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

• Published in: Epidemiology and infection Vol. 138; no. 10; pp. 1459 - 1467
• Main Authors: BREATHNACH, A. S., McHUGH, T. D., BUTCHER, P. D.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.10.2010
• Subjects: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Animals; Biological and medical sciences; Child; Child, Preschool; Cluster Analysis; Cysts; Diseases; DNA; Feces - parasitology; Female; Fundamental and applied biological sciences. Psychology; Gastrointestinal infections; Genes, rRNA; genetics; Genotype; Giardia lamblia; Giardia lamblia - classification; Giardia lamblia - genetics; Giardia lamblia - isolation & purification; Giardiasis; Giardiasis - epidemiology; Giardiasis - parasitology; Giardiasis - pathology; Humans; Infant; Infant, Newborn; Infections; Laboratories; London - epidemiology; Male; Medical genetics; Microbiology; Microscopy; Middle Aged; molecular epidemiology; Molecular Sequence Data; Other gastrointestinal infections; Polymerase Chain Reaction; Prevalence; Product category rules; Protozoa; Protozoan Proteins - genetics; rRNA genes; Seasons; Sequence Analysis, DNA; Sequence Homology; Sequencing; Surveillance; Surveys and Questionnaires; Travel; Triose-Phosphate Isomerase - genetics; typing; Urban Population; Young Adult; London; United Kingdom > UK; United States > US; molecular epidemiology; typing; Giardia lamblia; genetics; Gastrointestinal infections; Genetics; Prevalence; Epidemiology; Subtype
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268810000208

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.