Volume 92, Issue 1
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Although and cause the majority of human cryptosporidiosis cases, other species are also capable of infecting humans, particularly when individuals are immunocompromised. Ten cases have been reported, primarily in human immunodeficiency virus (HIV) -positive patients with diarrhea. However, asymptomatic cases were reported in two HIV-negative children, and in another case, age and immune status were not described. This study examines the infectivity of in six healthy adults. Volunteers were challenged with 10 oocysts and monitored for 6 weeks for infection and/or illness. All six patients became infected. Two patients experienced a self-limited diarrheal illness. Total oocysts shed during the study ranged from 6.7 × 10 to 4.1 × 10, and the number was slightly higher in volunteers with diarrhea (2.8 × 10) than asymptomatic shedders (4.4 × 10). -infected subjects shed oocysts longer than occurred with other species studied in healthy volunteers. Three volunteers shed oocysts for 7 months. Physical examinations were normal, with no reported recurrence of diarrhea or other gastrointestinal complaints. Two persistent shedders were treated with nitazoxanide, and the infection was resolved. Thus, healthy adults are susceptible to , which can cause mild diarrhea and result in persistent, asymptomatic infection.


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  1. Tyzzer EE, , 1907. A sporozoan found in the peptic glands of the common mouse. Proc Soc Exp Biol Med 5: 1213.[Crossref] [Google Scholar]
  2. Meisel JL, Perera DR, Meligro C, Rubin CE, , 1976. Overwhelming watery diarrhea associated with a Cryptosporidium in an immunosuppressed patient. Gastroenterology 70: 11561160. [Google Scholar]
  3. Nime FA, Burek JD, Page DL, Holscher MA, Yardley JH, , 1976. Acute enterocolitis in a human being infected with the protozoan Cryptosporidium . Gastroenterology 70: 592598. [Google Scholar]
  4. Guyot K, Follet-Dumoulin A, Lelievre E, Sarfati C, Rabodonirina M, Nevez G, Cailliez JC, Camus D, Dei-Cas E, , 2001. Molecular characterization of Cryptosporidium isolates obtained from humans in France. J Clin Microbiol 39: 34723480.[Crossref] [Google Scholar]
  5. Tiangtip R, Jongwutiwes S, , 2002. Molecular analysis of Cryptosporidium species isolated from HIV-infected patients in Thailand. Trop Med Int Health 7: 357364.[Crossref] [Google Scholar]
  6. Gatei W, Ashford RW, Beeching NJ, Kamwati SK, Greensill J, Hart CA, , 2002. Cryptosporidium muris infection in an HIV-infected adult, Kenya. Emerg Infect Dis 8: 204206.[Crossref] [Google Scholar]
  7. Palmer CJ, Xiao L, Terashima A, Guerra H, Gotuzzo E, Saldias G, Bonilla JA, Zhou L, Lindquist A, Upton SJ, , 2003. Cryptosporidium muris, a rodent pathogen, recovered from a human in Peru. Emerg Infect Dis 9: 11741176.[Crossref] [Google Scholar]
  8. Muthusamy D, Rao SS, Ramani S, Monica B, Banerjee I, Abraham OC, Mathai DC, Primrose B, Muliyil J, Wanke CA, Ward HD, Kang G, , 2006. Multilocus genotyping of Cryptosporidium sp. isolates from human immunodeficiency virus-infected individuals in South India. J Clin Microbiol 44: 632634.[Crossref] [Google Scholar]
  9. Azami M, Moghaddam DD, Salehi R, Salehi M, , 2007. The identification of Cryptosporidium species (protozoa) in Ifsahan, Iran by PCR-RFLP analysis of the 18S rRNA gene. Mol Biol (Mosk) 41: 934939.[Crossref] [Google Scholar]
  10. Neira-O P, Muñoz-S N, Wilson-L G, Barthel-M ME, Rosales-L MJ, Henríquez-R C, , 2012. Especies de Cryptosporidum en pacientes inmunodeficientes e inmunocompetentes de Valparaíso. Estudio descriptivo. Rev Chilena Infectol 29: 6371.[Crossref] [Google Scholar]
  11. Ozkul IA, Aydin Y, , 1994. Natural Cryptosporidium muris infection of the stomach in laboratory mice. Vet Parasitol 55: 129132.[Crossref] [Google Scholar]
  12. Taylor MA, Marshall RN, Green JA, Catchpole J, , 1999. The pathogenesis of experimental infections of Cryptosporidium muris (strain RN 66) in outbred nude mice. Vet Parasitol 86: 4148.[Crossref] [Google Scholar]
  13. Dubey JP, Speer CA, Fayer R, , eds, 1990. Cryptosporidiosis of Man and Animals. Boca Raton, FL: CRC Press, 199. [Google Scholar]
  14. Dubey JP, Markovits JE, Killary KA, , 2002. Cryptosporidium muris-like infection in stomach of cynomolgus monkeys (Macaca fascicularis). Vet Pathol 39: 363371.[Crossref] [Google Scholar]
  15. Iseki M, Maekawa T, Moriya K, Uni S, Takada S, , 1989. Infectivity of Cryptosporidium muris (strain RN66) in various laboratory animals. Parasitol Res 75: 218222.[Crossref] [Google Scholar]
  16. Katsumata T, Hosea D, Ranuh IG, Uga S, Yanagi T, Kohno S, , 2000. Short report: possible Cryptosporidium muris infection in humans. Am J Trop Med Hyg 62: 7072. [Google Scholar]
  17. Al-Brikan F, Salem H, Beeching N, Hilal N, , 2008. Multilocus genetic analysis of Cryptosporidium isolates from Saudi Arabia. J Egypt Soc Parasitol 38: 645658. [Google Scholar]
  18. Widmer G, Tchack L, Chappell CL, Tzipori S, , 1998. Sequence polymorphism in the β-tubulin gene reveals heterogeneous and variable population structures in Cryptosporidium parvum . Appl Environ Microbiol 64: 44774481. [Google Scholar]
  19. Akiyoshi DE, Feng X, Buckholt MA, Widmer G, Tzipori S, , 2002. Genetic analysis of a Cryptosporidium parvum human genotype 1 isolate passaged through different host species. Infect Immun 70: 56705675.[Crossref] [Google Scholar]
  20. Widmer G, Feng X, Tanriverdi S, , 2004. Genotyping of Cryptosporidium parvum with microsatellite markers. Methods Mol Biol 268: 177187. [Google Scholar]
  21. DuPont HL, Chappell CL, Sterling CR, Okhuysen PC, Rose JB, Jakubowski W, , 1995. The infectivity of Cryptosporidium parvum in healthy volunteers. N Engl J Med 332: 855859.[Crossref] [Google Scholar]
  22. Chappell CL, Okhuysen PC, White AC, Jr Thompson R, Armson A, Ryan U, , 2004. Cryptosporidium parvum: infectivity, pathogenesis and the host-parasite relationship. , eds. Cryptosporidium: From Molecules to Disease. Amsterdam, The Netherlands: Elsevier Science, 1950. [Google Scholar]
  23. Chappell CL, Okhuysen PC, Langer-Curry RC, Widmer G, Akiyoshi DE, Tanriverdi S, Tzipori S, , 2006. Cryptosporidium hominis: experimental challenge of healthy adults. Am J Trop Med Hyg 75: 851857. [Google Scholar]
  24. Chappell CL, Okhuysen PC, Langer-Curry RC, Akiyoshi DE, Widmer G, Tzipori S, , 2011. Cryptosporidium meleagridis: infectivity in healthy adult volunteers. Am J Trop Med Hyg 85: 238242.[Crossref] [Google Scholar]
  25. Lupo PJ, Langer-Curry RC, Robinson M, Okhuysen PC, Chappell CL, , 2008. Cryptosporidium muris in a Texas canine population. Am J Trop Med Hyg 78: 917921. [Google Scholar]
  26. Xiao L, Morgan UM, Limor J, Escalante A, Arrowood M, Shulaw W, Thompson RC, Fayer R, Lal AA, , 1999. Genetic diversity within Cryptosporidium parvum and related Cryptosporidium species. Appl Environ Microbiol 65: 33863391. [Google Scholar]
  27. Xiao L, Escalante L, Yang C, Sulaiman I, Escalante AA, Montali RJ, Fayer R, Lal AA, , 1999. Phylogenetic analysis of Cryptosporidium parasites based on the small-subunit rRNA gene locus. Appl Environ Microbiol 65: 15781583. [Google Scholar]
  28. Ungar BLP, Mulligan M, Nutman TB, , 1989. Serological evidence of Cryptosporidium infection in US volunteers before and during Peace Corp service in Africa. Arch Intern Med 149: 894897.[Crossref] [Google Scholar]
  29. Okhuysen PC, Chappell CL, Crabb JH, Sterling CR, DuPont HL, , 1999. Virulence of three distinct Cryptosporidium parvum isolates for healthy adults. J Infect Dis 180: 12751281.[Crossref] [Google Scholar]
  30. Okhuysen PC, Rich SM, Chappell CL, Grimes KA, Widmer G, Feng X, Tzipori S, , 2002. Infectivity of a Cryptosporidium parvum isolate of cervine origin for healthy adults and interferon-γ knockout mice. J Infect Dis 185: 13201325.[Crossref] [Google Scholar]
  31. Chappell CL, Okhuysen PC, Sterling CR, Wang C, Jakubowski W, DuPont H, , 1999. Infectivity of Cryptosporidium parvum in healthy adults with pre-existing anti-C. parvum serum immunoglobulin G. Am J Trop Med Hyg 60: 157164. [Google Scholar]
  32. Amadi BC, Mwiya M, Musuku J, Watuka A, Sianongo S, Ayoub A, Kelly P, , 2002. Effect of nitazoxanide on morbidity and mortality in Zambian children with cryptosporidiosis: a randomised controlled trial. Lancet 360: 13751380.[Crossref] [Google Scholar]
  33. White AC, , 2003. Nitazoxanide: an important advance in anti-parasitic therapy. Am J Trop Med Hyg 68: 382383. [Google Scholar]
  34. Mogi T, Kita K, , 2010. Diversity in mitochondrial metabolic pathways in parasitic protists Plasmodium and Cryptosporidium . Parasitol Int 59: 305312.[Crossref] [Google Scholar]
  35. Giles M, Webster KA, Marshall JA, Catchpole J, Goddard TM, , 2001. Experimental infection of a lamb with Cryptosporidium parvum genotype 1. Vet Rec 149: 523525.[Crossref] [Google Scholar]
  36. Okhuysen PC, Chappell CL, Sterling CR, Jakubowski W, DuPont HL, , 1998. Susceptibility of healthy adults to reinfection with Cryptosporidium parvum . Infect Immun 66: 4143. [Google Scholar]

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  • Received : 21 Aug 2014
  • Accepted : 04 Sep 2014
  • Published online : 07 Jan 2015

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