Graphidium strigosum

Esther van Praag, Ph.D.

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This cosmopolitan parasite is observed mainly in the wild rabbit (Oryctolagus cuniculus), and in palaearctic Leporidae, such as the hare (Lepus europaeus, L. capensis). Rabbits are probably the original host, as they tolerate the presence of G. strigosum much better hare, which present important stomach lesions. It is thus speculated that the presence of this worm in hare populations depends on the presence of population of wild rabbits. An association between Graphidium strigosum and Trichostrongylus retortaeformis has been reported for wild rabbits. House rabbits become infested by green forage, contaminated with eggs and infective larvae.

Not much is known about the biology and the life cycle of this parasite.

The eggs measure approximately 95*50 mm (micrometer) in size. They are laid in the morula stage. When environmental conditions are good, the larvae hatch about 10 h. later. The L₂ stage is reached within 2 to 3 days. Ensheathed L₃ larvae are infective and migrate along the herbage according to the period of the day: to the tip at dusk, downwards when exposed to sun light and heat, till they get ingested by their host. Male and female adult worms are red with many longitudinal lines and transversal striations. The males measure about 12 mm long, while females average 16 mm. The male possess paired and slender spicules and a well-developed copula-bursa.

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Oocyst of Graphidium strigosum

Clinical signs

Clinical signs are close to those of gastritis. Massive infestations can cause catarrhal gastritis with some fibrosis, and extreme inflammation of various parts of the intestinal tract (stomach, small intestine, cecum).

Necropsy shows that L₄ stage worms are coiled in the ducts of the gastric glands of the fundus. Adults worms are generally located in the mucus layers, with the head buried in the stomach grooves, without attachment to the mucosa.

Treatment

Benzimidazoles	fenbendazole	20 mg/kg, PO, repeated after 10-14 days
Macrolides	ivermectin	0.4 mg/kg, SC, repeated after 10-14 days

Further Information

B. Boag (1987) The Helminth Parasites of the Wild Rabbit Oryctolagus cuniculus and the brown hare Lepus capensis from the Island of Coll, Scotland. J. Zool. 212: 352-355.

B. Boag and H.H. Kolb (1989) Influence of the Host Age and Sex on Nematode Populations in the Wild Rabbit (Oryctolagus cuniculus L.). Proc. Helminth. Soc. Washington 56: 116-119.

Brookhuizen and Kemmers (1976) The Stomach Worm Graphidium strigosum (Dujardin) Railliet and Henry, in the European Hare, Lepus europaeus Pallas. In: Pielowski, Z. and Pucek Z. (eds) Ecology and Management of the European Hare Populations. Panstwowe Wydawnictwo Rolnicze i Lesne, Warshaw, Poland, pp 157-171.

J.D. Dunsmore, M.L Dudzinski (1968) Relationship of Numbers of Nematode Parasites in Wild Rabbits, Oryctolagus cuniculus (L.), to Host Sex, Age and Season. J. Parasitol. 54: 462-474.

E.A. Nickel and W. Haupt (1986) Experimental Studies on the Course and Consequences of Infection with Graphidium strigosum (Nematoda, Trichostrongylidae) in Oryctolagus cuniculus. Agnew. Parasitol. 27, 215-219.

E.J.L. Soulsby (1968) “Helminths, Arthropods, and Prorozoa of Domestic Animals”. Williams and Wilkins, Baltimore, Maryland.

R. Wetzel, K Enigk (1937) Zur Biologie von Graphidium strigosum, dem Magenwurm der Hasen und Kaninchen. Deutsch. Tierärtzliche Wochenschrift 45: 401-405.

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