Sporadic Diarrhea Caused By Rabbit Parasite

Molecular typing of stool samples has revealed that a protozoan parasite of rabbits, Cryptosporidium cuniculus may be a cause of seasonal diarrhea in humans.

The application of a modified polymerase chain reaction (PCR) assay on archived DNA samples has shown that a major cause of gastrointestinal disease, the protozoan parasite Cryptosporidium, may have the genotype of the species infecting rabbits.

Investigators at the UK Cryptosporidium Reference Unit (Swansea, UK) tested 3,030 Cryptosporidium-positive fecal samples submitted for routine typing from January 2007 to December 2008. Routine typing of archived DNA samples was based on PCR RsaI restriction fragment-length polymorphisms (RFLPs). These were retested by single-round small subunit (SSU) ribosomal ribonucleic acid (rRNA) PCR-RFLP using SspI, which generates a pattern unique to C. cuniculus. This assay was found to be unsustainable for typing large numbers of samples on a routine basis. C. cuniculus was confirmed by sequencing ≈830 base pairs (bp) of the SSU rRNA gene and ≈850 bp of the 60-kDa glycoprotein (GP60) gene by using nested PCR protocols.

In total, 37 of 3,030 infections were caused by C. cuniculus: 23 in 2007 and 14 in 2008. More C. cuniculus cases were detected in the late summer and autumn than in the winter and spring, similar to infections with C. hominis but not C. parvum. Occupational and environmental exposure data were available for 14 C. cuniculus case-patients, but no occupational risks were linked to rabbits. Two GP60 subtype families, Va and Vb, were detected in sporadic C. cuniculus isolates, linked to patient sex; 10/14 (71.4%) female patients had Va subtype, compared with 7/22 (31.8%) male patients. The study was published in March 2011, in the journal Emerging Infectious Diseases.

Related Links:
UK Cryptosporidium Reference Unit