Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 13, Number 1—January 2007

Correlation between Subtypes of Cryptosporidium parvum in Humans and Risk

Paul R. Hunter*, Stephen J. Hadfield†, Dawn Wilkinson*, Iain R. Lake*, Florence C.D. Harrison*, and Rachel M. Chalmers†Comments to Author 
Author affiliations: *University of East Anglia, Norwich, United Kingdom; †National Public Health Service for Wales, Swansea, United Kingdom;

Main Article

Table 2

Logistic regression model from case-control study (19) showing final model from original study and recalculated using only those strains with the ML1–242 polymorphism as cases*

Cases/variableCases, n (%)Controls, n (%)Odds ratio95% CIp value
All Cryptosporidium parvum strains
Touch or handle any farm animals
Yes24 (34)43 (11)2.6531.113–6.3230.028
Eat tomatoes
Yes24 (36)249 (50)0.3170.140–0.7190.005
Eat raw vegetables
Yes7 (12)157 (44)0.2220.086–0.5720.001
Only ML1–242 strains
Touch or handle any farm animals
Yes21 (43)43 (11)
Eat tomatoes
Yes17 (37)249 (50)0.4250.164–1.1040.079
Eat raw vegetables
Yes4 (10)157 (44)0.1410.042–0.4740.001

*CI, confidence interval. Also included in the models were age and Health Authority of residence.

Main Article

  1. McLauchlin J, Amar C, Pedraza-Díaz S, Nichols GL. Molecular epidemiological analysis of Cryptosporidium spp. in the United Kingdom: results of genotyping Cryptosporidium spp. in 1705 fecal samples from humans and 105 fecal samples from livestock animals.J Clin Microbiol. 2000;38:398490.PubMedGoogle Scholar
  2. The development of a national collection for oocysts of Cryptosporidium. Foundation for Water Research, Marlow, Bucks, UK, 2002 [cited 2006 Oct 11]. Available from
  3. Chen X-M, Keithly JS, Paya CV, LaRusso NF. Cryptosporidiosis.N Engl J Med. 2002;346:172331. DOIPubMedGoogle Scholar
  4. Health Protection Agency. 2006 [cited 2006 Oct 11]. Available from
  5. Hunter PR, Nichols G. The epidemiology and clinical features of cryptosporidium infection in immune-compromised patients.Clin Microbiol Rev. 2002;15:14554. DOIPubMedGoogle Scholar
  6. Hunter PR, Hughes S, Woodhouse S, Raj N, Syed Q, Chalmers RM, Health sequelae of human cryptosporidiosis in immunocompetent patients.Clin Infect Dis. 2004;39:50410. DOIPubMedGoogle Scholar
  7. Xiao L, Rayer R, Ryan U, Upton SJ. Cryptosporidium taxonomy: recent advances and implications for public health.Clin Microbiol Rev. 2004;17:7297. DOIPubMedGoogle Scholar
  8. Aeillo AE, Xiao L, Limor JR, Liu C, Abrahamson MS, Lal AA. Microsatellite analysis of the human and bovine genotypes of Cryptosporidium parvum.J Eukaryot Microbiol. 1999;46:46S7.PubMedGoogle Scholar
  9. Cacciò S, Homan W, Camilli R, Traldi G, Kortbeek T, Pozio E. A microsatellite marker reveals population heterogeneity within human and animal genotypes of Cryptosporidium parvum.Parasitology. 2000;120:23744. DOIPubMedGoogle Scholar
  10. Cacciò S, Spano F, Pozio E. Large sequence variation at two microsatellite loci among zoonotic (genotype C) isolates of Cryptosporidium parvum.Int J Parasitol. 2001;31:10826. DOIPubMedGoogle Scholar
  11. Enemark HL, Ahrens P, Juel CD, Petersen E, Petersen RF, Andersen JS, Molecular characterization of Danish Cryptosporidium parvum isolates.Parasitology. 2002;125:33141. DOIPubMedGoogle Scholar
  12. Mallon M, MacLeod A, Wastling J, Smith H, Reilly B, Tait A. Population structures and the role of genetic exchange in the zoonotic pathogen Cryptosporidium parvum.J Mol Evol. 2003;56:40717. DOIPubMedGoogle Scholar
  13. Mallon ME, MacLeod A, Wastling JM, Smith H, Tait A. Multilocus genotyping of Cryptosporidium parvum Type 2: population genetics and sub-structuring.Infect Genet Evol. 2003;3:20718. DOIPubMedGoogle Scholar
  14. Gasser RB. Abs EL-Osta Y, Prepens S, Chalmers RM. An improved “cold SSCP” for the genotypic and subgenotypic characterisation of Cryptosporidium.Mol Cell Probes. 2004;18:32932. DOIPubMedGoogle Scholar
  15. Strong WB, Gut J, Nelson RG. Cloning and sequence analysis of a highly polymorphic Cryptosporidium parvum gene encoding a 60-kilodalton glycoprotein and characterization of its 15- and 45-kilodalton zoite surface antigen products.Infect Immun. 2000;68:411734. DOIPubMedGoogle Scholar
  16. Alves M, Xiao L, Sulaiman I, Lal AA, Matos O, Antunes F. Subgenotype analysis of Cryptosporidium isolates from humans, cattle, and zoo ruminants in Portugal.J Clin Microbiol. 2003;41:27447. DOIPubMedGoogle Scholar
  17. Blasdall SA, Ongerth JE, Ashbolt NJ. Differentiation of Cryptosporidium parvum subtypes in calves of four dairy herds by a novel microsatellite-telomere PCR with PAGE. Proceedings of Cryptosporidium from Molecules to Disease, 7–12 October 2001, Fremantle, Australia. Melbourne: Water Services Association of Australia; 2001.
  18. Blasdall SA, Ongerth JE, Ashbolt NJ. Sub-species differentiation among Type 2 bovine C. parvum isolates using a RAPD microsatellite + telomere primer scheme. Proceedings of IWA World Water Congress, Berlin. 2001.London: International Water Association; 2001.
  19. Hunter PR, Hughes LS, Woodhouse S, Syed Q, Verlander N, Chalmers RM. Case-control study of sporadic cryptosporidiosis with genotyping.Emerg Infect Dis. 2004;10:12419.PubMedGoogle Scholar
  20. Casemore DP, Armstrong M, Sands RL. Laboratory diagnosis of cryptosporidiosis.J Clin Pathol. 1985;38:133741. DOIPubMedGoogle Scholar
  21. Elwin K, Chalmers RM, Roberts R, Guy EC, Casemore DP. The modification of a rapid method for the identification of gene-specific polymorphisms in Cryptosporidium parvum, and application to clinical and epidemiological investigations.Appl Environ Microbiol. 2001;67:55814. DOIPubMedGoogle Scholar
  22. Spano F, Putignani L, McLauchlin J, Casemore DP, Crisanti A. PCR-RFLP analysis of the Cryptosporidium oocyst wall protein (COWP) gene discriminates between C. wrairi and C. parvum, and between C. parvum isolates of human and animal origin.FEMS Microbiol Lett. 1997;150:20917.PubMedGoogle Scholar
  23. Xiao L, Singh A, Limor J, Graczyk TK, Gradus S, Lal A. Molecular characterization of Cryptosporidium oocysts in samples of raw surface water and wastewater.Appl Environ Microbiol. 2001;67:1097101. DOIPubMedGoogle Scholar
  24. Morgan UM, Constantine CC, Forbes DA, Thompson RCA. Differentiation between human and animal isolates of Cryptosporidium parvum using rDNA sequencing and direct PCR analysis.J Parasitol. 1997;83:82530. DOIPubMedGoogle Scholar
  25. Investigation of. Cryptosporidium clinical isolates and analysis with epidemiological data. Foundation for Water Research, Marlow, Bucks, UK, 2005 [cited 2006 Oct 11]. Available from
  26. Establishing the relationship between farm restocking and cryptosporidia: the Caldew catchment study. Foundation for Water Research, Marlow, Bucks, UK, 2005 [cited 2006 Oct 11]. Available from
  27. Hunter PR, Gaston MA. A numerical index of the discriminatory ability of typing systems: an application of Simpson’s index of diversity.J Clin Microbiol. 1988;26:24656.PubMedGoogle Scholar
  28. Hunter PR, Fraser CAM. Application of the theory of adaptive polymorphism to the ecology and epidemiology of pathogenic yeasts.Appl Environ Microbiol. 1990;56:221922.PubMedGoogle Scholar
  29. Tanriverdi S, Widmer G. Differential evolution of repetitive sequences in Cryptosporidium parvum and Cryptosporidium hominis.Infect Genet Evol. 2006;6:11322. DOIPubMedGoogle Scholar
  30. Robinson G. Investigating the public health significance of Cryptosporidium in the enivironment [PhD dissertation]. Cardiff (UK): University of Wales College of Medicine; 2005.

Main Article

Page created: July 08, 2010
Page updated: July 08, 2010
Page reviewed: July 08, 2010
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.