Abstract
BackgroundEntamoeba species harbored by humans have different degrees of pathogenicity. The present study explores the intra- and interspecific diversity, phylogenetic relationships, prevalence and distribution of tetra- and octonucleated cyst-producing Entamoeba in different Brazilian regions.MethodsCross-sectional studies were performed to collect fecal samples (n = 1728) and sociodemographic data in communities located in four Brazilian biomes: Atlantic Forest, Caatinga, Cerrado, and Amazon. Fecal samples were subjected to molecular analysis by partial small subunit ribosomal DNA sequencing (SSU rDNA) and phylogenetic analysis.ResultsLight microscopy analysis revealed that tetranucleated cysts were found in all the studied biomes. The highest positivity rates were observed in the age group 6–10 years (23.21%). For octonucleated cysts, positivity rates ranged from 1 to 55.1%. Sixty SSU rDNA Entamoeba sequences were obtained, and four different species were identified: the octonucleated E. coli, and the tetranucleated E. histolytica, E. dispar, and E. hartmanni. Novel haplotypes (n = 32) were characterized; however, new ribosomal lineages were not identified. The Entamoeba coli ST1 subtype predominated in Atlantic Forest and Caatinga, and the ST2 subtype was predominant in the Amazon biome. E. histolytica was detected only in the Amazon biome. In phylogenetic trees, sequences were grouped in two groups, the first containing uni- and tetranucleated and the second containing uni- and octonucleated cyst-producing Entamoeba species. Molecular diversity indexes revealed a high interspecific diversity for tetra- and octonucleated Entamoeba spp. (H ± SD = 0.9625 ± 0.0126). The intraspecific diversity varied according to species or subtype: E. dispar and E. histolytica showed lower diversity than E. coli subtypes ST1 and ST2 and E. hartmanni.ConclusionsTetra- and octonucleated cyst-producing Entamoeba are endemic in the studied communities; E. histolytica was found in a low proportion and only in the Amazon biome. With regard to E. coli, subtype ST2 was predominant in the Amazon biome. The molecular epidemiology of Entamoeba spp. is a field to be further explored and provides information with important implications for public health.Graphical
Highlights
Entamoeba species harbored by humans have different degrees of pathogenicity
We explored the species composition, the inter- and intraspecific genetic diversity and phylogenetic relationships, and the prevalence and distribution of Entamoeba species infecting populations living in different Brazilian biomes
Description of study area and population, study design and sampling Communities from cities located in four Brazilian biomes were selected: Cachoeiras de Macacu (CAM) in the state of Rio de Janeiro (Atlantic Forest biome), Teresina (TER) and São João do Piauí (SJPI) in Piauí (Cerrado and Caatinga biomes, respectively), and Santa Isabel do Rio Negro (SIRN) in Amazonas and Bagre (BAG) in Pará (Amazon biome) (Fig. 1)
Summary
Entamoeba species harbored by humans have different degrees of pathogenicity. Entamoeba species harbored by the human digestive tract have different degrees of pathogenicity and impact on public health [1]. The similarity of the cysts led to the adoption of the nomenclature E. histolytica/E. dispar complex, which includes Entamoeba moshkovskii, another tetranucleated cyst-producing species. E. dispar and E. moshkovskii are considered to have less pathogenic potential [3], they have occasionally been associated with invasive disease [4, 5]. These findings have led to the need for further studies to assess the epidemiology of indistinguishable tetranucleated amoebas [3]. Entamoeba species that parasitize other animals can infect humans [6]
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