Nematodirus
leporis
Esther van
Praag, Ph.D.
|
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)
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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