Nematodirus leporis
Esther van Praag,
Ph.D.
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N.
leporis is a thin-necked intestinal worm that is
occasionally found in wild rabbits and hares. Pet-rabbits that live in
temperate, cold, and elevated environments can also be infested. N.
neomexicanus, N. arizonensis and N. triangularis have
furthermore been reported in wild rabbits. There is no reported public health
danger related to this parasite. The life cycle of Nematodirus leporis
is direct, with no intermediate host. The thick-layered eggs are much larger
(250*100 mm - micrometer) than those from other
Trichostrongylidae and are extremely resistant to desiccation and to freezing
conditions or snow. Usually the eggs have started to divide rapidly and 1 to
8 dark cells can be observed. The development of the larvae is generally
slow, up to 2 months in temperate climates. It is dependent on the humidity
and the temperature of the environment. During hatching, the larva shed the
first-stage-cuticle, which is left behind in the egg-shell. The L3
larva remains within in the egg- shell, which provides protection against adverse
environmental conditions. The L3 larvae can thus survive up to one
year in pasture fields. Once the L3 larva is ingested by the host,
it will exsheath and move to the paramucosal lumen of the small intestine,
and molt into the L4 and immature adults.
The adult parasite is slender and
measures 30 mm long. Its body shape is curled and presents 18 longitudinal
striations. The anterior part is reduced, with an inflated cuticle, which is
usually striated. The anterior part is inflated with a noticeable dorsal
esophageal spicule. The male worms possess a bursa with 2 large lateral
lobes, covered with mediolateral and caudolateral striations. The
female has a tale that ends bluntly.
Clinical signs
The
clinical and pathological sign of the presence of Nematodirus sp. only
becomes noticeable with a severe infestation, leading to diarrhea, a loss of
weight and affected performance. Necropsy shows that the large numbers of
worms form clumps resembling cotton wool, and are usually intertwined around
the intestinal villi, causing atrophy, degeneration and necrosis of the
surface enterocytes. The
occurrence of Nematodirus sp. is analyzed by fecal flotation, for the
presence of the particularly large Strongyle-type eggs. Treatment
Further Information
Audebert F,
Cassone J, Kerboeuf D, Durette-Desset MC. The life cycle of Nematodiroides
zembrae (Nematoda, Trichostrongylina) in the rabbit. J Parasitol. 2002;
88(5):898-904. Hoste H,
Mallet S, Fort G. Histopathology of the small intestinal mucosa in Nematodirus
spathiger infection in rabbits. J Helminthol. 1993; 67(2):139-44. Hoste H, Fort
G. Experimental infections with Nematodirus spathiger in rabbits. J
Helminthol. 1992; 66(3):227-30. Andrews CL,
Davidson WR. Endoparasites of selected populations of cottontail rabbits (Sylvilagus
floridanus) in the southeastern United States. J Wildl Dis. 1980;
16(3):395-401. Knight RA.
Effect of dexamethasone on experimental infections of Trichostrongylus
affinis and Nematodirus spathiger in rabbits. J Parasitol. 1977;
63(5):957-8. Jansen J.
Where does Nematodirus battus Crofton & Thomas, 1951, come from?
Vet Rec. 1973; 92(26):697-8. Gallie GJ.
The pathogenicity of Nematodirus battus in weaned and unweaned
laboratory rabbits. J Helminthol. 1973; 47(4):377-88. Gallie GJ.
The development of acquired resistance and age resistance to Nematodirus
battus in the laboratory rabbit. J Helminthol. 1973; 47(4):369-76. Mapes CJ.
Bile and bile salts and exsheathment of the intestinal nematodes Trichostrongylus
colubriformis and Nematodirus battus. Int J Parasitol. 1972;
2(4):433-8. Gallie GJ. Development of the parasitic stages of Nematodirus
battus in the laboratory rabbit. Parasitology. 1972; 64(2):293-304. |
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