Page 158 - The Veterinary Laboratory and Field Manual 3rd Edition

Parasitology 127

Table 3.2 Examples of tapeworm species.

Tapeworm Final host Larvae** Intermediate host/site of
cyst
Taenia saginata* Human Cysticercus bovis Cattle/muscle
Taenia solium* Human Cysticercus cellulosae Pig, human/muscle
(‘pork measles’)
Taenia multiceps Dog, wild canids Coenurus cerebrallis Sheep, cattle, yaks/
(Multiceps multiceps) Central nervous system
(‘Gid’ disease)
Taenia hydatigena Dog, wild canids Cysticercus tenuicollis Sheep, cattle, pig/peritoneum
Taenia ovis Dog, wild canids Cysticercus ovis Sheep/muscle
(‘sheep measles’)
Taenia pisiformis Dog, wild canids Cysticercus pisiformis Rabbit/peritoneum
Taenia serialis Dog, wild canids Coenurus serialis Rabbit/connective tissue
Taenia taeniaformis Cat, wild felids Cysticercus fasciolaris Mouse, rat/Liver
Echinococcus Dog, wild canids Hydatid cyst Ruminants, horses, pigs,
granulosus* human/liver, abdominal cavity
Echinococcus Dog, wild canids, cat Hydatid cyst Rodents, other small
multilocularis* mammals, human/liver,
abdominal cavity
Notes: *These parasites are zoonotic, that is, they can be transmitted from animals to humans. Taenia sp. infection in humans
occurs due to ingestion of cysts in undercooked meat, humans are the definitive host. In some cases Cysticercus cellulosae
infection can occur in humans when T. solium eggs are accidentally ingested. Echinococcus sp. infection (or hydatids) in humans
occurs when parasite eggs from infected dogs (and other carnivores) are accidently ingested, this may happen if contaminated
salad greens and vegetables are harvested and consumed raw. Humans are a dead end host for this parasite. The common
canine and feline Taeniid worms are also transmitted via the food chain.
**Tapeworm larvae often have different names from their adult stage. In some cases this was because the larvae were named
before the full life cycle of the tapeworm was fully understood.

todes must be placed in water so they relax Other tapeworms may be transmitted by
and then transferred to appropriate preserva- vectors such as insects or mites, for example,
tives. It is advisable to save relaxed specimens Dipylidium caninum, the dog/cat tapeworm is
in 70% ethanol that further aid molecular transmitted by the dog/cat flea (Ctenocephalides
analysis. sp.), Anoplocephala perfoliatia the equine tape-
worm is transmitted by an oribatid mite. In
taPEWorM cyStS SEEn In LIvEStock SPEcIES these cases the cystic stage will be found in the
During a routine post-mortem the presence of arthropod vector and the adult worm is found in
cystic structures may be noted in the liver, lungs, the intestine of the dog/cat or horse respectively.
peritoneum, skeletal muscles, brain and other
organs in livestock. Many of these cysts are the trIcHInoScoPy and trIcHInELLa SP. dIGESt
intermediate stages of tapeworm parasites for Meat samples are examined for the presence
which the main final host is often the dog or other of Trichinella sp. as members of this genus are
predator. Table 3.2 lists the common tapeworms known to be zoonotic. This organism is a nema-
and their definitive and intermediate hosts. tode parasite which is found in the muscles of

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