Epidemiology of Giardia duodenalis infection in ruminant livestock and children in the Ismailia province of Egypt: insights by genetic characterization.

Yosra A Helmy,Hendrik Wilking,Toni Aebischer,Christian Klotz,Karl-H Zessin,Georg Von Samson-Himmelstjerna,Karsten Nöckler,Jürgen Krücken

doi:10.1186/1756-3305-7-321

Abstract

BackgroundGiardia duodenalis is a common flagellated protozoan parasite that infects the small intestine of a wide range of vertebrate hosts. This study aimed to determine whether tracing of G. duodenalis isolates by current genetic typing tools is possible using an exemplary set of samples from infected cattle, buffalo and children from the Ismailia province, Egypt.MethodA total of 804 fecal samples from ruminant animals was collected from 191 herds and 165 samples from diarrheal children below the age of 10 years. Parasites were detected in these samples using the copro-antigen RIDA®QUICK test and by real-time PCR. Samples were then genetically characterized based on the triosephosphate isomerase, glutamate dehydrogenase and β-giardin genes.ResultsThe prevalence of G. duodenalis was 53% in ruminants and 21% in symptomatic children and infection was not positively correlated with diarrheal symptoms. Sequence typing analysis confirmed predominance of B-type sequences (>67%) in humans and E-type sequences (>81%) in ruminants over A-type sequences. For 39 samples the complete sequence information of the three marker gene fragments could be derived. Integration of the concatenated sequence information of the three marker gene fragments with the spatial data of the respective sample revealed that identical or near identical (only up to 1 out of 1358 bp different) concatenated sequencing types were spatially related in 4 out of 5 cases.ConclusionThe risk of zoonotic infection emanating from ruminants even in high prevalence areas is negligible. Genetic characterization indicated a predominant anthropogenic cycle of infection within the pediatric population studied. Integration of sequence typing data with information on geographic origins of samples allows parasite sub-population tracing using current typing tools.

Highlights

Giardia duodenalis is a common flagellated protozoan parasite that infects the small intestine of a wide range of vertebrate hosts
The risk of zoonotic infection emanating from ruminants even in high prevalence areas is negligible
All polymerase chain reaction (PCR) reactions were performed using 2.5 U of the Estimation of the prevalence of Giardia infections in humans and accompanying livestock Copro-antigen tests are attractive for epidemiological surveys of the burden of gastrointestinal infections since they are highly processive

Summary

Introduction

Giardia duodenalis is a common flagellated protozoan parasite that infects the small intestine of a wide range of vertebrate hosts. G. lamblia and G. intestinalis) is one of the most frequent enteroparasites worldwide and has been included in the WHO ‘neglected disease initiative’ [1]. Children in resource-poor countries can be severely affected by G. duodenalis infections, which may lead to significant malabsorption, weight loss and growth retardation [1,2]. Infection that is not associated with such overt symptoms occurs frequently, especially in resource-poor countries [4]. These infections may often go unnoticed but epidemiological observations suggest that they are still associated with a malabsorption phenotype [5]

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