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Journal of Clinical Microbiology, January 2009, p. 153-157, Vol. 47, No. 1
0095-1137/09/$08.00+0     doi:10.1128/JCM.01777-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Cryptosporidium Genotype and Subtype Distribution in Raw Wastewater in Shanghai, China: Evidence for Possible Unique Cryptosporidium hominis Transmission

Yaoyu Feng,¹ Na Li,^2,3,4 Liping Duan,^2,3,4 and Lihua Xiao^3*

School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China,¹ School of Life Science and Technology, Tongji University, Shanghai 200295, China,² Division of Parasitic Diseases, National Center for Zoonotic, Vector-Borne and Enteric Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30341,³ Atlanta Research and Education Foundation, 1670 Clairmont Road, Decatur, Georgia 30033⁴

Received 15 September 2008/ Returned for modification 29 October 2008/ Accepted 4 November 2008

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To identify the genotype and subtype distributions of Cryptosporidium oocysts in domestic wastewater in Shanghai, China, and to facilitate the characterization of the endemic transmission of cryptosporidiosis, raw domestic wastewater samples were collected from four wastewater treatment plants in Shanghai, China, from December 2006 to April 2007. Genotypes of Cryptosporidium species were detected based on PCR-restriction fragment length polymorphism and sequence analyses of the small-subunit rRNA gene. Samples that contained Cryptosporidium hominis were further subtyped by DNA sequencing of the 60-kDa glycoprotein gene. Among a total of 90 samples analyzed, 63 were PCR positive, 10 of which had mixed genotypes. Fifty-nine (93.7%) of the PCR-positive samples had C. hominis, and 7 (11.1%) had C. meleagridis. The other seven Cryptosporidium species/genotypes identified included C. baileyi, C. parvum, C. suis, C. muris, rat genotype, avian genotype III, and a novel genotype. Forty-seven of the 59 C. hominis-positive samples were successfully subtyped, with 29 having subtype family Ib and the remaining belonging to subtype families Ia, Id, Ie, and If. The three Ib subtypes identified, IbA19G2, IbA20G2, and IbA21G2, were very different from the two common Ib subtypes (IbA9G3 and IbA10G2) found in other areas of the world. Likewise, the Ie subtype IeA12G3T3 was also different from the common IeA11G3T3 subtype. Thus, the presence of multiple subtype families and unique Ib, Ie, and If subtypes indicates that there might be endemic transmission of cryptosporidiosis in the study area and that C. hominis populations there might be very different from those in other areas.

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Cryptosporidium species are a significant cause of diarrheal diseases in both developing and industrialized nations. Recent molecular epidemiologic studies of cryptosporidiosis helped researchers to better understand the transmission of cryptosporidiosis in humans and the public health significance of Cryptosporidium spp. in animals and the environment. With the use of genotyping tools, five species of Cryptosporidium (Cryptosporidium hominis, C. parvum, C. meleagridis, C. felis, and C. canis) have been shown to be responsible for most human infections. Of these five species, C. hominis and C. parvum are the most common (49). Recently, a number of subtyping tools have been developed to characterize the transmission dynamics of C. parvum and C. hominis (2, 19, 30, 36-38, 40).

Subtyping tools based on sequence analysis of the 60-kDa glycoprotein (gp60) gene have proven to be effective in studying the transmission of human cryptosporidiosis, and the results of such studies were recently reviewed (51). These studies have shown the complexity of Cryptosporidium transmission in areas where it is endemic. Among the five common C. hominis subtype families, Ia, Ib, Id, Ie, and If, three or four C. hominis subtype families were seen in humans in India, Peru, New Orleans, Malawi, South Africa, Kuwait, and Portugal, with only one or two C. parvum subtype families usually found in humans in the same area (1, 2, 16, 30, 37, 40, 48-50).

Detection, genotyping, and subtyping of Cryptosporidium species in wastewater have served as tools for molecular surveillance and characterization of cryptosporidiosis transmission (51). Although Cryptosporidium species were reported to be present in clinical specimens and environmental samples in China (8-10, 13, 32, 44, 53, 55), the genotypes and subtypes involved are not clear. There is only one report on genetic characterization of five Cryptosporidium isolates from patients in China (36). Therefore, the transmission route and infection sources of cryptosporidiosis in China are unclear. The objectives of this study were to identify the genotype and subtype distributions of Cryptosporidium oocysts in domestic wastewater in Shanghai, China, and to infer the endemic transmission of cryptosporidiosis.

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Wastewater sample collection and processing. A total of 90 raw wastewater samples were obtained from four wastewater treatment plants in Shanghai, China, from December 2006 to April 2007, with an average of two or three samples per week. The raw wastewater was a combination of domestic wastewater and storm water. The sampling period was selected to coincide with the drought period in Shanghai to reduce the influence of rain events on the distributions of species, genotypes, and subtype families of Cryptosporidium in wastewater. Grab samples of 500 to 1,000 ml of raw wastewater were collected at the entrances of the treatment plants. Cryptosporidium oocysts in samples were concentrated by centrifugation at 6,000 x g for 10 min.

Cryptosporidium genotyping and subtyping. After washing of the samples twice in distilled water, genomic DNA was extracted from 0.5 ml of concentrate, using a FastDNA spin kit for soil (BIO 101, Carlsbad, CA), and eluted in 100 µl of reagent-grade water as described previously (26). Cryptosporidium oocysts present in the samples were genotyped by nested PCR amplification of an approximately 830-bp fragment of the small-subunit (SSU) rRNA gene and restriction fragment length polymorphism (RFLP) analysis of the secondary PCR products, using the restriction enzymes SspI and VspI (27). Each sample was analyzed five times by the PCR-RFLP technique, using 2 µl of the DNA extract per PCR. DNA of Cryptosporidium serpentis was used as a positive control in all SSU rRNA-based PCR-RFLP analyses. To neutralize residual PCR inhibitors in the extracted DNA, 400 ng/µl of nonacetylated bovine serum albumin (Sigma-Aldrich, St. Louis, MO) was used in the primary PCR. All secondary PCR products for the first 50 samples were sequenced to confirm the genotype identification. PCR products for the remaining 40 samples were sequenced only when RFLP analysis showed banding patterns different from that of C. hominis.

Specimens that contained C. hominis were further subtyped by DNA sequencing of the gp60 gene amplified by a nested PCR. The primers used were modifications of previously published ones (2), as follows: LX0374 (5'-TTA CTC TCC GTT ATA GTC TCC-3') and LX0375 (5'-GGA AGG AAC GAT GTA TCT GA-3') for the primary PCR and AL3532 (5'-TCC GCT GTA TTC TCA GCC-3') and AL3534 (5'-GCA GAG GAA CCA GCA TC-3') for the secondary PCR. Nonacetylated bovine serum albumin (final concentration, 400 ng/µl) was used in the primary PCR, and 52°C was used as the annealing temperature in both primary and secondary PCRs. Each sample was amplified at least three times (five times if the three gp60 PCR replicates were all negative) by PCR, using 2 µl of the DNA extract per PCR, and when available, at least two secondary PCR products per sample were sequenced.

Sequence analysis. After purification using Montage PCR filters (Millipore, Bedford, MA), the secondary PCR products of the SSU rRNA or gp60 gene were sequenced directly with the secondary PCR primers, using an ABI BigDye Terminator v. 3.1 cycle sequencing kit (Applied Biosystems, Foster City, CA) and the manufacturer-suggested procedures. Sequences were read on an ABI3130 genetic analyzer (Applied Biosystems). Sequence accuracy was confirmed by two-directional sequencing and sequencing of at least two PCR products for each positive sample. Nucleotide sequences obtained were aligned with reference SSU rRNA or gp60 sequences by use of the ClustalX 1.81 package (ftp://ftp-igbmc.u-strasbg.fr/pub/ClustalX/) to infer Cryptosporidium genotypes and C. hominis subtypes.

Nucleotide sequence accession numbers. Unique partial SSU rRNA and gp60 sequences obtained during the study were deposited in the GenBank database under accession numbers FJ153238 to FJ153248, FJ205699, and FJ205700.

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Cryptosporidium species and genotypes in wastewater. A total of 90 raw wastewater samples were examined in this study, 63 of which were positive for Cryptosporidium species by the SSU rRNA-based PCR-RFLP technique. Restriction analysis and DNA sequencing of PCR products revealed the presence of the following nine species/genotypes of Cryptosporidium in the samples (Table 1): C. hominis, C. meleagridis, C. parvum, C. baileyi, C. muris, C. suis, rat genotype, avian genotype III, and a new genotype. Cryptosporidium hominis was the most commonly detected species/genotype overall (found in 59 samples, or 93.7% of all PCR-positive samples), followed by C. meleagridis (found in 7 samples, or 11.1% of all PCR-positive samples). The other species/genotypes were detected in only one to three samples. Among the 63 positive samples, 10 showed the concurrent presence of two species/genotypes of Cryptosporidium, the majority of which were mixed with C. hominis, except for one sample, which had both the rat genotype and avian genotype III. The new genotype identified from sample 78 had eight base pair differences from C. hominis (GenBank accession no. AF093489) in the partial SSU rRNA gene (Table 2).

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TABLE 1. Prevalence and genotype distribution of Cryptosporidium species in raw wastewater samples from Shanghai

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TABLE 2. Nucleotide differences in the partial SSU rRNA gene between the new Cryptosporidium genotype and C. hominis

Subtypes of C. hominis in wastewater. Wastewater samples positive for C. hominis (59 samples) were subtyped by gp60 sequence analysis. Forty-seven (79.7%) of the 59 samples were positive by gp60 PCR. The reduced detection rate by gp60 PCR was probably due to the single-copy nature of the target gene (instead of five copies for the SSU rRNA gene) and the small numbers and random distribution of oocysts in water samples. The obtained nucleotide sequences were compared with the known subtype sequences deposited in GenBank. This analysis suggested that 43 samples had only one subtype and 4 samples had two subtypes. Altogether, there were 10 subtypes in five subtype families in the 47 positive wastewater samples, including Ia (two subtypes in 6 samples), Ib (three subtypes in 29 samples), Id (two subtypes in 4 samples), Ie (one subtype in 6 samples), and If (two subtypes in 5 samples) (Table 3). For the Ib subtype family, 22 of 29 (75.9%) positive samples had the IbA21G2 subtype (Table 3).

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TABLE 3. Cryptosporidium hominis subtypes in raw wastewater in Shanghai

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There are only a few reports available on genotyping of Cryptosporidium species in raw wastewater, and the results of these studies are summarized in Table 4. The results of this study support previous findings of the complexity of Cryptosporidium populations in raw urban wastewater (22-24, 45, 46, 52, 54). However, the compositions of the populations were quite different (Table 4). Nine Cryptosporidium species or genotypes were found in raw wastewater samples in Shanghai, with C. hominis being the dominant species. Because of the host adaptation nature of Cryptosporidium spp., the results of this study indicate that humans (C. hominis, C. parvum, C. meleagridis, and C. suis), farm animals (C. parvum and C. suis), rodents (C. muris and rat genotype), and birds (C. meleagridis, C. baileyi, and avian genotype III) all contributed to Cryptosporidium contamination in wastewater in this study. A noticeable difference was the absence of C. andersoni, which was seen in some of the earlier studies in other areas (Table 4). This is consistent with the absence of cattle slaughterhouses in the studied area. Previously, it was shown that humans, slaughtered farm animals, rodents, and birds all contributed to Cryptosporidium contamination in urban wastewater (22-24, 45, 46, 52, 54).

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TABLE 4. Cryptosporidium genotypes in raw urban wastewater by PCR-based techniques

The predominance of C. hominis in wastewater in Shanghai indicates that anthroponotic transmission is important in cryptosporidiosis epidemiology in this area. This is consistent with the finding by Peng et al. (36), who reported that all five specimens from patients in China belonged to C. hominis. Thus far, C. hominis is responsible for far more infections than C. parvum in humans in developing countries where genotyping studies have been conducted (3, 4, 12, 17, 18, 30, 34, 37, 39, 41-43, 47). In contrast, in the United Kingdom, other parts of Europe, and New Zealand, C. parvum is as common as C. hominis in humans (2, 6, 14, 20, 21, 25, 29, 31, 33). The differences in distribution of Cryptosporidium genotypes in humans are considered an indication of differences in infection sources (28, 29, 33).

The results of subtype analysis indicate that C. hominis transmission in Shanghai, China, is probably unique. The following are some features of C. hominis in wastewater in Shanghai.

(i) There are many subtype families and many subtypes within most families. In this study, there were five C. hominis subtype families, Ia, Ib, Id, Ie, and If, and two or three subtypes in each family except family Ie. This is similar to the complexity of Cryptosporidium populations in other developing countries, such as India, Malawi, and South Africa, where many subtype families and many subtypes within the subtype families Ia and Id were reported (16, 30, 37). In contrast, in developed countries, C. hominis heterogeneity is generally small, as reflected by the common occurrence of subtype family Ib and/or the low heterogeneity in subtype families Ia and Id (1, 2, 7, 19, 49). In this study, many subtypes were detected in not only families Ia and Id but also families Ib and If. Thus, like in other developing countries, the high C. hominis heterogeneity is also likely an indicator of endemic cryptosporidiosis transmission in the studied area.

(ii) In this study, there were three unique Ib subtypes, namely, IbA19G2, IbA20G2, and IbA21G2. Cryptosporidium hominis family Ib is a common subtype family, and IbA9G3 and IbA10G2 are the two common subtypes within this subtype family. IbA9G3 is commonly seen in humans in Malawi, Kenya, India, and Australia, and IbA10G2 is commonly seen in South Africa, Botswana, Jamaica, Peru, the United States, Canada, Australia, and European countries (1, 2, 7, 16, 18, 19, 30, 49). In addition, IbA10G2 is responsible for more than half of the waterborne outbreaks in the United States, United Kingdom, Canada, and France (11, 19, 35, 51). The C. hominis IbA19G2, IbA20G2, and IbA21G2 subtypes identified in this study are very different from the two common Ib subtypes found in other areas of the world.

(iii) The presence of subtype IeA12G3T3 was observed in this study. Within the C. hominis subtype family Ie, humans in most areas are infected with IeA11G3T3, with the exception of Kingston, Jamaica, New Orleans, LA, and Adelaide, Australia, where IeA12G3T3 is seen (7, 15, 49).

(iv) The presence of the If subtype family was observed. Cryptosporidium hominis family If was detected initially in children in South Africa (30). This family was not seen in most other studies but was occasionally seen in human immunodeficiency virus-positive adults in Portugal (1). It was identified in humans in India (34), but this was based on RFLP analysis of gp60 PCR products and its identity was not established (1, 34). The common occurrence of If subtypes (5/47 samples) in this study further supports the presence of unique transmission of C. hominis in Shanghai, China.

In summary, the results of this study indicate that there is probably extensive transmission of cryptosporidiosis between humans in Shanghai, that anthroponotic transmission may play an important role in cryptosporidiosis epidemiology, and that the C. hominis populations in China may be very different from those in other areas. Nevertheless, these hypotheses are based on molecular surveillance of Cryptosporidium species/genotypes and subtypes in urban wastewater and suffer from the intrinsic difficulty associated with interpreting cryptosporidiosis transmission data based on oocyst shedding at the community level, as some oocysts of Cryptosporidium species or subtypes may be shed in larger numbers than others, resulting in the overrepresentation of these species and subtypes in domestic wastewater. Therefore, further molecular epidemiologic studies of humans in diverse areas are needed to confirm these hypotheses and to characterize Cryptosporidium populations, transmission dynamics, and infection sources in China.

 
This study was supported in part by funds from the U.S. Centers for Disease Control and Prevention and the National Natural Science Foundation of China (grant no. 30771881).

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

 
* Corresponding author. Mailing address: Division of Parasitic Diseases, National Center for Zoonotic, Vector-Borne and Enteric Diseases, Centers for Disease Control and Prevention, Building 22, Mail Stop F-12, 4770 Buford Highway, Atlanta, GA 30341-3717. Phone: (770) 488-4840. Fax: (770) 488-4454. E-mail: lxiao{at}cdc.gov

Published ahead of print on 12 November 2008.

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1
1. Alves, M., L. Xiao, F. Antunes, and O. Matos. 2006. Distribution of Cryptosporidium subtypes in humans and domestic and wild ruminants in Portugal. Parasitol. Res. 99:287-292.[CrossRef][Medline]
2
2. Alves, M., L. Xiao, I. Sulaiman, A. A. Lal, O. Matos, and F. Antunes. 2003. Subgenotype analysis of Cryptosporidium isolates from humans, cattle, and zoo ruminants in Portugal. J. Clin. Microbiol. 41:2744-2747.[Abstract/Free Full Text]
3
3. Bushen, O. Y., A. Kohli, R. C. Pinkerton, K. Dupnik, R. D. Newman, C. L. Sears, R. Fayer, A. A. Lima, and R. L. Guerrant. 2007. Heavy cryptosporidial infections in children in northeast Brazil: comparison of Cryptosporidium hominis and Cryptosporidium parvum. Trans. R. Soc. Trop. Med. Hyg. 101:378-384.[CrossRef][Medline]
4
4. Cama, V. A., C. Bern, I. M. Sulaiman, R. H. Gilman, E. Ticona, A. Vivar, V. Kawai, D. Vargas, L. Zhou, and L. Xiao. 2003. Cryptosporidium species and genotypes in HIV-positive patients in Lima, Peru. J. Eukaryot. Microbiol. 50(Suppl.):531-533.[CrossRef][Medline]
5
5. Castro-Hermida, J. A., I. Garcia-Presedo, A. Almeida, M. Gonzalez-Warleta, J. M. Correia Da Costa, and M. Mezo. 2008. Contribution of treated wastewater to the contamination of recreational river areas with Cryptosporidium spp. and Giardia duodenalis. Water Res. 42:3528-3538.[Medline]
6
6. Chalmers, R. M., K. Elwin, A. L. Thomas, and D. H. Joynson. 2002. Infection with unusual types of Cryptosporidium is not restricted to immunocompromised patients. J. Infect. Dis. 185:270-271.[CrossRef][Medline]
7
7. Chalmers, R. M., C. Ferguson, S. Caccio, R. B. Gasser, Y. G. Abs El-Osta, L. Heijnen, L. Xiao, K. Elwin, S. Hadfield, M. Sinclair, and M. Stevens. 2005. Direct comparison of selected methods for genetic categorisation of Cryptosporidium parvum and Cryptosporidium hominis species. Int. J. Parasitol. 35:397-410.[CrossRef][Medline]
8
8. Chen, H., X. R. Mao, and X. M. Ling. 2001. Survey of Cryptosporidium infection in three areas in Gansu Province. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 19:112. (In Chinese.)[Medline]
9
9. Chen, Y. G., F. B. Yao, H. S. Li, W. S. Shi, M. X. Dai, and M. Lu. 1992. Cryptosporidium infection and diarrhea in rural and urban areas of Jiangsu, People's Republic of China. J. Clin. Microbiol. 30:492-494.[Abstract/Free Full Text]
10
10. Chen, Y. G., F. B. Yao, H. S. Li, W. S. Shi, M. X. Dai, and M. Lu. 1993. Epidemiological studies on human cryptosporidiosis in rural and urban areas of Jiangsu. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 11:207-210. (In Chinese.)[Medline]
11
11. Cohen, S., F. Dalle, A. Gallay, M. Di Palma, A. Bonnin, and H. D. Ward. 2006. Identification of Cpgp40/15 type Ib as the predominant allele in isolates of Cryptosporidium spp. from a waterborne outbreak of gastroenteritis in South Burgundy, France. J. Clin. Microbiol. 44:589-591.[Abstract/Free Full Text]
12
12. Das, P., S. S. Roy, K. MitraDhar, P. Dutta, M. K. Bhattacharya, A. Sen, S. Ganguly, S. K. Bhattacharya, A. A. Lal, and L. Xiao. 2006. Molecular characterization of Cryptosporidium spp. from children in Kolkata, India. J. Clin. Microbiol. 44:4246-4249.[Abstract/Free Full Text]
13
13. Feng, Y. Y., J. P. Cao, and L. X. Zhang. 2008. Water quality, reclamation and safety-advances in the detection and contamination source tracking of waterborne Cryptosporidium. Int. J. Med. Parasitic Dis. 35:169-174.
14
14. Fretz, R., P. Svoboda, U. M. Ryan, R. C. Thompson, M. Tanners, and A. Baumgartner. 2003. Genotyping of Cryptosporidium spp. isolated from human stool samples in Switzerland. Epidemiol. Infect. 131:663-667.[Medline]
15
15. Gatei, W., D. Barrett, J. F. Lindo, D. Eldemire-Shearer, V. Cama, and L. Xiao. 2008. Unique Cryptosporidium population in HIV-infected persons, Jamaica. Emerg. Infect. Dis. 14:841-843.[Medline]
16
16. Gatei, W., P. Das, P. Dutta, A. Sen, V. Cama, A. A. Lal, and L. Xiao. 2007. Multilocus sequence typing and genetic structure of Cryptosporidium hominis from children in Kolkata, India. Infect. Genet. Evol. 7:197-205.[CrossRef][Medline]
17
17. Gatei, W., J. Greensill, R. W. Ashford, L. E. Cuevas, C. M. Parry, N. A. Cunliffe, N. J. Beeching, and C. A. Hart. 2003. Molecular analysis of the 18S rRNA gene of Cryptosporidium parasites from patients with or without human immunodeficiency virus infections living in Kenya, Malawi, Brazil, the United Kingdom, and Vietnam. J. Clin. Microbiol. 41:1458-1462.[Abstract/Free Full Text]
18
18. Gatei, W., C. N. Wamae, C. Mbae, A. Waruru, E. Mulinge, T. Waithera, S. M. Gatika, S. K. Kamwati, G. Revathi, and C. A. Hart. 2006. Cryptosporidiosis: prevalence, genotype analysis, and symptoms associated with infections in children in Kenya. Am. J. Trop. Med. Hyg. 75:78-82.[Abstract/Free Full Text]
19
19. Glaberman, S., J. E. Moore, C. J. Lowery, R. M. Chalmers, I. Sulaiman, K. Elwin, P. J. Rooney, B. C. Millar, J. S. Dooley, A. A. Lal, and L. Xiao. 2002. Three drinking-water-associated cryptosporidiosis outbreaks, Northern Ireland. Emerg. Infect. Dis. 8:631-633.[Medline]
20
20. Guyot, K., A. Follet-Dumoulin, E. Lelievre, C. Sarfati, M. Rabodonirina, G. Nevez, J. C. Cailliez, D. Camus, and E. Dei-Cas. 2001. Molecular characterization of Cryptosporidium isolates obtained from humans in France. J. Clin. Microbiol. 39:3472-3480.[Abstract/Free Full Text]
21
21. Hajdusek, O., O. Ditrich, and J. Slapeta. 2004. Molecular identification of Cryptosporidium spp. in animal and human hosts from the Czech Republic. Vet. Parasitol. 122:183-192.[CrossRef][Medline]
22
22. Hanninen, M. L., A. Horman, R. Rimhanen-Finne, H. Vahtera, S. Malmberg, S. Herve, and K. Lahti. 2005. Monitoring of Cryptosporidium and Giardia in the Vantaa river basin, southern Finland. Int. J. Hyg. Environ. Health 208:163-171.[CrossRef][Medline]
23
23. Hashimoto, A., H. Sugimoto, S. Morita, and T. Hirata. 2006. Genotyping of single Cryptosporidium oocysts in sewage by semi-nested PCR and direct sequencing. Water Res. 40:2527-2532.[Medline]
24
24. Hirata, T., and A. Hashimoto. 2006. Genotyping of single Cryptosporidium oocysts isolated from sewage and river water. Water Sci. Technol. 54:197-202.[Medline]
25
25. Homan, W., T. van Gorkom, Y. Y. Kan, and J. Hepener. 1999. Characterization of Cryptosporidium parvum in human and animal feces by single-tube nested polymerase chain reaction and restriction analysis. Parasitol. Res. 85:707-712.[CrossRef][Medline]
26
26. Jiang, J., K. A. Alderisio, A. Singh, and L. Xiao. 2005. Development of procedures for direct extraction of Cryptosporidium DNA from water concentrates and for relief of PCR inhibitors. Appl. Environ. Microbiol. 71:1135-1141.[Abstract/Free Full Text]
27
27. Jiang, J., K. A. Alderisio, and L. Xiao. 2005. Distribution of Cryptosporidium genotypes in storm event water samples from three watersheds in New York. Appl. Environ. Microbiol. 71:4446-4454.[Abstract/Free Full Text]
28
28. Learmonth, J., G. Ionas, A. Pita, and R. Cowie. 2001. Seasonal shift in Cryptosporidium parvum transmission cycles in New Zealand. J. Eukaryot. Microbiol. 2001(Suppl.):34S-35S.[CrossRef]
29
29. Learmonth, J. J., G. Ionas, K. A. Ebbett, and E. S. Kwan. 2004. Genetic characterization and transmission cycles of Cryptosporidium species isolated from humans in New Zealand. Appl. Environ. Microbiol. 70:3973-3978.[Abstract/Free Full Text]
30
30. Leav, B. A., M. R. Mackay, A. Anyanwu, R. M. O'Connor, A. M. Cevallos, G. Kindra, N. C. Rollins, M. L. Bennish, R. G. Nelson, and H. D. Ward. 2002. Analysis of sequence diversity at the highly polymorphic Cpgp40/15 locus among Cryptosporidium isolates from human immunodeficiency virus- infected children in South Africa. Infect. Immun. 70:3881-3890.[Abstract/Free Full Text]
31
31. Leoni, F., C. Amar, G. Nichols, S. Pedraza-Diaz, and J. McLauchlin. 2006. Genetic analysis of Cryptosporidium from 2414 humans with diarrhoea in England between 1985 and 2000. J. Med. Microbiol. 55:703-707.[Abstract/Free Full Text]
32
32. Lu, J., and C. P. Li. 2004. The survey of Cryptosporidium infection among young children in kindergartens in Anhui Province. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 22:331-333. (In Chinese.)[Medline]
33
33. McLauchlin, J., C. Amar, S. Pedraza-Diaz, and G. L. Nichols. 2000. Molecular epidemiological analysis of Cryptosporidium spp. in the United Kingdom: results of genotyping Cryptosporidium spp. in 1,705 fecal samples from humans and 105 fecal samples from livestock animals. J. Clin. Microbiol. 38:3984-3990.[Abstract/Free Full Text]
34
34. Muthusamy, D., S. S. Rao, S. Ramani, B. Monica, I. Banerjee, O. C. Abraham, D. C. Mathai, B. Primrose, J. Muliyil, C. A. Wanke, H. D. Ward, and G. Kang. 2006. Multilocus genotyping of Cryptosporidium sp. isolates from human immunodeficiency virus-infected individuals in South India. J. Clin. Microbiol. 44:632-634.[Abstract/Free Full Text]
35
35. Ong, C. S., S. Chow, P. P. L. So, R. Chen, L. Xiao, I. Sulaiman, L. Zhou, A. Ellis, J. Aramini, G. Horsman, and J. L. Isaac-Renton. 2005. Identification of two different Cryptosporidium hominis subtypes from cases in the 2001 waterborne cryptosporidiosis outbreak in North Battleford, Saskatchewan, p. 628-638. In Proceedings of the 11th Canadian National Conference and 2nd Policy Forum on Drinking Water, Calgary, Canada, 3 to 6 April 2004. Canadian Water and Wastewater Association, Ottawa, Ontario, Canada.
36
36. Peng, M. M., O. Matos, W. Gatei, P. Das, M. Stantic-Pavlinic, C. Bern, I. M. Sulaiman, S. Glaberman, A. A. Lal, and L. Xiao. 2001. A comparison of Cryptosporidium subgenotypes from several geographic regions. J. Eukaryot. Microbiol. 2001(Suppl.):28S-31S.[CrossRef]
37
37. Peng, M. M., S. R. Meshnick, N. A. Cunliffe, B. D. Thindwa, C. A. Hart, R. L. Broadhead, and L. Xiao. 2003. Molecular epidemiology of cryptosporidiosis in children in Malawi. J. Eukaryot. Microbiol. 50(Suppl.):557-559.[CrossRef][Medline]
38
38. Peng, M. M., M. L. Wilson, R. E. Holland, S. R. Meshnick, A. A. Lal, and L. Xiao. 2003. Genetic diversity of Cryptosporidium spp. in cattle in Michigan: implications for understanding the transmission dynamics. Parasitol. Res. 90:175-180.[CrossRef][Medline]
39
39. Peng, M. M., L. Xiao, A. R. Freeman, M. J. Arrowood, A. A. Escalante, A. C. Weltman, C. S. Ong, W. R. Mac Kenzie, A. A. Lal, and C. B. Beard. 1997. Genetic polymorphism among Cryptosporidium parvum isolates: evidence of two distinct human transmission cycles. Emerg. Infect. Dis. 3:567-573.[Medline]
40
40. Sulaiman, I. M., P. R. Hira, L. Zhou, F. M. Al-Ali, F. A. Al-Shelahi, H. M. Shweiki, J. Iqbal, N. Khalid, and L. Xiao. 2005. Unique endemicity of cryptosporidiosis in children in Kuwait. J. Clin. Microbiol. 43:2805-2809.[Abstract/Free Full Text]
41
41. Tiangtip, R., and S. Jongwutiwes. 2002. Molecular analysis of Cryptosporidium species isolated from HIV-infected patients in Thailand. Trop. Med. Int. Health 7:357-364.[CrossRef][Medline]
42
42. Tumwine, J. K., A. Kekitiinwa, S. Bakeera-Kitaka, G. Ndeezi, R. Downing, X. Feng, D. E. Akiyoshi, and S. Tzipori. 2005. Cryptosporidiosis and microsporidiosis in Ugandan children with persistent diarrhea with and without concurrent infection with the human immunodeficiency virus. Am. J. Trop. Med. Hyg. 73:921-925.[Abstract/Free Full Text]
43
43. Tumwine, J. K., A. Kekitiinwa, N. Nabukeera, D. E. Akiyoshi, S. M. Rich, G. Widmer, X. Feng, and S. Tzipori. 2003. Cryptosporidium parvum in children with diarrhea in Mulago Hospital, Kampala, Uganda. Am. J. Trop. Med. Hyg. 68:710-715.[Abstract/Free Full Text]
44
44. Wang, K. X., C. P. Li, J. Wang, and B. R. Pan. 2002. Epidemiological survey of cryptosporidiosis in Anhui Province China. World J. Gastroenterol. 8:371-374.[Medline]
45
45. Ward, P. I., P. Deplazes, W. Regli, H. Rinder, and A. Mathis. 2002. Detection of eight Cryptosporidium genotypes in surface and waste waters in Europe. Parasitology 124:359-368.[Medline]
46
46. Xiao, L., K. Alderisio, and A. Singh. 2006. Development and standardization of a Cryptosporidium genotyping tool for water samples, p. 116. Awwa Research Foundation, Denver, CO.
47
47. Xiao, L., C. Bern, J. Limor, I. Sulaiman, J. Roberts, W. Checkley, L. Cabrera, R. H. Gilman, and A. A. Lal. 2001. Identification of 5 types of Cryptosporidium parasites in children in Lima, Peru. J. Infect. Dis. 183:492-497.[CrossRef][Medline]
48
48. Xiao, L., C. Bern, I. M. Suiaiman, and A. A. Lal. 2004. Molecular epidemiology of human cryptosporidiosis, p. 121-146. In R. C. A. Thompson, A. Armson, and U. M. Ryan (ed.), Cryptosporidium: from molecules to disease. Elsevier, Amsterdam, The Netherlands.
49
49. Xiao, L., R. Fayer, U. Ryan, and S. J. Upton. 2004. Cryptosporidium taxonomy: recent advances and implications for public health. Clin. Microbiol. Rev. 17:72-97.[Abstract/Free Full Text]
50
50. Xiao, L., and U. M. Ryan. 2004. Cryptosporidiosis: an update in molecular epidemiology. Curr. Opin. Infect. Dis. 17:483-490.[CrossRef][Medline]
51
51. Xiao, L., and U. M. Ryan. 2008. Molecular epidemiology, p. 119-172. In R. Fayer and L. Xiao (ed.), Cryptosporidium and cryptosporidiosis, 2nd ed. CRC Press, New York, NY.
52
52. Xiao, L., A. Singh, J. Limor, T. K. Graczyk, S. Gradus, and A. Lal. 2001. Molecular characterization of Cryptosporidium oocysts in samples of raw surface water and wastewater. Appl. Environ. Microbiol. 67:1097-1101.[Abstract/Free Full Text]
53
53. Zhang, B. X., H. Yu, L. L. Zhang, H. Tao, Y. Z. Li, Y. Li, Z. K. Cao, Z. M. Bai, and Y. Q. He. 2002. Prevalence survey on Cyclospora cayetanensis and Cryptosporidium spp. in diarrhea cases in Yunnan Province. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 20:106-108. (In Chinese.)[Medline]
54
54. Zhou, L., A. Singh, J. Jiang, and L. Xiao. 2003. Molecular surveillance of Cryptosporidium spp. in raw wastewater in Milwaukee: implications for understanding outbreak occurrence and transmission dynamics. J. Clin. Microbiol. 41:5254-5257.[Abstract/Free Full Text]
55
55. Zhu, F. 1991. Cryptosporidiosis in children in Wuhu. Zhonghua Liu Xing Bing Xue Za Zhi 12:286-288. (In Chinese.)[Medline]

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Journal of Clinical Microbiology, January 2009, p. 153-157, Vol. 47, No. 1
0095-1137/09/$08.00+0     doi:10.1128/JCM.01777-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

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