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

  • A. S. BREATHNACH (a1), T. D. McHUGH (a2) and P. D. BUTCHER (a1)

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.

Corresponding author
*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:
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Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
  • URL: /core/journals/epidemiology-and-infection
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