title: Molecular typing of Giardia duodenalis isolates from German travellers.
abstract: Giardia duodenalis isolates from German travellers returning from tropical areas were characterised by PCR amplification and sequencing of fragments of the beta-giardin (bg), glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) genes. Assignment of isolates to specific G. duodenalis assemblages was found to differ according to the marker used. Indeed, at the bg locus, assemblages A and B were identified, with a higher prevalence of the former over the latter, whereas at the tpi and gdh loci, most samples were classified as assemblage B. In agreement with previous studies, sequence analysis showed that assemblage B isolates have a higher genetic polymorphism than assemblage A isolates, and novel variants were described. The degree of polymorphism was shown in a graphical representation of the polymorphic sites generating a novel sequence, the heterogeneous positions common to assemblages A and B (double peaks), that may represent mixed assemblage infection and the heterogeneous positions detected at random sites. Notably, assemblage D, which is considered to be adapted to dogs, was found at the gdh locus in two samples originating from southern Asia, as novel genotypes. By comparing the geographical origin of the infected cases and the number of German travellers visiting the areas considered, India and west Africa appeared to be the areas associated to the highest risk of acquiring Giardia infection. The analysis of the geographical distribution of the genotypes did not suggest any particular geographical clustering pattern, but it may be useful to evaluate these results with a higher number of isolates. Most of the samples typed at the three markers could not be assigned unequivocally to either assemblage A or B, and this was confirmed also by a real-time PCR assay, using a set of assemblage-specific primers. The results of this study reinforce the notion that genetic exchanges and allelic sequence heterogeneity represent major obstacles towards understanding the epidemiology of giardiasis and that exposure to Giardia parasites in endemic areas often results in mixed infections in returning travellers.
authors.affiliation: European Food Safety Authority, via C.Magno 1, 43126, Parma, Italy, alessandro.broglia@efsa.europa.eu.
authors.forename: A
authors.initials: A
authors.lastname: Broglia
authors.forename: T
authors.initials: T
authors.lastname: Weitzel
authors.forename: G
authors.initials: G
authors.lastname: Harms
authors.forename: S M
authors.initials: SM
authors.lastname: Cacció
authors.forename: K
authors.initials: K
authors.lastname: Nöckler
mesh_terms: D016054:DNA, Protozoan / Q000235:genetics; D005243:Feces / Q000469:parasitology; D005838:Genotype; D005858:Germany; D016829:Giardia lamblia / Q000235:genetics*; D005873:Giardiasis / Q000453:epidemiology / Q000469:parasitology*; D006801:Humans; D010802:Phylogeny; D014195:Travel
chemical_list: D016054:DNA, Protozoan
references.citation: Am J Trop Med Hyg. 2005 Jun;72(6):825-30
references.pmid: 15964971
references.citation: Trans R Soc Trop Med Hyg. 2008 Jul;102(7):718-25
references.pmid: 18485429
references.citation: Eukaryot Cell. 2007 Aug;6(8):1421-30
references.pmid: 17557879
references.citation: PLoS Negl Trop Dis. 2011 Aug;5(8):e1262
references.pmid: 21829745
references.citation: Appl Environ Microbiol. 2008 Aug;74(16):5100-5
references.pmid: 18567681
references.citation: Mol Biol Evol. 1999 Sep;16(9):1135-44
references.pmid: 10486969
references.citation: Parasitology. 1996 Jan;112 ( Pt 1):1-12
references.pmid: 8587793
references.citation: J Infect Dis. 1996 Jul;174(1):233-6
references.pmid: 8656003
references.citation: Acta Trop. 2008 Apr;106(1):44-53
references.pmid: 18325480
references.citation: Vet Parasitol. 2011 Jun 10;178(3-4):342-5
references.pmid: 21324592
references.citation: Exp Parasitol. 2013 Jun;134(2):141-7
references.pmid: 23523861
references.citation: Appl Environ Microbiol. 2006 Mar;72(3):2212-7
references.pmid: 16517674
references.citation: Vet Parasitol. 2007 Nov 10;149(3-4):258-64
references.pmid: 17900812
references.citation: Parasitology. 2009 Sep;136(10):1161-8
references.pmid: 19631012
references.citation: BMC Microbiol. 2012 May 03;12:65
references.pmid: 22554281
references.citation: Parasitol Res. 1998 Sep;84(9):707-14
references.pmid: 9766898
references.citation: Clin Microbiol Rev. 2011 Jan;24(1):110-40
references.pmid: 21233509
references.citation: Int J Parasitol. 2011 Apr;41(5):495-503
references.pmid: 21176781
references.citation: Exp Parasitol. 2010 Jan;124(1):107-12
references.pmid: 19236865
references.citation: Vet Parasitol. 2008 Oct 1;156(3-4):205-9
references.pmid: 18617331
references.citation: Mem Inst Oswaldo Cruz. 2008 Feb;103(1):98-103
references.pmid: 18368240
references.citation: Science. 2007 Sep 28;317(5846):1921-6
references.pmid: 17901334
references.citation: Parasitol Res. 2012 Nov;111(5):2173-7
references.pmid: 22915269
references.citation: Vet Parasitol. 2008 Nov 25;158(1-2):159-60
references.pmid: 18823709
references.citation: Epidemiol Infect. 2012 Nov;140(11):2023-7
references.pmid: 22225911
references.citation: Appl Environ Microbiol. 2004 Jun;70(6):3776-80
references.pmid: 15184191
references.citation: Int J Parasitol. 2005 Feb;35(2):207-13
references.pmid: 15710441
references.citation: PLoS Negl Trop Dis. 2012;6(8):e1776
references.pmid: 22953009
references.citation: Methods Mol Biol. 2000;132:221-41
references.pmid: 10547838
references.citation: Emerg Infect Dis. 2003 Nov;9(11):1444-52
references.pmid: 14718089
references.citation: Int J Parasitol. 2006 Jun;36(7):849-58
references.pmid: 16701663
references.citation: J Clin Microbiol. 2004 Jul;42(7):3317-20
references.pmid: 15243104
references.citation: Int J Parasitol. 2010 Mar 1;40(3):293-7
references.pmid: 19703458
references.citation: Infect Genet Evol. 2004 Jun;4(2):125-30
references.pmid: 15157630
references.citation: Appl Environ Microbiol. 2010 Mar;76(6):1895-901
references.pmid: 20080999
references.citation: Parasitol Res. 2008 Oct;103(5):1177-81
references.pmid: 18622625
references.citation: Vet Parasitol. 2011 Apr 19;177(1-2):28-32
references.pmid: 21146935
references.citation: Parasitol Res. 2005 Aug;97(1):1-6
references.pmid: 15940523
references.citation: J Clin Microbiol. 2002 Feb;40(2):446-52
references.pmid: 11825955
references.citation: Parasitol Int. 2011 Dec;60(4):507-11
references.pmid: 21989040
references.citation: Parasitology. 2004 Mar;128(Pt 3):253-62
references.pmid: 15080083
references.citation: Clin Microbiol Rev. 2001 Jan;14(1):114-28
references.pmid: 11148005
references.citation: Parasitol Res. 2007 Aug;101(3):681-7
references.pmid: 17401723
references.citation: Parasitology. 2007 Nov;134(Pt 12):1795-821
references.pmid: 17577426
references.citation: Acta Trop. 2007 May;102(2):92-9
references.pmid: 17498637
references.citation: J Travel Med. 2000 Mar-Apr;7(2):70-3
references.pmid: 10759572
references.citation: PLoS Negl Trop Dis. 2009 Dec 01;3(12):e558
references.pmid: 19956662
references.citation: Int J Parasitol. 2008 Nov;38(13):1523-31
references.pmid: 18571176
references.citation: Vet Parasitol. 2010 Mar 25;168(3-4):231-9
references.pmid: 19969422
references.citation: Int J Parasitol. 2002 Jul;32(8):1023-30
references.pmid: 12076631
references.citation: Trends Parasitol. 2005 Sep;21(9):430-7
references.pmid: 16046184