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Fascioloides magna Infection Produced Liver Scarring and Regenerative Nodules in Red Deer

Red deer in natural habitat
Research · Disease, parasites & microbiology

A study of red deer (Cervus elaphus) livers from Croatia documented extensive liver damage caused by the giant liver fluke Fascioloides magna, together with areas where damaged tissue was being partially rebuilt. Researchers examined 136 livers and followed lesions ranging from migrating juvenile flukes and established pseudocysts to degrading pseudocysts after antiparasitic treatment. A pseudocyst is a capsule-like structure formed by the host around adult flukes in the liver; it limits continued parasite migration and tissue damage while allowing the flukes to survive and reproduce.

Some infected livers contained dozens of flukes and pseudocysts

Some infected livers carried a heavy parasite burden, with up to 45 pseudocysts and 70 adult flukes in a single liver. Juvenile flukes were also found migrating through the liver in some animals. The infection produced migratory channels, black iron-porphyrin pigment, inflammation and fibrous tissue, while treated pseudocysts could contain degrading material and remnants of dying flukes.

Repair produced regenerative nodules as well as scar tissue

Some livers contained nodules up to 7 cm across. Microscopic examination showed that these areas were divided by bands of fibrous connective tissue and contained pigment and remnants of trematode eggs. Within the nodules, the researchers found disorganised proliferating hepatocytes — liver cells multiplying during repair — together with fibrous bands and occasional blood vessels.

Regenerative nodules in two red deer livers
Regenerative nodules in two red deer livers from the study. Figure 2 from Konjević et al. (2026), Life, CC BY 4.0.

The sample was not suitable for estimating infection prevalence: only 136 of roughly 600 red deer livers from the county were submitted for examination, and they were obtained through non-random convenience sampling.

The authors describe the response as substantial repair of damaged liver tissue rather than complete restoration of the original structure. Part of the affected area may develop into new hepatic tissue, while the remainder becomes scar tissue. They propose that this response to severe acute and chronic injury could provide a model for studying abnormal liver repair.

Sources and image credit

  1. Konjević, D., Škvorc, N., Bujanić, M., Čurlík, J., Gašpar, A., Šoštarić-Zuckermann, I.-C., & Gudan Kurilj, A. (2026). Red Deer (Cervus elaphus) Fascioloidosis: From Liver Pathology to Regeneration. Life, 16(3), 502. https://doi.org/10.3390/life16030502Primary open-access research article published 19 March 2026. Examined 136 red deer livers collected during the 2024/2025 hunting season as part of regular game management in Bjelovar–Bilogora County, Croatia, and described Fascioloides magna-associated lesions, fibrosis and regenerative/reparative nodules.

Image: Donald Hobern — red deer (Cervus elaphus) at Rådvad, Denmark, 27 November 2016; Flickr / Wikimedia Commons; cropped to 16:9 for Wildlife Vagabond; representative species image, not a study animal · CC BY 2.0 · Source

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