Passalurus
ambiguus
Esther van
Praag, Ph.D.
|
This parasite is also known
under the name Oxyuris ambigua. It is a common, cosmopolitan parasite that
infests wild or petrabbits cottontails and hares. In the USA, the
presence of P. nonanulatus has also
sometimes been observed in rabbits. Auto-infection is common through
ingestion of the eggs with the food. The juvenile stages of Passalurus sp. are rather found in the mucosa of
the small intestine and the cecum, while the adult worms are located in the
anterior part of the cecum and the large intestine of rabbits. Passalurus ambiguus is specific to lagomorphs and
does not represent a public health danger. The life cycle of Passalurus sp.
is direct: the eggs are ingested by the animal. The eggs have typically a
flat side and measure about 100*43 mm. During their development,
resistance against dehydration increases. The larvae will emerge from the
eggs and develop in the mucous layer of the small intestine and the cecum,
where they will develop into mature adults. Two molts are reported, the first
after 24 hours, and the second on the 3rd day.
The adult worms have different sizes, the males being smaller (±
5 mm) than the females (± 10 mm). The females, characterized by a long and
narrow tale, are marked with about 40 circular, cuticular
striations. It seems that the female worms deposit the eggs around the anus.
The worms live about 106 days. Clinical signs
Passalurus sp.
parasites are non-pathologic and their presence remains asymptomatic, even
when the infestation is severe. A rabbit may be infested with over 1000 parasitic
worms. Eggs and occasionally live adult worms can be observed in freshly
excreted feces. Once out of the rabbit body, the worms will dry quickly and
cannot be seen anymore after 5 minutes.
It is interesting to note that the female worms emerging from the anus
of rabbits contain eggs in the gastrula stage that are able to develop into
an infective stage in the environment. The presence of mucus in the
droppings, frequently as threads, is an indication that a rabbit may be
infested by intestinal worms. This should be differentiated from mucoid
enteritis. An overpopulation of the
nematode worms in the digestive tract can lead to stasis and cecal impaction, pain and gas production. If not treated,
the stasis can become chronic, with a bout every 4
to 6 weeks. At necropsy, Passalurus sp.
worms have been found in the lumen of the cecum, as well as in the crypts and
mucosa of the colon. The site where the worms were located was inflammatory
and presented dystrophic modifications. The most profound inflammatory and
dystrophic changes were found in the cecum. Signs of vascular dystrophy were
furthermore observed in the hepatic and renal parenchyma.
DiagnosisThe presence of intestinal parasites
is determined by a fecal flotation test. In rare cases, the fecal flotation
test result of heavily infested rabbit can return negative. When left
untreated, the presence of worms can often be observed in the droppings Treatment
Further Information
H. Boecker (1953) Die Entwicklung des
Kaninchen Oxyuren Passalurus ambiguus.
Zeitschrift für Parasitenkunde 15: 491-518. S. Brown (1993) Rabbit Drug Dosages.
Rabbit Health News 10: 6-7 J. Burke (1994) Clinical Care and Medecine
of Pet Rabbits. In: Proceedings of the Michigan Veterinary Conference, pp
49-77. D. Duwel and K. Brech
(1981) Control of Oxyuriasis in Rabbits by
Fenbendazole. Lab. Anim. Sci. 15: 101-105. A.B. Erickson (1944) Helminth Infection
in Relation to Population Fluctuations in Snowshoe Hares. J. Wildl. Manage. 8: 134-153. E.V. Hillyer, K.E. Quesenberry
(1997) Ferrets, Rabbits, and Rodents. Clinical
Medicine and Surgery. W.B. Saunders Company pp. J.P. Hugot
(1984) L’Insémination Traumatique chez les Oxyures de Dermpotères
et de Léporidés. Etude Morphologique Comparée. Ann. de Parasitologie Humaine
et Comparée 59: 379-385. M.A. Palimpsestov, R.S. Chebotarev
(1935) Zur Frage des Therapie bei Passalurose (Passalarus ambiguus) des Kaninchen. Tierärtzliche Rundschau 41:
709-711. N.M. Patton, K.W. Hagen, J.R. Gorham,
R.E Flatt (1986) “Domestic Rabbits: Diseases and Parasites. “Pacific
Northwest Extension Publ. Oregon, Idaho, and Washington. K.I. Skrjabin,
N.P. Shikhobalova, E.A. Lagodovskaya
(1960) Oxyurata of Animals and Man. Part I. Oxyuroidea. In: Skrjabin, K.I.
(ed.), Essentials of Nematology, The Academy of
Sciences of the U.S.S.R., Moscow (published by the Israel Program for
Scientist Translations, Jerusalem, 1974). J. Theodoris
(1979) Contribution to the study of parasites in the rabbits of Northern
Greece. hellinike Kteniatrike (Hellenii
Veterinary Medecine) 22: 181-183. T.L.H Tsui and N.M. Patton (1991)
Comparative Efficiency of Subcutaneous Injection Doses of Invermectin
against Passalurus ambiguous in rabbits J. Appl. Rabbit
Res. 14: 266-269. N.B. Walden (1999) Rabbits: a Compendium (The T.G. Hungerford
VADE MECUM series for Domestic Animals: Series C.13). Post Graduate
Foundation in Veterinary Science, University of Sydney, Sydney. J.P. Wiggins, M. Cosgrove, H. Rothenbacher
(1980) Gastrointestinal Parasites of Eastern Cottontail Rabbits (Sylvilagus
floridanus) in Central Pennssylvania.
J. Wildl. Dis. 16:541-544. Fujiwara H, Uchida K, Takahashi M. [Occurrence of granulomatous
appendicitis in rabbits] Jikken Dobutsu. 1987; 36(3):277-80. Shirokova EP, Grishina EA. [Microstructural
changes in the organs of the rabbit with passaluriasis]
Med Parazitol (Mosk)
1997; (2):18-21. |
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