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Parasites of the Viking Age


In 2015, we had the opportunity to read on the Internet that Danish scientists published a study (Søe et al. 2015), which is interpreted as “the Vikings from Viborg suffered from intestinal parasites that caused them great pain and that may have been the reason behind their excessive aggressiveness” (Mirror 2015). I would like to comment on this opinion, although it is not my usual cup of coffee and I may be corrected by someone with more expertise.

Diseases and parasites are not often discussed in monographs focusing on the Viking Age, and therefore relatively little is known about them in non-specialist circles. Understandably, those interested are focused on the glitz and glory of the Viking Age, but not its grime. People are often fascinated by the Viking Age and dream of returning to that period, forgetting that ubiquitous disease and parasites were the scourge of the Middle Ages. Diseases and parasites are one of the reasons why we cannot fully understand that time from the perspective of modern Europeans. The reality of the Early Middle Ages should not be sought in publications, but in the least developed countries of the contemporary world.

Current articles that have swarmed the Internet write about parasites as if they were unique to Vikings. It can be doubted that the situation looked different in the surrounding Europe and in earlier or later centuries (e.g. Søe et al. 2018). At the same time, I would like to comment on the articles that relate the research from Viborg to warriors: I fundamentally reject the argument that the Old Norse people were aggressive because of parasites, because it turns out that the origin of their expansion and aggression was rather a socio-cultural disposition.

Due to their size and way of life, ancient parasites are difficult to prove, but modern science can do wonders. We can thus piece together information from uniquely preserved bog bodies from northern Germany and southern Scandinavia, in which, thanks to a suitable anaerobic and acidic environment, food remains with parasite eggs have been preserved, from coprolites (fossil excrement), the contents of latrines (Bouchet 2003) and other sources including written sources. Apart from human parasites, we can also examine animal parasites (e.g. Baker – Brothwell 1980; Buckland – Perry 1989), some of which can also live in humans. For research on Scandinavian parasites, I recommend the book Parasites of the Colder Climates. After a cursory acquaintance with the issue, it was confirmed to me that the situation regarding parasites was relatively uniform within the entire Viking world (Buckland 2008: 600-601).

We can divide ectoparasites (external parasites) and endoparasites (internal parasites). External parasites include, for example, lice (lús, pl. lýss; namely head lice and body lice) and fleas (fló, pl. flær), which are also noted in the sagas. Illustrative evidence is provided not only by the numerous finds of combs (see e.g. Ambrosiani 1981), but also by the monk Dicuil, who wrote around 825 in his notes about Thule (Iceland) that during the white night there is so much light that “whatever task a man wishes to perform, even picking lice from his shirt, he can manage as well as in clear daylight” (Akuffo et al. 2003: 34). Ectoparasites were a common problem in the past until modern times. Although virtually everyone had these parasites due to the absence of an effective exterminator, it appears that the Old Norse people condemned only those people who did not take care of themselves and did not adequately fight the parasites every day. That is why, for example, in the Fóstbrœðra saga (ch. 23) we can find the wanderer Oddi, who earned the surname Louse (Lúsa-Oddi) for insufficient care of his body.

As far as endoparasites are concerned, the most widespread seems to be the whipworm (Trichuris trichiura) – a new study confirms its occurrence in Viborg (Søe et al. 2015). It was also spread in Birka (Short 2010: 106), Ribe (Nansen 1991; Nansen – Jørgensen 1977) or York (Roesdahl 1992: 244, Pl. 5). It was also found in the stomach of Lindow Man (Bouchet 2003). In addition, research in Viborg and Ribe (Søe et al. 2015; Nansen – Jørgensen 1977) showed representatives of the roundworm genus (Ascaris), liver fluke (Fasciola hepatica) and tapeworm (Taenia).

Collection of herbs. Source: Paris, BnF, Latin 6862, 18v.

The situation must have been worst in densely populated towns, where wells stood right next to latrines. The inhabitants of these cities had to suffer from diarrhea and stomach upsets (Short 2010: 106). The Middle English terms rengwyrm and inwyrm (both for stomach worm) bear witness to the fact that people had an idea of what was in their digestive system. Surely it would not be wrong to suppose that the higher classes ate better, and thus prevented internal parasites more effectively, although they could not eradicate them completely. It is possible that the surviving healing incantations that address diseases (mostly fever) as giants were also part of the treatment for internal parasites (see Starý 2010: 196; Vlasatý 2023). Contemporary Anglo-Saxon works recommend decoctions, ointments, singing and other actions for diseases, which today we would definitely call alternative treatment (Komanec – Revická 2009). It is interesting that many Old Norse sources attribute a special healing (even magical) power to onion- or garlic-scented bulbous herbs, since garlic is very suitable for fighting internal parasites. It is therefore possible that this group of vegetables played some role in the Early Middle Ages as well.

With that, I would like to end this article. I would appreciate any comments because – as I have outlined – I am a total layman in this field with a background in high school biology. I would like to thank Jan Zbránek, who helped me shed light on fundamental problems. If you want to learn more and support our work, please, fund our project on PatreonBuymeacoffee or Paypal.


Internet sources

Mirror 2015 = Did marauding Vikings have such a bad attitude because they suffered from chronic WORMS?. In: [2023-07-28]. Online.


Komanec, Miloš – Revická, Veronika (2009). Anglosaská kouzla a magické průpovědi, texty prognostické a ranhojičské rady. In: Jan Čermák (ed.): Jako když dvoranou proletí pták. Antologie nejstarší anglické poezie a prózy (700–1100), Praha, 169–187.

Akuffo, Hannah et al. (2003). Parasites of the Colder Climates, London – New York. Online.

Amrosiani, Kristina (1981). Viking age combs, comb making and comb makers: In the light of finds from Birka and Ribe, Stockholm.

Baker, J. R.  Brothwell, D. R. (1980). Animal diseases in archaeology, London.

Bouchet, Françoise et al. (2003). Parasite Remains in Archaeological Sites. In: Memorias do Instituto do Oswaldo Cruz 98, 4752. Online.

Buckland, Paul (2008). The North Atlantic Farm: An Environmental View. In: Brink, Stefan et al. (eds.). The Viking World, London – New York, 598–603.

Buckland, P. C. – Perry D. W. (1989). Ectoparasites of sheep from Stóraborg, Iceland and their interpretation. Piss, parasites and people, a palaeoecological perspective. In: Hikuin 15, 37–46. Online.

Nansen, Peter (1991). Finds of Parasite Eggs in Manure Layers. In: Bencard, Mogens et al. (eds.). Ribe Excavations 1970-76 – Volume 3, Esbjerg, 37-41.

Nansen, Peter – Jørgensen, R. J. (1977). Parasite eggs identified in material from archaeological excavations in Ribe (The Viking Age). In: Nord Vet Med 29, 263-266. Online abstract.

Roesdahl, Else (1992). The Vikings, London – New York.

Short, W. R. (2010). Icelanders in the Viking Age: The People of the Sagas, Jefferson, NC.

Starý, Jiří (2010). Dávný byl věk, kdy Ymi vládl … : Řád a chaos u starých Seveřanů. In: Řád a chaos v archaických kulturách, Praha, 189-227.

Søe, M. J. et al. (2015). DNA typing of ancient parasite eggs from environmental samples identifies human and animal worm infections in Viking-age settlement. In: Journal of Parasitology 101, 57–63. Online.

Søe, M. J. et al. (2018). Ancient DNA from latrines in Northern Europe and the Middle East (500 BC–1700 AD) reveals past parasites and diet. In: PLoS ONE 13(4).

Vlasatý, Tomáš (2023). „I carve healing runes“. In: Project Forlǫg – Reenactment and science [online]. [2023-07-20]. Available at:

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