Introduction
In this special issue on palaeoparasitology, a noteworthy range of evidence has been brought together to improve our understanding of parasites in past populations. There are a number of factors that make this collection so strong. The first is the broad geographic spread, with papers from the Americas, Europe and Asia. The time scale covered is also very comprehensive, with evidence from early prehistory to the industrial period. However, the factor that could be its greatest strength is the range of techniques applied by contributing researchers to explore parasites in ancient civilizations. By exploring which techniques and approaches work best to answer different kinds of research questions, we can develop a more balanced approach to investigating ancient parasites. This should allow us to gain new insight into how parasites affected our ancestors and moulded the course of history. First, we will consider the sources of evidence available, and then the methods we can use to study these sources.
Sources of evidence
The most common material used in the study of ancient parasites is the remains of feces, where intestinal parasite eggs can be found. This may be recovered from within latrines and sewer drains, pelvic sediment of burials, coprolites (Figure 1) and the intestinal contents of mummies (Hong et al., Reference Hong, Yi, Seo, Baek, Han, Fujita, Oh and Shin2026; Ledger et al., Reference Ledger, Flammer, Smith, Birley and Mitchell2026; López-gijón et al., Reference López-Gijón, Duras, Jiménez-Brobeil, Fernández-Romero, Suliman, Maroto-Benavides, Sánchez-Montes and Mitchell2026; Minniti-Nogueras et al., Reference Minniti-Nogueras, Santana-Sagredo, Ramirez and Herrera-Soto2026; Ramirez et al., Reference Ramirez, Tavera Medina, Tantaleán and Nores2026). However, as demonstrated throughout this special issue, other equally valid source materials are available.
Human coprolite from the Aragon-1-site, Atacama Desert, Chile, dating to 240–370 CE (reproduced from Minniti-Nogueras et al., Reference Minniti-Nogueras, Santana-Sagredo, Ramirez and Herrera-Soto2026).
It has previously been noted that the most common parasites found in early settlements and later towns and cities are those spread by poor sanitation, such as whipworm (Trichuris sp.) and roundworm (Ascaris sp.) (Mitchell, Reference Mitchell2023). Instead of studying the latrines present in medieval Phanagoria on the Black Sea coast, Slepchenko’s team have cleverly studied sediment in the wells from the town in order to see if the water supply was clean or contaminated, and so better understand how these parasites were so successful (Slepchenko et al., Reference Slepchenko, Ostapenko, Khrustalev, Kashevskaya, Tretyakov and Bull2026).
Hair combs, clothes, mummies and sediment from past ground levels are all good sources of evidence for ectoparasites. When their hosts were alive some were stripped from hair using delousing combs and remain caught between their fine teeth, while others fell to the ground as their hosts engaged in their daily lives, to be mixed with all the other debris that made the soil surface of ancient settlements. Once their host died, the dried ectoparasite husks may still cling to the body or clothes of their long-deceased host, or be sieved from the sediment of their burials (Mitchell, Reference Mitchell2026; Panagiotakopulu, Reference Panagiotakopulu2026).
Written sources can be an excellent source of information about past diseases, what our ancestors thought caused them, and how they tried to treat them. However, in contrast to the number of studies analysing archaeological samples in the laboratory, only a small proportion of past research has focussed on ancient medical texts to find descriptions of parasites (see e.g. Trompoukis et al., Reference Trompoukis, German and Falagas2007; Jirsa and Winiwarter, Reference Jirsa and Winiwarter2010; Yeh et al., Reference Yeh, Zhan and Qi2019). In this issue, Jones has brought together descriptions in medieval medical texts from Europe to demonstrate what was understood about intestinal worms at that time (Jones, Reference Jones2026). Browning and Nicovich have used Roman and medieval descriptions of seasonal fevers in marshy regions to map malaria risk along trade routes in Turkiye (Browning and Nicovich, Reference Browning and Nicovich2026). In China, ancient texts dating back 3000 years were consulted to identify descriptions of illness that might be compatible with the periodic fevers associated with malaria (Li et al., Reference Li, Yuan and Wang2026). In a further study from China, texts from the Song Dynasty (960–1279 CE) were used to find evidence for intestinal parasites and the use of human feces to fertilize crops and increase agricultural yields (Chen et al., Reference Chen, Lee, Yapp and Yeh2026).
Methods for analysing these sources
Microscopy
Light microscopy is ideal for detecting the eggs of intestinal helminths. It is cost-efficient, and provides images that can be included in publications so that readers can be confident in the accuracy of the author’s diagnosis (Figure 2). This technique has successfully been used in papers in this special issue to identify the presence of Ascaris sp., Trichuris sp., Dibothriocephalus sp., Fasciola sp., Spirometra sp., Capillariids, Eimeria sp., Acanthocephala, strongylids, Dioctophymidae and others (Ledger et al., Reference Ledger, Flammer, Smith, Birley and Mitchell2026; López-Gijón et al., Reference López-Gijón, Duras, Jiménez-Brobeil, Fernández-Romero, Suliman, Maroto-Benavides, Sánchez-Montes and Mitchell2026; Minniti-Nogueras et al., Reference Minniti-Nogueras, Santana-Sagredo, Ramirez and Herrera-Soto2026; Ramirez et al., Reference Ramirez, Tavera Medina, Tantaleán and Nores2026; Slepchenko et al., Reference Slepchenko, Ostapenko, Khrustalev, Kashevskaya, Tretyakov and Bull2026).
Helminth eggs from wells at the Black Sea port city of Phanagoria dating to the 8th–9th century CE (reproduced from Slepchenko et al., Reference Slepchenko, Ostapenko, Khrustalev, Kashevskaya, Tretyakov and Bull2026). (A) Dibothriocephaliidae family (fish tapeworm), (B) Trichuris trichiura/suis (human or pig whipworm), (C) Trichuris muris (rodent whipworm), (D) Ascaris lumbricoides/suis (human or pig roundworm), (E) Calodium hepaticum and (F) Brachylaimidae sp. fluke.
Genetics
Ancient DNA can survive in archaeological contexts as short fragments of 50–100 base pairs. While recovering and identifying such fragments is clearly much more of a challenge than is the case for intact chromosomes in modern parasites, if the surviving fragments are unique to particular species of parasite they can be amplified and used to prove the presence of those species in that past population (Côté and Le Bailly, Reference Côté and Le Bailly2018). In this issue, the pelvic sediment of 2000-year-old burials from the coast of Brazil underwent ancient DNA analysis, identifying parasites of both humans and of the fish they consumed in their diet (Araújo et al., Reference Araújo, Brito, Pires, Furtado and Mayo Iñiguez2026). Recent genetic evidence for malaria in ancient human skeletal remains (Michel et al., Reference Michel, Skourtanioti, Pierini, Guevara, Mötsch, Kocher, Barquera, Bianco, Carlhoff, Bove, Freilich, Giffin, Hermes, Hiß, Knolle, Nelson, Neumann, Papac, Penske, Rohrlach, Salem, Semerau, Villalba-Mouco, Abadie, Aldenderfer, Beckett, Brown, Campus, Chenghwa, Berrocal, Damasek, Carlson, Durand, Ernée, Fântâneanu, Frenzel, Atiénzar, Guillén, Hsieh, Karwoski, Kelvin, Kelvin, Khokhlov, Kinaston, Korolev, Krettek, Küßner, Lai, Look, Majander, Mandl, Mazzarello, McCormick, de Miguel Ibáñez, Murphy, Németh, Nordqvist, Novotny, Obenaus, Olmo-Enciso, Onkamo, Orschiedt, Patrushev, Peltola, Romero, Rubino, Sajantila, Salazar-García, Serrano, Shaydullaev, Sias, Slaus, Stanco, Swanston, Teschler-Nicola, Valentin, Van de Vijver, Varney, Vigil-Escalera Guirado, Waters, Weiss-Krejci, Winter, Lamnidis, Prüfer, Nägele, Spyrou, Schiffels, Stockhammer, Haak, Posth, Warriner, Bos, Herbig and Krause2024) was also used to show which species of malaria were present in the past populations of Asia, so increasing the confidence in interpretation of textual descriptions of periodic fevers suggestive of malaria in both the eastern Mediterranean (Browning and Nicovich, Reference Browning and Nicovich2026) and China (Li et al., Reference Li, Yuan and Wang2026).
Enzyme-linked immunosorbent assay
Enzyme-linked immunosorbent assay (ELISA) is a biomolecular technique that employs antibodies that bind to proteins which are believed to be unique to particular parasite species. Their use allows the detection of protozoan parasites that have small and fragile reproductive phases that are often damaged by soil micro-organisms over the centuries and so extremely hard to detect using microscopy. In this issue ELISA test kits were employed to detect the cysts of Giardia duodenalis in the Roman period fort at Vindolanda, near Hadrian’s wall in northern Britain (Ledger et al., Reference Ledger, Flammer, Smith, Birley and Mitchell2026).
Historical texts
A logical starting point for investigating diseases in past societies would be to read the medical texts written by physicians of the time (Mitchell, Reference Mitchell2011). This approach has been used by Jones to bring together the relevant passages in medieval European manuscripts (Jones, Reference Jones2026). These describe the shape and size of those parasites the authors had seen, allowing us to speculate as to the species they likely witnessed. However, these texts take us further as they also tell us medieval views as to what caused parasites to form in the first place, and the preferred treatment options used by physicians.
Other approaches may choose to focus not on medical texts, but on different types of historical records. Chen and their team consulted 1000-year-old agricultural texts from China to better understand how human feces were used to fertilize crops (Chen et al., Reference Chen, Lee, Yapp and Yeh2026). Further texts describing life in Song period cities highlighted problems separating the water supply from sewage, and how foods such as raw and pickled fish and crustaceans were popular, which would all have placed the population at risk of parasite infection. In another study, descriptions of periodic fevers in ancient Chinese texts compatible with malaria dating back 3000 years were identified. The early Chinese character for malaria is a human on the left being attacked by a tiger on its hind legs on the right, showing how deadly malaria was regarded by the population (Figure 3). Changes to the environment made by humans were considered to explain why malaria became progressively more widespread over time (Li et al., Reference Li, Yuan and Wang2026).
Oracle bone script of the Chinese character for malaria, with a tiger on its back legs on the right attacking a standing human on the left (reproduced from Li et al., Reference Li, Yuan and Wang2026).
Geographic mapping
Once we know that a type of parasite was present in a region by a certain time period, we can start to ask more complex questions such as how common it was, and how prevalence might vary with changes in geography, seasonality, or with environmental conditions. In this way, maps can be created estimating infection prevalence at different time points. Browning and Nicovich (Reference Browning and Nicovich2026) delved deep into this by exploring malaria infection in Anatolia (modern Turkiye) in classical antiquity and the medieval period. By comparing data for malaria gathered in the early 1900s, knowledge of the past environment (such as the path of rivers and location of marshes) and the geographic variation in the region allowed them to develop a multilayer malaria risk model. This demonstrated that the malaria hot spots were present around the low-altitude coastal regions where rivers formed deltas and marshes (where the vector mosquitoes could breed) before emptying into the Mediterranean, Aegean and Black Sea (Figure 4).
Modelled malaria risk in Asia Minor/Anatolia in the Roman period; green low risk, red high risk (reproduced from Browing and Nicovich, Reference Browning and Nicovich2026).
Figure 4 Long description
Anatolia slash Asia Minor illustrates modeled malaria risk and Roman provinces around 0 dash AD. The legend indicates malaria risk with a gradient from low to high and outlines Roman provinces. Key regions labeled include Asia, Bithynia and Pontus, Galatia, Cappadocia, Lycia and Pamphylia, Cilicia and Syria. Coastal areas near the Mediterranean Sea and Black Sea show higher malaria risk, particularly around Cilicia and parts of Lycia and Pamphylia. Inland areas like Galatia and Cappadocia exhibit lower risk. The map also marks significant water bodies such as the Black Sea, Mediterranean Sea and Cyprus. Roads are depicted, connecting various regions, enhancing the understanding of historical connectivity. The scale bar indicates distances in kilometers, providing spatial context.
Another approach to mapping malaria risk has been applied to the medieval Netherlands, and exploited the ability of malaria infection to cause chronic anaemia. Schats employed a skeletal indicator that can be triggered by chronic anaemia (cribra orbitalia, Figure 5) in order to compare geographic regions where these changes were common or rare in medieval human skeletal remains. This geographic pattern was then compared to data for mosquito density in the Netherlands in the early 1900s (prior to modern drainage for agriculture). The variation matched, with the greatest prevalence of cribra orbitalia being found in areas with the highest mosquito density in the past (Schats, Reference Schats2026).
Cribra orbitalia lesions in the orbital roofs of medieval human skeletal remains from Vlaardingen in the Netherlands (reproduced from Schats, Reference Schats2026).
Epidemiology
Bringing together data from the existing published literature to create datasets of a more meaningful size can allow statistical interrogation to identify patterns that would not be recognized from each site separately. Speredakos et al. (Reference Speredakos, Penman and Smith2026) used this approach to investigate factors associated with changes in whipworm and roundworm infection in humans in Europe over the last 9000 years. It was found that population density and climate were the most important factors explaining variation in the success of these parasites, with roundworm having a greater tolerance for environmental temperature variation than did whipworm.
Reviews
Combining and integrating all forms of evidence for ancient parasites should give the most complete and contextualized understanding of parasites in past societies. Hong et al. (Reference Hong, Yi, Seo, Baek, Han, Fujita, Oh and Shin2026) present the known evidence for intestinal parasites and sanitation infrastructure in South Korea from the neolithic to industrialization. The trends identified showed how population density, sanitation, fertilizer use and dietary preferences affected infection by soil-transmitted helminths, Chinese liver fluke, food-borne trematodes and cestodes. Mitchell gives a worldwide view of the origins and evolutionary interaction in the major parasite groups that affect humans. Using genetic data for modern and ancient parasites, biomolecular techniques such as ELISA, archaeological and historical evidence, the way humans have changed their environment over the last 10 000 years is shown to have dramatically affected the way in which a range of endo- and ectoparasites infect and cause debilitating disease in our species (Mitchell, Reference Mitchell2026). Panagiotakopulu brings together a detailed set of evidence for ectoparasites in humans and other mammals to consider their evolutionary origins, spread around the planet with migrations and burden upon past populations (Panagiotakopulu, Reference Panagiotakopulu2026).
Conclusion
While microscopy has been the default technique for the vast majority of published research on ancient parasites, here we can see that so many more techniques can enlighten us as to the presence and consequences of parasites in past populations. Genetic analysis, ELISA to detect antigens, historical texts, lesions associated with anaemia in skeletal remains, geographic mapping and epidemiology all have great potential to provide new insights into parasite infection in ancient civilizations. When we can combine information from such diverse approaches, then reviews focusing on infection by particular parasite taxa, or on certain geographic regions or time periods, will be able to give the most comprehensive and contextualized understanding of the long and intimate association between humans and other animals with parasites through time.
Acknowledgements
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Author contributions
This editorial is all the work of Piers Mitchell.
Financial support
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Competing interests
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