Alena Mayo Iñiguez

Are Ascaris lumbricoides and Ascaris suum a single species

Since the original description and naming of Ascaris lumbricoides from humans by Linnaeus in 1758 and later of Ascaris suum from pigs by Goeze 1782, these species have been considered to be valid. Four hypotheses relative to the conspecificity or lack thereof (and thus origin of these species) are possible: 1) Ascaris lumbricoides (usually infecting humans) and Ascaris suum (recorded mostly from pigs) are both valid species, with the two species originating via a speciation event from a common ancestor sometime before the domestication of pigs by humans, or 2) Ascaris lumbricoides in humans is derived directly from the species A. suum found in pigs with A. suum then existing as a persistent ancestor after formation of A. lumbricoides, or 3) Ascaris suum is derived directly from A. lumbricoides with the persistent ancestor being A. lumbricoides and A. suum being the newly derived species, and finally, 4) Ascaris lumbricoides and A. suum are the same species, this hypothesis being supported by studies showing both low morphological and low genetic divergence at several genes. We present and discuss paleoparasitological and genetic evidence that complement new data to evaluate the origin and evolution of Ascaris spp. in humans and pigs, and the uniqueness of the species in both hosts. Finally, we conclude that Ascaris lumbricoides and A. suum are a single species and that the name A. lumbricoides Linnaeus 1758 has taxonomic priority; therefore A. suum Goeze 1782 should be considered a synonym of A. lumbricoides.

Enterobius vermicularis: ancient DNA from north and south American human coprolites

A molecular paleoparasitological diagnostic approach was developed for Enterobius vermicularis. Ancient DNA was extracted from 27 coprolites from archaeological sites in Chile and USA. Enzymatic amplification of human mtDNA sequences confirmed the human origin. We designed primers specific to the E. vermicularis 5S ribosomal RNA spacer region and they allowed reproducible polymerase chain reaction identification of ancient material. We suggested that the paleoparasitological microscopic identification could accompany molecular diagnosis, which also opens the possibility of sequence analysis to understand parasite-host evolution.

Paleoparasitology: Perspectives with New Techniques

Paleoparasitology is the study of parasites found in archaeological material. The development of this field of research began with histological identification of helminth eggs in mummy tissues, analysis of coprolites, and recently through molecular biology. An approach to the history of paleoparasitology is reviewed in this paper, with special reference to the studies of ancient DNA identified in archaeological material.

Molecular paleoparasitological diagnosis of Ascaris sp. from coprolites: new scenery of ascariasis in pre-Colombian South America times

Paleoparasitological studies using microscopy showed that Ascarisand Trichuris trichiura are the human intestinal parasites most found in archaeological sites. However, in pre-Columbian South American archaeological sites, Ascaris is rare. In this work we standardized a molecular methodology for Ascaris diagnosis directly from ancient DNA retrieved from coprolites. Using cythochrome b gene (142 bp) target, ancient DNA sequences were retrieved from South American samples, negative by microscopy. Moreover, the methodology applied was sensitive enough to detect ancient DNA extracted from 30 Ascaris eggs from an European coprolite. These results revealed a new scenery for the paleodistribution of Ascaris in South America.

Genetic and morphological characterisation of a new species of the genus Hysterothylacium (Nematoda) from Paralichthys isosceles Jordan, 1890 (Pisces: Teleostei) of the Neotropical Region, state of Rio de Janeiro, Brazil

Taking into account the difficulties of taxonomic identification of larval anisakid nematodes based on morphological characters, genetic analyses were performed, together with those usually applied, in order to identify anisakid larvae found in the flounder Paralichthys isosceles from the littoral of the state of Rio de Janeiro, Brazil. The analysis of 1,820 larvae revealed a new species, similar to Hysterothylacium MD, Hysterothylacium 2, Hysterothylacium KB and Hysterothylacium sp regarding the absence of the larval tooth, an excretory pore situated below the nerve ring level, and slender lateral alae. Moreover, the new species differs from Hysterothylacium fortalezae and Hysterothylacium reliquens with regard to the number and size of spines present on the tail end and from Hysterothylacium patagonicus by the absence of interlabia. The maximum parsimony and neighbour joining tree topologies based on the 18S ribosomal DNA gene, complete internal transcribed spacer region and cytochrome oxidase 2 (COII) gene demonstrated that the Brazilian larvae belong to Raphidascarididae and represent a unique genetic entity, confirmed as a new Hysterothylacium species. Furthermore, the new species presents COII genetic signatures and shares polymorphisms with Raphidascarididae members. This is the first description of a new anisakid species from Brazil through the integration of morphological and molecular taxonomy data.

Food, parasites, and epidemiological transitions: A broad perspective

Pathoecology provides unique frameworks for understanding disease transmission in ancient populations. Analyses of Old and New World archaeological samples contribute empirically to our understanding of parasite infections. Combining archaeological and anthropological data, we gain insights about health, disease, and the way ancient people lived and interacted with each other and with their environments. Here we present Old and New World parasite evidence, emphasizing how such information reflects the different ways ancient populations exploited diverse environments and became infected with zoonotic parasites. It is clear that the most common intestinal helminths (worm endoparasites) were already infecting ancient inhabitants of the New World prior to the European conquest, although not so intensely as in ancient Europe. The first paleoepidemiological transition from hunting-gathering to agriculture did not change the zoonotic infection pattern of people in the Americas. However, the same transition in Europe resulted in increased zoonotic parasitism with parasites from domestic animals. Therefore, there is a demonstrable difference in the impact of the first paleoepidemiologic transition in the Americas compared to Europe.

Molecular diagnosis of ascariasis from human feces and description of a new Ascaris sp. genotype in Brazil.

It is estimated that 120 million people are infected by Ascaris lumbricoides in Latin America, but few genomic studies have been conducted. We tested protocols for DNA extraction to obtain an Ascaris sp. molecular diagnosis from human feces, with the emphasis on PCR specificity and sensitivity. Ascaris sp. was detected in 100% of positive fecal samples using physico-chemical DNA extraction and the cytb gene and ITS1 as molecular targets. The method was sufficiently sensitive to detect Ascaris sp. from one isolated egg or four eggs in a fecal sample. Regarding the PCR specificity, there was no cross-reactivity when applied to Trichuris trichiura-positive fecal samples or in Ascaris sp. samples also positive to T. trichiura or Enterobius vermicularis. The ITS1 sequence analysis revealed two genotypes among the sample: the G1 genotype, the most prevalent in humans, and a new genotype, G6, described for the first time in Brazilian samples.

Analysis of Ancient DNA from Coprolites: a Perspective with Random Amplified Polymorphic DNA-Polymerase Chain Reaction Approach

The aim of this work was to determine approaches that would improve the quality of ancient DNA (aDNA) present in coprolites to enhance the possibility of success in retrieving specific sequence targets. We worked with coprolites from South American archaeological sites in Brazil and Chile dating up to 7,000 years ago. Using established protocols for aDNA extraction we obtained samples showing high degradation as usually happens with this kind of material. The reconstructive polymerization pretreatment was essential to overcome the DNA degradation and the serial dilutions helped with to prevent polymerase chain reaction (PCR) inhibitors. Moreover, the random amplified polymorphic DNA-PCR has been shown to be a reliable technique for further experiments to recover specific aDNA sequences.

ITS1 intra-individual variability of Ascaris isolates from Brazil.

The zoonotic potential of Ascaris infecting pigs has stimulated studies of molecular epidemiology with internal transcribed spacer 1 (ITS1) as the target. The aim of this study was to determine the value of Ascaris ITS1 as a molecular marker through assessing the intra-individual genetic diversity of Ascaris isolates from two geographical areas of Brazil. DNA was extracted from single isolated eggs, ITS1 PCR was performed, and the PCR products were cloned and sequenced. Clone analysis showed high ITS1 intra-individual variability revealed by 2-4 ITS1 genotypes/haplotypes per sample (egg). Two genotypes, G1 and G6, and 13 new haplotypes were detected and characterized. The most prevalent in humans, G1 and/or the Brazilian G6, were detected in all samples. Except for genotype G1, no relationship was observed between Brazilian ITS1 genotypes/haplotypes and those previously described in China, Bangladesh, Japan, United Kingdom, Australia, and Denmark, with respect to geographic origin or host affiliation. However, an association between the two geographically separated Brazilian ITS1 isolates was observed. The ITS1 intra-individual variability revealed in this study indicated that the use of this genetic region to discriminate human and pig Ascaris genotypes should be reconsidered.

Genetic characterization of Anisakis typica and Anisakis physeteris from marine mammals and fish from the Atlantic Ocean off Brazil.

Until now, Anisakis typica has been the sole anisakid identified by means of genetic markers from the Atlantic Ocean off Brazil. In this study we developed, and applied to larvae and adults, an A. typica-specific molecular identification protocol based on the complete intergenic transcribed spacer (ITS) region. Anisakids from the dolphin Sotalia guianensis and from the frigate tuna, Auxis thazard, caught off the coast of Brazil, were processed using two DNA extraction methods. Molecular diagnosis identified A. typica in 13 of 15 samples. Complete ITS analysis showed that the remaining two isolates were in fact A. physeteris. Maximum parsimony analysis of complete ITS region (915 bp) confirmed these results. Our study verified the dominance of A. typica infecting hosts from the Brazilian coast and showed, for the first time, the presence of A. physeteris in the intermediate/paratenic host A. thazard in this region.