Daniela Leles

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.

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.

Studies on protozoa in ancient remains - A Review

Paleoparasitological research has made important contributions to the understanding of parasite evolution and ecology. Although parasitic protozoa exhibit a worldwide distribution, recovering these organisms from an archaeological context is still exceptional and relies on the availability and distribution of evidence, the ecology of infectious diseases and adequate detection techniques. Here, we present a review of the findings related to protozoa in ancient remains, with an emphasis on their geographical distribution in the past and the methodologies used for their retrieval. The development of more sensitive detection methods has increased the number of identified parasitic species, promising interesting insights from research in the future.

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.

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.

PALEOEPIDEMIOLOGY OF INTESTINAL PARASITES AND LICE IN PRE-COLUMBIAN SOUTH AMERICA

Some human parasites originated in prehominid ancestors in Africa. Nematode species, such as Enterobius vermicularis (pinworm), hookworms and Trichuris trichiura are shared by humans and other close phylogenetic primates (Pan and Gorilla), showing that they infected a common ancestor to this group. When humans migrated from Africa to other continents they carried these parasites wherever climate conditions allowed parasite transmission from host to host. Other parasites, however, were acquired throughout human biological and social evolutive history when new territories were occupied. Paleoparasitology data is a valuable source to recover emergence and disappearance of parasite infections through analysis of archaeological remains. Parasites can be used as biological markers of prehistoric human migrations. They are also indicators of diet, as parasite life cycles are related to specific kinds of food consumed by human groups in the different habitats they occupied. We review paleoparasitological findings in South America, comparing human-host and intestinal parasites with life conditions and environmental relationships through time.

Discovery of a 240 million year old nematode parasite egg in a cynodont coprolite sheds light on the early origin of pinworms in vertebrates

BackgroundWe report the discovery of a nematode parasite egg (Nemata: Oxyurida) from a coprolite closely associated with the remains of several species of Cynodontia, dated to 240 million years old. This finding is particularly significant because this is the oldest record of an oxyurid nematode yet discovered, and because the cynodonts are considered a stem-group of the mammals.MethodsWe extracted material from a fully mineralized coprolite by both scraping the surface, and removing fragments from its interior with clean dental instruments used a single time. A single drop of glycerol from a new vial was added as a clearing reagent. Each slide was sealed with wax and examined with an optical microscope at 100× to 400× magnification.ResultsFrom one coprolite, 550 slides were examined; from 275 of these slides, sediment was examined that was scraped from the surface of the coprolite, and from the other 275 slides, material was examined that was extracted from the interior of the coprolite. All microscopic structures encountered were photographed, measured, and identified when possible.ConclusionsFrom the coprolite examined, we discovered an egg representing a new species of pinworm that, based on the egg structure, clearly places it in the family Heteroxynematidae. Nematodes of the order Oxyurida have very constrained life-histories, occurring only in animals that are not strictly carnivorous and also ingest large amounts of plant material. This fact enabled us to determine which species of cynodont, from several collected at the site in Brazil, are most likely the depositors of the coprolite, and therefore were the putative host of the parasite.

A new ascarid species in cynodont coprolite dated of 240 million years

Cynodonts represent the transition from reptiles to mammals. They are classified as synapsids, or tetrapod animals with mammalian characteristics. We present here the finding of helminth eggs in a coprolite identified as of cynodont origin dated of nearly 240 million years. Microscopy revealed the presence of very well preserved intestinal parasite eggs. Up to now we identified an ascarid egg by morphological characteristics. Based on a previous description of the new genus Ascarites Poinar Jr and Boucot 2006 in coprolites of iguanodons from Belgium, we propose a new species, Ascarites rufferi n.sp. in cynodonts, a host that inhabited the Southern Region of Brazil in the Triassic period.

Leishmania tarentolae molecular signatures in a 300 hundred-years-old human Brazilian mummy.

BackgroundL. tarentolae, the lizard-infecting species of Old World geckos, has been classified as non-pathogenic to man. While it has been demonstrated that L. tarentolae is capable of infecting human phagocytic cells and to differentiate into amastigote-like forms, there is no clear evidence for its efficient replication within macrophages. Here we provide first evidence for L. tarentolae ancient DNA sequences from bone marrow and intestines of a 300yo adult male.MethodsWe identified molecular signatures of Leishmania tarentolae, the lizard-infecting species of Old World geckos, in hard and soft tissue biopsies from a Brazilian mummy (A74) uncovered in Itacambira (Brazil) and dating to the Colonial Period (end of 18th/beginning of the 19th century).ResultsOur results imply that efficient replication of the parasite occurred within human macrophage and to lead to a systemic spread and visceralization in this individual. The ancient sequences show a 100% similarity with those of isolated L. tarentolae parasites grown on artificial nutrient media and a 99% similarity with two modern sequences isolated from reptiles.ConclusionsDe facto, our findings re-open the debate about the potential survival of ancient L. tarentolae strain within human macrophage and its ability to spread systemically. They also raise ecological issues since it is unknown whether this parasite circulates in the reptilian reservoir in modern day Brazil or not. Investigations on fossil fauna and arthropods are needed to shed light on the interactions between saurian Leishmania and lizards in Brazil’s remote and recent past.