Molecular typing ofGiardia duodenalisin humans in Queensland – first report of Assemblage E

Abstract

SUMMARYLittle is known about the genetic diversity of the protozoan parasite, Giardia duodenalis, infecting humans in Queensland, Australia. The present study typed 88 microscopically Giardia-positive isolates using assemblage-specific primers at the triose phosphate isomerase (tpi) gene and sequenced a subset of isolates at the glutamate dehydrogenase (gdh) gene (n = 30) and tpi locus (n = 27). Using the tpi-assemblage specific primers, G. duodenalis assemblage A and assemblage B were detected in 50% (44/88) and 38·6% (34/88) of samples, respectively. Mixed infections with assemblages A and B were identified in 4·5% (4/88) and assemblage E was identified in 6·8% (6/88) of samples. Sequence analysis at the gdh and tpi loci also confirmed the presence of assemblage E in these isolates. Cyst numbers per gram of feces (g−1) were determined using quantitative polymerase chain reaction and of the isolates that were typed as assemblage E, cyst numbers ranged 13·8–68·3 × 106 cysts g−1. This is the first report of assemblage E in humans in Australia, indicating that in certain settings, this assemblage may be zoonotic.

Molecular investigation of Cryptosporidium and Giardia in pre- and post-weaned calves in Hubei Province, China

“…Although current preliminary results of G. duodenalis from calves in Hubei Province suggest that the public health risk of zoonotic giardiasis is low here, previous longitudinal investigations of cattle giardiasis have indicated the possibility of the transient presence of zoonotic assemblages [ 60 ]. Although assemblage E, identified in the present study, had not been considered zoonotic [ 3 , 4 ], some recent studies describe the occurrence of assemblage E in humans in Queensland, Australia [ 61 ], Brazil [ 62 ] and Egypt [ 63 – 65 ], indicating that this assemblage can indeed be zoonotic. These recent findings could have important public implications in rural regions of countries such as China, where there is a close relationship between livestock and humans.…”

Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in deer in Henan and Jilin, China

“…However, assemblage E has rarely been identified in wild hoofed animals, and thus may reflect an adaption to these animals following domestication [ 19 ]. Moreover, assemblage E has also been found in NHPs from western Uganda and China [ 79 , 80 ] and in humans from Egypt, Brazil and Australia, suggesting zoonotic transmission of assemblage E [ 81 – 85 ]. Although assemblage E was detected in low numbers in this study, it is still important to understand the public health risk posed by the Giardia species and assemblages infection in cervids in the region.…”

The Intersection of Immune Responses, Microbiota, and Pathogenesis in Giardiasis

“…G. duodenalis , G. intestinalis ) is a protozoan parasite that infects both humans and other mammals through the ingestion of parasite-contaminated water or food [1, 2]. This parasite is divided into 8 genetic groups, termed assemblages A-H. Assemblages A and B are the main assemblages found to infect humans [2], although a recent report has described human infections with assemblage E [3]. The Giardia lifecycle has two distinct phases: a vegetative trophozoite and an infective cyst that is resistant to harsh environmental conditions.…”