Morphological and molecular characterization of Isospora amphiboluri (Apicomplexa: Eimeriidae), a coccidian parasite, in a central netted dragon (Ctenophorus nuchalis) (De Vis, 1884) in Australia

An Isospora species, Isospora amphiboluri, originally described by Canon in 1967 and later by McAllister et al. (1995), was isolated from a central netted dragon (Ctenophorus nuchalis) housed at a wildlife rehabilitation centre in Perth, Western Australia. Sporulated oocysts of Isospora amphiboluri (n = 30) are spherical, 24.2 (26.5-23.0) μm in length and 23.9 (22.4-25.9) μm in width, with a shape index of 1.01. The bilayered oocyst wall is smooth and light-yellow in color. Polar granule, oocyst residuum and micropyle are absent. The sporocysts are lemon-shaped, 15.7 (15.2-18.0) × 10.2 (8.9-11.2) μm, with a shape index (length/width) of 1.53. Stieda and substieda bodies are present, the Stieda body being small and hemidome-shaped and the substieda half-moon-shaped. Each sporocyst contains four vermiform sporozoites arranged head to tail. The sporozoites are 11.7 (9.9-16.2) × 3.0 (2.4-3.5) μm, with a shape index (length/width) of 3.87. A sporocyst residuum is present. Sporozoites contain a central nucleus with a finely distributed granular residuum. Comparison of oocyst measurements and their features with other valid Isospora species from hosts in the Agamid family confirmed that this Isospora species is Isospora amphiboluri. Molecular characterization of I. amphiboluri at the 18S rRNA and MTCOI loci showed the highest similarity with I. amphiboluri from the central bearded dragon, 99.8% and 99.7% respectively. This is the first report of I. amphiboluri from a central netted dragon in Australia.

Correlative light and electron microscopy of wall formation in Eimeria nieschulzi

Coccidian parasites possess complex life cycles involving asexual proliferation followed by sexual development leading to the production of oocysts. Coccidian oocysts are persistent stages which are secreted by the feces and transmitted from host to host guaranteeing life cycle progression and disease transmission. The robust bilayered oocyst wall is formed from the contents of two organelles, the wall-forming bodies type I and II (WFBI, WFBII), located exclusively in the macrogametocyte. Eimeria nieschulzi has been used as a model parasite to study and follow gametocyte and oocyst development. In this study, the gametocyte and oocyst wall formation of E. nieschulzi was analyzed by electron microscopy and immuno-histology. A monoclonal antibody raised against the macrogametocytes of E. nieschulzi identified a tyrosine-rich glycoprotein (EnGAM82) located in WFBII. Correlative light and electron microscopy was used to examine the vesicle-specific localization and spatial distribution of GAM82-proteins during macrogametocyte maturation by this monoclonal antibody. In early and mid-stages, the GAM82-protein is ubiquitously distributed in WFBII. Few hours later, the protein is arranged in subvesicular structures. It was possible to show that the substructure of WFBII and the spatial distribution of GAM82-proteins probably represent pre-synthesized cross-linked materials prior to the inner oocyst wall formation. Dityrosine-cross-linked gametocyte proteins can also be confirmed and visualized by fluorescence microscopy (UV light, autofluorescence of WFBII).

Assessment of differences between DNA content of cell-cultured and freely suspended oocysts of Cryptosporidium parvum and their suitability as DNA standards in qPCR

BACKGROUND

Although more modern methods are available, quantitative PCR (qPCR) is reproducible, sensitive and specific with instruments and expertise readily available in many laboratories. As such, the use of qPCR in Cryptosporidium research is well established and still widely used by researchers globally. This method depends upon the generation of standards at different concentrations to generate standard curves subsequently used for the quantification of DNA.

METHODS

We assessed four types of DNA template used to generate standard curves in drug screening studies involving Cryptosporidium spp.: (i) serially diluted Cryptosporidium parvum oocysts (106-1); (ii) diluted template DNA from pure oocysts (×10-×106 dilution of 106 oocyst DNA template); (iii) oocysts incubated in human ileocecal adenocarcinoma (HCT-8) cells (105-1 and 5 × 104-50); and (iv) diluted DNA template (5 × 104) from cell culture incubated parasites (×10-×1000).

RESULTS

Serial dilutions of both cell culture and pure oocyst suspension DNA template yielded better linearity than cell culture derived standards, with dilutions of 106 oocysts exhibiting similar quantification cycle (Cq) values to those obtained from DNA template dilutions of 106 oocysts. In contrast, cell culture incubated oocysts demonstrated significantly higher DNA content than equivalent freely suspended oocysts and diluted DNA template from both cell culture derived and freely suspended oocysts across numerous concentrations.

CONCLUSIONS

For many studies involving Cryptosporidium, only relative DNA content is required and as such, the superior linearity afforded by freely suspended oocysts and diluted DNA template (from either cell culture derived standards or freely suspended oocysts) will allow for more accurate relative quantification in each assay. Parasite division in the cell culture standards likely explains the higher DNA content found. These standards, therefore, have the potential to more accurately reflect DNA content in cell culture assays, and despite more modern methods available for absolute quantification, i.e. droplet digital PCR (ddPCR), the ubiquity of qPCR for the foreseeable future encourages further investigation into the reduced linearity observed in these standards such as varying oocyst seeding density, non-linear growth rates and assay efficiency.

Epidemiological survey and risk factor analysis on Eimeria infections in calves and young cattle up to 1 year old in Colombia

A large-scale cross-sectional epidemiological study was conducted to evaluate prevalence, species diversity, and associated risk factors of Eimeria infections in 55 cattle farms across seven states of Colombia, including subtropical and tropical regions. In total, 1333 fecal samples from young animals (< 1 year of age) were examined at a single sampling date from August 2016 to December 2016. Flotation and McMaster techniques were conducted for parasitological investigation. Excreted Eimeria oocysts were allowed to sporulate in vitro and thereafter identified to species level based on morphological and morphometric characteristics. The overall Eimeria prevalence was 75.5% (1006/1333), with no difference observed between age categories. In total, 13 different Eimeria species were identified. The most prevalent species was E. bovis (33.5%), followed by E. auburnensis (12.5%) and E. zuernii (11.9%). Analysis of extrinsic associated risk factors revealed the floor type, feeding system, watering system, and herd size as significant (p < 0.05) risk factors for Eimeria spp. infections. Based on these data, it can be assumed that bovine coccidiosis infections occur ubiquitously in the country and might play an important role especially in its subclinical form by affecting production parameters in conventional cattle management systems.

Cryptosporidium parvum as a risk factor of diarrhea occurrence in neonatal alpacas in Peru

Cryptosporidiosis has been reported as an important cause of neonatal diarrhea and mortality in cattle, sheep, and other ruminants, but its impact on alpaca health has not been studied thoroughly. In this study, we have determined the prevalence and evaluated the role of cryptosporidiosis as a risk factor for diarrhea occurrence in newborn alpacas. During the calving season (January-March) of 2006, stool specimens (N = 1312) were collected from 24 herds of newborn alpacas in Puno and Cuzco, departments that account for the largest populations of alpacas in Peru. All the specimens were microscopically screened for Cryptosporidium spp. using the acid-fast technique. The association between Cryptosporidium detection and diarrhea was analyzed using χ² test and generalized lineal model. Cryptosporidium species were determined by PCR-RFLP analysis of the small subunit rRNA gene. Cryptosporidium oocysts were detected in 159 of 1312 (12.4%) newborn alpacas. Results of the analyses demonstrated that crypstosporidiosis was significantly associated with diarrhea (PR = 3.84; CI_95% 2.54-5.81; p < 0.0001). Only Cryptosporidium parvum was detected in the 153 Cryptosporidium-infected animals. Thus, there is an association of C. parvum infection with diarrhea in neonatal alpacas.

Plasmodium kinesin-8X associates with mitotic spindles and is essential for oocyst development during parasite proliferation and transmission

Kinesin-8 proteins are microtubule motors that are often involved in regulation of mitotic spindle length and chromosome alignment. They move towards the plus ends of spindle microtubules and regulate the dynamics of these ends due, at least in some species, to their microtubule depolymerization activity. Plasmodium spp. exhibit an atypical endomitotic cell division in which chromosome condensation and spindle dynamics in the different proliferative stages are not well understood. Genome-wide shared orthology analysis of Plasmodium spp. revealed the presence of two kinesin-8 motor proteins, kinesin-8X and kinesin-8B. Here we studied the biochemical properties of kinesin-8X and its role in parasite proliferation. In vitro, kinesin-8X has motility and depolymerization activities like other kinesin-8 motors. To understand the role of Plasmodium kinesin-8X in cell division, we used fluorescence-tagging and live cell imaging to define its location, and gene targeting to analyse its function, during all proliferative stages of the rodent malaria parasite P. berghei life cycle. The results revealed a spatio-temporal involvement of kinesin-8X in spindle dynamics and an association with both mitotic and meiotic spindles and the putative microtubule organising centre (MTOC). Deletion of the kinesin-8X gene revealed a defect in oocyst development, confirmed by ultrastructural studies, suggesting that this protein is required for oocyst development and sporogony. Transcriptome analysis of Δkinesin-8X gametocytes revealed modulated expression of genes involved mainly in microtubule-based processes, chromosome organisation and the regulation of gene expression, supporting a role for kinesin-8X in cell division. Kinesin-8X is thus required for parasite proliferation within the mosquito and for transmission to the vertebrate host.

Use of ultrasound irradiation to inactivate Cryptosporidium parvum oocysts in effluents from municipal wastewater treatment plants

Water reuse is currently considered an innovative way to addressing water shortage that can provide significant economic, social and environmental benefits, particularly -but not exclusively- in water deficient areas. The potential transmission of infectious diseases is the most common concern in relation to water reclamation. Cryptosporidium is an important genus of protozoan enteropathogens that infect a wide range of vertebrate hosts, including humans. The infective form (oocyst) is highly resistant to the environmental conditions and disinfection treatments. Consequently, Cryptosporidium is the most common etiological agent identified in waterborne outbreaks attributed to parasitic protozoa worldwide. The present study evaluates the efficacy of ultrasound disinfection, at three power levels (60, 80 and 100 W), pulsed at 50% or in continuous mode, for inactivating the waterborne protozoan parasite Cryptosporidium parvum in simulated and real effluents from municipal wastewater treatment plants (MWTPs). Overall interpretation of the results shows that the application of ultrasound irradiation at 80 W power in continuous mode for an exposure time of 10 min drastically reduced the viability of C. parvum. Thus, oocyst viabilities of 4.16 ± 1.93%; 1.29 ± 0.86%; 3.16 ± 0.69%; and 3.15 ± 0.87% were obtained in distilled water, simulated, real and filtered MWTP effluents, respectively (vs 98.57 ± 0.01%, initial oocyst viability), as determined using inclusion/exclusion of the fluorogenic vital dye propidium iodide, an indicator of the integrity of the oocyst wall. Independently of the mode used (pulsed/continuous) and at 80 W power, higher level of oocyst inactivation was detected in MWTP effluents than in distilled water used as a control solution, may be due to the differences in the chemical composition of the samples. Comparison of the results obtained in both modes showed that use of the continuous mode yielded significantly lower oocyst viability. However, when the Dose parameter was considered (energy per volume unit), no statistically significant differences in oocyst viability were observed in relation to the type of mode used. The results demonstrate that ultrasound technology represents a promising alternative to the disinfection methods (ultraviolet irradiation and chlorine products) currently used in water reclamation as it drastically reduces the survival of Cryptosporidium oocysts, without changing the chemical composition of the water or producing toxic by-products.

Selective electrohydrodynamic concentration of waterborne parasites on a chip

Concentrating diluted samples is a key step to improve detection capabilities. The wise use of scaling laws shows the advantages of working with sub-microliter-sized samples. Rapid progress in MEMS technologies has driven the design of integrated platforms performing many biochemical operations. Here we report a new concentrator device based on electro-hydrodynamic forces which can be easily integrated into electrowetting-on-dielectric (EWOD) platforms. This approach is label-free and applicable to a wide range of micro-objects. The detection and analysis of two common waterborne parasites, Cryptosporidium and Giardia, is a perfect test case due to their global health relevance. By fully controlling the interplay of the various forces acting on the micron-sized Cryptosporidium parvum and Cryptosporidium muris oocysts, we show that it is possible to concentrate them on the side of a 10 μL initial drop and then extract them efficiently from a droplet of a few hundred nanoliters. We performed a finite element modeling of the forces acting on the parasites' oocysts to optimize the electrodes' shapes. We obtained state-of-the-art concentration factors of 12 ± 0.4 times and 2 to 4 times in the sub-region of the drop and the extracted droplet, respectively, with an efficiency of 70 ± 6%. Furthermore, this device had the ability to selectively concentrate parasites of different species out of a mix. We demonstrated this by segregating C. parvum oocysts from either Giardia lamblia cysts or its related species, C. muris oocysts.

Morphological variations on microscopy in oocysts of coccidian parasites: A prospective study from a tertiary care hospital in north India

The modified acid fast staining technique is a commonly used procedure for the detection of coccidian parasites in developing countries. The morphological variations observed in these parasites play a significant role to some extent in both identification and diagnosis of these parasitic infections. A prospective cross sectional study was performed over three years. The fecal smears were stained by modified Kinyoun acid-fast staining technique and were extensively studied for morphological variations in the coccidian parasites. Out of a total of two thousand one hundred fifty one (n = 2,151) fecal samples received during the study period, 259 samples (12%) were positive for any one of the coccidian parasites. Morphological variations, especially in the staining character was noted in all the three coccidian parasites. This study was an attempt to characterize different variations in size, shape and staining characteristics of the three coccidian parasites.

An alternative method to recover Toxoplasma gondii from greenery and fruits

Toxoplasma gondii oocysts are an important form of contamination with a high dispersion in the environment, but their detection is still a challenge. This study evaluated the recovery of oocysts from strawberries and crisphead lettuce. Samples (250 g of strawberries or one head of lettuce) were experimentally inoculated with 10, 10(2), 10(3) and 10(4) T. gondii oocysts, by two separate processes, spot dripping and immersion. Then, 50 g of each sample was washed, filtered through a cellulose ester membrane, and concentrated by centrifugation. Three aliquots were taken for DNA extraction in a direct way, after freeze-thaw (FT) cycles or ultrasound (US), followed by PCR (B22-B23 and Tox4-Tox5 primers). The T. gondii DNA was amplified with the primers B22-B23 in all samples contaminated by dripping and when DNA extraction was carried out after FT or US. These techniques may be useful in epidemiological surveillance in the control of this zoonosis.

Accipiter hawks (Accipitridae) confirmed as definitive hosts of Sarcocystis turdusi, Sarcocystis cornixi and Sarcocystis sp. ex Phalacrocorax carbo

Sarcocystis is a large genus of protozoan parasites with complex heteroxenous life cycles. For many species, either the intermediate or the definitive host is still unknown. In this study, 116 Accipiter hawks (Eurasian sparrowhawks and northern goshawks) were investigated for the presence of Sarcocystis spp. in their intestinal tract or their faeces. To gain a wide distribution, samples were collected throughout Germany within 2 years. It was possible to detect Sarcocystis-like oocysts in 65 samples. Sequencing of the ITS region or species-specific PCR identified 33 samples as Sarcocystis turdusi/Sarcocystis sp. ex A. nisus (18), Sarcocystis calchasi (6), Sarcocystis columbae (3), Sarcocystis cornixi (3) and Sarcocystis sp. ex Phalacrocorax carbo (3). Besides the known infestation with S. columbae, S. sp. ex A. nisus and S. calchasi the Accipiter hawks were thereby confirmed as definitive host of S. turdusi, S. cornixi and S. sp. ex Phalacrocorax carbo for the first time.

A new isosporoid coccidia (Apicomplexa: Eimeriidae)from the southern house wren Troglodytes musculus Naumann, 1823 (Passeriformes: Troglodytidae) from Brazil

A new isosporoid coccidian species (Protozoa: Apicomplexa: Eimeriidae) is reported from the southern house wren Troglodytes musculus, a very well distributed species in South and Central America. Isospora corruirae sp. nov. oocysts are subspherical to ovoidal, 24.1 × 21.4 μm, with smooth, bilayered wall. Micropyle and oocyst residuum are absent, but small spherules and splinter-like granules are frequently present. Sporocysts are ovoidal to piriform, 14.0 × 9.5 μm. Stieda body is prominent knob-like and substieda body is delicate. Sporocyst residuum is composed of scattered fragments of different sizes. Sporozoites are vermiform with posterior refractile bodies, anterior striations and a nucleus. This is the second description of an isosporoid coccidium infecting a New World wren.

[REPRODUCTION OF SCHISTOSOMA MANSONI MOTHER SPOROCYST]

The development of generative elements of Schistosoma mansoni mother sporocysts (MS) was examined by histological methods. About 20 large cells, on average, determined as germinal cells (GC) were found in the miracidium. These cells formed a C-shape cellular aggregation (a band) beginning in the caudal part of the larva, and reaching the nerve ganglion in the anterior part. At the level of the 3d tier of epithelial plates of the miracidium, this band shifted to the external body wall, bypassing the zone of excretory channels. Apparently, this shift resulted in the subdivision of a single pool of GC into two structurally associated groups. A group of several undifferentiated cells (UC) was also revealed in the caudal part of the body. After the metamorphosis of the miracidium into sporocysts, GC had increased in size and on the 3d day started to divide, forming first embryos of daughter sporocysts. During the same time, germinal masses were being formed in the subtegumental area of the MS body. Since this time point, proliferation of UC occured only in germinal masses. A part of UC also differentiated there into GC. These cells formed sporocystoid embryos, developing as far as the germinal ball, and then came out into the sporocyst schizocoel (approximately in 10 days p. i.). Thus, in S. mansoni, the formation of generative elements into MS occurs in two stages. Primary GC are formed during the development of the miracidium into the egg, whereas secondary GC develop in germinal masses of the sporocyst.

A new coccidian (Apicomplexa: Eimeriidae), from midland brown snake, Storeria dekayi wrightorum Trapido (Ophidia: Colubridae) from Arkansas, USA

A new species of coccidian (Protista: Apicomplexa: Eimeriidae) collected from the faeces of a midland brown snake Storeria dekayi wrightorum Trapido (Ophidia: Colubridae) in Arkansas, USA, is described. Oöcysts of Isospora holbrooki n. sp. are subspherical to ovoidal with a smooth, colourless, bi-layered wall, measure on average 27.1 × 24.0 µm, and have a length/width (L/W) ratio of 1.1; both micropyle and oöcyst residuum are absent, but a polar granule is present. Sporocysts are ovoidal, 14.8 × 10.0 µm on average (L/W 1.5); the Stieda body is nipple-like, the sub-Stieda body is ellipsoidal and the sporocyst residuum is composed of coarse granules in a cluster. Sporozoites have a spheroidal anterior refractile body, a subspheroidal posterior refractile body, and one centrally-located nucleus. This is the first description of an isosporan from the snake genus Storeria Baird & Girard as well as the largest oöcysts and sporocysts of any previous snake isosporan to date.

Point-of-Use Removal of Cryptosporidium parvum from Water: Independent Effects of Disinfection by Silver Nanoparticles and Silver Ions and by Physical Filtration in Ceramic Porous Media

Ceramic water filters (CWFs) impregnated with silver nanoparticles are a means of household-level water treatment. CWFs remove/deactivate microbial pathogens by employing two mechanisms: metallic disinfection and physical filtration. Herein we report on the independent effects of silver salt and nanoparticles on Cryptosporidium parvum and the removal of C. parvum by physical filtration in porous ceramic filter media. Using a murine (mouse) model, we observed that treatment of oocysts with silver nitrate and proteinate-capped silver nanoparticles resulted in decreased infection relative to untreated oocysts. Microscopy and excystation experiments were conducted to support the disinfection investigation. Heat and proteinate-capped silver-nanoparticle treatment of oocysts resulted in morphological modifications and decreased excystation rates of sporozoites. Subsequently, disk-shaped ceramic filters were produced to investigate the transport of C. parvum. Two factors were varied: sawdust size and clay-to-sawdust ratio. Five disks were prepared with combinations of 10, 16, and 20 mesh sawdust and sawdust percentage that ranged from 9 to 11%. C. parvum removal efficiencies ranged from 1.5 log (96.4%) to 2.1 log (99.2%). The 16-mesh/10% sawdust had the greatest mean reduction of 2.1-log (99.2%), though there was no statistically significant difference in removal efficiency. Based on our findings, physical filtration and silver nanoparticle disinfection likely contribute to treatment of C. parvum for silver impregnated ceramic water filters, although the contribution of physical filtration is likely greater than silver disinfection.

Comparison of selected methods for recovery of Giardia spp. cysts and Cryptosporidium spp. oocysts in wastewater

More precise methods are needed to recover Giardia and Cryptosporidium (oo)cysts from wastewater in order to advance research related to their inactivation, removal, quantification, and species differentiation. This study applied different methods to recover the maximum number of (oo)cysts from wastewater samples using ColorSeed®. Immunomagnetic separation assisted in capturing oocysts mainly in samples with medium and low turbidity. A triple centrifugation method reached recovery rates of 85% and 20%, for Giardia cysts and Cryptosporidium oocysts, respectively, in raw wastewater, and 62.5 and 17.5% in secondary-treated effluent. For low turbidity-treated effluent, membrane filtration reached 67.5% recovery for Giardia cysts and 22.5% for Cryptosporidium oocysts. Simple, quick and low-cost methods do not involve much handling of the samples and could be useful, particularly in developing countries.

Differentiation between Viable and Dead Cryptosporidium Oocysts Using Fluorochrome Staining

The use of nucleic acid staining with a fluorochrome dye to differentiate viable and dead (heat-killed) Cryptosporidium oocysts was assessed. The specificities (percentage of unstained viable oocysts) and sensitivities (percentage of stained dead oocysts) of the seven tested dyes (SYTO-17® and SYTO-59® to 64®) ranged from 65 to 76% (average 71%) and 83 to 95% (average 91%), respectively. SYTO-59 and SYTO-17 imparted greater color (4+) intensity than the other dyes (2+ or less). Of these two dyes, SYTO-17 exhibited more brightness and slower discoloration and was selected for use in further experiments. The optimum staining time for SYTO-17 at 37℃ was one hour or more (sensitivity of 96%). Dye concentrations of 20 and 30 µM resulted in maximal color intensity, and no further improvement was observed with further increases in dye concentration. Staining a mixture of viable and dead oocysts (1:1 ratio) with 20 µM dye at 37℃ for one hour yielded the expected results (approximately 50%), but no remarkable increase in the percent staining with time (up to 8 hours) was observed. In this study, no ghost oocysts were observed. The present study indicated that the fluorogenic nucleic acid dye SYTO-17 could be used to discriminate between live and dead Cryptosporidium oocysts.

Cryptosporidium and Giardia removal by secondary and tertiary wastewater treatment

Wastewater disposal may be a source of environmental contamination by Cryptosporidium and Giardia. This study was conducted to evaluate the prevalence of Cryptosporidium oocysts and Giardia cysts in raw and treated wastewater effluents. A prevalence of 100% was demonstrated for Giardia cysts in raw wastewater, at a concentration range of 10 to 12,225 cysts L(-1), whereas the concentration of Cryptosporidium oocysts in raw wastewater was 4 to 125 oocysts L(-1). The removal of Giardia cysts by secondary and tertiary treatment processes was greater than those observed for Cryptosporidium oocysts and turbidity. Cryptosporidium and Giardia were present in 68.5% and 76% of the tertiary effluent samples, respectively, at an average concentration of 0.93 cysts L(-1) and 9.94 oocysts L(-1). A higher detection limit of Cryptosporidium oocysts in wastewater was observed for nested PCR as compared to immune fluorescent assay (IFA). C. hominis was found to be the dominant genotype in wastewater effluents followed by C. parvum and C. andersoni or C. muris. Giardia was more prevalent than Cryptosporidium in the studied community and treatment processes were more efficient for the removal of Giardia than Cryptosporidium. Zoonotic genotypes of Cryptosporidium were also present in the human community. To assess the public health significance of Cryptosporidium oocysts present in tertiary effluent, viability (infectivity) needs to be assessed.

Occurrence of Eimeria species parasites on small-scale commercial chicken farms in Africa and indication of economic profitability

Small-scale commercial poultry production is emerging as an important form of livestock production in Africa, providing sources of income and animal protein to many poor households, yet the occurrence and impact of coccidiosis on this relatively new production system remains unknown. The primary objective of this study was to examine Eimeria parasite occurrence on small-scale commercial poultry farms in Ghana, Tanzania and Zambia. Additionally, farm economic viability was measured by calculating the farm gross margin and enterprise budget. Using these economic measures as global assessments of farm productivity, encompassing the diversity present in regional husbandry systems with a measure of fundamental local relevance, we investigated the detection of specific Eimeria species as indicators of farm profitability. Faecal samples and data on production parameters were collected from small-scale (less than 2,000 birds per batch) intensive broiler and layer farms in peri-urban Ghana, Tanzania and Zambia. All seven Eimeria species recognised to infect the chicken were detected in each country. Furthermore, two of the three genetic variants (operational taxonomic units) identified previously in Australia have been described outside of Australia for the first time. Detection of the most pathogenic Eimeria species associated with decreased farm profitability and may be considered as an indicator of likely farm performance. While a causal link remains to be demonstrated, the presence of highly pathogenic enteric parasites may pose a threat to profitable, sustainable small-scale poultry enterprises in Africa.

Analytical recovery of protozoan enumeration methods: have drinking water QMRA models corrected or created bias?

Quantitative microbial risk assessment (QMRA) is a tool to evaluate the potential implications of pathogens in a water supply or other media and is of increasing interest to regulators. In the case of potentially pathogenic protozoa (e.g. Cryptosporidium oocysts and Giardia cysts), it is well known that the methods used to enumerate (oo)cysts in samples of water and other media can have low and highly variable analytical recovery. In these applications, QMRA has evolved from ignoring analytical recovery to addressing it in point-estimates of risk, and then to addressing variation of analytical recovery in Monte Carlo risk assessments. Often, variation of analytical recovery is addressed in exposure assessment by dividing concentration values that were obtained without consideration of analytical recovery by random beta-distributed recovery values. A simple mathematical proof is provided to demonstrate that this conventional approach to address non-constant analytical recovery in drinking water QMRA will lead to overestimation of mean pathogen concentrations. The bias, which can exceed an order of magnitude, is greatest when low analytical recovery values are common. A simulated dataset is analyzed using a diverse set of approaches to obtain distributions representing temporal variation in the oocyst concentration, and mean annual risk is then computed from each concentration distribution using a simple risk model. This illustrative example demonstrates that the bias associated with mishandling non-constant analytical recovery and non-detect samples can cause drinking water systems to be erroneously classified as surpassing risk thresholds.

Role of collector alternating charged patches on transport of Cryptosporidium parvum oocysts in a patchwise charged heterogeneous micromodel

The role of collector surface charge heterogeneity on transport of Cryptosporidium parvum oocyst and carboxylate microsphere in 2-dimensional micromodels was studied. The cylindrical silica collectors within the micromodels were coated with 0, 10, 20, 50, and 100% Fe(2)O(3) patches. The experimental values of average removal efficiencies (η) of the Fe(2)O(3) patches and on the entire collectors were determined. In the presence of significant (>3500 kT) Derjaguin-Landau-Verwey-Overbeek (DLVO) energy barrier between the microspheres and the silica collectors at pH 5.8 and 8.1, η determined for Fe(2)O(3) patches on the heterogeneous collectors were significantly less (p < 0.05, t test) than those obtained for collectors coated entirely with Fe(2)O(3). However, η calculated for Fe(2)O(3) patches for microspheres at pH 4.4 and for oocysts at pH 5.8 and 8.1, where the DLVO energy barrier was relatively small (ca. 200-360 kT), were significantly greater (p < 0.05, t test) than those for the collectors coated entirely with Fe(2)O(3). The dependence of η for Fe(2)O(3) patches on the DLVO energy barrier indicated the importance of periodic favorable and unfavorable electrostatic interactions between colloids and collectors with alternating Fe(2)O(3) and silica patches. Differences between experimentally determined overall η for charged heterogeneous collectors and those predicted by a patchwise geochemical heterogeneous model were observed. These differences can be explained by the model's lack of consideration for the spatial distribution of charge heterogeneity on the collector surface.

Qualification of standard membrane-feeding assay with Plasmodium falciparum malaria and potential improvements for future assays

Vaccines that interrupt malaria transmission are of increasing interest and a robust functional assay to measure this activity would promote their development by providing a biologically relevant means of evaluating potential vaccine candidates. Therefore, we aimed to qualify the standard membrane-feeding assay (SMFA). The assay measures the transmission-blocking activity of antibodies by feeding cultured P. falciparum gametocytes to Anopheles mosquitoes in the presence of the test antibodies and measuring subsequent mosquito infection. The International Conference on Harmonisation (ICH) Harmonised Tripartite Guideline Q2(R1) details characteristics considered in assay validation. Of these characteristics, we decided to qualify the SMFA for Precision, Linearity, Range and Specificity. The transmission-blocking 4B7 monoclonal antibody was tested over 6 feeding experiments at several concentrations to determine four suitable concentrations that were tested in triplicate in the qualification experiments (3 additional feeds) to evaluate Precision, Linearity and Range. For Specificity, 4B7 was tested in the presence of normal mouse IgG. We determined intra- and inter-assay variability of % inhibition of mean oocyst intensity at each concentration of 4B7 (lower concentrations showed higher variability). We also showed that % inhibition was dependent on 4B7 concentration and the activity is specific to 4B7. Since obtaining empirical data is time-consuming, we generated a model using data from all 9 feeds and simulated the effects of different parameters on final readouts to improve the assay procedure and analytical methods for future studies. For example, we estimated the effect of number of mosquitoes dissected on variability of % inhibition, and simulated the relationship between % inhibition in oocyst intensity and % inhibition of prevalence of infected mosquitos at different mean oocysts in the control. SMFA is one of the few biological assays used in preclinical and early clinical development of transmission-blocking vaccines, and this study strongly supports its further development and application.

[Reproduction of trematode Leucochloridium paradoxum sporocysts (Trematoda: Leucochloridiidae)]

The histological study of the trematoda sporocysts Leucochloridium paradoxum confirmed the presence of three morphological zones in it: 1) central part (reproductive), where embryos are forming, 2) narrow tubes through which the embryos penetrate in colored broodsacs (3), where the development of metecercaria completes. It was found that germinal mass only is the reproduction organ of the sporocysts, located in reproductive zone. There are young (without embryos), mature (with embryos) and degenerated germinal masses. So, in the process of sporocysts development the centre of multiplication of germinal elements was changed. The old parts of central part are degenerated, but the new ones with young germinal masses appear. The multiplication of generative elements does not take place in the broodsacs which are breeding cameras functionally.

Comprehensive genetic dissection of the hemocyte immune response in the malaria mosquito Anopheles gambiae

Reverse genetics in the mosquito Anopheles gambiae by RNAi mediated gene silencing has led in recent years to an advanced understanding of the mosquito immune response against infections with bacteria and malaria parasites. We developed RNAi screens in An. gambiae hemocyte-like cells using a library of double-stranded RNAs targeting 109 genes expressed highly or specifically in mosquito hemocytes to identify novel regulators of the hemocyte immune response. Assays included phagocytosis of bacterial bioparticles, expression of the antimicrobial peptide CEC1, and basal and induced expression of the mosquito complement factor LRIM1. A cell viability screen was also carried out to assess dsRNA cytotoxicity and to identify genes involved in cell growth and survival. Our results identify 22 novel immune regulators, including proteins putatively involved in phagosome assembly and maturation (Ca²⁺ channel, v-ATPase and cyclin-dependent protein kinase), pattern recognition (fibrinogen-domain lectins and Nimrod), immune modulation (peptidase and serine protease homolog), immune signaling (Eiger and LPS-induced factor), cell adhesion and communication (Laminin B1 and Ninjurin) and immune homeostasis (Lipophorin receptor). The development of robust functional cell-based assays paves the way for genome-wide functional screens to study the mosquito immune response to infections with human pathogens.

[Comparative analysis of the efficiency of methods for the diagnosis of cryptosporidiosis]

The paper comparatively analyzes the efficiency of two methods for the diagnosis ofcryptosporidiosis: microscopy of Ziehl-Neelsen- or Romanovsky-Gimse-stained smears and immunofluorescence labeling using the diagnostic reagent kit Crypt-a-Glo A400 BIOT (Cryptosporidium oocysts) (Stailab Co.) in fecal samples. The efficiency of the reagent kit Crypt-a-Glo A400 BIOT has been shown to be sufficiently high in diagnosing cryptosporidiosis. The authors propose to use the immunofluorescence labeling [a diagnostic reagent kit Crypt-a-Glo A400 BIOT (Cryptosporidium oocysts)] to increase the detection rate of persons suspected as having cryptosporidiosis who are invaded during comprehensive examination.

Deposition of Cryptosporidium parvum oocysts in porous media: a synthesis of attachment efficiencies measured under varying environmental conditions

An extensive set of column experiments was performed with freshly harvested Cryptosporidium parvum oocysts to evaluate the effects of solution chemistry, surface coatings, interactions with other suspended particles, and pore fluid velocity on the fate and transport of this widely occurring waterborne pathogen in sandy porous media. We synthesized our data set with a comprehensive literature survey of similar experiments, to compute attachment (collision) efficiencies (α) used in colloid filtration theory (CFT) using three models for the single collector efficiency (η) across a wide range of experimental conditions. Most prior experiments have observed the transport of surface-treated, sterile C. parvum oocyst in porous media. Our column data confirm for freshly harvested oocysts that the presence of iron coatings on the sand medium and the presence of suspended illite clay drastically enhance oocyst deposition. Increasing ionic strength and decreasing pH also systematically enhance the attachment efficiency. Attachment efficiency decreases only at a very high ionic strength, most likely as a result of steric repulsion and possibly other changes in oocyst surface properties. Attachment efficiencies vary with fluid flow rate but without showing specific trends. We found that the computed attachment efficiency across all reported experiments could be reliably estimated using a regression model based on parameters related to ionic strength and pH. The regression model performed better with the Nelson-Ginn η model and Tufenkji-Elimelech η model than with the Rajagopalan-Tien η model. When CFT is used in environmental assessments, the proposed regression model provides a practical estimator for attachment efficiencies of C. parvum oocyst deposition in porous media for a variety of environmental conditions unfavorable to attachment.

Two new species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from the flap-necked chameleon Chamaeleo dilepis (Sauria: Chamaeleonidae) in the Republic of Namibia

Two new species of Isospora Schneider, 1881 from flap-necked chameleons Chamaeleo dilepis Leach are described from the faeces of specimens collected in the Republic of Namibia. Oöcysts of Isospora freedi n. sp. from one of four (25%) C. dilepis collected in the East Caprivi District are spherical to subspherical, with a smooth, colourless, bilayered wall, measure 23.7 × 21.2 μm and have a length/width (L/W) ratio of 1.1. The micropyle and the oöcyst residuum are absent but a polar granule is sometimes present. Sporocysts are ovoidal to ellipsoidal and 13.9 × 10.3 μm in size with prominent Stieda and sub-Stieda bodies; and the sporocyst residuum is composed of a compact mass of large globules. The sporozoites contain anterior and posterior refractile bodies with a nucleus between them. Oöcysts of Isopora mandelai n. sp. from three of seven (43%) C. dilepis collected in the Outjo District are ellipsoidal to cylindroidal, with a smooth, colourless, bilayered wall, measure 36.9 × 31.0 μm and have an L/W ratio of 1.2. The micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ovoidal to ellipsoidal, 15.3 × 11.1 μm in size and contain Stieda and sub-Stieda bodies; and the non-membranous sporocyst residuum is composed of granules of various sizes. The sporozoites contain anterior and posterior refractile bodies with a nucleus between them. These two new taxa represent the third and fourth coccidian species reported from C. dilepis.

piggyBac transposon-mediated transgenesis in the apicomplexan parasite Eimeria tenella

piggyBac, a type II transposon that is useful for efficient transgenesis and insertional mutagenesis, has been used for effective and stable transfection in a wide variety of organisms. In this study we investigate the potential use of the piggyBac transposon system for forward genetics studies in the apicomplexan parasite Eimeria tenella. Using the restriction enzyme-mediated integration (REMI) method, E. tenella sporozoites were electroporated with a donor plasmid containing the enhanced yellow fluorescent protein (EYFP) gene flanked by piggyBac inverted terminal repeats (ITRs), an Asc I-linearized helper plasmid containing the transposase gene and the restriction enzyme Asc I. Subsequently, electroporated sporozoites were inoculated into chickens via the cloacal route and transfected progeny oocysts expressing EYFP were sorted by flow cytometry. A transgenic E. tenella population was selected by successive in vivo passage. Southern-blotting analysis showed that exogenous DNA containing the EYFP gene was integrated into the parasite genome at a limited number of integration sites and that the inserted part of the donor plasmid was the fragment located between the 5′ and 3′ ITRs as indicated by primer-specific PCR screening. Genome walking revealed that the insertion sites were TTAA-specific, which is consistent with the transposition characteristics of piggyBac.

Targeting Cryptosporidium parvum capture

Polymer microarrays offer a high-throughput approach to the screening and assessment of a large number of polymeric materials. Here, we report the first study of protozoan-polymer interactions using a microarray approach. Specifically, from screening hundreds of synthetic polymers, we identified materials that either trap the waterborne protozoan parasite, Cryptosporidium parvum, or prevent its adhesion, both of which have major practical applications. Comparison of array results revealed differences in the adhesion characteristics of viable and non-viable C. parvum oocysts. Material properties, including polymer composition, wettability and surface chemistry, allowed correlation of binding and identification of structure function relationships. Understanding C. parvum binding interactions could assist in improved water treatment processes and the identified polymers could find applications in sensor and filter materials.

Determining potential indicators of Cryptosporidium oocysts throughout the wastewater treatment process

Most research on wastewater treatment efficiency compliance focuses on physicochemical and microbial indicators; however, very little emphasis has been placed so far on determining suitable indicator organisms to predict the discharge level of pathogens from treatment plants. In this study, raw wastewater, activated sludge, and the resulting final effluents and biosolids in four municipal wastewater treatment plants (WWTPs A, B, C and D) were seasonally investigated for human-virulent water-borne pathogens Cryptosporidium parvum/hominis and Giardia duodenalis, and microsporidia (e.g. Encephalitozoon hellem, E. intestinalis, and Enterocytozoon bieneusi) between 2008 and 2009. A suite of potential microbial indicators for human-virulent protozoa and microsporidia was also determined. A combination of multiple fluorescent in situ hybridization and immunofluorescent antibody assays were applied to detect Cryptosporidium oocysts, Giardia cysts, and microsporidian spores. Escherichia coli, enterococci and Clostridium perfringens spores were cultivated in selective media. Positive correlations were found between the abundance of enterococci and E. coli and abundance of Cryptosporidium oocysts (r(s) > 0.47, p < 0.01) and Giardia cysts (r(s) > 0.44, p < 0.01) at WWTPs A-D. Cryptosporidium perfringens spores were positively correlated to Cryptosporidium oocysts (r(s) = 0.40, p < 0.01) and Giardia cysts (r(s) = 0.46, p < 0.01). There was a strong positive correlation between abundance of Giardia cysts and that of Cryptosporidium oocysts (r(s) > 0.89, p < 0.01). To sum up, a suite of faecal indicator bacteria can be used as indicators for the presence of Cryptosporidium oocysts and Giardia cysts in these activated-sludge systems (WWTPs A, B and C). Overall, Giardia duodenalis was noted to be the best Cryptosporidium indicator for human health in the community-based influent wastewater and throughout the treatment process.

Associations among pathogenic bacteria, parasites, and environmental and land use factors in multiple mixed-use watersheds

Over a five year period (2004-08), 1171 surface water samples were collected from up to 24 sampling locations representing a wide range of stream orders, in a river basin in eastern Ontario, Canada. Water was analyzed for Cryptosporidium oocysts and Giardia cyst densities, the presence of Salmonella enterica subspecies enterica, Campylobacter spp., Listeria monocytogenes, and Escherichia coli O157:H7. The study objective was to explore associations among pathogen densities/occurrence and objectively defined land use, weather, hydrologic, and water quality variables using CART (Classification and Regression Tree) and binary logistical regression techniques. E. coli O157:H7 detections were infrequent, but detections were related to upstream livestock pasture density; 20% of the detections were located where cattle have access to the watercourses. The ratio of detections:non-detections for Campylobacter spp. was relatively higher (>1) when mean air temperatures were 6% below mean study period temperature values (relatively cooler periods). Cooler water temperatures, which can promote bacteria survival and represent times when land applications of manure typically occur (spring and fall), may have promoted increased frequency of Campylobacter spp. Fifty-nine percent of all Salmonella spp. detections occurred when river discharge on a branch of the river system of Shreve stream order = 9550 was >83 percentile. Hydrological events that promote off farm/off field/in stream transport must manifest themselves in order for detection of Salmonella spp. to occur in surface water in this region. Fifty seven percent of L. monocytogenes detections occurred in spring, relative to other seasons. It was speculated that a combination of winter livestock housing, silage feeding during winter, and spring application of manure that accrued during winter, contributed to elevated occurrences of this pathogen in spring. Cryptosporidium and Giardia oocyst and cyst densities were, overall, positively associated with surface water discharge, and negatively associated with air/water temperature during spring-summer-fall. Yet, some of the highest Cryptosporidium oocyst densities were associated with low discharge conditions on smaller order streams, suggesting wildlife as a contributing fecal source. Fifty six percent of all detections of ≥ 2 bacteria pathogens (including Campylobacter spp., Salmonella spp., and E. coli O157:H7) in water was associated with lower water temperatures (<∼ 14 °C; primarily spring and fall) and when total rainfall the week prior to sampling was >∼ 27 mm (62 percentile). During higher water temperatures (>∼ 14 °C), a higher amount of weekly rainfall was necessary to promote detection of ≥ 2 pathogens (primarily summer; weekly rainfall ∼>42 mm (>77 percentile); 15% of all ≥ 2 detections). Less rainfall may have been necessary to mobilize pathogens from adjacent land, and/or in stream sediments, during cooler water conditions; as these are times when manures are applied to fields in the area, and soil water contents and water table depths are relatively higher. Season, stream order, turbidity, mean daily temperature, surface water discharge, cropland coverage, and nearest upstream distance to a barn and pasture were variables that were relatively strong and recurrent with regard to discriminating pathogen presence and absence, and parasite densities in surface water in the region.

Improvement of the observational method for Plasmodium berghei oocysts in the midgut of mosquitoes

BACKGROUND

There is a need for improving the method for counting oocysts of Plasmodium berghei in the midgut of Anopheles mosquitoes. The two methods currently used, the formalin fixation method and the mercurochrome staining method, have contradicting advantages and disadvantages. In the formalin fixation method, the specimen can be preserved but unstained oocysts were often indistinct from the insect tissue. While in the mercurochrome staining method, stained oocysts can be clearly distinguished from insect tissue but the specimen are not well preserved. These two methods were combined in this study to develop a new improved technique in counting the oocysts, in which the specimen can be both stained and preserved well. This technique was evaluated for its accuracy and suitability in observing the oocyst development.

FINDINGS

In the improved technique, the parasite-infected midgut was first stained with mercurochrome, and then fixed with formalin. The specimens were finally observed using light microscopy. To evaluate the accuracy in the oocyst counting with the improved technique, mosquitoes were infected with the green fluorescent protein (GFP)-expressing parasite. Then, the midgut oocysts were counted using both the GFP marker and the improved technique. Results were then compared and showed that the improved technique retrieved 78%-123% (arithmetic mean = 97%) of the oocysts counted using the GFP marker. Furthermore, it was also possible to evaluate the oocyst development with a green filter using the light microscopy.

CONCLUSIONS

The improved technique for oocyst counting will be a useful tool for evaluating midgut oocyst numbers and determining the developmental stage of oocysts in parasite-infected mosquitoes.

Amphiphile disruption of pathogen attachment at the hematite (α-Fe2O3)-water interface

Prior studies have indicated that the subsurface transport of Cryptosporidium parvum oocysts is diminished in sediments containing iron oxides and that inner-sphere complexation of oocyst surficial carboxylate plays a role in the retardation. However, the impacts of natural organic matter (NOM) remain poorly understood. In this study, we used a model anionic surfactant, sodium dodecyl sulfate (SDS), as a surrogate for amphiphilic NOM components to examine the impacts of amphiphilic components on oocyst adhesion mechanisms. We employed in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to determine the effects of SDS on the molecular bonds that mediate interactions between oocyst surficial biomolecules and hematite (α-Fe(2)O(3)) surface functional groups over a wide range of solution pH. The results show that the presence of SDS significantly diminishes Fe-carboxylate complexation, as indicated by progressive decreases in intensity of asymmetric and symmetric stretching vibrations of carboxylate [ν(as)(COO(-)) and ν(s)(COO(-))] with reaction time. In addition, one of the ν(s)(COO(-)) bands shifted from 1370 to 1418 cm(-1) upon SDS introduction, suggesting that SDS also changed the complexation mode. The data indicate that competition from the sulfonate groups (OSO(3)(-)) of SDS at α-Fe(2)O(3) surface sites is a primary mechanism resulting in decreased Fe-carboxylate complexation. Sorptive competition from amphiphilic NOM components may therefore increase the mobility of C. parvum oocysts in the environment through disruption of interfacial pathogen-mineral surface bonds.

A new role for an old antimicrobial: lysozyme c-1 can function to protect malaria parasites in Anopheles mosquitoes

BACKGROUND

Plasmodium requires an obligatory life stage in its mosquito host. The parasites encounter a number of insults while journeying through this host and have developed mechanisms to avoid host defenses. Lysozymes are a family of important antimicrobial immune effectors produced by mosquitoes in response to microbial challenge.

METHODOLOGY/PRINCIPAL FINDINGS

A mosquito lysozyme was identified as a protective agonist for Plasmodium. Immunohistochemical analyses demonstrated that Anopheles gambiae lysozyme c-1 binds to oocysts of Plasmodium berghei and Plasmodium falciparum at 2 and 5 days after infection. Similar results were observed with Anopheles stephensi and P. falciparum, suggesting wide occurrence of this phenomenon across parasite and vector species. Lysozyme c-1 did not bind to cultured ookinetes nor did recombinant lysozyme c-1 affect ookinete viability. dsRNA-mediated silencing of LYSC-1 in Anopheles gambiae significantly reduced the intensity and the prevalence of Plasmodium berghei infection. We conclude that this host antibacterial protein directly interacts with and facilitates development of Plasmodium oocysts within the mosquito.

CONCLUSIONS/SIGNIFICANCE

This work identifies mosquito lysozyme c-1 as a positive mediator of Plasmodium development as its reduction reduces parasite load in the mosquito host. These findings improve our understanding of parasite development and provide a novel target to interrupt parasite transmission to human hosts.

[Cardiomyocyte myosin heavy chain composition change after cryptosporidial gastroenteritis]

Cardiovascular diseases are the most common case of human death in developed countries. Thus, the discovering of their new risk factors is of primary importance. Based on epidemiology studies, vertebrate life-history traits comparison and cross-species cardiomyocyte transcriptome analysis, we suggest that one of these factors could be infectious gastroenteritis. This disease outflows recourses from cardio-vascular system and triggers pathological stimuli, like tachyarrhythmia, inflammation, malapsorption and energy depletion thereby disturbing cardiomyocyte metabolism and function. To test this hypothesis, we challenged gastroenteritis in neonatal rats with widespread human parasite Cryptosporidium parvum (Apicomplexa, Sporozoa). The results obtained by the methods of immunocytochemistry, quantitative morphometry and real-time PCR, indicate that moderate cryptosporidiosis lasting four days induces dramatic shift in myosin isoform expression ration toward isoform beta (with low ATPase activity) both at mRNA (by 1.7-4.5 folds) and protein (by 2.5-6 folds) levels. Antithetical manner of this shift and coherence between changes in mRNA and protein suggest that cryptosporidiosis affects all main steps of a complex myosin heavy chain regulatory network. Since the overexpression of myosin heavy chain beta (showing several times lower ATPase activity than myosin heavy chain alfa) is a generally accepted marker of human cardiac failure, we can consider cryptosporidial gastroenteritis as a new risk factor of cardiac contractile ability impairment. Our data can be interesting for clinicians.

Eimeria species in wild rabbits (Oryctolagus cuniculus) in Fars province, Iran

This investigation was accomplished during February to November 2008. A total of 71 wild rabbits (Oryctolagus cuniculus) of about 5 to 12 months age were collected alive from different parts of Fars province, south of Iran. Faecal sampling was carried out directly from recti and the oocysts were isolated using sedimentation and floatation techniques and the sporulated oocyst were identified based on morphological and biological characteristics. All the rabbits were apparently healthy and showed no clinical symptoms. Twenty two rabbits (31.0%) were positive for infection with Eimeria and six species including Eimeria perforans (18.3%), Eimeria magna (16.9%), Eimeria media (14.1), Eimeria irresidua (11.2%), Eimeria flavescens (4.2%), and Eimeria coecicola (2.8%) were identified. Eighty six percent of the infected rabbits showed mixed infections with two or three Eimeria species. Lack of clinical signs could be due to the agro ecological and environmental conditions of rabbit habitats specifically dry and hot climatic features in recent years. In addition, immunity induced by long term exposure to low doses of oocysts shedded by the carrier animals probably have pivotal role in impairing parasitic developmental cycles and preventing acute coccidiosis.

Comparison of transport and attachment behaviors of Cryptosporidium parvum oocysts and oocyst-sized microspheres being advected through three minerologically different granular porous media

In order to gain more information about the fate of Cryptosporidium parvum oocysts in tropical volcanic soils, the transport and attachment behaviors of oocysts and oocyst-sized polystyrene microspheres were studied in the presence of two soils. These soils were chosen because of their differing chemical and physical properties, i.e., an organic-rich (43-46% by mass) volcanic ash-derived soil from the island of Hawaii, and a red, iron (22-29% by mass), aluminum (29-45% by mass), and clay-rich (68-76% by mass) volcanic soil from the island of Oahu. A third agricultural soil, an organic- (13% by mass) and quartz-rich (40% by mass) soil from Illinois, was included for reference. In 10-cm long flow-through columns, oocysts and microspheres advecting through the red volcanic soil were almost completely (98% and 99%) immobilized. The modest breakthrough resulted from preferential flow-path structure inadvertently created by soil-particle aggregation during the re-wetting process. Although a high (99%) removal of oocysts and microsphere within the volcanic ash soil occurred initially, further examination revealed that transport was merely retarded because of highly reversible interactions with grain surfaces. Judging from the slope of the substantive and protracted tail of the breakthrough curve for the 1.8-μm microspheres, almost all (>99%) predictably would be recovered within ∼4000 pore volumes. This suggests that once contaminated, the volcanic ash soil could serve as a reservoir for subsequent contamination of groundwater, at least for pathogens of similar size or smaller. Because of the highly reversible nature of organic colloid immobilization in this soil type, C. parvum could contaminate surface water should overland flow during heavy precipitation events pick up near-surface grains to which they are attached. Surprisingly, oocyst and microsphere attachment to the reference soil from Illinois appeared to be at least as sensitive to changes in pH as was observed for the red, metal-oxide rich soil from Oahu. In contrast, colloidal attachment in the organic-rich, volcanic ash soil was relatively insensitive to changes in pH in spite of the high iron content. Given the fundamental differences in transport behavior of oocyst-sized colloids within the two volcanic soils of similar origin, agricultural practices modified to lessen C. parvum contamination of ground or surface water would necessitate taking the individual soil properties into account.

Light microscopic study on Eimeria species infecting Japanese quails reared in Saudi Arabian farms

Japanese quails Coturnix coturnix japonica reared in economic farms were individually investigated for coccidian infections. The results indicated the absence of infections in birds younger than 1 month. An Eimeria infection rate of up to 80% was detected in birds 7-9 weeks old with a general infection rate of 29%. The infection rate decreased to 21.42% in birds older than 10 weeks. Morphometric characteristics of freshly shed, unsporulated oocysts were taken. These oocysts appeared pale yellow in color, were oval to subspherical in shape being limited by a bilayered oocyst wall of 1.2 microm. The unsporulated oocysts measured 17.73 +/- 12.92 x 12.79 +/- 1.69 microm (mean of 100) and possessed a polar granule, a micropyle and an oocyst residuum. The sporulation took 72 h and resulted in the formation of four elongated sporocysts containing two sporozoites, in addition to a stieda body and a sporocyst residuum. The life cycle of this Eimeria species was followed in experimentally infected quails. Three asexual generations (at 60, 78, and 96 h p.i.) were detected in the epithelium of the small intestine before the sexual cycle started at 84 h p.i. The prepatent period was 5 days, while the patent period covered 6-7 days. Besides this well-defined species, another Eimeria species occurred, the oocysts of which were excreted in low numbers and were characterized by the absence of a micropyle and an oocyst residuum. These oocysts measured 15.73 +/- 2.22 x 14.18 +/- 1.89 microm (mean of 100) and sporulated already within 60 h.

Culture for genetic manipulation of developmental stages of Schistosoma mansoni

Genomes of the major human helminth parasites, and indeed many others of agricultural significance, are now the research focus of intensive genome sequencing and annotation. A draft genome sequence of the filarial parasite Brugia malayi was reported in 2007 and draft genomes of two of the human schistosomes, Schistosoma japonicum and S. mansoni reported in 2009. These genome data provide the basis for a comprehensive understanding of the molecular mechanisms involved in schistosome nutrition and metabolism, host-dependent development and maturation, immune evasion and invertebrate evolution. In addition, new potential vaccine candidates and drug targets will likely be predicted. However, testing these predictions is often not straightforward with schistosomes because of the difficulty and expense in maintenance of the developmental cycle. To facilitate this goal, several developmental stages can be maintained in vitro for shorter or longer intervals of time, and these are amenable to manipulation. Our research interests focus on experimental studies of schistosome gene functions, and more recently have focused on development of transgenesis and RNA interference with the longer term aim of heritable gene manipulation. Here we review methods to isolate and culture developmental stages of Schistosoma mansoni, including eggs, sporocysts, schistosomules and adults, in particular as these procedures relate to approaches for gene manipulation. We also discuss recent advances in genetic manipulation of schistosomes including the deployment of square wave electroporation to introduce reporter genes into cultured schistosomes.

Detection of Toxoplasma gondii oocysts and surrogate microspheres in water using ultrafiltration and capsule filtration

While reports on waterborne infections with Toxoplasma gondii are emerging worldwide, detection of this zoonotic parasite in water remains challenging. Lack of standardized and quantitative methods for detection of T. gondii oocysts in water also limits research on the transport and fate of this pathogen through aquatic habitats. Here, we compare the ability of hollow-fiber ultrafiltration and capsule filtration to concentrate oocysts in spiked tap water, fresh surface water, and seawater samples. Detection of T. gondii oocysts in concentrated samples was achieved using molecular methods, as well as visually via epifluorescent microscopy. In addition to oocysts, water samples were spiked with T. gondii surrogate microspheres, and detection of microspheres was performed using flow cytometry and epifluorescent microscopy. Results demonstrate that both water concentration methods followed by microscopy allowed for quantitative detection of T. gondii oocysts and surrogate microspheres. For T. gondii oocysts, microscopy was more sensitive than TaqMan and conventional PCR, and allowed for detection of oocysts in all water samples tested. Compared with flow cytometry, microscopy was also a more cost-efficient and precise method for detection of fluorescent surrogate microspheres in tap, fresh and seawater samples. This study describes a novel approach for quantitative detection of T. gondii oocysts in drinking and environmental water samples. The techniques described for concentrating and detecting surrogate microspheres have broad application for evaluating the transport and fate of oocysts, as well as the efficiency of water treatment methods for removal of T. gondii from water supplies.

Comparison of three methods to concentrate Giardia cysts and Cryptosporidium oocysts from surface and drinking waters

In this study, three methods commercialized by Pall (Envirochek HV), Idexx (FiltaMax) and Whatman (Cryptest) to concentrate Giardia cysts and Cryptosporidium oocysts from surface and drinking waters were compared according to the EPA standard protocol. Twenty litres of surface and 100 litres of drinking waters were inoculated with 10(3) (oo)cysts before being concentrated by filtration. Our results show that recovery rates of Giardia cysts from surface water was significantly higher using FiltaMax (91+/-12%) than Cryptest (57+/-9%) or Envirochek HV (60+/-4%) while recovery from drinking water was equivalent using FiltaMax (84+/-7%) or Cryptest (78+/-7%) but lower using Envirochek HV (34+/-29%). Recovery of Cryptosporidium oocysts from surface water was significantly higher using Envirochek HV (65+/-5%) than using FiltaMax (45+/-7%) or Cryptest (50+/-7%) while recovery rates from drinking water was equivalent using either FiltaMax (48+/-8%), Cryptest (57+/-4%) or Envirochek HV (64+/-22%). Finally, regardless of the water type, all methods tested allowed recovery rates superior to 24% complying with the EPA standard protocol. Timing, material and practicability associated with each method are discussed.

Obtaining highly purified Toxoplasma gondii oocysts by a discontinuous cesium chloride gradient

Toxoplasma gondii is an obligate intracellular protozoan pathogen that commonly infects humans. It is a well characterized apicomplexan associated with causing food- and water-borne disease outbreaks. The definitive host is the feline species where sexual replication occurs resulting in the development of the highly infectious and environmentally resistant oocyst. Infection occurs via ingestion of tissue cysts from contaminated meat or oocysts from soil or water. Infection is typically asymptomatic in healthy individuals, but results in a life-long latent infection that can reactivate causing toxoplasmic encephalitis and death if the individual becomes immunocompromised. Meat contaminated with T. gondii cysts have been the primary source of infection in Europe and the United States, but recent changes in animal management and husbandry practices and improved food handling and processing procedures have significantly reduced the prevalence of T. gondii cysts in meat. Nonetheless, seroprevalence in humans remains relatively high suggesting that exposure from oocyst contaminated soil or water is likely. Indeed, waterborne outbreaks of toxoplasmosis have been reported worldwide supporting the theory exposure to the environmental oocyst form poses a significant health risk. To date, research on understanding the prevalence of T. gondii oocysts in the water and environment are limited due to the lack of tools to detect oocysts in the environment. This is primarily due to the lack of efficient purification protocols for obtaining large numbers of highly purified T gondii oocysts from infected cats for research purposes. This study describes the development of a modified CsCl method that easily purifies T. gondii oocysts from feces of infected cats that are suitable for molecular biological and tissue culture manipulation.

Two new Isospora species from Brazilian tanager (Ramphocelus bresilius dorsalis) of South America

Two new coccidian (Protozoa: Apicomplexa: Eimeriidae) species from the Brazilian tanager Ramphocelus bresilius dorsalis are reported in the current study. Isospora cadimi n. sp. oocysts are spheroidal to sub-spheroidal, 24.2 x 22.9 microm, with a smooth and bi-layered wall, approximately 1.1 microm. Micropyle, oocyst residuum, and polar granule are absent. Sporocysts are broadly ovoidal, 16.9 x 11.6 microm. Stieda and substieda bodies are present. Sporocyst residuum is present and sporozoites have refractile body and nucleus. Isospora navarroi n. sp. oocysts are spheroidal to sub-spheroidal, 21.4 x 20.6 microm, with a smooth and bi-layered wall, approximately 1.1 microm. Micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ellipsoidal, 16.1 x 10.2 microm. Stieda and substieda bodies are present. Sporocyst residuum is present and sporozoites have a robust posterior refractile body.

The glutathione biosynthetic pathway of Plasmodium is essential for mosquito transmission

Infection of red blood cells (RBC) subjects the malaria parasite to oxidative stress. Therefore, efficient antioxidant and redox systems are required to prevent damage by reactive oxygen species. Plasmodium spp. have thioredoxin and glutathione (GSH) systems that are thought to play a major role as antioxidants during blood stage infection. In this report, we analyzed a critical component of the GSH biosynthesis pathway using reverse genetics. Plasmodium berghei parasites lacking expression of gamma-glutamylcysteine synthetase (γ-GCS), the rate limiting enzyme in de novo synthesis of GSH, were generated through targeted gene disruption thus demonstrating, quite unexpectedly, that γ-GCS is not essential for blood stage development. Despite a significant reduction in GSH levels, blood stage forms of pbggcs⁻ parasites showed only a defect in growth as compared to wild type. In contrast, a dramatic effect on development of the parasites in the mosquito was observed. Infection of mosquitoes with pbggcs⁻ parasites resulted in reduced numbers of stunted oocysts that did not produce sporozoites. These results have important implications for the design of drugs aiming at interfering with the GSH redox-system in blood stages and demonstrate that de novo synthesis of GSH is pivotal for development of Plasmodium in the mosquito.

The antioxidant systems of malaria parasites (Plasmodium spp.) are potential targets for the development of antimalarials. The glutathione (GSH) redox system constitutes one of the Plasmodium primary lines of defense against damage caused by reactive oxygen species and other forms of chemical stress. GSH is synthesized de novo by the sequential action of gamma-glutamylcysteine synthase (γ-GCS) and GSH synthase (GS). Biochemical studies have suggested that parasite survival depends on functional de novo GSH synthesis. Using reverse genetics we interrupted the GSH biosynthetic pathway in the rodent malaria Plasmodium berghei by disrupting the pbggcs gene. The mutation caused minor changes in parasite growth in the mammalian host but development in the mosquito was completely arrested at the oocyst stage. These results suggest that the GSH biosynthetic pathway, while essential for mosquito stage development, is not an appropriate target for antimalarials against blood stages of the parasite.

Surface-enhanced resonance raman spectroscopy for the rapid detection of Cryptosporidium parvum and Giardia lamblia

A rapid surface-enhanced resonance Raman spectroscopy (SERRS) method has been developed for the detection of two waterborne pathogens, Cryptosporidium parvum and Giardia lambia. Raman labels were prepared by conjugating gold nanoparticles with commercial antibodies and dye molecules. After incubation with the immunogold labels, C. parvum oocysts and G. lamblia could easily be measured and differentiated by Raman spectroscopy. The immunogold signal intensities were optimized by testing several sizes of gold nanoparticles, four different commercially available dye molecules, and two Raman excitation wavelengths. Raman maps were collected across fixed and labeled Cryptosporidium oocysts and Giardia cysts, and the maps were used to determine which C. parvum and G. lamblia antibodies exhibited the best specificities and organism coverages. Ultimately, 40 nm gold nanoparticles were conjugated with rhodamine B isothiocyanate and malachite green isothiocyanate for the C. parvum and G. lamblia immunogold syntheses, respectively. C. parvum monoclonal IgM antibodies and G. lamblia monoclonal IgG1 antibodies resulted in the best immunogold coverage. The research presented here demonstrates the feasibility of utilizing SERRS labeling for sensitive multipathogen monitoring strategies.

Deposition of Cryptosporidium parvum oocysts on natural organic matter surfaces: microscopic evidence for secondary minimum deposition in a radial stagnation point flow cell

A radial stagnation point flow (RSPF) system combined with a microscope was used to determine the deposition kinetics of Cryptosporidium parvum oocysts on quartz surfaces and silica surfaces coated with Suwannee River natural organic matter (SRNOM) in solutions with different ionic strengths. Microscopic evidence of C. parvum oocysts entrapped in the secondary minimum energy well was presented to show that among the entrapped C. parvum oocysts some were washed away by the radial flow and some were able to transfer to deep primary minima and become irreversibly deposited. Experimental data were compared with simulation results obtained by the convective-diffusion equation and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The experimental results suggested that surface charge heterogeneity led to a higher attachment efficiency at low ionic strength. In addition, the maximum attachment efficiency was less than 1 at high ionic strength due to steric interaction.

Development and evaluation of a reverse transcription-loop-mediated isothermal amplification assay for rapid and high-sensitive detection of Cryptosporidium in water samples

We describe a novel assay for simple, rapid and high-sensitive detection of Cryptosporidium oocysts in water samples using a reverse transcription-loop-mediated isothermal amplification (RT-LAMP). The assay is based on the detection of 18S rRNA specific for Cryptosporidium oocysts. The detection limit of the developed RT-LAMP assay was as low as 6 x 10(-3) oocysts/test tube, which theoretically enables us to detect a Cryptosporidium oocyst and perform duplicated tests even if water samples contain only one oocyst. The developed RT-LAMP assay could more sensitively detect Cryptosporidium oocysts in real water samples than the conventional assay based on microscopic observation.

The role of free-ranging, captive, and domestic birds of Western Poland in environmental contamination with Cryptosporidium parvum oocysts and Giardia lamblia cysts

As Cryptosporidium parvum and Giardia lamblia can be disseminated in the environment by avian hosts, a total of 499 fecal dropping from 308 free-ranging, 90 captive, and 101 domestic birds were tested by conventional, immunological, and molecular techniques for these human enteropathogens. Twenty-six (5.2%) tested positive for G. lamblia cysts and 19 (3.8%) for C. parvum oocysts. A bird total of 23 (7.5%) free-ranging, two (2.2%) captive, and one (0.1%) domestic tested positive for cysts, whereas 18 (5.8%) free-ranging, one (1.1%) captive, and zero livestock birds tested positive for oocysts. G. lamblia cysts and C. parvum oocysts were found significantly more frequently in fecal droppings of free-ranging aquatic birds than in birds not normally associated with water. No specimen tested positive for both pathogens simultaneously. Aquatic birds represent an important epidemiologic link in water-associated transmission cycles of Cryptosporidium and Giardia and play a significant role in environmental contamination of aquatic habitats with these anthropozoonotic pathogens.

[Oocysts from Cryptosporidium spp. isolated from cattle: pleomorfism in relationship to diagnosis methodology]

The aim of this study was to analyze the pleomorfism of Cryptosporidium spp. oocysts isolated from calves feces throughout the comparison of two diagnostic techniques. One hundred of cattle feces were collected and the samples were submitted to both flotation sucrose centrifugation and to Ziehl-Neelsen modified tests. The results obtained showed a statistically significant reduction on the size of the Cryptosporidium oocysts observed through Ziehl-Neelsen technique when compared to the flotation sucrose centrifugation technique, and that the difference on the diameter of the oocysts suggests the there were different species of Cryptosporidium circulating in the animals analyzed.

New species of Cryptosporidium Tyzzer, 1907 (Apicomplexa) from amphibian host: morphology, biology and phylogeny

Cryptosporidium fragile sp. n. (Apicomplexa) is described from black-spined toads, Duttaphrynus melanostictus (Schneider) (Amphibia, Anura, Bufonidae) from the Malay Peninsula. The parasitized animals were directly imported from Malaysia and harboured C. fragile at the time of arrival. Oocysts were subspherical to elliptical with irregular contour in optical section, measuring 6.2 (5.5-7.0) x 5.5 (5.0-6.5) microm. Oocyst wall was smooth and colourless in light microscopy. The endogenous development of C. fragile in the stomach of black-spined toad was analysed in detail using light and electron microscopy. Cryptosporidian developmental stages were confined to the surface of gastric epithelial cells. In transmission experiments, C. fragile has not been infective for one fish species, four amphibian species, one species of reptile and SCID mice. Full length small subunit rRNA gene sequence was obtained. Phylogenetic reconstruction revealed distinct status of C. fragile within the clade of species with gastric localisation including Cryptosporidium muris Tyzzer, 1907, Cryptosporidium serpentis Levine, 1980 and Cryptosporidium andersoni Lindsay, Upton, Owens, Morgan, Mead et Blagburn, 2000. Described characteristics differentiate C. fragile from the currently recognized Cryptosporidium species. Our experience with the description of C. fragile has led us to revise the recommended criteria for an introduction of a new Cryptosporidium species name. C. fragile is the first species described and named from an amphibian host. Its prevalence of 83% (15/18) in black-spined toads within the 3 months after importation calls for strict quarantine measures and import regulation for lower vertebrates.