Research Article

Detection and species identification of Cryptosporidium oocysts using a system based on PCR and endonuclease restriction

F. M. Awad-El-Kariema1, D. C. Warhursta2 and V. McDonalda1

a1 Departments of Clinical Sciences, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1 7HT

a2 Medical Parasitology, London School of Hygiene and Tropical Medicine, Keppel Street, London WCI 7HT


The polymerase chain reaction (PCR) was used to produce a 556 bp nucleotide stretch, employing primers based on the published sequence of the 18S rRNA genes in Cryptosporidium parvum and C. muris. This sequence was found to contain 3 Mae I endonuclease restriction sites, 1 of which was present only in C. parvum. Mae I restriction of PCR products from 2 C. parvum isolates (one of human origin and the other of bovine origin), 1 C. muris isolate, and 1 C. baileyi isolate, showed a specific and reproducible profile for C. parvum that was different from the one obtained for both C. muris and C. baileyi. From these data, new Mae I restriction maps were proposed for the three species. The system was then used to screen 6 C. parvum isolates (from human and bovine hosts), and the C. parvum-specific profile was obtained for all isolates examined. It should be possible to adapt this protocol to detect small numbers of C. parvum oocysts in environmental samples (e.g. in water supplies).

(Received September 20 1993)

(Revised November 22 1993)

(Accepted November 22 1993)

Key words

  • Cryptosporidium parvum;
  • Cryptosporidium muris;
  • Cryptosporidium baileyi;
  • PCR;
  • endonuclease restriction