Caspian Journal of Veterinary Sciences

Caspian Journal of Veterinary Sciences

Ligula intestinalis in aquatic systems: taxonomy, epidemiology, pathology, and control — a concise narrative review

Document Type : Review article

Authors
1 Department of Pathobiology, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran.
2 Department of Nutritional Sciences, School of Health, Golestan University of Medical Sciences, Gorgan, Iran.
3 Food, Drug and Natural Products Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
Abstract
Ligula intestinalis (Cestoda: Diphyllobothriidae) is a cosmopolitan tapeworm with a three‑host life cycle involving copepods, cyprinid fishes, and piscivorous birds. Its plerocercoid stage grows extensively within the fish's body cavity, compressing the viscera and causing profound reproductive impairment. Here we synthesize taxonomy and morphology, life cycle, epidemiology (with emphasis on Iran), pathology, zoonotic considerations, and control options. Molecular data increasingly support the synonym of Digramma with Ligula and indicate low interspecific divergence within the complex. Regionally, prevalence varies widely (≈3–60% in Iran, depending on host, season, and locality) and can reach double‑digit levels in African lakes. Gross lesions include abdominal distension and gonadal atrophy; histopathology commonly reveals ovarian/testicular degeneration and hepatic vacuolation. Despite sporadic claims, confirmed human infection by L. intestinalis has not been documented; risk is minimized by proper cooking and avoidance of raw freshwater fish. Effective control requires interrupting the life cycle (reducing copepods, excluding piscivorous birds from aquaculture), routine monitoring, biosecurity in semi‑closed systems, and public education.
Keywords
Subjects

Arme, C and Owen, RW (1968). Occurrence and
pathology of Ligula intestinalis infections in British
fishes. J. Parasitol., 54: 272-280.
Ahmadiara, E and Nikpay, A (2024). Study of Abramis
brama (Berg, 1905) infection with Ligula intestinalis
(Linnaeus, 1758) in Siah Darvishan River and survey
of them molecular diversity by evaluation of the
ribosomal ITS2 region. Aqua. Physiol. Biotechnol.,
11: 1-14.
Ahmadiara, E; Hosseini, SH; Jalousian, F and
Ebrahimzadeh Mousavi, HA (2013). The study of
the plerocercoid of Diphyllobothriidae (Cestoda,
Pseudophyllidea) in two cyprinid hosts, Abramis
brama and Alburnoides bipunctatus, from North and
Northwest of Iran. Iran. J. Vet. Med., 7: 103–109.
Ahmadiara, E (2017). Is Ligula intestinalis really a
probable threat for public health? J. Food Qual.
Hazards Control, 4: 36.
Ahmadiara, E; Hosseini, SH; Jalousian, F and
Ebrahimzadeh Mousavi, HA (2018). The taxonomic
position and phylogenetic relationship between
Digramma interrupta and Ligula intestinalis based
on morphological and molecular diagnosis. Iran. J.
Parasitol., 13: 648–654.
Bouzid, W; Štefka, J; Hypša, V; Lek, S; Scholz, T; Legal,
L and Morand, S (2008). Geography and host
specificity: Two forces behind the genetic structure
of Ligula intestinalis (Cestoda: Diphyllobothriidae).
Int. J. Parasitol., 38: 1465–1479.
Bozorgnia, A; Omidzahir, SH; Hoseini, SM and Darzi,
SH (2016). Occurrence and histopathological effect
of Ligula intestinalis on sea bream (Abramis brama
orientalis). Iran. J. Aqua. Anim. Health, 2: 34–43.
Britton, JR; Jackson, MC and Harper, DM (2009).
Ligula intestinalis (Cestoda: Diphyllobothriidae) in
Kenya: A field investigation into host specificity and
behavioural alterations. Parasitol., 136: 1367–1373.
Dubinina, MN (1980). Tapeworms (Cestoda, Ligulidae)
of the Fauna of the USSR. New Delhi: Amerind
Publishing Co. Pvt. Ltd.
Eslami, A (2006). Veterinary helminthology: Cestoda
(Vol. 2). Tehran: University of Tehran Press.
Geta, TG; Gebremedhin, S; Abdiwali, SA and
Omigbodun, AO (2024). Dietary diversity and other
predictors of low birth weight in Gurage Zone,
Ethiopia: Prospective study. PloS one, 19: e0300480.
Jalali, B and Barzegar, M (2006). Fish parasites in
Zarivar Lake. J. Agri. Sci. Technol., 8: 47–58.
Li, J and Liao, X (2003). The taxonomic status of
Digramma (Pseudophyllidea: Ligulidae) inferred
from DNA sequences. J. Parasitol., 89: 792-799.
Olson, PD; Littlewood, DTJ; Griffiths, D; Kennedy, CR
and Arme, C (2002). Evidence for the co-existence
of separate strains or species of Ligula in Lough
Neagh, Northern Ireland. J. Helminthol., 76: 171–
174.
Rahmati-Holasoo, H; Hajimohammadi, B;
Ahmadiara, E and Ebrahimzadeh Mousavi H
(2011). A study of infestation of Alburnoides
bipunctatus with Ligula intestinalis in Latian
reservoir dam lake, Tehran Province, Iran: A
histopathological study. Human Vet. Med., 3: 18–24.
Rahnama, M; Siamardi, AA; AlipourEskandani, M;
Lotfalizadeh, N; Sadr, S; Saadati, D and Khedri, J
(2024). Exploring the prevalence and impact of
Ligula intestinalis infection across fish species in
Sistan region, Iran. J. Parasitic Dis., 48: 630–637.
Silva, JAM; Mininel, VA; FernandesAgreli, H; Peduzzi,
M; Harrison, R and Xyrichis, A (2022). Collective
leadership to improve professional practice,
healthcare outcomes and staff well-being. Cochrane
Database Sys. Rev., 10: CD013850.
Yavuzcan, H; Korkmaz, AS and Zencir, O (2003). The
infection of tench (Tincatinca) with Ligula
intestinalis plerocercoid in Lake Beyşehir, Turkey.
Bull. Eur. Assoc. Fish Pathol., 23: 223–227.
Volume 2, Issue 2
December 2025
Pages 21-25

  • Receive Date 02 August 2025
  • Accept Date 18 August 2025