The objective of the present study was to evaluate two commercially available dip-stick assays for the diagnosis of Giardia infections in faecal samples from calves suspected of clinical giardiasis. The dip-stick assays provide an on-site and hence quick alternative to laboratory diagnosis. A three-test Bayesian model was used, including the test results of the Coris Giardia strip (Coris Bioconcept, Gembloux, Belgium), the Speed Giardia or BVT dip-stick (Bio Veto Test/Virbac, La Seyne sur Mer, France), and the Meridian immunofluorescence assay (IFA: Meridian Diagnostics Inc., Cincinnati, OH). In total, 421 faecal samples were examined with the three diagnostic assays between October 2008 and November 2009. Overall, the number of positive samples was markedly higher using the IFA compared to both dip-stick assays, resulting in a high sensitivity (se: 88%, with a 95% probability interval (PI) 60-99%) compared to the Coris dip-stick assay (se: 28%; PI: 16-41%) and the BVT dip-stick assay (se: 26%, PI: 16-35). The specificities of all the three assays were very high (IFA sp: 94%, PI: 90-99%; Coris sp: 92%, PI 86-98%; BVT sp: 93%, PI 88-98%). A positive diagnosis by the dip-stick assays was significantly correlated with a higher cyst excretion level, as measured by IFA. The majority (76%) of the positive samples in the present study contained less than 5000cyst per gram of faeces, even though all these animals displayed clinical symptoms of diarrhea potentially due to Giardia. The low level of cyst excretion in these samples might in part explain the poor sensitivity of both dip-stick assays. Although multiple samplings might be an option to increase the sensitivity of the dip-stick assays, the laboratory based IFA seems at current to be the best option for clinical diagnosis of Giardia in calves.
[Show abstract][Hide abstract] ABSTRACT: Giardiasis is a gastrointestinal disease of humans and other animals caused by species of parasitic protists of the genus Giardia. This disease is transmitted mainly via the faecal–oral route (e.g., in water or food) and is of socioeconomic importance worldwide. The accurate detection and genetic characterisation of the different species and population variants (usually referred to as assemblages and/or sub-assemblages) of Giardia are central to understanding their transmission patterns and host spectra. The present article provides a background on Giardia and giardiasis, and reviews some key techniques employed for the identification and genetic characterisation of Giardia in biological samples, the diagnosis of infection and the analysis of genetic variation within and among species of Giardia. Advances in molecular techniques provide a solid basis for investigating the systematics, population genetics, ecology and epidemiology of Giardia species and genotypes as well as the prevention and control of giardiasis.
[Show abstract][Hide abstract] ABSTRACT: Giardia duodenalis is a flagellate protozoan that parasitizes humans and several other mammals. Protozoan contamination has been regularly documented at important environmental sites, although most of these studies were performed at the species level. There is a lack of studies that correlate environmental contamination and clinical infections in the same region. The aim of this study is to evaluate the genetic diversity of a set of clinical and environmental samples and to use the obtained data to characterize the genetic profile of the distribution of G. duodenalis and the potential for zoonotic transmission in a metropolitan region of Brazil.
The genetic assemblages and subtypes of G. duodenalis isolates obtained from hospitals, a veterinary clinic, a day-care center and important environmental sites were determined via multilocus sequence-based genotyping using three unlinked gene loci. Cysts of Giardia were detected at all of the environmental sites. Mixed assemblages were detected in 25% of the total samples, and an elevated number of haplotypes was identified. The main haplotypes were shared among the groups, and new subtypes were identified at all loci. Ten multilocus genotypes were identified: 7 for assemblage A and 3 for assemblage B.
There is persistent G. duodenalis contamination at important environmental sites in the city. The identified mixed assemblages likely represent mixed infections, suggesting high endemicity of Giardia in these hosts. Most Giardia isolates obtained in this study displayed zoonotic potential. The high degree of genetic diversity in the isolates obtained from both clinical and environmental samples suggests that multiple sources of infection are likely responsible for the detected contamination events. The finding that many multilocus genotypes (MLGs) and haplotypes are shared by different groups suggests that these sources of infection may be related and indicates that there is a notable risk of human infection caused by Giardia in this region.
PLoS ONE 12/2014; 9(12):e115489. DOI:10.1371/journal.pone.0115489 · 3.23 Impact Factor
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