Viability and infectivity of Cryptosporidium parvum oocysts detected in river water in Hokkaido, Japan

Yoshinori Tsushima, Panagiotis Karanis, Takenori Kamada, Xuenan Xuan, Levi H.C. Makala, Yukinobu Tohya, Hiroomi Akashi, Hideyuki Nagasawa

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The viability and infectivity of Cryptosporidium parvum (C. parvum) oocysts, detected in water samples collected from river water in Hokkaido, were investigated using Severe Combined Immunodeficient (SCID) mice. The water samples collected from September 27 through October 10, 2001 by filtration using Cuno cartridge filters were purified and concentrated by the discontinuous centrifugal flotation method. From 1.2 × 105 liters of the raw river water, approximately 2 × 104 oocysts were obtained and designated as Hokkaido river water 1 isolate (HRW-1). Oocyst identification was carried out using microscopic and immunological methods. Six 8-week-old female SCID mice were each inoculated orally with 1 × 103 oocysts. Infection was successfully induced, resulting in fecal oocyst shedding. Oocysts were then maintained by sub-inoculation into SCID mice every 3 months. Infectivity was evaluated by making comparisons with two known C. parvum stocks, HNJ-1 and TK-1, which were bovine genotypes detected in fecal samples from a cryptosporidiosis patient and young cattle raised in Tokachi, Hokkaido respectively. The oocyst genotypes were determined from a small subunit ribosomal RNA (SSU-rRNA) gene by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) analysis. No significant differences were observed in the average number of oocysts per gram of feces (OPG) in any of the isolates. Our data indicates that the C. parvum oocysts detected in the sampled river water were of C. parvum genotype 2. Moreover, our data on the continued isolation, detection and identification of the C. parvum isolates is consistent with the available epidemiological data for the Tokachi area.

Original languageEnglish (US)
Pages (from-to)585-589
Number of pages5
JournalJournal of Veterinary Medical Science
Issue number5
StatePublished - May 2003
Externally publishedYes


  • Cryptosporidium parvum oocyst
  • Infectivity
  • SCID mouse
  • Viability
  • Water

ASJC Scopus subject areas

  • General Veterinary


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