RESUMO

Some helminth species belonging to the order Strongylida are parasites of the digestive tract of vertebrates, including man and domestic animals. In humans, infections with Oesophagostomum spp. and Trichostrongylus spp. may be misdiagnosed as hookworm disease on parasitological stool examination, mainly in regions where these infections are coendemic, since eggs released in hosts' feces are morphologically similar. This study presents the morphologic characterization of Strongylida larvae recovered from humans and pigs living in close proximity, exploring putative zoonotic cycles. One hundred three humans and 27 pigs were included in low-resource rural communities in the state of Piauí, northeastern Brazil. Strongylida eggs were present in 12 (11.7%) humans and 23 (85.2%) pigs through conventional parasitological examination. Strongylida-positive fecal samples were submitted to coprocultures using the Harada-Mori technique. All 22 larvae obtained from human feces were classified as hookworms (Ancylostomatidae). From a total of 37 larvae obtained from swine, 23 (62.3%) were classified as Oesophagostomum, 6 (16.2%) were Hyostrongylus, and 4 (10.8%) were Trichostrongylus. Four larvae (10.8%) obtained from pigs were classified as Strongyloides. The morphological study of filariform larvae obtained in coprocultures is a useful and inexpensive tool in the screening of intestinal helminthiasis in a One Health approach.

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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.

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Human infections with gut protozoan parasites are neglected and not targeted by specific control initiatives, leading to a knowledge gap concerning their regional diversity and epidemiology. The present study aims to explore Giardia duodenalis genetic diversity and assess the epidemiologic scenario of subclinical infections in different Brazilian biogeographic regions. Cross-sectional surveys (n = 1334 subjects) were conducted in four municipalities in order to obtain fecal samples and socioenvironmental data. Microscopy of non-diarrheal feces and nucleotide sequencing of a ß-giardin gene fragment were performed. From a total of 51 samples that could be sequenced, 27 (52.9%) ß-giardin sequences were characterized as assemblage A and 24 (47.1%) as assemblage B. In the Amazon, assemblage B was the most frequently detected, predominantly BIII, and with two novel sub-assemblages. Assemblage A predominated in the extra-Amazon region, with five novel sub-assemblages. Prevalence reached 17.8% (64/360) in the Amazon, 8.8% (48/544) in the Atlantic Forest, 7.4% (22/299) in Cerrado and 2.3% (3/131) in the Semiarid. People living in poverty and extreme poverty presented significantly higher positivity rates. In conclusion, subclinical giardiasis is endemic in Brazilian communities in different biogeographic regions, presenting high genetic diversity and a heterogeneous genotypic distribution.

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BACKGROUND: This study assessed the interactions between income, nutritional status and intestinal parasitism in children in Brazil. METHODS: A cross-sectional study (n = 421 children aged 1 to 14 years living in the states of Piauí (rural communities in the city of Teresina) and Rio de Janeiro (rural and periurban communities in the city of Cachoeiras de Macacu) was performed in order to obtain income and anthropometric data, as well as fecal samples for parasitological analyses through the Ritchie technique. RESULTS: Children infected with Ascaris lumbricoides had significantly lower means of height-for-age z scores (- 1.36 ± 0.75 vs. - 0.11 ± 1.02; p < 0.001), weight-for-age z scores (- 1.23 ± 0.74 vs. 0.09 ± 1.15; p = 0.001), and weight-for-height z scores (- 0.68 ± 0.44 vs. 0.23 ± 1.25; p = 0.006) when compared with uninfected children. Infection with hookworm was also associated with lower means of height-for-age z scores (- 1.08 ± 1.17 vs. - 0.12 ± 1.02; p = 0.015) and weight-for-age z scores (- 1.03 ± 1.13 vs. 0.08 ± 1.15; p = 0.012). Children infected with Entamoeba coli presented significantly lower means of height-for-age z scores (- 0.54 ± 1.02 vs. - 0.09 ± 1.02; p = 0.005) and weight-for-age z scores (- 0.44 ± 1.15 vs. 0.12 ± 1.15; p = 0.002). The multivariate multiple linear regression analysis showed that height-for-age z scores are independently influenced by monthly per capita family income (ß = 0.145; p = 0.003), female gender (ß = 0.117; p = 0.015), and infections with A. lumbricoides (ß = - 0.141; p = 0.006) and Entamoeba coli (ß = - 0.100; p = 0.043). Weight-for-age z scores are influenced by monthly per capita family income (ß = 0.175; p < 0.001), female gender (ß = 0.123; p = 0.010), and infections with A. lumbricoides (ß = - 0.127; p = 0.012), and Entamoeba coli (ß = - 0.101; p = 0.039). Monthly per capita family income (ß = 0.102; p = 0.039) and female gender (ß = 0.134; p = 0.007) positively influences mid upper arm circumpherence. CONCLUSIONS: Intestinal parasitism and low family income negatively influence the physical development of children in low-income communities in different Brazilian regions.

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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 (cox1) and ~400 bp of the NADH dehydrogenase subunit 1 (nad1) 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 cox1 locus (383 bp) revealed three main clusters, one centered around haplotypes H01/H28/H32 and the other around H07/H11. The cox1 haplotypes had a heterogeneous distribution, showing no pattern by geographic region, and high haplotype diversity. The ML trees based on cox1 and nad1 loci showed a similar topology with each other, and with the haplotype networks. Three distinct clusters were observed. Sequences of cox1 and nad1 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.

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