Paleoparasitological report on Ascaris aDNA from an ancient East Asian sample

Paleoparasitology research on ancient helminth eggs and larvae in the Republic of Korea

Paleoparasitology is a discipline that applies existing conventional and molecular techniques to study parasites found in ancient ruins. This review focuses on the history of the discovery of parasites (mostly helminth eggs and larvae) in archaeological soil samples and mummies in Korea from the Three Kingdoms Period to the Joseon Dynasty (100 BCE-1910 CE). We also briefly review important milestones in global paleoparasitology. The helminth species reported so far in Korea included Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis (larva), Trichostrongylus sp. (larva), Paracapillaria philippinensis (syn. Capillaria philippinensis), Enterobius vermicularis, Fasciola hepatica, dicrocoeliids, Paragonimus westermani, Clonorchis sinensis, Metagonimus yokogawai, Pygidiopsis summa, Gymnophalloides seoi, Isthmiophora hortensis, Dibothriocephalus nihonkaiensis (syn. Diphyllobothrium nihonkaiense), and Taenia spp. tapeworms. The findings obtained by Korean paleoparasitologists/archaeologists have brought about deep insight into the status of helminthic infections in Korea's past populations. Continued paleoparasitological research is essential for further understanding of ancient parasites and parasitic diseases in Korea.

Gastrointestinal parasite burden in 4th-5th c. CE Florence highlighted by microscopy and paleogenetics

The study of ancient parasites, named paleoparasitology, traditionally focused on microscopic eggs disseminated in past environments and archaeological structures by humans and other animals infested by gastrointestinal parasites. Since the development of paleogenetics in the early 1980s, few paleoparasitological studies have been based on the ancient DNA (aDNA) of parasites, although such studies have clearly proven their utility and reliability. In this paper, we describe our integrative approach for the paleoparasitological study of an ancient population from Florence in Italy, dated to the 4th-5th c. CE. The first stage consisted in the study of sediment samples from the pelvic area of 18 individuals under light microscopy. This allowed us to detect Ascarid-type eggs belonging very probably to the human-infesting roundworm Ascaris lumbricoides. Ten subsamples were selected corresponding to five individuals, and we extracted their whole DNA following sediment aDNA protocols. A targeted approach allowed us to detect two nematodes and one trematode aDNA fragments, namely Ascaris sp., Trichuris trichiura, and Dicrocoelium dendriticum. Among the five individuals tested for microscopic eggs and aDNA, three of them showed the remains of eggs (only Ascarid-type), but all of them tested positive to the presence of at least one parasite aDNA. Microscopic diagnosis first guided our research for the selection of promising samples while the targeted aDNA approach significantly improved our knowledge in terms of parasitic diversity and frequency in this population subgroup. These results enabled us to discuss the possible impact of latent parasitism in this past population at the time of an epidemic, as suggested in Florence. In particular, the singular case of D. dendriticum detection is discussed in light of the present-day scarcity of genuine human infections. Nevertheless, actual infections are known in the paleoparasitological record, and food habits may have led to false parasitism in this historical context. aDNA leaching from overlying strata may also explain this detection. This study strongly pleads for a systematic integrative approach combining microscopy and aDNA in paleoparasitology.

Estimating molecular preservation of the intestinal microbiome via metagenomic analyses of latrine sediments from two medieval cities

Ancient latrine sediments, which contain the concentrated collective biological waste of past whole human communities, have the potential to be excellent proxies for human gastrointestinal health on the population level. A rich body of literature explores their use to detect the presence of gut-associated eukaryotic parasites through microscopy, immunoassays and genetics. Despite this interest, a lack of studies have explored the whole genetic content of ancient latrine sediments through consideration not only of gut-associated parasites, but also of core community gut microbiome signals that remain from the group that used the latrine. Here, we present a metagenomic analysis of bulk sediment from medieval latrines in Riga (Latvia) and Jerusalem. Our analyses reveal survival of microbial DNA representative of intestinal flora as well as numerous parasites. These data are compared against parasite taxon identifications obtained via microscopy and ELISA techniques. Together, these findings provide a first glimpse into the rich prokaryotic and eukaryotic intestinal flora of pre-industrial agricultural populations, which may give a better context for interpreting the health of modern microbiomes.

This article is part of the theme issue ‘Insights into health and disease from ancient biomolecules’.

African helminth infection out of Africa: Paleoparasitological and paleogenetic investigations in Pretos Novos cemetery, Rio de Janeiro, Brazil (1769-1830)

Pretos Novos cemetery (PNC), Rio de Janeiro, Brazil (1769-1830) was created exclusively to bury enslaved Africans who died upon arrival at the city or before being sold in the slave market. The PNC site may be unique in the Americas in allowing the study of African parasite infections acquired in Africa. We aimed to identify parasites infecting PNC individuals through paleoparasitological and paleogenetic analyses. The bodies had been dismembered, placed in mass graves, and burned, and most human remains collected from the site are highly fragmented and show extensive degradation. Sacrum and pelvic sediments were collected from five individuals along with seven samples of sediment from other areas of the body, as controls. Samples were submitted to three parasitological techniques and, in paleogenetic analysis, to four molecular targets. Larvae, mites, pollen grains, and structure suggestive of plants and fungus were observed, but we found no evidence of helminth infection. Ascaris sp. cytb sequence was recovered in one individual. We emphasize that, even with the extensive degradation of PNC human remains and the process of curation of samples, it was possible to recover helminth aDNA. The origin of PNC individuals confirms that these infections were brought to Brazil from western and central Africa during the colonial era.

Mummification in Korea and China: Mawangdui, Song, Ming and Joseon Dynasty Mummies

Over the decades, mummy studies have expanded to reconstruct a multifaceted knowledge about the ancient populations' living conditions, pathologies, and possible cause of death in different spatiotemporal contexts. Mainly due to linguistic barriers, however, the international knowledge of East Asian mummies has remained sketchy until recently. We thus analyse and summarize the outcomes of the studies so far performed in Korea and China in order to provide mummy experts with little-known data on East Asian mummies. In this report, similarities and differences in the mummification processes and funerary rituals in Korea and China are highlighted. Although the historical periods, the region of excavation, and the structures of the graves differ, the cultural aspects, the mechanisms of mummification, and biological evidence appear to be essentially similar to each other. Independently from the way they are called locally, the Korean and Chinese mummies belong to the same group with a shared cultural background.

DNA barcoding of ancient parasites

Ancient samples present a number of technical challenges for DNA barcoding, including damaged DNA with low endogenous copy number and short fragment lengths. Nevertheless, techniques are available to overcome these issues, and DNA barcoding has now been used to successfully recover parasite DNA from a wide variety of ancient substrates, including coprolites, cesspit sediment, mummified tissues, burial sediments and permafrost soils. The study of parasite DNA from ancient samples can provide a number of unique scientific insights, for example: (1) into the parasite communities and health of prehistoric human populations; (2) the ability to reconstruct the natural parasite faunas of rare or extinct host species, which has implications for conservation management and de-extinction; and (3) the ability to view in ‘real-time’ processes that may operate over century- or millenial-timescales, such as how parasites responded to past climate change events or how they co-evolved alongside their hosts. The application of DNA metabarcoding and high-throughput sequencing to ancient specimens has so far been limited, but in future promises great potential for gaining empirical data on poorly understood processes such as parasite co-extinction.

Paleogenetic study on the 17th century Korean mummy with atherosclerotic cardiovascular disease

While atherosclerotic cardiovascular disease (ASCVD) is known to be common among modern people exposed to various risk factors, recent paleopathological studies have shown that it affected ancient populations much more frequently than expected. In 2010, we investigated a 17^th century Korean female mummy with presumptive ASCVD signs. Although the resulting report was a rare and invaluable conjecture on the disease status of an ancient East Asian population, the diagnosis had been based only on anatomical and radiological techniques, and so could not confirm the existence of ASCVD in the mummy. In the present study, we thus performed a paleogenetic analysis to supplement the previous conventional diagnosis of ASCVD. In aDNA extracted from the same Korean mummy, we identified the risk alleles of seven different SNPs (rs5351, rs10757274, rs2383206, rs2383207, rs10757278, rs4380028 and rs1333049) that had already been revealed to be the major risk loci of ASCVD in East Asian populations. The reliability of this study could be enhanced by cross-validation using two different analyses: Sanger and SNaPshot techniques. We were able to establish that the 17^th century Korean female had a strong genetic predisposition to increased risk of ASCVD. The current paleogenetic diagnosis, the first of its kind outside Europe, re-confirms its utility as an adjunct modality for confirmatory diagnosis of ancient ASCVD.

Palaeoparasitology and palaeogenetics: review and perspectives for the study of ancient human parasites

While some species of parasites can be identified to species level from archaeological remains using microscopy (i.e.Enterobius vermicularis,Clonorchis sinensis), others can only be identified to family or genus level as different species produce eggs with similar morphology (i.e.Tæniasp. andEchinococcussp.). Molecular and immunological approaches offer the possibility to provide more precise determination at the species level. They can also identify taxa when classic parasite markers such as eggs or cysts have been destroyed over time. However, biomolecules can be poorly preserved and modern reference DNA is available only for a limited number of species of parasites, leading to the conclusion that classic microscopic observation should be combined with molecular analyses. Here we present a review of the molecular approaches used over the past two decades to identify human pathogenic helminths (Ascarissp.,Trichurissp.,E. vermicularis,Fasciolasp. etc.) or protists (Giardiasp.,Trypanosomasp.,Leishmaniasp. etc.). We also discuss the prospects for studying the evolution of parasites with genetics and genomics.

Ancient Ascaris DNA Sequences of Cytochrome B, Cytochrome C Oxidase Subunit 1, NADH Dehydrogenase Subunit 1, and Internal Transcribed Spacer 1 Genes from Korean Joseon Mummy Feces

We analyzed Ascaris ancient DNA of cytochrome b, cytochrome c oxidase subunit 1, NADH dehydrogenase subunit 1, and internal transcribed spacer 1 genes extracted from the feces or precipitates of 15- to 18th-century Korean mummies. After multiple Ascaris genes in ancient samples were successfully amplified by polymerase chain reaction (PCR), consensus sequences could be determined by the alignment of the sequences of cloned PCR products. The obtained sequences of each gene were highly similar to those of Ascaris spp. reported thus far but were genetically distinct from Baylisascaris, Parascaris, and Toxascaris spp. The current report establishes that the genetic characteristics of the Ascaris spp. infecting pre-modern Korean societies were not uniform but were diverse to some degree.

A Case of Ectopic Paragonimiasis in a 17th Century Korean Mummy

Archaeoparasitological studies on fossilized feces obtained from Joseon Dynasty (1392-1910 CE) mummies have provided invaluable data on the patterns of parasitic infection in pre-modern Korean societies. In our recent radiological investigation of a 17th century Joseon mummy discovered in Cheongdo (South Korea), we located a liver mass just below the diaphragm. Anatomical dissection confirmed the presence of a mass of unknown etiology. A subsequent parasitological examination of a sample of the mass revealed a large number of ancient Paragonimus sp. eggs, making the current report the first archaeoparasitological case of liver abscess caused by ectopic paragonimiasis.

Ancient mitochondrial DNA analyses of ascaris eggs discovered in coprolites from joseon tomb

Analysis of ancient DNA (aDNA) extracted from Ascaris is very important for understanding the phylogenetic lineage of the parasite species. When aDNAs obtained from a Joseon tomb (SN2-19-1) coprolite in which Ascaris eggs were identified were amplified with primers for cytochrome b (cyt b) and 18S small subunit ribosomal RNA (18S rRNA) gene, the outcome exhibited Ascaris specific amplicon bands. By cloning, sequencing, and analysis of the amplified DNA, we obtained information valuable for comprehending genetic lineage of Ascaris prevalent among pre-modern Joseon peoples.

Palaeoparasitology - Human Parasites in Ancient Material

Parasite finds in ancient material launched a new field of science: palaeoparasitology. Ever since the pioneering studies, parasites were identified in archaeological and palaeontological remains, some preserved for millions of years by fossilization. However, the palaeoparasitological record consists mainly of parasites found specifically in human archaeological material, preserved in ancient occupation sites, from prehistory until closer to 2015. The results include some helminth intestinal parasites still commonly found in 2015, such as Ascaris lumbricoides, Trichuris trichiura and hookworms, besides others such as Amoebidae and Giardia intestinalis, as well as viruses, bacteria, fungi and arthropods. These parasites as a whole provide important data on health, diet, climate and living conditions among ancient populations. This chapter describes the principal findings and their importance for knowledge on the origin and dispersal of infectious diseases.

DNA typing of ancient parasite eggs from environmental samples identifies human and animal worm infections in Viking-age settlement

Ancient parasite eggs were recovered from environmental samples collected at a Viking-age settlement in Viborg, Denmark, dated 1018-1030 A.D. Morphological examination identified Ascaris sp., Trichuris sp., and Fasciola sp. eggs, but size and shape did not allow species identification. By carefully selecting genetic markers, PCR amplification and sequencing of ancient DNA (aDNA) isolates resulted in identification of: the human whipworm, Trichuris trichiura , using SSUrRNA sequence homology; Ascaris sp. with 100% homology to cox1 haplotype 07; and Fasciola hepatica using ITS1 sequence homology. The identification of T. trichiura eggs indicates that human fecal material is present and, hence, that the Ascaris sp. haplotype 07 was most likely a human variant in Viking-age Denmark. The location of the F. hepatica finding suggests that sheep or cattle are the most likely hosts. Further, we sequenced the Ascaris sp. 18S rRNA gene in recent isolates from humans and pigs of global distribution and show that this is not a suited marker for species-specific identification. Finally, we discuss ancient parasitism in Denmark and the implementation of aDNA analysis methods in paleoparasitological studies. We argue that when employing species-specific identification, soil samples offer excellent opportunities for studies of human parasite infections and of human and animal interactions of the past.

Paleoparasitological studies on mummies of the Joseon Dynasty, Korea

Paleoparasitology is the application of conventional or molecular investigative techniques to archeological samples in order to reveal parasitic infection patterns among past populations. Although pioneering studies already have reported key paleoparasitological findings around the world, the same sorts of studies had not, until very recently, been conducted in sufficient numbers in Korea. Mummified remains of individuals dating to the Korean Joseon Dynasty actually have proved very meaningful to concerned researchers, owing particularly to their superb preservation status, which makes them ideal subjects for paleoparasitological studies. Over the past several years, our study series on Korean mummies has yielded very pertinent data on parasitic infection patterns prevailing among certain Joseon Dynasty populations. In this short review, we summarized the findings and achievements of our recent paleoparasitological examinations of Joseon mummies and discussed about the prospects for future research in this vein.

Insights about echinostomiasis by paleomolecular diagnosis

Echinostomiasis is a zoonosis caused by intestinal trematodes and transmitted by the ingestion of mollusks, crustaceans, fish, amphibians, and reptiles, either raw or poorly cooked. Today human infection is endemic in Southeast Asia and the Far East, but has been reported more recently in other regions of the world. Interestingly eggs identified as Echinostoma sp. were found in coprolites from a mummified body human in Brazil, dated 560 ± 40 BP (before present). However, the specific diagnosis based on morphology of the eggs has not been resolved at the species level. As a follow-up to the previous finding, the current study now aims to standardize the methodology for molecular diagnosis and apply it to the coprolite, using current Echinostoma paraensei-positive feces as the reference, and also the same fecal material dried in a stove as an experimental coprolite model. Isolated eggs of E. paraensei and adult worm were included to verify the sensibility and as positive control, respectively. An adult worm of E. luisreyi was used for comparison. PCR using primers in-house for ITS1 region (126 bp) and cox1 (123 bp) of Echinostoma spp. and subsequent nucleotide sequencing were performed. This is the first molecular paleoparasitological diagnosis for echinostomiasis. The methodology was able to amplify specific DNA fragments for the genus Echinostoma sp. in all samples: adult worm, feces, and a single egg of the parasite, in both the experimental coprolite and archaeological sample. Additionally we observed that ancient DNA can also be retrieved without rehydrating the material. The nucleotide sequences from E. paraensei and E. luisreyi are very similar in the fragment analyzed that difficult the differentiation these species, but DNA sequence analysis recovered in the parasite found in the mummy showed more similarity with the species E. paraensei.

Polyphasic analysis of a middle ages coprolite microbiota, Belgium

Paleomicrobiological investigations of a 14(th)-century coprolite found inside a barrel in Namur, Belgium were done using microscopy, a culture-dependent approach and metagenomics. Results were confirmed by ad hoc PCR--sequencing. Investigations yielded evidence for flora from ancient environment preserved inside the coprolite, indicated by microscopic observation of amoebal cysts, plant fibers, seeds, pollens and mold remains. Seventeen different bacterial species were cultured from the coprolite, mixing organisms known to originate from the environment and organisms known to be gut inhabitants. Metagenomic analyses yielded 107,470 reads, of which known sequences (31.9%) comprised 98.98% bacterial, 0.52% eukaryotic, 0.44% archaeal and 0.06% viral assigned reads. Most abundant bacterial phyla were Proteobacteria, Gemmatimonadetes, Actinobacteria and Bacteroidetes. The 16 S rRNA gene dataset yielded 132,000 trimmed reads and 673 Operational Taxonomic Units. Most abundant bacterial phyla observed in the 16 S rRNA gene dataset belonged to Proteobacteria, Firmicutes, Actinobacteria and Chlamydia. The Namur coprolite yielded typical gut microbiota inhabitants, intestinal parasites Trichuris and Ascaris and systemic pathogens Bartonella and Bordetella. This study adds knowledge to gut microbiota in medieval times.

The changing pattern of parasitic infection among Korean populations by paleoparasitological study of Joseon Dynasty mummies

In the coprolites of 4 recently discovered Joseon mummies of Korea, we found Ascaris lumbricoides , Trichuris trichiura , Metagonimus yokogawai , Paragonimus westermani , and Clonorchis sinensis eggs. The current finding was compared with previous paleoparasitological data, and with recent national survey data from Korea. For A. lumbricoides and T. trichiura , similar patterns of infection prevalence were observed between the national survey of 1961 and our current Joseon data. Some of the trematode species (C. sinenesis and P. westermani) showed much higher infection prevalences among the Joseon Koreans than among their 1960s descendants. The present results indicate that the decrease in trematode infection rates might have begun earlier than was the case for nematode infection.

Palaeopathology and genes: investigating the genetics of infectious diseases in excavated human skeletal remains and mummies from past populations

The aim of this paper is to review the use of genetics in palaeomicrobiology, and to highlight the importance of understanding past diseases. Palaeomicrobiology is the study of disease pathogens in skeletal and mummified remains from archaeological contexts. It has revolutionarised our understanding of health in the past by enabling a deeper knowledge of the origins and evolution of many diseases that have shaped us as a species. Bacterial diseases explored include tuberculosis, leprosy, bubonic plague, typhoid, syphilis, endemic and epidemic typhus, trench fever, and Helicobacter pylori. Viral diseases discussed include influenza, hepatitis B, human papilloma virus (HPV), human T-cell lymphotrophic virus (HTLV-1) and human immunodeficiency virus (HIV). Parasitic diseases investigated include malaria, leishmaniasis, Chagas' disease, roundworm, whipworm, pinworm, Chinese liver fluke, fleas and lice. Through a better understanding of disease origins and their evolution, we can place into context how many infectious diseases are changing over time, and so help us estimate how they may change in the future.

Sixteenth century Gymnophalloides seoi infection on the coast of the Korean Peninsula

Gymnophalloides seoi is a trematode species discovered as recently as 1993. Interestingly, ancient G. seoi eggs were identified in our earlier study on a 17th Century female mummy unearthed in a Korean county (HD-1) where G. seoi infection, according to a nationwide survey of 2001, was considered not to have been endemic. Although we suspected that the geographical distribution of G. seoi might have contracted over the past several hundred years from wider coastal areas on the Korean peninsula to the much more restricted region delineated by the survey, there has been only the single, above-noted report of an ancient G. seoi infection in a currently non-endemic area. As such, more evidence is needed before our contraction theory of G. seoi infection prevalence can be confirmed as fact. Our current report in this regard will perhaps help to end the controversy. In a newly discovered 17th Century male mummy found in another Korean county considered non-endemic by the 2001 survey, we identified a large number of ancient G. seoi eggs. We believe that this additional evidence for a wider distribution of G. seoi infection prior to the 20th Century is invaluable support for our earlier hypothesis.

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.

Museums and disease: using tissue archive and museum samples to study pathogens

Molecular studies of archival and fossil samples have traditionally focused on the nucleic acids derived from the host species. However, there has recently been an increase in ancient DNA research on the identification and characterization of infectious agents within the hosts. The study of pathogens from the past provides great opportunities for discovering the causes of historical infection events, characterizing host-microorganism co-evolution and directly investigating the evolution of specific pathogens. Several research teams have been able to isolate and characterize a variety of different bacterial, parasite and viral microorganisms. However, this emerging field is not without obstacles. The diagenetic processes that make ancient DNA research generally difficult are also impediments to ancient pathogen research and perhaps more so given that their DNA may represent an even rarer proportion of the remaining nucleic acids in a fossil sample than host DNA. However, studies performed under controlled conditions and following stringent ancient DNA protocols can and have yielded reliable and often surprising results. This article reviews the advantages, problems, and failures of ancient microbiological research.