Insights about echinostomiasis by paleomolecular diagnosis

Epidemiology and Geographical Distribution of Human Trematode Infections

Digenetic trematodes infecting humans are more than 109 species that belong to 49 genera all over the world. According to their habitat in the definitive hosts, they are classified as 6 blood flukes (Schistosoma japonicum. S. mekongi, S. malayensis, S. mansoni, S. intercalatum, and S. haematobium), 15 liver flukes (Fasciola hepatica, F. gigantica, Clonorchis sinensis, Opisthorchis viverrini, O. felineus, Dicrocoelium dendriticum, D. hospes, Metorchis bilis, M. conjunctus, M. orientalis, Amphimerus sp., A. noverca, A. pseudofelineus, Pseudamphistomum truncatum, and P. aethiopicum), nine lung flukes (Paragonimus westermani, P. heterotremus, P. skrjabini, P. skrjabini miyazakii, P. kellicotti, P. mexicanus, P. africanus, P. uterobilateralis, and P. gondwanensis), 30 heterophyid intestinal flukes (Metagonimus yokogawai, M. takahashii, M. miyatai, M. suifunensis, M. katsuradai, M. pusillus, M. minutus, Heterophyes heterophyes, H. nocens, H. dispar, Haplorchis taichui, H. pumilio, H. yokogawai, H. vanissinus, Centrocestus formosanus, C. armatus, C. cuspidatus, C. kurokawai, Procerovum calderoni, P. varium, Pygidiopsis genata, P. summa, Stictodora fuscata, S. lari, Stellantchasmus falcatus, Heterophyopsis continua, Acanthotrema felis, Apophallus donicus, Ascocotyle longa, and Cryptocotyle lingua), 24 echinostome intestinal flukes (Echinostoma revolutum, E. cinetorchis, E. mekongi, E. paraensei, E. ilocanum, E. lindoense, E. macrorchis, E. angustitestis, E. aegyptica, Isthmiophora hortensis, I. melis, Echinochasmus japonicus, E. perfoliatus, E. lilliputanus, E. caninus, E. jiufoensis, E. fujianensis, Artyfechinostomum malayanum, A. sufrartyfex, A. oraoni, Acanthoparyphium tyosenense, Echinoparymphium recurvatum, Himasthla muehlensi, and Hypoderaeum conoideum), 23 miscellaneous intestinal flukes (Brachylaima cribbi, Caprimolgorchis molenkampi, Phaneropsolus bonnei, P. spinicirrus, Cotylurus japonicus, Fasciolopsis buski, Gastrodiscoides hominis, Fischoederius elongatus, Watsonius watsoni, Gymnophalloides seoi, Gynaecotyla squatarolae, Microphallus brevicaeca, Isoparorchis hypselobagri, Nanophyetus salmincola, N. schikobalowi, Neodiplostomum seoulense, Fibricola cratera, Plagiorchis muris, P. vespertilionis, P. harinasutai, P. javensis, P. philippinensis, and Prohemistomum vivax), one throat fluke (Clinostomum complanatum), and one pancreatic fluke (Eurytrema pancreaticum). The mode of transmission to humans includes contact with cercariae contaminated in water (schistosomes) or ingestion of raw or improperly cooked food, including fish (liver flukes, heterophyid flukes, echinostomes, and throat flukes), snails (echinostomes, brachylaimids, and gymnophallid flukes), amphibia, reptiles (neodiplostomes), aquatic vegetables (fasciolids and amphistomes), and insect larvae or adults (lecithodendriids, plagiorchiids, and pancreatic flukes). Praziquantel has been proven to be highly effective against almost all kinds of trematode infections except Fasciola spp. Epidemiological surveys and detection of human infections are required for a better understanding of the prevalence, intensity of infection, and geographical distribution of each trematode species.

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.

Taxonomy of Echinostoma revolutum and 37-Collar-Spined Echinostoma spp.: A Historical Review

Echinostoma flukes armed with 37 collar spines on their head collar are called as 37-collar-spined Echinostoma spp. (group) or 'Echinostoma revolutum group'. At least 56 nominal species have been described in this group. However, many of them were morphologically close to and difficult to distinguish from the other, thus synonymized with the others. However, some of the synonymies were disagreed by other researchers, and taxonomic debates have been continued. Fortunately, recent development of molecular techniques, in particular, sequencing of the mitochondrial (nad1 and cox1) and nuclear genes (ITS region; ITS1-5.8S-ITS2), has enabled us to obtain highly useful data on phylogenetic relationships of these 37-collar-spined Echinostoma spp. Thus, 16 different species are currently acknowledged to be valid worldwide, which include E. revolutum, E. bolschewense, E. caproni, E. cinetorchis, E. deserticum, E. lindoense, E. luisreyi, E. mekongi, E. miyagawai, E. nasincovae, E. novaezealandense, E. paraensei, E. paraulum, E. robustum, E. trivolvis, and Echinostoma sp. IG of Georgieva et al., 2013. The validity of the other 10 species is retained until further evaluation, including molecular analyses; E. acuticauda, E. barbosai, E. chloephagae, E. echinatum, E. jurini, E. nudicaudatum, E. parvocirrus, E. pinnicaudatum, E. ralli, and E. rodriguesi. In this review, the history of discovery and taxonomic debates on these 26 valid or validity-retained species are briefly reviewed.

Foodborne intestinal flukes: A brief review of epidemiology and geographical distribution

Foodborne intestinal flukes are highly diverse consisting of at least 74 species with a diverse global distribution. Taxonomically they include 28 species of heterophyids, 23 species of echinostomes, and 23 species of miscellaneous groups (amphistomes, brachylaimids, cyathocotylids, diplostomes, fasciolids, gymnophallids, isoparorchiids, lecithodendriid-like group, microphallids, nanophyetids, plagiorchiids, and strigeids). The important heterophyid species (15 species) include Metagonimus yokogawai, M. takahashii, M. miyatai, Heterophyes heterophyes, H. nocens, Haplorchis taichui, H. pumilio, H. yokogawai, Heterophyopsis continua, Centrocestus formosanus, Pygidiopsis genata, P. summa, Stellantchasmus falcatus, Stictodora fuscata, and S. lari. The echinostome species of public health significance (15 species) include Echinostoma revolutum, E. cinetorchis, E. lindoense, E. ilocanum, Isthmiophora hortensis, Echinochasmus japonicus, E. perfoliatus, E. liliputanus, E. fujianensis, E. caninus, Acanthoparyphium tyosenense, Artyfechinostomum malayanum, A. sufrartyfex, A. oraoni, and Hypoderaeum conoideum. Among the other zoonotic intestinal flukes, Gastrodiscoides hominis, Brachylaima cribbi, Neodiplostomum seoulense, Fasciolopsis buski, Gymnophalloides seoi, Caprimolgorchis molenkampi, Phaneropsolus bonnei, Microphallus brevicaeca, Nanophyetus salmincola, and N. schikhobalowi (10 species) have drawn considerable medical attention causing quite a fair number of human infection cases. The principal mode of human infections include ingestion of raw or improperly cooked fish (heterophyids and echinostomes), snails including oysters (echinostomes and G. seoi), amphibians and reptiles (N. seoulense), aquatic vegetables (amphistomes and F. buski), and insect larvae or adults (C. molenkampi and P. bonnei). Epidemiological characteristics such as the prevalence, geographical distribution, and clinical and public health significance are poorly known in many of these species. Praziquantel has been proved to be highly effective against most species of intestinal fluke infections. Surveys and detection of human infection cases are urgently required for better understanding of the global status and public health significance of each species.

Intestinal parasites at the Late Bronze Age settlement of Must Farm, in the fens of East Anglia, UK (9th century B.C.E.)

Little is known about the types of intestinal parasites that infected people living in prehistoric Britain. The Late Bronze Age archaeological site of Must Farm was a pile-dwelling settlement located in a wetland, consisting of stilted timber structures constructed over a slow-moving freshwater channel. At excavation, sediment samples were collected from occupation deposits around the timber structures. Fifteen coprolites were also hand-recovered from the occupation deposits; four were identified as human and seven as canine, using fecal lipid biomarkers. Digital light microscopy was used to identify preserved helminth eggs in the sediment and coprolites. Eggs of fish tapeworm (Diphyllobothrium latum and Diphyllobothrium dendriticum), Echinostoma sp., giant kidney worm (Dioctophyma renale), probable pig whipworm (Trichuris suis) and Capillaria sp. were found. This is the earliest evidence for fish tapeworm, Echinostoma worm, Capillaria worm and the giant kidney worm so far identified in Britain. It appears that the wetland environment of the settlement contributed to establishing parasite diversity and put the inhabitants at risk of infection by helminth species spread by eating raw fish, frogs or molluscs that flourish in freshwater aquatic environments, conversely the wetland may also have protected them from infection by certain geohelminths.

Epidemiology of Trematode Infections: An Update

Digenetic trematodes infecting humans are more than 91 species which belong to 46 genera all over the world. According to their habitat in definitive hosts, they are classified as blood flukes (Schistosoma japonicum. S. mekongi, S. mansoni, S. haematobium, and S. intercalatum), liver flukes (Clonorchis sinensis, Opisthorchis viverrini, O. felineus, Metorchis conjunctus, M. bilis, M. orientalis, Fasciola hepatica, F. gigantica, Dicrocoelium dendriticum, and D. hospes), lung flukes (Paragonimus westermani, P. heterotremus, P. skrjabini, P. miyazakii, P. kellicoti, P. mexicanus, P. africanus, and P. uterobilateralis), throat fluke (Clinostomum complanatum), pancreatic fluke (Eurytrema pancreaticum), and intestinal flukes (Metagonimus yokogawai, M. miyatai, M. takahashii, Heterophyes nocens, H. heterophyes, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus formosanus, Echinostoma revolutum, E. ilocanum, Isthmiophora hortensis, Echinochasmus japonicus, E. lilliputanus, Artyfechinostomum malayanum, A. sufrartyfex, A. oraoni, Fasciolopsis buski, Gymnophalloides seoi, Neodiplostomum seoulense, Caprimolgorchis molenkampi, Phaneropsolus bonnei, and Plagiorchis muris). The mode of transmission to humans includes contact with cercariae contaminated in water (schistosomes) and ingestion of raw or improperly cooked fish (liver and throat flukes, heterophyids, and echinostomes), snails (echinostomes and gymnophallids), amphibia, reptiles (neodiplostomes), aquatic vegetables (amphistomes), or insect larvae or adults (plagiorchiids, lecithodendriids, and pancreatic fluke). Praziquantel has been proved to be highly effective against most species of trematode infections except fascioliasis. Epidemiological surveys and detection of human infections are required for better understanding of the geographical distribution and endemicity of each trematode species.

Echinochasmus swabiensis n. sp. (Digenea: Echinostomatidae) from Black Kite (Milvus Migrans Migrans) in Swabi District, Pakistan

A new species of the genus Echinochasmushas been described from the small intestine of the black kite (Milvus m. migrans) collected from Swabi, Khyber Pakhtunkhwa, Pakistan and identified as E. swabiensis n. sp. The new species is different from its congeners in its body size; it has 22 collar spines which includes two corner spines on one side, four on the other side and eight marginal plus ventral spines on each side. There aretegumental-scale like spines interspersed on the anterior margin of the ventral sucker with a smaller, terminal oral sucker. The pharynx is nearly twice as large as the oral sucker, while the ventral sucker is nearly six times as large as the oral sucker. The suckers’ width ratio is 1 : 4.7 to 1 : 5.6. The vitelline follicles are compact and denser at the lateral sides masking the caeca. This species has been added to the record of trematodes circulating among avian species, especially in the study area.

Reestablishing rigor in archaeological parasitology

Archaeological parasitology originated in the mid-twentieth century with interdisciplinary teams of specialists directed by archaeologists. The goals of such studies were detailed analyses of dietary, medicinal, and environmental factors that shaped the patterns of infection. By the 1970s, a cadre of unique coprolite analysts was trained to analyze macroscopic and microscopic remains for integrated reconstructions of the cultural determinants of parasitism. During these first phases of research, diagnostic rigor was maintained by direct training of specialists in parasitology and archaeology sub-disciplines including archaeobotany and archaeopalynology. Near the end of the twentieth century, however, "paleoparasitology" was defined as a separate field focusing on defining parasite distribution through time and space. Ironically, this focus resulted in an increase in misdiagnosis, especially prominent after 2000. Paleoparasitology does not explicitly include other specialized studies in it research design. Thus, dietary, environmental and medicinal inferences have been neglected or lost as samples were destroyed solely for the purpose of parasitological analysis. Without ancillary archaeological studies, paleoparasitology runs the risk of separation from archaeological context, thereby reducing its value to the archaeologists who recover samples for analysis.

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.

Prehistoric Pathoecology as Represented by Parasites of a Mummy from the Peruaçu Valley, Brazil

Paleopathologists have begun exploring the pathoecology of parasitic diseases in relation to diet and environment. We are summarizing the parasitological findings from a mummy in the site of Lapa do Boquete, a Brazilian cave in the state of Minas Gerais. These findings in context of the archaeology of the site provided insights into the pathoecology of disease transmission in cave and rockshelter environments. We are presenting a description of the site followed by the evidence of hookworm, intestinal fluke, and Trypanosoma infection with resulting Chagas disease in the mummy discovered in the cave. These findings are used to reconstruct the transmission ecology of the site.

Past Intestinal Parasites

This chapter aims to provide some key points for researchers interested in the study of ancient gastrointestinal parasites. These few pages are dedicated to my colleague and friend, Prof. Adauto Araújo (1951-2015), who participated in the writing of this chapter. His huge efforts in paleoparasitology contributed to the development and promotion of the discipline during more than 30 years.

Echinostomes in Felid Coprolites from Brazil

The first record of Echinostoma (Trematoda: Echinostomatidae) in coprolites was from a mummified human body in Minas Gerais State, Brazil. The finding raised questions on this parasite's incidence in prehistoric populations and the natural hosts of each species in remote times. Echinostomes occur worldwide and, despite the wide range of hosts, there is no record of Echinostomatidae in felines in Brazil. This study reports the finding of Echinostomatidae eggs in felid coprolites in the Furna do Estrago Archaeological Site, located in Pernambuco State in the Brazilian semiarid. Despite the possibility of false parasitism, the finding expands the distribution of this Digenea in remote times and raises the hypothesis of other cases of echinostomiasis in pre-Colombian populations.

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.

History of echinostomes (Trematoda)

Echinostomatidae (Trematoda) is the largest family within the class Trematoda. Members of this family have been studied for many years in relation to their utility as basic research models in biodiversity and systematics and also as experimental models in parasitology since they offer many advantages. Echinostomes have contributed significantly to numerous developments in many areas studied by parasitologists and experimental biologists. In this review, we examine the history of the echinostomebased studies from the beginnings to the present. For this purpose, we have divided the history of echinostomes into four periods (i.e. 18(th) and 19(th) centuries, first half of the 20(th) century, second half of the 20(th) century and the late 20(th) and 21(th) century) according to the types of studies performed in each of them. Moreover, we also briefly review the history of echinostome infections in humans.