Ribosomal RNA Sequencing Reveals Differences between the Genotypes of Giardia Isolates Recovered from Humans and Dogs Living in the Same Locality

Abstract

ABSTRACT:A polymerase chain reaction-based method for genotyping Giardia duodenalis isolates using a polymorphic region near the 5' end of the small subunit ribosomal (SSU) RNA gene is described. Analysis was performed using Giardia cysts purified directly from feces. Isolates were collected from humans and dogs living in isolated Aboriginal communities where Giardia infections are highly endemic. This is the first report of the genetic characterization of Giardia from dogs and humans living in the same locality. Comparison of the SSU-rRNA sequences from 13 human and 9 dog isolates revealed 4 different genetic groups. Groups 1 and 2 contained all of the human isolates, whereas groups 3 and 4 consisted entirely of Giardia samples recovered from dogs. One dog sample contained templates from both groups 2 and 3. These results suggest that zoonotic transmission of Giardia infections between humans and dogs does not occur frequently in these communities. The dog-associated SSU-rRNA sequences have not been reported before, suggesting a new G. duodenalis subgroup. A genetic basis for the differences observed between the groups was supported by sequence analysis of 9 in vitro cultured isolates that were placed into the same genetic groups established by enzyme electrophoresis. . To circumvent this, we have applied the PCR to characterize Giardia isolates recovered directly from human and canine fecal samples, without the need for in vitro culture. The genotype of isolates was determined by PCR amplification and sequencing of a 292-bp region near the 5' end of the small subunit-rRNA gene (SSU-rRNA). This report describes the application of this technique to characterize Giardia isolates taken from both humans and dogs living in the same local environment in order to determine the potential for zoonotic transmission. An understanding of this problem is important for examining the epidemiology of Giardia in these communities and also for the design of effective control strategies. Giardia duodenalis (syn. Giardia intestinalis, Giardia lam-

Transmission cycles of Giardia duodenalis in dogs and humans in Temple communities in Bangkok—A critical evaluation of its prevalence using three diagnostic tests in the field in the absence of a gold standard

“…DNA was then isolated from the supernatant using the QIAamp A nested PCR was utilised to amplify a 130 bp region of the SSU-rDNA gene using primers RH11, RH4 and GiarF and GiarR as previously described by Hopkins et al (1997) and Read et al (2002).…”

“…Sequence chromatograms were edited and analysed using the software programs Finch TV version 1.4.0 (Geospiza Inc. © ). Human and dog isolates were grouped into Assemblages A, B, C or D according to Hopkins et al (1997).…”

“…This conclusion has largely been drawn from data showing that G. duodenalis is one of the most common enteric parasites of dogs in both developed as well as disadvantaged communities worldwide (Itoh et al, 2001;PonceMacotela et al, 2005) and that genetically identical, potentially zoonotic genotypes of G. duodenalis (predominantly Assemblage A) may exist in humans and dogs living within the same locality (Ponce-Macotela et al, 2002;Traub et al, 2004;Eligio-Garcia et al, 2005;Lalle et al, 2005) . On the other hand, non-zoonotic or dog-specific cycles of G. duodenalis transmission have also been shown to exist in dogs in communities where it is hypothesised that the frequency of transmission of Giardia among dogs is high (Hopkins et al, 1997;Itagaki et al, 2005;Palmer et al, 2008). In this study we determine the prevalence, genotypes and associated risk factors for G. duodenalis occurring in dogs and humans in Temples and their surrounding communities in Bangkok, Thailand.…”

Efficacy of oxfendazole for the treatment of giardiosis in dogs. Experiments in dog breeding kennels

“…It is considered by several authors to be a zoonosis, even though various adjusted strains host species are genetically singled out (Capon, 1989;Gasser, 1990;Hopkins, 1997;Thompson et al, 2000). Some strains seem to be able to infect human from livestock or dogs and vice versa, and, in the opposite, other strains seem to be very specific.…”

“…Some strains seem to be able to infect human from livestock or dogs and vice versa, and, in the opposite, other strains seem to be very specific. Further genetic studies are needed to understand these variations (Gasser, 1990;Hopkins, 1997;Meloni et al, 1995;Thompson et al, 2000). Giardiosis is the most commonly non viral reported intestinal infection in humans.…”