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IntroductionGiardiasis is an intestinal infection that affects more than two hundred million people annually worldwide; it is caused by the flagellated protozoan Giardia duodenalis. In tropical countries and in low or middle-income settings, like Brazil, its prevalence can be high. There is currently no systematic review on the presence of G. duodenalis in patients, animals or water sources in Brazil.MethodsThis systematic review was performed according to recommendations established by Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). As databases for our searches, we have used PubMed, Embase, Scopus and the Brazilian database SciELO using the keywords Giardia* and Brazil.ResultsThis systematic review identified research studies related to G. duodenalis in water, giardiasis in animals, prevalence of giardiasis across Brazilian regions, genotyping of strains isolated in humans, and giardiasis in indigenous populations. We also propose a network of G. duodenalis transmission in Brazil based on genotypes analyses.ConclusionThis is the first time within the last twenty years that a review is being published on the occurrence of G. duodenalis in Brazil, addressing relevant issues such as prevalence, molecular epidemiology and analytical methods for parasite detection.

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The goals of this study were to investigate the occurrence of Cryptosporidium oocysts and Giardia cysts in main springs of Campos do Jordão, an important tourist city, in Brazil and to gather the largest amount of parasitological data from autochthonous population that live in rural areas of this city. The membrane filtration technique followed by direct immunofluorescence assay was employed for concentration and visualization of waterborne protozoa. In the period between June 2003 and May 2004, the presence of at least one pathogenic protozoa was detected in 25.0% (3/12) of the springs studied, with mean concentrations ranging from 0.2 to 0.3 Cryptosporidium sp. oocysts and 0.07 to 0.1 Giardia sp. cysts/L. The coproparasitological investigation conducted in dwellers from two rural communities from this city revealed that 49.2% (91/185) of people had intestinal parasites. Among pathogenic protozoa, Cryptosporidium was the most prevalent species (8.1%) followed by Giardia duodenalis (5.9%), Entamoeba histolytica/Entamoeba dispar (2.7%), and Blastocystis hominis (2.2%). The most prevalent geohelminths were Ascaris lumbricoides (14.9%) and Trichuris trichiura (9.7%). This study demonstrated the contamination and the distribution of intestinal parasites, especially Cryptosporidium and Giardia species, in different springs of an important tourist city in Brazil, highlighting the need of monitoring natural water sources. The high prevalence of intestinal parasitosis detected in some specific populations of this city may function as a link of transmission of different intestinal parasitosis due to soil and water contamination, contributing to the maintenance of parasite life cycles. Therefore, the inclusion of consistent public health interventions with measures that include the protection of springs, the installation of minimum health infrastructure, and primary education of the population are widely necessary, aiming the control and prevention of parasite infections.

Giardia duodenalis is a flagellated intestinal protozoan responsible for infections in various hosts including humans and several wild and domestic animals. Few studies have correlated environmental contamination and clinical infections in the same region. The aim of this study was to compare groups of Giardia duodenalis from clinical and environmental sources through population genetic analyses to verify haplotype sharing and the degree of genetic similarity among populations from clinical and environmental sources in the metropolitan region of Campinas. The results showed high diversity of haplotypes and substantial genetic similarity between clinical and environmental groups of G. duodenalis. We demonstrated sharing of Giardia genotypes among the different populations studied. The comparison between veterinary and human sequences led us to identify new zoonotic genotypes, including human isolates from genetic assemblage C. The application of a population genetic analysis in epidemiological studies allows quantification of the degree of genetic similarity among populations of Giardia duodenalis from different sources of contamination. The genetic similarity of Giardia isolates among human, veterinary, and environmental groups reinforced the correlation between clinical and environmental isolates in this region, which is of great importance for public health.

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