Epidemiology and Infection

Original Papers

Other gastrointestinal infections

Prevalence and clinical correlations of genetic subtypes of Giardia lamblia in an urban setting

A. S. BREATHNACHa1 c1, T. D. McHUGHa2 and P. D. BUTCHERa1

a1 Centre for Infection, Division of Cellular and Molecular Medicine, St George's University of London, London, UK

a2 Department of Infection, Royal Free Campus, University College London, London, UK

SUMMARY

The clinical significance of different genetic subtypes or assemblages of Giardia lamblia is uncertain. Cases of giardiasis in south-west London between 1999 and 2005 were studied, comparing molecular-typing results with clinical and epidemiological findings from routine surveillance. We identified 819 cases, of whom 389 returned surveillance questionnaires. A subset of 267 faecal samples was submitted for typing by sequencing of the triose phosphate isomerase (tpi) and ribosomal RNA genes, and/or a separate duplex PCR of the tpi gene. Typing was successful in 199 (75%) samples by at least one of the molecular methods. Assemblage A accounted for 48 (24%) samples and Assemblage B for 145 (73%); six (3%) were mixed. Both assemblages had similar seasonality, age distribution and association with travel. Clinical features were available for 59 successfully typed cases: both assemblages caused similar illness, but Assemblage A was significantly more frequently associated with fever than Assemblage B.

(Accepted January 05 2010)

(Online publication February 10 2010)

Correspondence:

c1 Author for correspondence: Dr A. S. Breathnach, Centre for Infection, Division of Cellular and Molecular Medicine, St George's University of London, London SW17 0RE, UK. (Email: aodhan.breathnach@stgeorges.nhs.uk)

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