DISEASE SUMMARY PAGE

Tapeworm Cyst Infection in Lagomorphs

Click here for full page view with caption. Cysticercus of Taenia pisiformis from a rabbit Click here for full page view with caption. Section through cysticercus of Taenia pisiformis from a rabbit Click here for full page view with caption. Cysticercus of Taenia pisiformis from a rabbit - scolex and part of cyst wall Click here for full page view with caption. Taenia pisiformis in a rabbit. Liver section.

Summary Information
Diseases / List of Parasitic Diseases / Disease summary
Alternative Names Synonyms:
Disease Agents Cysticercus pisiformis: cysticercus stage of the tapeworm Taenia pisiformis (B614.11.w11)
  • Morphology: The cysticercus is a transparent, fluid-filled ellipsoid or sphere that measures up to 18mm. There is a single inverted scolex that forms a stalk from the cysticercus wall. (B614.11.w11)
  • Life cycle: 
    • Adult Taenia pisiformis inhabit the small intestine of its definitive host: the carnivores, primarily canids. (B614.11.w11)
    • The gravid proglottids which contain infective eggs, are passed in the faeces and subsequently ingested by the intermediate host: lagomorphs. (B614.11.w11)
    • Embryos hatch out in the lagomorph and migrate to the liver via the hepatic portal veins and, less commonly, the mesenteric lymph nodes and the lungs. (B614.11.w11)
    • Migration through the liver requires fifteen to thirty days because this is a developmental phase of the parasite. The larvae then penetrate the liver parenchyma and mature to the cysticercus phase. (B614.11.w11)
    • Transmission to the definitive host occurs via the ingestion of the infected viscera of lagomorphs. (B614.11.w11)

Coenurus serialis cysts of the tapeworm Taenia serialis, found in dogs and foxes. (B600.9.w9, B601.13.w13, B610.23.w23) Coenurus serialis is the larval stage that can be found in the intramuscular and subcutaneous tissues of rabbits. These cysts apparently do not clinically affect the rabbit. (B600.9.w9)
  • Morphology: 
    • The coenurus is a fluid-filled cyst that is four to five centrimetres in diameter. (B600.9.w9, B614.11.w11) It usually has several scolices, each on a separate stalk that is invaginated into a common bladder. (B614.11.w11) 
      • The fluid filled cyst has secondary buds which protrude to the inside, with each bud having an inverted scolex. (B600.9.w9)
  • Life cycle: 
    • Adult Taenia serialis inhabit the small intestine of its definitive hosts: dogs and foxes. (B600.9.w9, B614.11.w11)
    • The gravid proglottids which contain infective eggs, are passed in the faeces and subsequently ingested by the intermediate hosts, lagomorphs. (B614.11.w11)
    • The eggs end up in the small intestine where oncospheres emerge from the eggs and migrate to the intermuscular connective tissue or subcutaneous tissue. It is at this stage that the oncospheres develop into a cyst (coenurus). (B600.9.w9, B614.11.w11)
    • The coenurus may also develop secondary external or internal cysts. (B600.9.w9, B614.11.w11)
    • Transmission to the definitive host occurs via the ingestion of infected lagomorphs. (B614.11.w11)

Echinococcus oligarthus tapeworms are found in wild felids; the usual intermediate hosts include rodents and opossums. (J11.70.w3)

Multiceps sp. (J1.11.w13, J427.63.w1)
Infectious Agent(s)
Non-infectious Agent(s) --
Physical Agent(s) --
General Description
Clinical findings 
  • In heavy Cysticercus pisiformis infection:
    • Hepatitis that may lead to acute death or chronic wasting. (B614.11.w11)
    • Decreased appetite for a few days, depression and death of two laboratory rabbits. Cysticercosis was diagnosed in both rabbits although one was considered to have died from pregnancy toxaemia. (J501.40.w2)
  • In Coenurus serialis infections:
    • Coenurus serialis infections are generally reported to be non-pathogenic. (B600.9.w9, B614.11.w11)
      • Note: Cysts that develop in areas other than muscular or subcutaneous tissue (e.g. in the brain or the abdomen) can compromise the host. (B614.11.w11)
    • Fluctuant subcutaneous swellings may be seen. (B601.13.w13, B610.23.w23)
    • Distribution of cysts reported in pet rabbits: 
      • Cheek (B600.9.w9)
      • Axilla (B600.9.w9)
      • Flank (B614.11.w11)
      • Note: Cysts may also be found in skeletal muscle. (B336.42.w42)
      • Retrobulbar space (B600.9.w9): in a 16-month-old male Dwarf Lop with unilateral exophthalmia, a cyst was found (2 cm diameter, mobile) ventrolaterally posterior to the globe of the affected eye. (J354.5.w2)
Pathology
  • In Cysticercus pisiformis infection:
    • The infective larval stage may be found attached to the viscera or the mesentery. (B614.11.w11)
    • Younger metacestode stages that migrate through the liver are not often seen, but there may be scarring from the migration or focal granulomatous hepatitis. (B614.11.w11)
    • Yellowish-white foci in the liver and occasionally in other organs. Histologically, focal granulomas, with caseous necrosis centrally and fibroblasts, lymphocytes and plasma cells around this. Often, no cysticerci are found at necropsy but liver lesions are seen histologically. (J1.16.w19)
    • Cysticercus pisiformis (Taenia pisiformis) sometimes occurs in very large numbers (hundreds) in cottontails (Sylvilagus floridanus - Eastern Cottontail), with the rabbit in poor condition: "the liver is often virtually studded with cysts. Many cysts lie free in the peritoneal cavity and the perirectal space may actually be packed with them. Some are found in the lungs, and others are attached to the base of the heart, to the large blood vessels, spleen, mesenteries, or omenta." The peritoneam may be discoloured, with increased peritoneal fluid which may be thick and cloudy. (J40.3.w2)
    • In a study of cottontails [probably Sylvilagus floridanus - Eastern Cottontail] in the eastern USA, liver damage from migration of larvae was noted in some rabbits, and in one immature rabbit, damage to the liver from tapeworm larvae appeared to be the cause of death. (J40.7.w1)
    • In Sylvilagus floridanus - Eastern cottontail in Alabama the cysts were generally found in the liver, lungs and visceral mesentery. In one individual, a large cysticercus was found in the urinary bladder. On average there were about six per infected rabbit, with a maximum of 34. (J332.28.w3)
    • In one laboratory rabbit: several clear fluid-filled cysts, about 1 cm diameter, each containing a white spot, 1-3 mm, either free in the peritoneal cavity, or attached to omentum. Histologically, in the mesentry were fluid-filled cysts surrounded by fibrous connective tissue containing mononuclear inflammatory cells and heterophils. In the liver, multifocal areas of fibrosis were noted in the portal triads, sometimes with tracts of mononuclear cells, loss of hepatocytes and minimal fibrosis adjacent to the foci; these lesions were considered to be due to migration of cestode larvae. The cysts contained "profiles of immature cestode larvae containing an invaginated scolex armed with hooks and suckers but no ova." (J501.40.w2)
      • In a second laboratory rabbit, five ovoid cysts, each about 1 cm diameter and containing a prominent white spot were found attached to abdominal fat, with another cyst free in the abdominal cavity. (J501.40.w2)
  • In Coenurus serialis infections:
    • In a 16-month-old male Dwarf Lop with unilateral exopthalmia, a clear membranous bladder was found with numerous dots, cream in colour, on its surface; surrounding this was greyish tissue presumed to be a host reaction. Histologically, the "dots" were confirmed as scoleces consistent with Taenia serialis, while the surrounding tissue was dense fibrous tissue containing eosinophils and clusters of lymphocytes. (J354.5.w2)
  • In Echinococcus multilocularis and Echinococcus shiquicus infection of Ochotona curzoniae - Plateau pika:
    • "both unilocular and alveolar metacestodes in the liver". (J91.75.w1)
Transmission
  • Cysticercus pisiformis infection: contamination of caging, food, bedding material of lagomorphs by infected dog faeces. (B614.11.w11)
  • In cases in two laboratory rabbits, infection may have been from hay fed to the rabbits. (J501.40.w2)
Further Information
Diagnosis
  • Cysticercus pisiformis infection: "Antemortem diagnosis is not likely". (B614.11.w11)
  • In Coenurus serialis infection:
    • In a 16-month-old male Dwarf Lop with unilateral exophthalmos, diagnosis was made by close examination of the cyst, with confirmation by histopathological examination. (J354.5.w2)
Treatment
  • Cysticercus pisiformis infection: 
    • Mebendazole at one gram per kilogram of feed for fourteen days (approximately 50 mg/kg bodyweight per day) has been reported to kill "both the mature and immature cysticerci of T.pisiformis". (B614.11.w11)
  • Cysticercus pisiformis infection:
    • Remove surgically. (B601.13.w13, B610.23.w23)
    • Alternatively, puncture the cyst and aspirate the contents. (B600.9.w9)
    • Praziquantel may be used to kill the cestode. (B600.9.w9)
  • In Coenurus serialis infections:
    • In a 16-month-old male Dwarf Lop with unilateral exopthalmia, the cyst was removed surgically; this was curative. (J354.5.w2)
Prevention
  • Prevent the contamination of caging, food, bedding material by infected dog faeces. (B614.11.w11)
Occurrence
Taenia pisiformis (Cysticercus pisiformis) Taenia serialis

Taenia sp.

Other species

Associated Techniques
Host taxa groups /species
Disease Author Nikki Fox BVSc MRCVS (V.w103); Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referees John Chitty BVetMed CertZooMed MRCVS (V.w65); Sheila Crispin MA VetMB BSc PhD DipECVO DVA DVOphthal FRCVS (V.w130); William Lewis BVSc CertZooMed MRCVS (V.w129); Anna Meredith MA VetMB CertLAS DZooMed (Mammalian) MRCVS (V.w128); Richard Saunders BVSc BSc CertZooMed MRCVS (V.w121); Lord Soulsby of Swaffham Prior MA,PhD,DSc (H c: Mult) , AM(H c),DVM&S (H.c),DVMS(H.c) ,DVM(H,c) F.Med Sci.,Hon FRCVS F.Inst Biol. F.R.C.Path (H.c), DVSM, MRCVS (V.w135)

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