNA from oocysts stored in dH(2)O was inconsistently amplified after 6 months. Storage at -70 degrees C for up to 12 months was effective regardless of media type. Oocysts stored in formalin at RT or 4 degrees C could not be amplified by PCR despite washing prior to gDNA extraction. To maintain gDNA quality suitable for PCR, it is recommended that coccidian oocysts be stored at -70 degrees C in dH(2)O, ethanol, PBS, TE or A-A solution, at 4 degrees C in A-A or ethanol, or at RT in ethanol where refrigerated storage is unavailable.

Environmental inactivation of Cryptosporidium parvum oocysts in waste stabilization ponds

The survival of Cryptosporidium parvum oocysts in a waste stabilization pond system in northwestern Spain and the effects of sunlight and the depth and type of pond on oocyst viability were evaluated using an assay based on the exclusion or inclusion of two fluorogenic vital dyes, 4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI). All tested factors had significant effects (P < 0.01) over time on C. parvum oocyst viability. Sunlight exposure was the most influential factor for oocyst inactivation. A 40% reduction was observed after 4 days exposure to sunlight conditions compared with dark conditions. The type of pond also caused a significant reduction in C. parvum oocyst viability (P < 0.01). Inactivation rates reflected that the facultative pond was the most aggressive environment for oocysts placed both at the surface (presence of sunlight) and at the bottom (absence of sunlight) of the pond, followed by the maturation pond and the anaerobic pond. The mean inactivation rates of oocysts in the ponds ranged from 0.0159 to 0.3025 day(-1).

Investigation of Swedish cases reveals an outbreak of cryptosporidiosis at a Norwegian hotel with possible links to in-house water systems

Background

In March 2007, the Norwegian Institute of Public Health was notified of Swedish individuals diagnosed with cryptosporidiosis after staying at a Norwegian hotel. In Norway, cryptosporidiosis is not reportable, and human infections are rarely diagnosed.

Methods

A questionnaire on illness and exposure history was e-mailed to seven organised groups who had visited the hotel in March. Cases were defined as persons with diarrhoea for more than two days or laboratory-confirmed cryptosporidiosis during or within two weeks of the hotel visit. The risk factor analysis was restricted to two groups with the highest attack rates (AR) and same hotel stay period. Local food safety authorities conducted environmental investigations.

Results

In total, 25 diarrhoeal cases (10 laboratory-confirmed) were identified among 89 respondents. Although environmental samples were negative, epidemiological data suggest an association with in-house water consumption. In one group, the AR was higher amongst consumers of water from hotel dispenser (relative risk [RR] = 3.0; 95% confidence interval [CI]: 0.9–9.8), tap water (RR = 2.3; CI: 0.9–5.8), and lower amongst commercial bottled water drinkers (RR = 0.6; CI: 0.4–1.0). Consumption of ice cubes was a risk-factor (RR = 7.1; CI: 1.1–45.7) in the two groups combined.

Conclusion

This outbreak would probably have remained undetected without the alert from Swedish health authorities, illustrating the difficulties in outbreak detection due to low health care seeking behaviour for diarrhoea and limited parasite diagnostics in Norway. Awareness of cryptosporidiosis should be raised amongst Norwegian medical personnel to improve case and outbreak detection, and possible risks related to in-house water systems should be assessed.

High-yield amplification of Cryptosporidium parvum in interferon gamma receptor knockout mice

To date, large-scale production of Cryptosporidium parvum oocysts has only been achieved by amplification in neonatal calves and sheep. Many laboratories currently depend on supplies from external sources and store oocysts for prolonged periods which results in progressive loss of viability. Six to 8-week-old interferon gamma receptor knockout (IFN gamma R-KO) mice on a C57BL/6 background were inoculated by gavage (2000 oocysts/animal). Fecal pellets were collected daily from 7 days post-infection (p.i.) up to 2 weeks p.i. Intestinal oocyst yield was assessed at days 11, 12 and 14 p.i. by homogenization of intestinal tissues. Ether extraction and one or more NaCl flotations were used to purify oocysts. Total recoveries averaged 2.6 x 10(6) oocysts/mouse from fecal material and 3.8 x 10(7) oocysts/mouse from intestinal tissues. Overall, 2.3 x 10(9) purified oocysts were obtained from 60 mice. Recovered oocysts were capable of sporulation and were shown to be infectious both in vitro and in vivo. Oocyst amplification was achieved in only 11-14 days with minimal expense. The simplicity of this method presents a practical alternative for the routine passage, maintenance and storage of C. parvum in biomedical laboratories.

Cryptosporidium--biotechnological advances in the detection, diagnosis and analysis of genetic variation

Cryptosporidiosis is predominantly a gastrointestinal disease of humans and other animals, caused by various species of protozoan parasites representing the genus Cryptosporidium. This disease, transmitted mainly via the faecal-oral route (in water or food), is of major socioeconomic importance worldwide. The diagnosis and genetic characterization of the different species and population variants (usually recognised as "genotypes" or "subgenotypes") of Cryptosporidium is central to the prevention, surveillance and control of cryptosporidiosis, particularly given that there is presently no broadly applicable treatment regimen for this disease. Although traditional phenotypic techniques have had major limitations in the specific diagnosis of cryptosporidiosis, there have been major advances in the development of molecular analytical and diagnostic tools. This article provides a concise account of Cryptosporidium and cryptosporidiosis, and focuses mainly on recent advances in nucleic acid-based approaches for the diagnosis of cryptosporidiosis and analysis of genetic variation within and among species of Cryptosporidium. These advances represent a significant step toward an improved understanding of the epidemiology as well as the prevention and control of cryptosporidiosis.

Surface plasmon resonance-based inhibition assay for real-time detection of Cryptosporidium parvum oocyst

A surface plasmon resonance (SPR)-based inhibition assay method using a polyclonal anti-mouse IgM arrayed Cryptosporidium sensor chip was developed for the real-time detection of Cryptosporidium parvum oocysts. The Cryptosporidium sensor chip was fabricated by subsequent immobilization of streptavidin and polyclonal anti-mouse IgM (secondary antibody) onto heterogeneous self-assembled monolayers (SAMs). The assay consisted of the immunoreaction step between monoclonal anti-C. parvum oocyst (primary antibody) and oocysts, followed by the binding step of the unbound primary antibody onto the secondary antibody surface. It enhanced not only the immunoreaction yield of the oocysts by batch reaction but also the accessibility of analytes to the chip surface by antibody-antibody interaction. Furthermore, the use of optimum concentration of the primary antibody maximized its binding response on the chip. An inversely linear calibration curve for the oocyst concentration versus SPR signal was obtained in the range of 1x10(6)-1x10(2)oocystsml(-1). The oocyst detection was also successfully achieved in natural water systems. These results indicate that the SPR-based inhibition assay using the Cryptosporidium sensor chip has high application potential for the real-time analysis of C. parvum oocyst in laboratory and field water monitoring.

Effects of low and high temperatures on infectivity of Cryptosporidium muris oocysts suspended in water

Cryptosporidium muris oocysts suspended in 200 microl of water were pipetted into plastic microcentrifuge tubes which were stored at 4 degrees C or frozen at -5 degrees C for 1, 3, 5, 7, and 10 days and at -20 degrees C for 1, 3, 5, and 8h, respectively. Other samples of C. muris oocysts suspended in water were heated in the metal block of a thermal DNA cycler. Block temperatures were set at 5 degrees C incremental temperatures from 40 to 70 degrees C. At each high temperature setting microcentrifuge tubes containing C. muris oocysts were exposed for 1 min. Both, frozen and heated oocyst suspensions as well as untreated control oocyst suspensions were then inoculated into each of four ICR mice by gastric intubation. Untreated, freeze-thawed or heated oocysts were considered infectious when oocysts of C. muris were found microscopically in the faeces of mice after inoculation. All inoculated mice that received oocysts frozen at -5 degrees C for 3, 5, 7, and 10 days and -20 degrees C for 1, 3, 5, and 8h had no oocysts in faeces. In contrast, C. muris oocysts frozen at -5 degrees C for 1 day remained infective for inoculated mice. Our results also indicated that when water containing C. muris oocysts was exposed at a temperature of 55 degrees C or higher for 1 min, the infectivity of oocysts was lost.

Solar UV reduces Cryptosporidium parvum oocyst infectivity in environmental waters

AIMS

To determine the effect of solar radiation on Cryptosporidium parvum in tap and environmental waters.

METHODS AND RESULTS

Outdoor tank experiments and a cell culture infectivity assay were used to measure solar inactivation of C. parvum oocysts in different waters. Experiments conducted on days with different levels of solar insolation identified rapid inactivation of oocysts in tap water (up to 90% inactivation within the first hour). Increased dissolved organic carbon content in environmental waters decreased solar inactivation. The role of solar ultraviolet (UV) in inactivation was confirmed by long-pass filter experiments, where UV-B was identified as the most germicidal wavelength. Reductions in oocyst infectivity following solar radiation were not related to a loss of excystation capacity.

CONCLUSIONS

Solar UV can rapidly inactivate C. parvum in environmental waters.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study to assess natural sunlight inactivation of C. parvum oocysts in surface waters and drinking water using an infectivity measure and determines the wavelengths of light responsible for the inactivation. The findings presented here provide valuable information for determining the relative risks associated with Cryptosporidium oocysts in aquatic environments and identify solar radiation as a critical process affecting the oocyst survival in the environment.

Effect of various environmental factors on the viability of Cryptosporidium parvum oocysts

AIMS

To evaluate individual and combined effects of temperature (4, 18 and 25 degrees C), pH (7 and 10), ammonia (5 and 50 mg l(-1)) and exposure time (1, 2, 4 and 6 days) on the viability of Cryptosporidium parvum oocysts in water.

METHODS AND RESULTS

The viability of oocysts was evaluated using the fluorogenic vital dyes assay (4',6-diamidino-2-phenylindole and propidium iodide). All the factors analysed (temperature, pH, ammonia and exposure time) and their interaction were statistically significant (P < 0.005). Exposure of oocysts to pH 10 for 6 days at 25 degrees C reduced oocyst viability from approximately 80% to 51%. Similarly, the exposure of C. parvum oocysts to 5 mg NH(3) l(-1) and 50 mg NH(3) l(-1) for 4 days reduced their viability from between approximately 80% to 41.5% and 14.8%, respectively.

CONCLUSIONS

The interaction between pH, temperature and exposure time may have adverse effects on the survival of C. parvum oocysts in water. Low concentrations of ammonia, as commonly found in alga-based wastewater systems, over a long period of time can produce high C. parvum oocyst inactivation rates.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides relevant data on the inactivation of C. parvum oocysts in alga-based wastewater-treatment systems in the northwest of Spain.

Effect of sunlight on the infectivity ofCryptosporidium parvumin seawater

The prevalence of pathogenic microorganisms in seawater can result in waterborne and food borne outbreaks. This study was performed to determine the effect of sunlight and salinity on the die-off of Cryptosporidium parvum . Cryptosporidium parvum oocysts, Escherichia coli , and MS2 coliphage were seeded into tap water and seawater samples and then exposed to sunlight. The die-off of C. parvum in seawater, as measured by infectivity, was greater under sunlight (–3.08 log10) than under dark conditions (–1.31 log10). While, no significant difference was recorded in the die-off of C. parvum, under dark conditions, in tap water as compared to seawater (P < 0.05), indicating that the synergistic effect of salinity and sunlight was responsible for the enhanced die-off in seawater. The die-off of MS2 coliphage and E. coli was greater than that observed for C. parvum under all tested conditions. This indicates that these microorganisms cannot serve as indicators for the presence of C. parvum oocysts in seawaters. The results of the study suggest that C. parvum can persist as infectious oocysts for a long time in seawater and can thus pose a serious hazard by direct and indirect contact with humans.

Disinfection of drinking water contaminated with Cryptosporidium parvum oocysts under natural sunlight and using the photocatalyst TiO2

The results of a batch-process solar disinfection (SODIS) and solar photocatalytic disinfection (SPCDIS) on drinking water contaminated with Cryptosporidium are reported. Cryptosporidium parvum oocyst suspensions were exposed to natural sunlight in Southern Spain and the oocyst viability was evaluated using two vital dyes [4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI)]. SODIS exposures (strong sunlight) of 8 and 12h reduced oocyst viability from 98% (+/-1.3%) to 11.7% (+/-0.9%) and 0.3% (+/-0.33%), respectively. SODIS reactors fitted with flexible plastic inserts coated with TiO2 powder (SPCDIS) were found to be more effective than those which were not. After 8 and 16 h of overcast and cloudy solar irradiance conditions, SPCDIS reduced oocyst viability from 98.3% (+/-0.3%) to 37.7% (+/-2.6%) and 11.7% (+/-0.7%), respectively, versus to that achieved using SODIS of 81.3% (+/-1.6%) and 36.0% (+/-1.0%), respectively. These results confirm that solar disinfection of drinking water can be an effective household intervention against Cryptosporidium contamination.

Cryptosporidium and Giardia as foodborne zoonoses

Cryptosporidium and Giardia are major causes of diarrhoeal disease in humans, worldwide and are major causes of protozoan waterborne diseases. Both Cryptosporidium and Giardia have life cycles which are suited to waterborne and foodborne transmission. There are 16 'valid'Cryptosporidium species and a further 33+ genotypes described. Parasites which infect humans belong to the Giardia duodenalis "type", and at least seven G. duodenalis assemblages are recognised. Cryptosporidium parvum is the major zoonotic Cryptosporidium species, while G. duodenalis assemblages A and B have been found in humans and most mammalian orders. In depth studies to determine the role of non-human hosts in the transmission of Cryptosporidium and Giardia to humans are required. The use of harmonised methodology and standardised and validated molecular markers, together with sampling strategies that provide sufficient information about all contributors to the environmental (oo)cyst pool that cause contamination of food and water, are recommended. Standardised methods for detecting (oo)cysts in water are available, as are optimised, validated methods for detecting Cryptosporidium in soft fruit and salad vegetables. These provide valuable data on (oo)cyst occurrence, and can be used for species and subspecies typing using appropriate molecular tools. Given the zoonotic potential of these organisms, epidemiological, source and disease tracking investigations involve multidisciplinary teams. Here, the role of the veterinarian is paramount, particularly in understanding the requirement for adopting comprehensive sampling strategies for analysing both sporadic and outbreak samples from all potential non-human contributors. Comprehensive sampling strategies increase our understanding of parasite population biology and structure and this knowledge can be used to determine what level of discrimination is required between isolates. Genetic exchange is frequent in C. parvum populations, leading to recombination between alleles at different loci, the generation of a very large number of different genotypes and a high level of resolution between isolates. In contrast, genetic exchange appears rare in Cryptosporidium hominis and populations are essentially clonal with far fewer combinations of alleles at different loci, resulting in a much lower resolution between isolates with many being of the same genotype. Clearly, more markers provide more resolution and high throughput sequencing of a variety of genes, as in multilocus sequence typing, is a way forward. Sub-genotyping tools offer increased discrimination, specificity and sensitivity, which can be exploited for investigating the epidemiology of disease, the role of asymptomatic carriers and contaminated fomites and for source and disease tracking for food and water contaminated with small numbers of (oo)cysts.

Use of cell culture to assess Cryptosporidium parvum survival rates in natural groundwaters and surface waters

Bench-scale survival studies with Cryptosporidium parvum were conducted with representative aquifer and reservoir waters of Florida. C. parvum inactivation rates ranged from 0.0088 log(10)/day at 5 degrees C to -0.20 log(10)/day at 30 degrees C. Temperature, surface water or groundwater type, and the interaction of these factors had statistically significant effects on the survival of C. parvum.

Blind trials evaluating in vitro infectivity ofCryptosporidiumoocysts using cell culture immunofluorescence

An optimized cell culture immunofluorescence (IFA) procedure, using the HCT-8 cell line, was evaluated in blind trials to determine the sensitivity and reproducibility of measuring the infectivity of flow-cytometry-prepared inocula of Cryptosporidium parvum oocysts. In separate trials, suspensions consisting of between 0% and 100% viable oocysts were prepared at the US Environmental Protection Agency, shipped to the American Water Laboratory, and analyzed blindly by cell culture IFA. Data indicated the control (100% live) oocyst suspensions yielded statistically similar results to cell culture dose–response curve data developed previously at the American Water Laboratory. For test samples containing oocyst suspensions of unknown infectivity, cell culture IFA analyses indicated a high degree of correlation (r2= 0.89; n = 26) with the values expected by the US Environmental Protection Agency. Cell culture infectivity correlates well with neonatal mouse infectivity assays, and these blind validation trials provide credibility for the cell culture IFA procedure as a cost-effective and expedient alternative to mouse infectivity assays for determining in vitro infectivity of C. parvum oocysts.

Batch solar disinfection inactivates oocysts of Cryptosporidium parvum and cysts of Giardia muris in drinking water

AIM

To determine whether batch solar disinfection (SODIS) can be used to inactivate oocysts of Cryptosporidium parvum and cysts of Giardia muris in experimentally contaminated water.

METHODS AND RESULTS

Suspensions of oocysts and cysts were exposed to simulated global solar irradiation of 830 W m(-2) for different exposure times at a constant temperature of 40 degrees C. Infectivity tests were carried out using CD-1 suckling mice in the Cryptosporidium experiments and newly weaned CD-1 mice in the Giardia experiments. Exposure times of > or =10 h (total optical dose c. 30 kJ) rendered C. parvum oocysts noninfective. Giardia muris cysts were rendered completely noninfective within 4 h (total optical dose >12 kJ). Scanning electron microscopy and viability (4',6-diamidino-2-phenylindole/propidium iodide fluorogenic dyes and excystation) studies on oocysts of C. parvum suggest that inactivation is caused by damage to the oocyst wall.

CONCLUSIONS

Results show that cysts of G. muris and oocysts of C. parvum are rendered completely noninfective after batch SODIS exposures of 4 and 10 h (respectively) and is also likely to be effective against waterborne cysts of Giardia lamblia.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results demonstrate that SODIS is an appropriate household water treatment technology for use as an emergency intervention in aftermath of natural or man-made disasters against not only bacterial but also protozoan pathogens.

The role of wastewater treatment in protecting water supplies against emerging pathogens

Traditionally, regulators, dischargers, and even water suppliers believed that wastewater discharge meeting the levels of 200 cfu/ 100 mL of fecal coliforms in wastewater effluent was sufficient to protect against downstream microbial effects. However, these beliefs are now being challenged by emerging pathogens that are resistant to standard water and wastewater treatment processes, exhibit extended survival periods in the environment, can adversely affect sensitive subpopulations, and require extremely low doses for human infection. Based on this new information, it is estimated that discharges of emerging pathogens from conventional wastewater treatment plants as far as 160 km upstream and cumulative amounts of wastewater discharge ranging from 2 to 20 ML/d have the potential to reach a water supply intake in a viable state at significant concentrations that could exceed regulatory limits for drinking water supplies, increase endemic risk from drinking water, and/or require additional drinking water treatment. Wastewater dischargers may be able mitigate this potential effect and achieve upwards of 6 log combined removal and inactivation of emerging pathogens to mitigate drinking water effects by using alternative treatment processes, such as filtration or UV light disinfection, or optimizing these processes based on site-specific conditions.

Temporal occurrence of Cryptosporidium in the Manila clam Ruditapes philippinarum in northern Adriatic Italian lagoons

In order to evaluate the temporal occurrence of Cryptosporidium oocysts in Ruditapes philippinarum clams bred along the northeastern Italian Adriatic coast and molecularly characterize the isolates, 2,160 specimens (180 clams per month) were collected from three clam farms from January to December 2004. Two farms (sites A and B) were located in Venice (Chioggia, Veneto region) and one (site C) in the Marano Lagoons (Friuli Venezia Giulia region). Clams from 36 pools (i.e., one pool of 60 clams per month per site) were subjected to a high-sensitivity seminested PCR assay specific for a 360-bp diagnostic region internal to the Cryptosporidium spp. outer wall protein gene. Positive amplicons were sequenced and analyzed. Cryptosporidium DNA was found in clams from seven pools (sites A and B) during 1 month of sampling at site A and 6 months of sampling at site B, with Cryptosporidium hominis and Cryptosporidium parvum being detected. The expected infection rate of the clams was 0.36%. Site B showed a significantly higher expected infection rate (1.15%) than did the other sites (A = 0.14% and C = 0%). Given its high sensitivity and specificity, this seminested PCR assay can be considered a reliable tool for detecting and distinguishing species within the Cryptosporidium genus. The seasonal pattern of contamination and the related public health risks are of particular concern.

Cryptosporidium and Giardia in commercial and non-commercial oysters (Crassostrea gigas) and water from the Oosterschelde, the Netherlands

The intestinal parasites Cryptosporidium and Giardia cause gastro-enteritis in humans and can be transmitted via contaminated water. Oysters are filter feeders that have been demonstrated to accumulate pathogens such as Salmonella, Vibrio, norovirus and Cryptosporidium from contaminated water and cause foodborne infections. Oysters are economically important shellfish that are generally consumed raw. Commercial and non-commercial oysters (Crassostrea gigas) and oyster culture water from the Oosterschelde, The Netherlands, were examined for the presence of Cryptosporidium oocysts and Giardia cysts. Nine of 133 (6.7%) oysters from two non-commercial harvesting sites contained Cryptosporidium, Giardia or both. Six of 46 (13.0%) commercial oysters harboured Cryptosporidium or Giardia in their intestines. Data on the viability of (oo)cysts recovered from Oosterschelde oysters were not obtained, however viable (oo)cysts were detected in surface waters that enter the Oosterschelde oyster harvesting areas. The detection of Cryptosporidium and Giardia in oysters destined for human consumption has implications for public health only when human pathogenic (oo)cysts that have preserved infectivity during their stay in a marine environment are present. Our data suggest that consumption of raw oysters from the Oosterschelde may occasionally lead to cases of gastro-intestinal illness.

Critical processes affecting Cryptosporidium oocyst survival in the environment

Cryptosporidium are parasitic protozoans that cause gastrointestinal disease and represent a significant risk to public health. Cryptosporidium oocysts are prevalent in surface waters as a result of human, livestock and native animal faecal contamination. The resistance of oocysts to the concentrations of chlorine and monochloramine used to disinfect potable water increases the risk of waterborne transmission via drinking water. In addition to being resistant to commonly used disinfectants, it is thought that oocysts can persist in the environment and be readily mobilized by precipitation events. This paper will review the critical processes involved in the inactivation or removal of oocysts in the terrestrial and aquatic environments and consider how these processes will respond in the context of climate change.

Fate of Cryptosporidium oocysts and Giardia cysts in the Norwegian aquatic environment over winter

We investigated the survival of Cryptosporidium oocysts and Giardia cysts during winter in an aquatic environment (approximate temperature measurements between 1 and 7 degrees C) in Norway, using morphology and uptake of dyes as indicators of viability. Previous research has shown that in the terrestrial environment, shear forces caused by freeze and thaw cycles probably cause the parasites to be inactivated. Such forces occurred infrequently in the aquatic environment, as freezing of the water around the parasites was not observed during the study period (although freezing of the water surface did occur). The rate of decline in viability (log(10) N (t)/N (0)) was similar in control and experimental environments for both parasites; no Cryptosporidium oocysts with viable morphology were detected after approximately 20 weeks and no Giardia cysts with apparently viable morphology could be detected after 1 month. These results suggest that infection with these parasites in Norway is not usually from transmission stages that have over-wintered in the Norwegian environment.