Genetic characterisation and molecular epidemiology of Ascaris spp. from humans and pigs in Brazil

Iñiguez, Alena Mayo; Leles, Daniela; Jaeger, Lauren Hubert; Carvalho-Costa, Filipe Aníbal; Araújo, Adauto

doi:10.1016/j.trstmh.2012.06.009

Cited by 27 publications

(23 citation statements)

References 31 publications

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“…These data strongly infer the absence of a major genetic barrier between the two taxa and therefore suggest that A. suum and A. lumbricoides may be variants of the same species, as suggested by Leles et al [3] and Liu et al [35], and more recently by Iniguez et al [30]. Together all four studies have found no evidence of diagnostic genetic heterogeneity between human and pig Ascaris , plus an absence of genetic clusters discriminating each host.…”

Section: Discussionsupporting

confidence: 69%

Phylogeographical Studies of Ascaris spp. Based on Ribosomal and Mitochondrial DNA Sequences

et al. 2013

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BackgroundThe taxonomic distinctiveness of Ascaris lumbricoides and A. suum, two of the world's most significant nematodes, still represents a much-debated scientific issue. Previous studies have described two different scenarios in transmission patterns, explained by two hypotheses: (1) separated host-specific transmission cycles in highly endemic regions, (2) a single pool of infection shared by humans and pigs in non-endemic regions. Recently, A. suum has been suggested as an important cause of human ascariasis in endemic areas such as China, where cross-infections and hybridization have also been reported. The main aims of the present study were to investigate the molecular epidemiology of human and pig Ascaris from non-endemic regions and, with reference to existing data, to infer the phylogenetic and phylogeographic relationships among the samples.Methodology151 Ascaris worms from pigs and humans were characterized using PCR-RFLP on nuclear ITS rDNA. Representative geographical sub-samples were also analysed by sequencing a portion of the mitochondrial cox1 gene, to infer the extent of variability at population level. Sequence data were compared to GenBank sequences from endemic and non-endemic regions.Principal FindingsNo fixed differences between human and pig Ascaris were evident, with the exception of the Slovak population, which displays significant genetic differentiation. The RFLP analysis confirmed pig as a source of human infection in non-endemic regions and as a corridor for the promulgation of hybrid genotypes. Epidemiology and host-affiliation seem not to be relevant in shaping molecular variance. Phylogenetic and phylogeographical analyses described a complex scenario, involving multiple hosts, sporadic contact between forms and an ancestral taxon referable to A. suum. Conclusions/SignificanceThese results suggest the existence of homogenizing gene flow between the two taxa, which appear to be variants of a single polytypic species. This conclusion has implications on the systematics, transmission and control programs relating to ascariasis.

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Section: Discussionsupporting

confidence: 69%

Phylogeographical Studies of Ascaris spp. Based on Ribosomal and Mitochondrial DNA Sequences

et al. 2013

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“…The cox 1 haplotypes identified add to the growing database of Ascaris cox 1 sequences from human and pig hosts [12, 15, 19, 20, 39, 40]. They fell into 3 groups, which correspond to clusters A – C, identified previously [12, 40].…”

Section: Discussionmentioning

confidence: 85%

Molecular Epidemiology of Ascariasis: A Global Perspective on the Transmission Dynamics of Ascaris in People and Pigs

Betson¹,

Nejsum²,

Bendall³

et al. 2014

The Journal of Infectious Diseases

114

117

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Background. The roundworm Ascaris lumbricoides infects 0.8 billion people worldwide, and Ascaris suum infects innumerable pigs across the globe. The extent of natural cross-transmission of Ascaris between pig and human hosts in different geographical settings is unknown, warranting investigation.Methods. Adult Ascaris organisms were obtained from humans and pigs in Europe, Africa, Asia, and Latin America. Barcodes were assigned to 536 parasites on the basis of sequence analysis of the mitochondrial cytochrome c oxidase I gene. Genotyping of 410 worms was also conducted using a panel of microsatellite markers. Phylogenetic, population genetic, and Bayesian assignment methods were used for analysis.Results. There was marked genetic segregation between worms originating from human hosts and those originating from pig hosts. However, human Ascaris infections in Europe were of pig origin, and there was evidence of cross-transmission between humans and pigs in Africa. Significant genetic differentiation exists between parasite populations from different countries, villages, and hosts.Conclusions. In conducting an analysis of variation within Ascaris populations from pig and human hosts across the globe, we demonstrate that cross-transmission takes place in developing and developed countries, contingent upon epidemiological potential and local phylogeography. Our results provide novel insights into the transmission dynamics and speciation of Ascaris worms from humans and pigs that are of importance for control programs.

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“…Samples were ground in liquid nitrogen and DNA extraction was conducted using the QIAamp® DNA Mini Kit (Qiagen), as described by Iñiguez et al (2012). DNA was quantified using a spectrophoto meter (Gene Quant II, Pharmacia Biotech).…”

Section: Dna Extraction and Pcr Assaymentioning

confidence: 99%

Morphological and genetic identification of Anisakis paggiae (Nematoda: Anisakidae) in dwarf sperm whale Kogia sima from Brazilian waters

Azevedo¹,

Knoff²,

Carvalho³

et al. 2015

Dis. Aquat. Org.

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Anisakid nematodes have been identified in a wide variety of fish and marine mammal species. In Brazil, Anisakis physeteris, A. insignis, A. typica, A. nascetti, and those of the A. simplex complex have been reported infecting fishes and cetaceans. In this study, specimens collected from a dwarf sperm whale Kogia sima (Owen, 1866) stranded on the northeastern coast of Brazil were identified through morphological and genetic analyses as A. paggiae. Anisakids were examined through differential interference contrast light and scanning electron microscopy (SEM). Morphological and morphometric analysis revealed that these specimens belonged to Anisakis sp. clade II and more specifically to A. paggiae, exhibiting a violin-shaped ventriculus and 3 denticulate caudal plates, which are taxonomic characters considered unique to this species. Genetic analysis based on the mtDNA cox2 gene confirmed our identification of A. paggiae. Phylogenetic trees using both maximum likelihood and neighbor-joining methods revealed a strongly supported monophyletic clade (bootstrap support = 100%) with all available A. paggiae sequences. Integrative taxonomic analysis allowed the identification of A. paggiae for the first time in Brazilian waters, providing new data about their geographical distribution. Moreover, here we present the first SEM images of this species.

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Genetic characterisation and molecular epidemiology of Ascaris spp. from humans and pigs in Brazil

Cited by 27 publications

References 31 publications

Phylogeographical Studies of Ascaris spp. Based on Ribosomal and Mitochondrial DNA Sequences

Phylogeographical Studies of Ascaris spp. Based on Ribosomal and Mitochondrial DNA Sequences

Molecular Epidemiology of Ascariasis: A Global Perspective on the Transmission Dynamics of Ascaris in People and Pigs

Morphological and genetic identification of Anisakis paggiae (Nematoda: Anisakidae) in dwarf sperm whale Kogia sima from Brazilian waters

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