The Immunological Enigma of Human Giardiasis

Klotz, Christian; Aebischer, Toni

doi:10.1007/s40475-015-0050-2

Cited by 13 publications

(9 citation statements)

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“…Giardiasis caused by the flagellated protozoan Giardia duodenalis (syn. G. lamblia and G. intestinalis ) is one of the most frequent gastrointestinal parasitic diseases in humans worldwide [ 1 , 2 ]. Giardia duodenalis is considered as a species complex of genetically different but morphologically identical organisms with varying zoonotic potential and host preferences.…”

Section: Introductionmentioning

confidence: 99%

Occurrence and distribution of Giardia species in wild rodents in Germany

et al. 2018

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BackgroundGiardiasis is an important gastrointestinal parasitic disease in humans and other mammals caused by the protozoan Giardia duodenalis. This species complex is represented by genetically distinct groups (assemblages A-H) with varying zoonotic potential and host preferences. Wild rodents can harbor potentially zoonotic assemblages A and B, and the rodent-specific assemblage G. Other Giardia spp. found in these animals are Giardia muris and Giardia microti. For the latter, only limited information on genetic typing is available. It has been speculated that wild rodents might represent an important reservoir for parasites causing human giardiasis. The aim of this study was to investigate the occurrence and distribution of Giardia spp. and assemblage types in wild rodents from different study sites in Germany.ResultsScreening of 577 wild rodents of the genera Apodemus, Microtus and Myodes, sampled at eleven study sites in Germany, revealed a high overall Giardia prevalence. Giardia species determination at the SSU rDNA gene locus revealed that Apodemus mice, depending on species, were predominantly infected with one of two distinct G. muris sequence types. Giardia microti was the predominant parasite species found in voles of the genera Microtus and Myodes. Only a few animals were positive for potentially zoonotic G. duodenalis. Subtyping at the beta-giardin (bg) and glutamine dehydrogenase (gdh) genes strongly supported the existence of different phylogenetic subgroups of G. microti that are preferentially harbored by distinct host species.ConclusionsThe present study highlights the preference of G. muris for Apodemus, and G. microti for Microtus and Myodes hosts and argues for a very low prevalence of zoonotic G. duodenalis assemblages in wild rodents in Germany. It also provides evidence that G. muris and G. microti subdivide into several phylogenetically distinguishable subgroups, each of which appears to be preferentially harbored by species of a particular rodent host genus. Finally, the study expands the database of sequences relevant for sequence typing of G. muris and G. microti isolates which will greatly help future analyses of these parasites’ population structure.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2802-z) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Occurrence and distribution of Giardia species in wild rodents in Germany

et al. 2018

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“…This hypothesis was based on recent studies showing that stunted children generally show the first signs of a downward trend in growth within the first 6 months of life [ 21 ]. We also hypothesized that infection with Giardia would be protective against all-cause diarrhea during the period of active giardiasis, regardless of pathogenic cause of the diarrhea as it is possible Giardia stimulates innate immunity that provides bystander protection from other enteric infections [ 22 ].…”

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A Prospective Longitudinal Cohort to Investigate the Effects of Early Life Giardiasis on Growth and All Cause Diarrhea

et al. 2016

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“…The reasons for these fundamental differences of the outcomes of infections remain unclear (Adam, 2001 ; Troeger et al, 2007 ; Klotz and Aebischer, 2015 ; Tysnes and Robertson, 2015 ). A mechanism that was proposed to link to acute symptoms was the breakdown of the intestinal barrier function of the epithelium, leading to increased permeability with bacterial invasion as a possible result (Buret, 2007 ; Ankarklev et al, 2010 ).…”

Section: The Challenge: Symptomatic Vs Asymptomatic Infectionsmentioning

confidence: 99%

Giardia's Epithelial Cell Interaction In Vitro: Mimicking Asymptomatic Infection?

Kraft

Klotz

Bücker

et al. 2017

Front. Cell. Infect. Microbiol.

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The protozoan parasite Giardia duodenalis is responsible for more than 280 million cases of gastrointestinal complaints (“giardiasis”) every year, worldwide. Infections are acquired orally, mostly via uptake of cysts in contaminated drinking water. After transformation into the trophozoite stage, parasites start to colonize the duodenum and upper jejunum where they attach to the intestinal epithelium and replicate vegetatively. Outcome of Giardia infections vary between individuals, from self-limiting to chronic, and asymptomatic to severely symptomatic infection, with unspecific gastrointestinal complaints. One proposed mechanism for pathogenesis is the breakdown of intestinal barrier function. This has been studied by analyzing trans-epithelial electric resistances (TEER) or by indicators of epithelial permeability using labeled sugar compounds in in vitro cell culture systems, mouse models or human biopsies and epidemiological studies. Here, we discuss the results obtained mainly with epithelial cell models to highlight contradictory findings. We relate published studies to our own findings that suggest a lack of barrier compromising activities of recent G. duodenalis isolates of assemblage A, B, and E in a Caco-2 model system. We propose that this epithelial cell model be viewed as mimicking asymptomatic infection. This view will likely lead to a more informative use of the model if emphasis is shifted from aiming to identify Giardia virulence factors to defining non-parasite factors that arguably appear to be more decisive for disease.

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The Immunological Enigma of Human Giardiasis

Cited by 13 publications

References 113 publications

Occurrence and distribution of Giardia species in wild rodents in Germany

Occurrence and distribution of Giardia species in wild rodents in Germany

A Prospective Longitudinal Cohort to Investigate the Effects of Early Life Giardiasis on Growth and All Cause Diarrhea

Giardia's Epithelial Cell Interaction In Vitro: Mimicking Asymptomatic Infection?

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