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Affiliation(s)
- H V Smith
- Department of Bacteriology, Stobhill General Hospital, Glasgow
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Abstract
Improved filtration is associated with reduced prevalence of antibodies against Cryptosporidium spp. Continuous exposure to low levels of Cryptosporidium oocysts is associated with production of protective antibodies. We investigated prevalence of antibodies against the 27-kDa Cryptosporidium oocyst antigen among blood donors in 2 areas of Scotland supplied by drinking water from different sources with different filtration standards: Glasgow (not filtered) and Dundee (filtered). During 2006–2009, seroprevalence and risk factor data were collected; this period includes 2007, when enhanced filtration was introduced to the Glasgow supply. A serologic response to the 27-kDa antigen was found for ≈75% of donors in the 2 cohorts combined. Mixed regression modeling indicated a 32% step-change reduction in seroprevalence of antibodies against Cryptosporidium among persons in the Glasgow area, which was associated with introduction of enhanced filtration treatment. Removal of Cryptosporidium oocysts from water reduces the risk for waterborne exposure, sporadic infections, and outbreaks. Paradoxically, however, oocyst removal might lower immunity and increase the risk for infection from other sources.
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Abstract
In the past ten years Cryptosporidium oocysts have been shown to be common contaminants of water, causing at least 19 waterborne outbreaks of cryptosporidiosis which have affected more than 427 000 individuals. Recommended methods for oocyst isolation and enumeration are time-consuming and inefficient and experts state that the absence of Cryptosporidium oocysts in drinking water can never be guaranteed. In the UK alone, a National Research Programme costing pound3 million has been undertaken. Here, Huw Smith and Joan Rose review the current status of knowledge and identify approaches taken by UK and USA Government regulatory bodies in order to reduce the likelihood of waterborne transmission.
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Affiliation(s)
- H V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill NHS Trust, Glasgow, UK G21 3UW
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Pollock KGJ, Ternent HE, Mellor DJ, Chalmers RM, Smith HV, Ramsay CN, Innocent GT. Spatial and temporal epidemiology of sporadic human cryptosporidiosis in Scotland. Zoonoses Public Health 2011; 57:487-92. [PMID: 19638164 DOI: 10.1111/j.1863-2378.2009.01247.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The spatial and temporal epidemiology of human cryptosporidiosis was described by analysing sporadic cases reported in Scotland from 2005 to 2007. Measures of livestock density and human population density were explored as indicators of the geographical variation in prevalence. Cryptosporidium parvum was more common in areas with lower human population densities, with a higher ratio of the number of farms to human inhabitants and with a higher ratio of the number of private water supplies to human inhabitants. Cryptosporidium parvum caused disease in humans in rural areas and in areas with high ruminant livestock density, whereas Cryptosporidium hominis was more common in the more densely human populated areas of Scotland. The association of private water supplies and increased Cryptosporidium reports merits further public health efforts.
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Lim YAL, Iqbal A, Surin J, Sim BLH, Jex AR, Nolan MJ, Smith HV, Gasser RB. First genetic classification of Cryptosporidium and Giardia from HIV/AIDS patients in Malaysia. Infect Genet Evol 2011; 11:968-74. [PMID: 21439404 DOI: 10.1016/j.meegid.2011.03.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2011] [Revised: 03/14/2011] [Accepted: 03/14/2011] [Indexed: 12/20/2022]
Abstract
Given the HIV epidemic in Malaysia, genetic information on opportunistic pathogens, such as Cryptosporidium and Giardia, in HIV/AIDS patients is pivotal to enhance our understanding of epidemiology, patient care, management and disease surveillance. In the present study, 122 faecal samples from HIV/AIDS patients were examined for the presence of Cryptosporidium oocysts and Giardia cysts using a conventional coproscopic approach. Such oocysts and cysts were detected in 22.1% and 5.7% of the 122 faecal samples, respectively. Genomic DNAs from selected samples were tested in a nested-PCR, targeting regions of the small subunit (SSU) of nuclear ribosomal RNA and the 60kDa glycoprotein (gp60) genes (for Cryptosporidium), and the triose-phosphate isomerase (tpi) gene (for Giardia), followed by direct sequencing. The sequencing of amplicons derived from SSU revealed that Cryptosporidium parvum was the most frequently detected species (64% of 25 samples tested), followed by C. hominis (24%), C. meleagridis (8%) and C. felis (4%). Sequencing of a region of gp60 identified C. parvum subgenotype IIdA15G2R1 and C. hominis subgenotypes IaA14R1, IbA10G2R2, IdA15R2, IeA11G2T3R1 and IfA11G1R2. Sequencing of amplicons derived from tpi revealed G. duodenalis assemblage A, which is of zoonotic importance. This is the first report of C. hominis, C. meleagridis and C. felis from Malaysian HIV/AIDS patients. Future work should focus on an extensive analysis of Cryptosporidium and Giardia in such patients as well as in domestic and wild animals, in order to improve the understanding of transmission patterns and dynamics in Malaysia. It would also be particularly interesting to establish the relationship among clinical manifestation, CD4 cell counts and genotypes/subgenotypes of Cryptosporidium and Giardia in HIV/AIDS patients. Such insights would assist in a better management of clinical disease in immuno-deficient patients as well as improved preventive and control strategies.
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Affiliation(s)
- Yvonne A L Lim
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.
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Abstract
Of 1346 faecal samples from the Chikwawa and Thyolo districts of Malawi, analysed for the presence of Cryptosporidium oocysts between October 2001 and May 2003, 61.3% were from cattle (29.8% of these were from calves <6 months old). Cryptosporidium oocysts were detected during all three seasons studied in Chikwawa and Thyolo. In Chikwawa, 13.6% of adult cattle and 11.7% of calves were infected, compared to 28.9% of adult cattle and 36.7% of calves in Thyolo. Dependent on season, between 7.8% and 37.7% (Chikwawa) and 16.7% and 39.3% (Thyolo) of cattle samples contained oocysts. In Chikwawa, the highest percentage of infections occurred in the cool season, whereas in Thyolo, the highest percentage of infections occurred in the dry season. Faecal samples from goats [n=225], pigs [n=92], sheep [n=6]), rabbits, guinea pigs, chickens, ducks, turkeys, doves and guinea fowls were also analysed. Up to 5.6% of goat samples contained oocysts in Chikwawa, compared to between 16.7% and 39.3% in Thyolo. Again, in Chikwawa, the highest percentage of infections occurred in the cool season and the lowest in the rainy season, whereas, in Thyolo, the highest percentage of infections occurred in the dry season and the lowest in the cool season. In pigs, more infections were detected in the dry season in Chikwawa, but infections in the cool season were similar (17.7%), whereas in Thyolo, infections occurred in all three seasons (17.9% in the rainy season, 25% in the cool season and 60% in the dry season). Of ten diarrhoeic, oocyst positive cattle faecal samples collected from Chikwawa and subjected to PCR-RFLP, four oocyst positive samples (two from heifers, one from a cow and one unknown) were amplified at an 18S rRNA and Cryptosporidium oocyst wall protein (COWP) loci. RFLP of the 18S rRNA locus indicated that Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium bovis and/or Cryptosporidium ryanae DNA, or a mixture of them was present. Cryptosporidium parvum DNA was identified in one sample that amplified at the COWP locus, indicating the presence of the major zoonotic Cryptosporidium species in Malawi.
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Affiliation(s)
- Z Banda
- Department of Environmental Health, University of Malawi, Polytechnic, Private Bag 303, Chichiri, Blantyre 3, Malawi
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Abstract
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.
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Affiliation(s)
- A T Campbell
- Scottish Parasite Diagnostic Laboratory, Stobhill General Hospital, Springburn, Glasgow G21 3UW, and Division of Environmental Health, University of Strathclyde, Glasgow G1 1XQ, Scotland
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Molloy SF, Smith HV, Kirwan P, Nichols RAB, Asaolu SO, Connelly L, Holland CV. Identification of a high diversity of Cryptosporidium species genotypes and subtypes in a pediatric population in Nigeria. Am J Trop Med Hyg 2010; 82:608-13. [PMID: 20348508 PMCID: PMC2844578 DOI: 10.4269/ajtmh.2010.09-0624] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 12/26/2009] [Indexed: 11/07/2022] Open
Abstract
A longitudinal study was conducted to determine the epidemiology of Cryptosporidium in 1,636 children in Nigeria. Oocyst prevalence ranged from 15.6% to 19.6% over one year. Cryptosporidium hominis (34), C. parvum (25), C. parvum/C. hominis (4), C. meleagridis (5), Cryptosporidium rabbit genotype (5), Cryptosporidium cervine genotype (3), and C. canis (1) were identified by polymerase chain reaction-restriction fragment length polymorphism analysis. Glycoprotein 60 subgenotyping showed that 28 amplifiable C. hominis isolates consisted of 12 subtypes that belonged to 5 subtype families (Ia, Ib, Id, Ie, and 1 novel subtype family, Ih) and 23 amplifiable C. parvum isolates consisted of 6 subtypes that belonged to 4 subtype families (IIa, IIc, Iii, and IIm). Three C. meleagridis isolates sub-genotyped by sequence analysis of the small subunit ribosomal RNA gene fragment were type 1. This study is the first one to genetically characterize Cryptosporidium species and subtypes in Nigeria and highlights the presence of a high Cryptosporidium diversity in this pediatric population.
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Affiliation(s)
- Síle F Molloy
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Ireland.
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Rzezutka A, Nichols RAB, Connelly L, Kaupke A, Kozyra I, Cook N, Birrell S, Smith HV. Cryptosporidium oocysts on fresh produce from areas of high livestock production in Poland. Int J Food Microbiol 2010; 139:96-101. [PMID: 20153065 DOI: 10.1016/j.ijfoodmicro.2010.01.027] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 01/18/2010] [Accepted: 01/19/2010] [Indexed: 11/24/2022]
Abstract
Samples of fresh vegetables and soft fruit were collected from farmers' markets in the Lublin Area of Poland during 2006-2007; the produce was grown in areas of high to moderate livestock production. Cryptosporidium sp. oocysts were eluted from food surfaces, separated from residual food materials by IMS and identified by immunofluorescence and Nomarski differential interference contrast microscopy. Cryptosporidium sp. oocysts were detected in 6 of 128 vegetable samples (range 1-47 oocysts), but not in any of 35 fruit samples. Both empty and intact oocysts were detected. Species identity of oocyst-positive samples was performed by molecular analysis at four genetic loci. One of two 18S rRNA loci amplified DNA from 5 of the 6 oocyst-positive samples, but insufficient DNA for RFLP or sequencing analysis was available from 4 of these samples. An oocyst-positive celery sample generated an RFLP pattern consistent with C. parvum at two loci, but insufficient DNA was available for subtyping (GP60 sequencing) this isolate. Oocyst-contaminated foods originated from districts with the highest numbers of homesteads possessing cattle herds and no contaminated produce was detected from districts containing lower numbers of cattle-owning homesteads, strengthening the assumption that the origin of the contamination was livestock. The results of this study strengthen the evidence for the potential for zoonotic foodborne transmission of Cryptosporidium.
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Affiliation(s)
- A Rzezutka
- National Veterinary Research Institute, Department of Food and Environmental Virology, Puławy, Poland
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Lim YAL, Lai MM, Mahdy MAK, Mat Naim HR, Smith HV. Molecular detection of Giardia contamination in water bodies in a zoo. Environ Res 2009; 109:857-859. [PMID: 19664767 DOI: 10.1016/j.envres.2009.07.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 07/07/2009] [Accepted: 07/20/2009] [Indexed: 05/28/2023]
Abstract
We used a combined microscopy-molecular approach to determine the occurrence and identities of waterborne Giardia sp. cysts isolated from 18 separate, 10l grab samples collected from a Malaysian zoo. Microscopy revealed that 17 of 18 samples were Giardia cyst positive with concentrations ranging from 1 to 120 cysts/l. Nine (52.9%) of the 17 cyst positive samples produced amplicons of which 7 (77.8%) could be sequenced. Giardia duodenalis assemblage A (6 of 7) and assemblage B (1 of 7), both infectious to humans, were identified at all sampling sites at the zoo. The presence of human infectious cysts raises public health issues, and their occurrence, abundance and sources should be investigated further. In this zoo setting, our data highlight the importance of incorporating environmental sampling (monitoring) in addition to routine faecal examinations to determine veterinary and public health risks, and water monitoring should be considered for inclusion as a separate element in hazard analysis, as it often has a historical (accumulative) connotation.
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Affiliation(s)
- Yvonne A L Lim
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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Ramos NL, Saayman ML, Chapman TA, Tucker JR, Smith HV, Faoagali J, Chin JC, Brauner A, Katouli M. Genetic relatedness and virulence gene profiles of Escherichia coli strains isolated from septicaemic and uroseptic patients. Eur J Clin Microbiol Infect Dis 2009; 29:15-23. [PMID: 19763642 DOI: 10.1007/s10096-009-0809-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 08/08/2009] [Indexed: 10/20/2022]
Abstract
We investigated the relationship between clonality and virulence factors (VFs) of a collection of Escherichia coli strains isolated from septicaemic and uroseptic patients with respect to their origin of translocation. Forty septicaemic and 30 uroseptic strains of E. coli were tested for their phylogenetic groupings, genetic relatedness using randomly amplified polymorphic DNA (RAPD), biochemical fingerprinting method (biochemical phenotypes [BPTs]), adherence to HT-29 cells and the presence of 56 E. coli VF genes. Strains belonging to phylogenetic groups B2 and D constituted 93% of all strains. Fifty-four (77%) strains belonged to two major BPT/RAPD clusters (A and B), with cluster A carrying significantly (P = 0.0099) more uroseptic strains. The degree of adhesion to HT-29 cells of uroseptic strains was significantly (P = 0.0012) greater than that of septicaemic strains. Of the 56 VF genes tested, pap genes was the only group that were found significantly (P < 0.0001) more often among uroseptic isolates. Phylogenetic group B2 contained a significantly higher number of strains carrying pap genes than those in group D. We conclude that uroseptic E. coli are clonally different from septicaemic strains, carry more pap genes and predominantly adhere more to the HT-29 cell model of the gut.
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Affiliation(s)
- N L Ramos
- Faculty of Science, Health and Education, University of the Sunshine Coast, Maroochydore, DC, Queensland, Australia
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Ortega-Pierres G, Smith HV, Cacciò SM, Thompson RA. New tools provide further insights into Giardia and Cryptosporidium biology. Trends Parasitol 2009; 25:410-6. [DOI: 10.1016/j.pt.2009.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 06/02/2009] [Accepted: 06/12/2009] [Indexed: 12/12/2022]
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Lim YAL, Romano N, Colin N, Chow SC, Smith HV. Intestinal parasitic infections amongst Orang Asli (indigenous) in Malaysia: has socioeconomic development alleviated the problem? Trop Biomed 2009; 26:110-122. [PMID: 19901897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Orang Asli are the indigenous minority peoples of peninsular Malaysia. Despite proactive socioeconomic development initiated by the Malaysian Government in upgrading the quality of life of the Orang Asli communities since 1978, they still remained poor with a current poverty rate of 76.9%. Poverty exacerbates the health problems faced by these communities which include malnourishment, high incidences of infectious diseases (eg. tuberculosis, leprosy, malaria) and the perpetual problem with intestinal parasitic infections. Studies reported that the mean infection rate of intestinal parasitic infections in Orang Asli communities has reduced from 91.1% in 1978, to 64.1% in the subsequent years. Although the results was encouraging, it has to be interpreted with caution because nearly 80% of studies carried out after 1978 still reported high prevalence (i.e. >50%) of soil-transmitted helminthiases (STH) among Orang Asli communities. Prior to 1978, hookworm infection is the most predominant STH but today, trichuriasis is the most common STH infections. The risk factors for intestinal parasitic infections remained unchanged and studies conducted in recent years suggested that severe STH infections contributed to malnutrition, iron deficiency anaemia and low serum retinol in Orang Asli communities. In addition, STH may also contribute to poor cognitive functions and learning ability. Improvements in socioeconomic status in Malaysia have shown positive impact on the reduction of intestinal parasitic infections in other communities however, this positive impact is less significant in the Orang Asli communities. In view of this, a national parasitic infections baseline data on morbidity and mortality in the 18 subgroups of Orang Asli, will assist in identifying intervention programmes required by these communities. It is hope that the adoption of strategies highlighted in the World Health Organisation- Healthy Village Initiatives (WHO-HVI) into Orang Asli communities will ensure the whole mechanism of delivery and empowerment by the government agencies become more efficient and productive in alleviating intestinal parasitic infections in these communities.
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Affiliation(s)
- Y A L Lim
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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Abstract
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.
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Affiliation(s)
- Huw V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, Scotland, UK.
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Kurniawan A, Karyadi T, Dwintasari SW, Sari IP, Yunihastuti E, Djauzi S, Smith HV. Intestinal parasitic infections in HIV/AIDS patients presenting with diarrhoea in Jakarta, Indonesia. Trans R Soc Trop Med Hyg 2009; 103:892-8. [PMID: 19327806 DOI: 10.1016/j.trstmh.2009.02.017] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 11/30/2022] Open
Abstract
We investigated the occurrence of intestinal parasites in Indonesian HIV/AIDS patients with chronic diarrhoea prior to administering antiretroviral therapy. The influence of age, CD4(+) cell count and season on parasite occurrence was also studied. In total, 318 unconcentrated stool samples were analysed using Lugol's iodine and modified acid fast staining to detect intestinal coccidia. Most samples (94.5%) were from males aged 21-40 years with CD4(+) counts < or = 50 cells/mm(3). Parasites were found in 84.3% of samples (single species infections, 71.4%; polyparasitism, 12.9%), with protozoan pathogens occurring most commonly. Cryptosporidium (4.9%), Cyclospora cayetanensis (4.5%) and Giardia duodenalis (1.9%) were the most frequent single infections, but Blastocystis hominis (72.4%) was the most commonly occurring protist. Cryptosporidium and C. cayetanensis occurred in 11.9% and 7.8% of all (single and mixed) infections. The most common co-infection was with B. hominis and Cryptosporidium (6.3%). Intestinal protozoan pathogens were detected more frequently in cases with CD4(+) counts < or = 200/mm(3). No seasonal influence was determined for Cryptosporidium, C. cayetanensis or B. hominis, but gross seasonal disturbances may have influenced our findings. Intestinal parasites should be looked for routinely in this group of individuals and should be treated to reduce complications and the likelihood of transmission.
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Affiliation(s)
- A Kurniawan
- Department of Parasitology, Faculty of Medicine, University of Indonesia, Salemba Raya No. 6, Jakarta 10430, Indonesia.
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Stensvold CR, Nielsen HV, Mølbak K, Smith HV. Pursuing the clinical significance of Blastocystis--diagnostic limitations. Trends Parasitol 2008; 25:23-9. [PMID: 19013108 DOI: 10.1016/j.pt.2008.09.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 08/11/2008] [Accepted: 09/23/2008] [Indexed: 11/17/2022]
Abstract
The clinical significance of one of the most prevalent single-celled intestinal parasites worldwide, Blastocystis, remains unsettled. A plethora of clinical and epidemiological studies have been undertaken to generate data on its prevalence in different populations and investigate the role of the parasite as a cause of gastro- and extra-intestinal disease. In this article, we pinpoint limitations of studies that seek to determine the clinical significance of Blastocystis, based on shortcomings in our understanding of Blastocystis diagnosis and biology, and identify methodologies for further studies aimed at determining the molecular epidemiology and clinical impact of this parasite.
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Affiliation(s)
- C Rune Stensvold
- Department of Bacteriology, Mycology and Parasitology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark.
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Zylan K, Bailey T, Smith HV, Silvanose C, Kinne J, Schuster RK, Hyland K. An outbreak of cryptosporidiosis in a collection of Stone curlews (Burhinus oedicnemus) in Dubai. Avian Pathol 2008; 37:521-6. [DOI: 10.1080/03079450802357019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Kasamyra Zylan
- a 6 Clevedon Terrace , Bristol , BS6 5TX , UK
- b The Dubai Falcon Hospital , PO Box 23919, Dubai, United Arab Emirates
| | - Tom Bailey
- b The Dubai Falcon Hospital , PO Box 23919, Dubai, United Arab Emirates
| | - Huw V. Smith
- c Scottish Parasite Diagnostic Laboratory , Stobhill Hospital , Glasgow , G21 3UW , UK
| | | | - Joerg Kinne
- d Central Veterinary Research Laboratory , PO Box 597, Dubai, United Arab Emirates
| | - Rolf K. Schuster
- d Central Veterinary Research Laboratory , PO Box 597, Dubai, United Arab Emirates
| | - Kevin Hyland
- e Wildlife Protection Office , PO Box 27942, Dubai, United Arab Emirates
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Tan TC, Suresh KG, Smith HV. Phenotypic and genotypic characterisation of Blastocystis hominis isolates implicates subtype 3 as a subtype with pathogenic potential. Parasitol Res 2008; 104:85-93. [PMID: 18795333 DOI: 10.1007/s00436-008-1163-5] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 08/13/2008] [Indexed: 11/24/2022]
Abstract
Despite frequent reports on the presence of Blastocystis hominis in human intestinal tract, its pathogenicity remains a matter of intense debate. These discrepancies may be due to the varying pathogenic potential or virulence of the isolates studied. The present study represents the first to investigate both phenotypic and genotypic characteristics of B. hominis obtained from symptomatic and asymptomatic individuals. Symptomatic isolates had a significantly greater size range and lower growth rate in Jones' medium than asymptomatic isolates. The parasite cells of symptomatic isolates exhibited rougher surface topography and greater binding affinity to Canavalia ensiformis (ConA) and Helix pomatia (HPA). The present study also identifies further phenotypic characteristics, which aided in differentiating the pathogenic forms from the non-pathogenic forms of B. hominis. Blastocystis subtype 3 was found to be correlated well with the disease.
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Affiliation(s)
- T C Tan
- Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
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21
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Abstract
'Swimmer's itch' or cercarial dermatitis (CD) results from an immunological reaction to free-swimming non-human schistosome parasites released from aquatic snails. Affected bathers develop a self-limiting, pruritic, macular or papular eruption shortly after leaving the water. The condition is well-recognized in continental Europe, Asia and America, but has not to date been recorded in the UK.
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Affiliation(s)
- S J Fraser
- Department of Dermatology, Victoria Hospital, Kirkcaldy, UK.
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Abstract
Cryptosporidium and Giardia are major causes of diarrhoeal diseases of humans worldwide, and are included in the World Health Organisation's 'Neglected Diseases Initiative'. Cryptosporidium and Giardia occur commonly in Malaysian human and non-human populations, but their impact on disease, morbidity and cost of illness is not known. The commonness of contributions from human (STW effluents, indiscriminate defaecation) and non-human (calving, lambing, muck spreading, slurry spraying, pasturing/grazing of domestic animals, infected wild animals) hosts indicate that many Malaysian environments, particularly water and soil, are sufficiently contaminated to act as potential vehicles for the transmission of disease. To gain insight into the morbidity and mortality caused by human cryptosporidiosis and giardiasis, they should be included into differential diagnoses, and routine laboratory testing should be performed and (as for many infectious diseases) reported to a centralised public health agency. To understand transmission routes and the significance of environmental contamination better will require further multidisciplinary approaches and shared resources, including raising national perceptions of the parasitological quality of drinking water. Here, the detection of Cryptosporidium and Giardia should be an integral part of the water quality requirement. A multidisciplinary approach among public health professionals in the water industry and other relevant health- and environment-associated agencies is also required in order to determine the significance of Cryptosporidium and Giardia contamination of Malaysian drinking water. Lastly, adoption of validated methods to determine the species, genotype and subgenotype of Cryptosporidium and Giardia present in Malaysia will assist in developing effective risk assessment, management and communication models.
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Affiliation(s)
- Y A L Lim
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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Watthanakulpanich D, Smith HV, Hobbs G, Whalley AJ, Billington D. Application of Toxocara canis excretory-secretory antigens and IgG subclass antibodies (IgG1-4) in serodiagnostic assays of human toxocariasis. Acta Trop 2008; 106:90-5. [PMID: 18343348 DOI: 10.1016/j.actatropica.2008.01.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 01/28/2008] [Accepted: 01/28/2008] [Indexed: 11/26/2022]
Abstract
A major problem in the serodiagnosis of human toxocariasis in tropical countries is cross-reaction with antibodies to other helminthic diseases and a lack of sensitivity. The majority of tests currently available use total IgG and, in this study, the use of peroxidase-conjugated anti-human IgG subclass antibodies (IgG1-4) was compared with total IgG for the diagnosis of human toxocariasis by using Toxocara excretory-secretory (TES) antigens in an enzyme-linked immunosorbent assay (ELISA) format. All four IgG subclass antibodies gave approximately 10-fold increases in optical density (OD) values for 50 toxocariasis patients compared to 29 healthy normals; this was significantly greater than the approximate doubling of OD values seen in the total IgG-ELISA format. IgG2 gave by far the greatest sensitivity (values: IgG, 50%; IgG1, 60%; IgG2, 98%; IgG3, 78%; IgG4, 64%). Significant cross-reactivity using all IgG subclasses in the TES ELISA was seen with 141 serum samples from patients with 10 other helminthic infections. However, IgG3 gave the best specificity (values: IgG, 73%; IgG1, 76%; IgG2, 71%; IgG3, 81%; IgG4, 71%). Thus, of the IgG subclass antibodies, IgG2 appeared best and employing this subclass can improve the serodiagnosis of human toxocariasis since it recognises carbohydrate epitopes of TES antigens.
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Abstract
Coagulation and rapid gravity filtration coincided with a significant reduction in cryptosporidiosis cases. Previous evidence has suggested an association between consumption of unfiltered water from Loch Lomond, Scotland, and cryptosporidiosis. Before November 1999, this water had been only microstrained and disinfected with chlorine; however, since that time, physical treatment of the water (coagulation, rapid gravity filtration) has been added. To determine risk factors, including drinking water, for cryptosporidiosis, we analyzed data on laboratory-confirmed cases of cryptosporidiosis collected from 1997 through 2003. We identified an association between the incidence of cryptosporidiosis and unfiltered drinking water supplied to the home. The association supports the view that adding a filtration system to minimally treated water can substantially reduce the number of confirmed cryptosporidiosis cases.
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Affiliation(s)
- Kevin G J Pollock
- Gastro-intestinal/Zoonoses Section, Health Protection Scotland, Clifton House, Clifton Place, Glasgow, Scotland, UK.
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Jex AR, Smith HV, Monis PT, Campbell BE, Gasser RB. Cryptosporidium--biotechnological advances in the detection, diagnosis and analysis of genetic variation. Biotechnol Adv 2008; 26:304-17. [PMID: 18430539 DOI: 10.1016/j.biotechadv.2008.02.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 01/29/2008] [Accepted: 02/14/2008] [Indexed: 11/19/2022]
Abstract
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.
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Affiliation(s)
- A R Jex
- Department of Veterinary Science, The University of Melbourne, Werribee, Victoria, Australia.
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Anthony JP, Fyfe L, Stewart D, McDougall GJ, Smith HV. The effect of blueberry extracts on Giardia duodenalis viability and spontaneous excystation of Cryptosporidium parvum oocysts, in vitro. Methods 2007; 42:339-48. [PMID: 17560322 DOI: 10.1016/j.ymeth.2007.02.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 02/08/2007] [Accepted: 02/15/2007] [Indexed: 01/12/2023] Open
Abstract
The protozoan parasites Giardia duodenalis and Cryptosporidium parvum are common causes of diarrhoea, worldwide. Effective drug treatment is available for G. duodenalis, but with anecdotal evidence of resistance or reduced compliance. There is no effective specific chemotherapeutic intervention for Cryptosporidium. Recently, there has been renewed interest in the antimicrobial properties of berries and their phenolic compounds but little work has been done on their antiparasitic actions. The effect of various preparations of blueberry (Vaccinium myrtillus) extract on G. duodenalis trophozoites and C. parvum oocysts were investigated. Pressed blueberry extract, a polyphenolic-rich blueberry extract, and a commercially produced blueberry drink (Bouvrage) all demonstrated antigiardial activity. The polyphenol-rich blueberry extract reduced trophozoite viability in a dose dependent manner. At 167 microgml(-1), this extract performed as well as all dilutions of pressed blueberry extract and the Bouvrage beverage (9.6+/-2.8% live trophozoites remaining after 24h incubation). The lowest dilution of blueberry extract tested (12.5% v/v) contained >167 microgml(-1) of polyphenolic compounds suggesting that polyphenols are responsible for the reduced survival of G. duodenalis trophozoites. The pressed blueberry extract, Bouvrage beverage and the polyphenolic-rich blueberry extract increased the spontaneous excystation of C. parvum oocysts at 37 degrees C, compared to controls, but only at a dilution of 50% Bouvrage beverage, equivalent to 213 microgml(-1) gallic acid equivalents in the polyphenolic-rich blueberry extract. Above this level, spontaneous excystation is decreased. We conclude that water soluble extracts of blueberries can kill G. duodenalis trophozoites and modify the morphology of G. duodenalis and C. parvum.
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Affiliation(s)
- J-P Anthony
- Dietetics, Nutrition and Biological Sciences, Queen Margaret University, Clerwood Terrace, Edinburgh EH12 8TS, UK
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Morrison LJ, Mallon ME, Smith HV, MacLeod A, Xiao L, Tait A. The population structure of the Cryptosporidium parvum population in Scotland: a complex picture. Infect Genet Evol 2007; 8:121-9. [PMID: 18077222 PMCID: PMC2684618 DOI: 10.1016/j.meegid.2007.10.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 10/30/2007] [Accepted: 10/31/2007] [Indexed: 12/31/2022]
Abstract
We genotyped 297 Scottish C. parvum samples using micro- and minisatellites. Treated as a single population, the population structure was epidemic. When regional populations were analysed, there was evidence of sub-population structure variations. This was dependent upon excluding sub-groups exhibiting significant genetic distance from the main population, implying genetic sub-structuring. We tested the hypothesis that these sub-groups originated outside the UK and demonstrated that one sub-group clustered with Peruvian samples. A geographically comprehensive panel of isolates would fully confirm this result. These data indicate limited sub-structuring within a small geographical area, but substantial sub-structuring over larger geographical distances. Host movement influences parasite diversity and population structure, evidenced by strong correlation (r2 = 0.9686) between cattle movements and parasite diversity. Thus, the population structure of C. parvum is complex, with sub-populations differing in structure and being influenced by host movements, including the introduction of novel multilocus genotypes from geographically distinct regions.
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Affiliation(s)
- Liam J Morrison
- Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow Biomedical Research Centre, 120 University Place, Glasgow G12 8TA, UK.
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Cook N, Nichols RAB, Wilkinson N, Paton CA, Barker K, Smith HV. Development of a method for detection of Giardia duodenalis cysts on lettuce and for simultaneous analysis of salad products for the presence of Giardia cysts and Cryptosporidium oocysts. Appl Environ Microbiol 2007; 73:7388-91. [PMID: 17890337 PMCID: PMC2168210 DOI: 10.1128/aem.00552-07] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Accepted: 09/10/2007] [Indexed: 11/20/2022] Open
Abstract
We report a method for detecting Giardia duodenalis cysts on lettuce, which we subsequently use to examine salad products for the presence of Giardia cysts and Cryptosporidium oocysts. The method is based on four basic steps: extraction of cysts from the foodstuffs, concentration of the extract and separation of the cysts from food materials, staining of the cysts to allow their visualization, and identification of cysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Cyst staining is also performed using proprietary reagents. The method recovered 46.0% +/- 19.0% (n = 30) of artificially contaminating cysts in 30 g of lettuce. We tested the method on a variety of commercially available natural foods, which we also seeded with a commercially available internal control, immediately prior to concentration of the extract. Recoveries of the Texas Red-stained Giardia cyst and Cryptosporidium oocyst internal controls were 36.5% +/- 14.3% and 36.2% +/- 19.7% (n = 20), respectively. One natural food sample of organic watercress, spinach, and rocket salad contained one Giardia cyst 50 g(-1) of sample as an indigenous surface contaminant.
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Affiliation(s)
- N Cook
- Central Science Laboratory, Sand Hutton, York YO41 1LZ, United Kingdom
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Abstract
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.
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Affiliation(s)
- R Reinoso
- Environmental Research Institute, University of León, León, Spain.
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Abstract
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.
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Affiliation(s)
- H V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, 133 Balornock Road, Glasgow G21 3UW, UK.
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Leoni F, Mallon ME, Smith HV, Tait A, McLauchlin J. Multilocus analysis of Cryptosporidium hominis and Cryptosporidium parvum isolates from sporadic and outbreak-related human cases and C. parvum isolates from sporadic livestock cases in the United Kingdom. J Clin Microbiol 2007; 45:3286-94. [PMID: 17687021 PMCID: PMC2045344 DOI: 10.1128/jcm.02536-06] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cryptosporidium parvum and Cryptosporidium hominis isolates from sporadic, drinking water-associated, and intrafamilial human cases together with C. parvum isolates from sporadic cases in livestock were collected in the United Kingdom between 1995 and 1999. The isolates were characterized by analysis of three microsatellite markers (ML1, GP15, and MS5) using PCR amplification. Within C. hominis, four alleles were detected within the GP15 and MS5 loci, and a single type was detected with ML1. C. parvum was more polymorphic; 12 alleles were detected with GP15, 6 were detected with MS5, and 3 were detected with ML1. Multilocus analysis of polymorphisms within the three microsatellite loci was combined with those reported previously for an extrachromosomal small double-stranded RNA. Forty multilocus types were detected within these two species: 9 were detected in C. hominis, and 31 were detected in C. parvum. In C. hominis, heterogeneity was almost exclusively found in samples from sporadic cases. Similarity analysis identified three main groups within C. parvum, and the group that predominated in human infection was also found in livestock. Multilocus types of C. parvum previously identified only in humans were not detected in livestock. Isolates of both C. hominis and C. parvum from separate waterborne outbreaks were genetically homogeneous, suggesting preferential or point source transmission of certain types of these two species of parasites.
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Affiliation(s)
- Francesca Leoni
- Health Protection Agency, Centre for Infections, 61 Colindale Avenue, London NW9 5HT, United Kingdom
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Zintl A, Neville D, Maguire D, Fanning S, Mulcahy G, Smith HV, De Waal T. Prevalence ofCryptosporidiumspecies in intensively farmed pigs in Ireland. Parasitology 2007; 134:1575-82. [PMID: 17565758 DOI: 10.1017/s0031182007002983] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYNaturalCryptosporidiuminfections in pigs are widespread but generally apathogenic. This study was undertaken to determine the prevalence of zoonoticCryptosporidiumspp. in piggeries in Ireland, where the drinking water supply is particularly vulnerable to contamination with zoonotic species. Overall, infections were detected in 39 out of 342 animals (11·4%), with highest infection rates among weaners (15%) and sows (13·3%). Twenty-nine positive samples were genotyped based on SSU rRNA sequence analysis. Infections withCryptosporidium parvum, the most important zoonotic species were rare and are likely to be of greater concern to animal handlers than suppliers of drinking water. In addition toC. parvum,Cryptosporidium suis,Cryptosporidiumpig genotype II,Cryptosporidium murisand a previously undescribed genotype were identified. ABI-profiles indicated the presence of different alleles in at least 40% of all genotyped isolates. This was confirmed in 3 isolates by cloning of the PCR products. Since chronic mixed infections appear to be quite common in pigs they could be considered as models for mixed infections in immunocompromised humans.
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Affiliation(s)
- A Zintl
- School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
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Morse TD, Nichols RAB, Grimason AM, Campbell BM, Tembo KC, Smith HV. Incidence of cryptosporidiosis species in paediatric patients in Malawi. Epidemiol Infect 2007; 135:1307-15. [PMID: 17224087 PMCID: PMC2870691 DOI: 10.1017/s0950268806007758] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
We determined the incidence of cryptosporidiosis in children aged <5 years presenting with diarrhoea in an urban and rural hospital-based setting in Malawi. Stools were collected over a 22-month period during both rainy and dry seasons. A range of microscopic methods were used to determine the presence of Cryptosporidium spp. oocysts. Species determination was by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of oocyst-extracted DNA using 18S rRNA and COWP gene loci. Cryptosporidium spp. oocysts were seen in 5.9% (50/848) of samples, of which 43 amplified by PCR-RFLP indicated the following species: C. hominis, C. parvum, C. hominis/C. parvum, C. meleagridis and C. andersoni. Seven samples could not be amplified by PCR. Wider species diversity was found in the rural setting, and may be a result of increased malnutrition and zoonotic exposure in this area. Improvements in water, sanitation, household hygiene and animal control are required to reduce the incidence of infection in this population.
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Affiliation(s)
- T D Morse
- Department of Civil Engineering, University of Strathclyde, Glasgow, UK.
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Abstract
We developed and validated a PCR-based method for identifying Cryptosporidium species and/or genotypes present on oocyst-positive microscope slides. The method involves removing coverslips and oocysts from previously examined slides followed by DNA extraction. We tested four loci, the 18S rRNA gene (N18SDIAG and N18SXIAO), the Cryptosporidium oocyst wall protein (COWP) gene (STN-COWP), and the dihydrofolate reductase (dhfr) gene (by multiplex allele-specific PCR), for amplifying DNA from low densities of Cryptosporidium parvum oocysts experimentally seeded onto microscope slides. The N18SDIAG locus performed consistently better than the other three tested. Purified oocysts from humans infected with C. felis, C. hominis, and C. parvum and commercially purchased C. muris were used to determine the sensitivities of three loci (N18SDIAG, STN-COWP, and N18SXIAO) to detect low oocyst densities. The N18SDIAG primers provided the greatest number of positive results, followed by the N18SXIAO primers and then the STN-COWP primers. Some oocyst-positive slides failed to generate a PCR product at any of the loci tested, but the limit of sensitivity is not entirely based on oocyst number. Sixteen of 33 environmental water monitoring Cryptosporidium slides tested (oocyst numbers ranging from 1 to 130) contained mixed Cryptosporidium species. The species/genotypes most commonly found were C. muris or C. andersoni, C. hominis or C. parvum, and C. meleagridis or Cryptosporidium sp. cervine, ferret, and mouse genotypes. Oocysts on one slide contained Cryptosporidium muskrat genotype II DNA.
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Affiliation(s)
- Rosely A B Nichols
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, United Kingdom
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Al-Adhami BH, Nichols RAB, Kusel JR, O'Grady J, Smith HV. Detection of UV-induced thymine dimers in individual Cryptosporidium parvum and Cryptosporidium hominis oocysts by immunofluorescence microscopy. Appl Environ Microbiol 2006; 73:947-55. [PMID: 17012589 PMCID: PMC1800761 DOI: 10.1128/aem.01251-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To investigate the effect of UV light on Cryptosporidium parvum and Cryptosporidium hominis oocysts in vitro, we exposed intact oocysts to 4-, 10-, 20-, and 40-mJ x cm-2 doses of UV irradiation. Thymine dimers were detected by immunofluorescence microscopy using a monoclonal antibody against cyclobutyl thymine dimers (anti-TDmAb). Dimer-specific fluorescence within sporozoite nuclei was confirmed by colocalization with the nuclear fluorogen 4',6'-diamidino-2-phenylindole (DAPI). Oocyst walls were visualized using either commercial fluorescein isothiocyanate-labeled anti-Cryptosporidium oocyst antibodies (FITC-CmAb) or Texas Red-labeled anti-Cryptosporidium oocyst antibodies (TR-CmAb). The use of FITC-CmAb interfered with TD detection at doses below 40 mJ x cm-2. With the combination of anti-TDmAb, TR-CmAb, and DAPI, dimer-specific fluorescence was detected in sporozoite nuclei within oocysts exposed to 10 to 40 mJ x cm-2 of UV light. Similar results were obtained with C. hominis. C. parvum oocysts exposed to 10 to 40 mJ x cm-2 of UV light failed to infect neonatal mice, confirming that results of our anti-TD immunofluorescence assay paralleled the outcomes of our neonatal mouse infectivity assay. These results suggest that our immunofluorescence assay is suitable for detecting DNA damage in C. parvum and C. hominis oocysts induced following exposure to UV light.
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Affiliation(s)
- B H Al-Adhami
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, United Kingdom
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Al-Adhami BH, Nichols RAB, Kusel JR, O'Grady J, Smith HV. Cryptosporidium parvum sporozoites contain glutathione. Parasitology 2006; 133:555-63. [PMID: 16817993 DOI: 10.1017/s0031182006000497] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 04/11/2006] [Accepted: 04/13/2006] [Indexed: 11/07/2022]
Abstract
We used the fluorescent dye monochlorobimane (MCB) which binds glutathione (GSH) to localize between 2 and 6 distinctly labelled nuclear and cytoplasmic GSH foci in recently excreted and aged, intact Cryptosporidium parvum oocysts and sporozoites. Buthionine sulfoximine (BSO), a potent and specific inhibitor of GSH, was used to determine whether GSH is synthesized in BSO-treated C. parvum oocysts, by labelling treated oocysts with MCB. Both visual and electronic quantifications were performed. At 5 mM BSO, a significant inhibition of MCB fluorescence, reflecting reduced MCB uptake, was observed in GSH-depleted oocysts (mean +/- S.D. 35 +/- 3.7) compared with controls (3.3 +/- 1.2, P = 0). This clear reduction occurred only in viable oocysts. 1 mM BSO-treated oocysts exhibited weak or no MCB fluorescence, although they were viable (excluded propidium iodide, PI)), and intact and contained sporozoites by differential interference contrast microscopy (DIC). MCB was used in conjunction with PI to determine C. parvum oocyst viability. Oocysts labelled with MCB/PI or 4'6-diamidino-2-phenyl indole (DAPI)/PI produced comparable labelling patterns. Viable oocysts were labelled with MCB or DAPI whereas dead oocysts were labelled with PI only. The localization of GSH in viable, intact oocysts and excysted sporozoites and UV light-irradiated oocysts and sporozoites revealed no changes in MCB uptake at levels up to 40 mJ.cm(-2) irradiation. Although GSH can be detected following MCB localization in both the nucleus and cytoplasm of sporozoites, and can be specifically depleted by BSO treatment, MCB is unlikely to be useful as a surrogate for detecting UV damage in UV-treated Cryptosporidium oocysts.
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Affiliation(s)
- B H Al-Adhami
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, UK
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Cook N, Paton CA, Wilkinson N, Nichols RAB, Barker K, Smith HV. Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 2: validation. Int J Food Microbiol 2006; 109:222-8. [PMID: 16546283 DOI: 10.1016/j.ijfoodmicro.2005.12.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 12/14/2005] [Accepted: 12/31/2005] [Indexed: 10/24/2022]
Abstract
We report the results of interlaboratory collaborative trials of methods to detect oocysts of the protozoan parasite Cryptosporidium parvum on lettuce and raspberries. The trials involved eight expert laboratories in the United Kingdom. Samples comprised 30 g lettuce, and 60 g raspberries. Lettuce samples were artificially contaminated at three levels: low (8.5-14.2 oocysts), medium (53.5-62.6 oocysts), and high (111.3-135.0 oocysts). Non-contaminated lettuce samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated lettuce samples) of 89.6%, and a specificity (correct identification of non-contaminated samples) of 85.4%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 30.4%. The method was just as reproducible between laboratories, as repeatable within a laboratory. Raspberry samples were artificially contaminated at three levels: low (8.5-26.8 oocysts), medium (29.7-65.7 oocysts), and high (53.9-131.3 oocysts). Non-contaminated raspberry samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated raspberry samples) of 95.8%, and a specificity (correct identification of non-contaminated samples) of 83.3%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 44.3%. The method was just as reproducible between laboratories, as repeatable within a laboratory. The results of the collaborative trial indicate that these assays can be used effectively in analytical microbiological laboratories.
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Affiliation(s)
- N Cook
- Central Science Laboratory, Sand Hutton, York YO41 1LZ, UK
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Cook N, Paton CA, Wilkinson N, Nichols RAB, Barker K, Smith HV. Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 1: development and optimization of methods. Int J Food Microbiol 2006; 109:215-21. [PMID: 16529835 DOI: 10.1016/j.ijfoodmicro.2005.12.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 12/14/2005] [Accepted: 12/31/2005] [Indexed: 11/18/2022]
Abstract
No standard method is available for detecting protozoan parasites on foods such as soft fruit and salad vegetables. We report on optimizing methods for detecting Cryptosporidium parvum on lettuce and raspberries. These methods are based on four basic stages: extraction of oocysts from the foodstuffs, concentration of the extract and separation of the oocysts from food materials, staining of the oocysts to allow their visualization, and identification of oocysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Oocyst staining is also performed using proprietary reagents. The performance parameters of the extraction steps were extensively optimized, using artificially contaminated samples. The fully developed methods were tested several times to determine their reliability. The method to detect C. parvum on lettuce recovered 59.0+/-12.0% (n=30) of artificially contaminated oocysts. The method to detect C. parvum on raspberries recovered 41.0+/-13.0% (n=30) of artificially contaminated oocysts.
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Affiliation(s)
- N Cook
- Central Science Laboratory, Sand Hutton, York YO41 1LZ, UK
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Nichols RAB, Moore JE, Smith HV. A rapid method for extracting oocyst DNA from Cryptosporidium-positive human faeces for outbreak investigations. J Microbiol Methods 2006; 65:512-24. [PMID: 16290112 DOI: 10.1016/j.mimet.2005.09.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Revised: 09/13/2005] [Accepted: 09/14/2005] [Indexed: 11/24/2022]
Abstract
We describe a rapid method for extracting and concentrating Cryptosporidium oocysts from human faecal samples with subsequent DNA preparation for mainstream PCR applications. This method consists of extracting faecal lipids using a modified water-ether treatment and releasing DNA from semi-purified oocysts by freeze thawing in lysis buffer. Following immunomagnetisable separation (IMS), recovery rates of 29.5%, 43.2% and 49.8% were obtained from oocyst-negative solid, semi-solid and liquid faeces, respectively, seeded with 100 +/- 2 C. parvum oocysts, which were enumerated by flow cytometry. A retrospective analysis was conducted on 92 positive human faecal samples including 78 oocyst-positive cases from 2 UK cryptosporidiosis outbreaks (outbreak A = 34 samples, outbreak B = 44 samples) and 14 oocyst-positive, sporadic cases. We used primers targeting the Cryptosporidium oocyst wall protein gene (COWP; STN-COWP), the 18S rRNA (direct PCR) and the dihydrofolate reductase gene (dhfr, MAS-PCR) fragments to evaluate extracted DNA by PCR. PCR inhibitors were present in 20 samples when template was co-amplified with the 18S rRNA gene primers and an internal control. Template dilution (1/5) in polyvinylpyrrolidone (10 mg ml(-1), pH 8.0) transformed four PCR-negative samples to PCR-positive and increased amplicon intensity in previously positive samples. Eighteen of 20 PCR-negative samples produced visible amplicons when Taq polymerase concentration in the STN-COWP PCR was increased from 2.5 to 5 U. The STN-COWP PCR assay amplified 90 of 92 samples (97.8%) and the MAS-PCR assay amplified 70 of 92 samples (76.1%) tested. In the absence of inhibitors, DNA equivalent to 3 C. parvum oocysts was amplified.
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Tan TC, Suresh KG, Thong KL, Smith HV. PCR fingerprinting of Blastocystis isolated from symptomatic and asymptomatic human hosts. Parasitol Res 2006; 99:459-65. [PMID: 16628457 DOI: 10.1007/s00436-006-0177-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 03/08/2006] [Indexed: 10/24/2022]
Abstract
Genomic DNA from 16 Blastocystis hominis isolates comprising of eight asymptomatic isolates (A1-A8) and eight symptomatic isolates (S1-S8) was amplified by arbitrarily primed polymerase chain reaction (AP-PCR) using 38 arbitrary 10-mer primers. Six primers (A10, B5, C20, D1, F6, and F10) generated reproducible DNA fingerprints. AP-PCR amplification revealed similar DNA fingerprints among all symptomatic isolates (S1-S8) with common bands at 850 bp using primer A10, 920 bp using primer B5, and 1.3 kbp using primer D1. Isolates A1, A3, A4, A5, A6, and A7 showed similar DNA banding patterns and all asymptomatic isolates (A1-A8) shared a major band at 1 kbp using primer B5. Isolates A2 and A8 showed distinct DNA banding patterns that differed from the remainder of the isolates. The results of the phylogenetic analyses showed that all symptomatic isolates (S1-S8) formed a clade with >70% similarity among the isolates and which were clearly separate from asymptomatic isolates A1, A3, A4, A5, A6, and A7. Asymptomatic isolates A2 and A8 formed two distinct and separate clades. AP-PCR revealed higher genetic variability within the asymptomatic isolates than within the symptomatic isolates. The present study suggests that AP-PCR can be a valuable method for differentiating between isolates of B. hominis and our results support the hypothesis that our asymptomatic and symptomatic B. hominis isolates may represent two different strains/species with varying pathogenic potential.
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Affiliation(s)
- T C Tan
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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Smith HV, Cacciò SM, Tait A, McLauchlin J, Thompson RCA. Tools for investigating the environmental transmission of Cryptosporidium and Giardia infections in humans. Trends Parasitol 2006; 22:160-7. [PMID: 16503418 DOI: 10.1016/j.pt.2006.02.009] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Revised: 01/05/2006] [Accepted: 02/10/2006] [Indexed: 11/28/2022]
Abstract
Cryptosporidiosis and giardiasis are major public health concerns. The role of water and food in the epidemiology of these diseases is now well recognized. Molecular techniques are available to determine the species and genotypes of Cryptosporidium and Giardia and to distinguish human from non-human pathogens. Validated methods to determine the species, genotype and subgenotype that are present in heterologous mixtures should be applied to environmental samples to enable the monitoring and characterization of infection sources, disease tracking and the establishment of causative links to both waterborne and foodborne outbreaks. Meaningful interpretation of population structures and occurrence-prevalence baselines can be performed only by analysing a well-planned set of samples from all possible sources taken regularly over time, rather than focusing on outbreak investigations. For food, this includes such analyses in the country of origin.
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Affiliation(s)
- Huw V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow, UK, G21 3UW.
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Abstract
Electrorotation is a non-invasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. The first detailed electrorotation study of the egg (ovum) of a parasitic nematode, namely Ascaris suum is described to show that electrorotation can rapidly differentiate between fertilized and non-fertilized eggs. Support for this conclusion is by optical microscopy of egg morphology, and also from modelling of the electrorotational response. Modelling was used to determine differences in the dielectric properties of the unfertilized and fertilized eggs, and also to investigate specific differences in the spectra of fertilized eggs only, potentially reflecting embryogenesis. The potential of electrorotation as an investigative tool is shown, as undamaged eggs can be subjected to further non-destructive and destructive techniques, which could provide further insight into parasite biology and epidemiology.
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Affiliation(s)
- C Dalton
- Bio Systems Research and Applications Group, Department of Electrical and Computer Engineering, University of Calgary, Calgary T2N 1N4, Canada.
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Affiliation(s)
- K G J Pollock
- Health Protection Scotland (HPS), Clifton House, Clifton Place, Glasgow, G3 7LN, UK.
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Cacciò SM, Thompson RCA, McLauchlin J, Smith HV. Unravelling Cryptosporidium and Giardia epidemiology. Trends Parasitol 2005; 21:430-7. [PMID: 16046184 DOI: 10.1016/j.pt.2005.06.013] [Citation(s) in RCA: 319] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 05/10/2005] [Accepted: 06/06/2005] [Indexed: 11/15/2022]
Abstract
Molecular biology has provided insights into the taxonomy and epidemiology of Cryptosporidium and Giardia, which are major causes of protozoal diarrhoea in humans worldwide. For both genera, previously unrecognized differences in disease, symptomatology, zoonotic potential, risk factors and environmental contamination have been identified using molecular tools that are appropriate for species, genotype and subtype analysis. In this article, to improve understanding of the epidemiology of cryptosporidiosis and giardiasis, we consider specific requirements for the development of more-effective molecular identification and genotyping systems that should be applicable to both clinical and environmental samples.
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Affiliation(s)
- Simone M Cacciò
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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Abstract
Blastocystis cysts were detected in 38% (47/123) (37 Scottish, 17 Malaysian) of sewage treatment works. Fifty percent of influents (29% Scottish, 76% Malaysian) and 28% of effluents (9% Scottish, 60% Malaysian) contained viable cysts. Viable cysts, discharged in effluent, provide further evidence for the potential for waterborne transmission of Blastocystis.
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Affiliation(s)
- K Suresh
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, 133 Balornock Road, Glasgow G21 3UW, Scotland
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Smith HV, Nichols RAB, Mallon M, Macleod A, Tait A, Reilly WJ, Browning LM, Gray D, Reid SWJ, Wastling JM. Natural Cryptosporidium hominis infections in Scottish cattle. Vet Rec 2005; 156:710-1. [PMID: 15923554 DOI: 10.1136/vr.156.22.710] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- H V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, Scotland
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Abstract
Cryptosporidium parvum excystation and host cell invasion have been characterized in some detail ultrastructurally. However, until recently, the biochemical and molecular basis of host-parasite interactions and parasite- and host-specific molecules involved in excystation, motility and host cell invasion have been poorly understood. This article describes our understanding of Cryptosporidium excystation and the events leading to host cell invasion, and draws from information available about these processes in other apicomplexans. Many questions remain but, once the specific mechanisms are identified, they could prove to be novel targets for drug delivery.
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Affiliation(s)
- Huw V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, Scotland, UK.
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Abstract
PURPOSE OF REVIEW There is a history of inadequate treatments for cryptosporidiosis and a lack of understanding of the species that cause human disease. Against this background, we review the efficacy of antiparasitic agents, particularly nitazoxanide, which has led to increased treatment options, the potential for immunotherapy, and consider the role of highly active antiretroviral therapy in reducing the incidence of this opportunistic infection. RECENT FINDINGS Nitazoxanide is effective for cryptosporidiosis in immunocompetent and probably immunocompromised patients (with an alteration in the duration of treatment or the dosing regimen). HIV-infected patients on highly active antiretroviral therapy have a dramatically lower incidence of cryptosporidiosis, attributable to the effects of intestinal immune reconstitution as well as the effect on the CD4 cell count. Protease inhibitors have a direct inhibitory effect on Cryptosporidium infection, suggesting a further reason for the reduction in the incidence of cryptosporidiosis and implying a further possible therapeutic modality. SUMMARY Cryptosporidiosis remains a significant public health threat. Risk avoidance guidance could be viewed in the more relative terms of risk management depending on the degree of immunosuppression. Of established efficacy in immunocompetent patients, nitazoxanide is also useful for immunocompromised patients. Better prevention and treatment options mean that, in the immunocompromised, this disease is now less common. Immune reconstitution is the key to prevention. Further database mining of the Cryptosporidium genome will assist in the discovery of new genes, biochemical pathways and protective antigens that can be targeted to develop novel therapies for cryptosporidiosis.
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Affiliation(s)
- Huw V Smith
- Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow G21 3UW, UK.
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