21st European Congress of Clinical Microbiology and Infectious Diseases

Cryptosporidium: the role of speciation in understanding epidemiological trends

Abstract number: R2611

Awadel-Kariem F.M., Raghwani J., Gough H., Manzoor R.N.

Background:Cryptosporidium sp taxonomy has gone through a number of changes in the last three decades. Initially a single species, C parvum – with a number of clonal genotypes loosely corresponding to specific vertebrate hosts, had been proposed. The current nomenclature suggests, for all cryptosporidial organisms with an oocyst size of 4–6 um, a number of cryptic species that are identified based on molecular genotyping. This is believed to facilitate better understanding of transmission and other epidemiological factors.

Objectives: This study was designed to assess the value, to the clinician and the epidemiologist, of the new cryptic species and whether this information would improve practice.

Methods: Isolates that were positive for Cryptosporidium oocysts by auramine staining were typed by PCR. The resulting molcular speciation was then analysed with clinical data (age, travel history, contact with animals, sporadic or part of an outbreak).

Results: In this study 27 isolates were typed, 13 C. parum, 12 C. hominis, 1 C. meleagridis and 1 C. felis. There were some trends. Two isolates from Egypt and 1 from Greece were identified as C. hominis, while isolates from Pakistan and St Lucia were identified as C. parvum. This may represent epidemiological differences between the various travel desinations. One patient has both C. parvum and Shigella sonnei isolated, this would be strongly suggestive of a contaminated water source of infection. A second patient had both C. felis and Campylobacter sp isolated. This patient had recently acquired a kitten. It is possible that both pathogens contributed to the diarrhoea, or that the Campylobacter was the cause of the diarrhoea while the presence C. felis oocysts (a primary pathogen of feline hosts) may represent oocysts passing through the patient's gut rather than tissue invasion.

Conclusions: Identification of cryptosporidial isolates either by genotype or as one of the cryptic species allows better understanding of potential source. Further studies are needed to confirm the trends seen in this study.