Introduction: The present study aimed to determine the prevalence and factors associated with Giardia intestinalis infection, verifying its impact on the nutritional status of children in northeastern Brazil. Methodology: A cross-sectional study was conducted to obtain parasitological, sociodemographic, and anthropometric data in two municipalities in the states of Piauí and Ceará, northeastern Brazil. 3%], p = 0.038, OR = 3.54, 95% CI = 1.13-11.09, respectively). Infection with G. intestinalis remained significantly associated with stunting and being underweight after adjustment for poverty, municipality, sex, and age in a logistic regression multivariate model. Conclusions: In rural areas in northeastern Brazil, giardiasis has acquired great public health importance in the soil-transmitted helminths control era, impacting the nutritional status of children and requiring new approaches to diagnosis and treatment and translational research that could generate applicable solutions at the community level.

In this study, we assessed the genetic diversity of Ascaris lumbricoides / Ascaris suum circulating in humans and pigs, exploring potential zoonotic cycles in endemic areas in Brazil. We carried out cross-sectional surveys in four municipalities: Santa Isabel do Rio Negro (SIRN-AM) (n = 328); Nossa Senhora de Nazaré (NSN-PI) and Teresina (TER-PI) (n = 605 and n = 297, respectively); and Cachoeiras de Macacu (CAM-RJ) (n = 543). We also studied 61 fecal samples/adult worms obtained from pigs (n = 53 in NSN-PI and n = 8 in TER-PI). A ~450 bp fragment of the Ascaris cytochrome c oxidase subunit 1 ( cox 1) and ~400 bp of the NADH dehydrogenase subunit 1 ( nad 1) were amplified and sequenced. Maximum-likelihood (ML) tree and Median-joining (MJ) haplotype network analyses were performed. We also performed scanning electron micrographs of adult specimens. Positivity rates were 93/328 (28.4%) in SIRN-AM, 6/297 (2.0%) in TER-PI, 0/605 (0%) in NSN-PI, and 6/543 (1.1%) in CAM-RJ. In NSN-PI it reached 11/53 (20.7%) in pigs. The MJ network based on cox 1 locus (383 bp) revealed three main clusters, one centered around haplotypes H01/H28/H32 and the other around H07/H11. The cox 1 haplotypes had a heterogeneous distribution, showing no pattern by geographic region, and high haplotype diversity. The ML trees based on cox 1 and nad 1 loci showed a similar topology with each other, and with the haplotype networks. Three distinct clusters were observed. Sequences of cox 1 and nad 1 from humans and animals were distributed throughout the tree and it was not possible to differentiate specimens of human and swine origin. Ascaris populations obtained from humans and swine in different Brazilian regions are not discriminable through the genetic markers used, which indicates the potential for zoonotic transmission and the need for better control of these infections in swine herds, mainly when created in a peridomestic environment.

Background Entamoeba 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. Methods Cross-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. Results Light 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. Conclusions Tetra- 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.

Metastrongylosis is an infection of the respiratory tract of pigs caused by parasites of the genus Metastrongylus, whose eggs are similar to other Strongylida through light microscopy; species-specific identification can be performed with molecular tools. We explored the species composition and the genetic diversity of Metastrongylus infecting pigs in close contact with humans in impoverished rural communities in the state of Piauí, in northeastern Brazil. Fecal samples ( n = 78) were collected for parasitologic tests. Egg morphometry and molecular characterization, using the cytochrome c oxidase subunit 1 ( cox1) gene, were performed. For strongyliform eggs, 62 of 78 (80%) pigs were positive and 6 of 99 (6%) eggs had dimensions compatible with Metastrongylus. Of the 37 samples submitted to PCR, 10 were identified as M. salmi. We found 3 M. salmi haplotypes, including 2 new and 1 described previously in Europe. Overall, M. salmi demonstrated lower intraspecific genetic diversity: diversity index (H) ± SD = 0.318 ± 0.164, n = 12, compared with published M. pudendotectus sequences (1.000 ± 0.272, n = 3). To our knowledge, M. salmi DNA sequences have not been published previously from pigs in South America.