Multilocus Genotyping of Giardia duodenalis in Mostly Asymptomatic Indigenous People from the Tapirapé Tribe, Brazilian Amazon.

Pamela Carolina Köster,Begoña Bailo,David Carmena,Rafael Calero-Bernal,Larissa M S Lemos,Luciana Melhorança Moreira,Antonio F Malheiros,Jeffrey J Shaw,Alejandro Dashti,Solange Maria Gennari,Arlei Marcili,Héloïse Lucaccioni,Herbert Sousa Soares,Sooria Balasegaram,David González-Barrio,Alexander Prendergast

doi:10.3390/pathogens10020206

Abstract

Little information is available on the occurrence and genetic variability of the diarrhoea-causing enteric protozoan parasite Giardia duodenalis in indigenous communities in Brazil. This cross-sectional epidemiological survey describes the frequency, genotypes, and risk associations for this pathogen in Tapirapé people (Brazilian Amazon) at four sampling campaigns during 2008–2009. Microscopy was used as a screening test, and molecular (PCR and Sanger sequencing) assays targeting the small subunit ribosomal RNA, the glutamate dehydrogenase, the beta-giardin, and the triosephosphate isomerase genes as confirmatory/genotyping methods. Associations between G. duodenalis and sociodemographic and clinical variables were investigated using Chi-squared test and univariable/multivariable logistic regression models. Overall, 574 individuals belonging to six tribes participated in the study, with G. duodenalis prevalence rates varying from 13.5–21.7%. The infection was positively linked to younger age and tribe. Infected children <15 years old reported more frequent gastrointestinal symptoms compared to adults. Assemblage B accounted for three out of four G. duodenalis infections and showed a high genetic diversity. No association between assemblage and age or occurrence of diarrhoea was demonstrated. These data indicate that the most likely source of infection was anthropic and that different pathways (e.g., drinking water) may be involved in the transmission of the parasite.

Highlights

A total of 574 individuals of the Tapirapé ethnicity living in six independent tribes were censed and invited to participate in four consecutive sampling campaigns during July 2008 and January 2010, in both dry and wet seasons
This study has been approved by the National Research Ethics Commission (CONEP), Ministry of Health (Brazil), under reference number 120/2008. This microscopy-based survey demonstrates that symptomatic and asymptomatic giardiasis are common in indigenous people from the Brazilian Amazon
G. duodenalis infection rates varied largely among the surveyed tribes and sampling periods, suggesting that different pathways may be involved in the transmission of the parasite

Summary

Introduction

Giardiasis is the most reported intestinal protozoan infection globally, with an estimated 280 million symptomatic cases every year [1]. Asymptomatic infections are even more frequent, both in developing [2,3] and developed [4] countries. Large epidemiological case-control studies conducted in high-prevalence settings have demonstrated that G. duodenalis infection was significantly more common in asymptomatic controls than in cases with diarrhoea [5,6,7]. Clinical manifestations associated with G. duodenalis infection may include self-limiting acute diarrhoea, persistent diarrhoea, epigastric pain, nausea, and vomiting [10]. Contrary to severe infections by other diarrhoea-causing protozoan parasites such as Cryptosporidium spp. or Entamoeba histolytica, giardiasis is rarely fatal and is better considered as a debilitating condition

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Discussion

Conclusion