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Endoparasites - Coenururus Cerebralis

Coenurus cerebralis: Adult tapeworm is Taenia multiceps.

General Description: Adults (Taenia multiceps) occur in the small intestine of dogs and wild carnivores, and can reach lengths of up to 1 metre. The Coenurus (intermediary stage) occurs in sheep and is usually localised in the brain or spinal cord. Other ruminants and man can also be infected. The Coenurus is a large cyst full with liquid and many floating scolices, it could reach 5cm or more in diameter.

Life Cycle: Indirect cestode life cycle. Adults in dogs pass gravid proglottides with eggs in the faeces. When the proglottides burst the eggs are disseminated in the environment contaminating pastures and water supplies. When ingested by sheep (or other ruminants) the eggs hatch. The hexacanths develop into metacestods which penetrate the intestinal wall and enter the blood stream. Only those parasites which reach the nervous system will develop into a fully developed Coenurus in 7 to 8 months. The definitive host (dog) gets infected by eating infected sheep tissue.

Location: Adult tapeworms live in the small intestine of dogs. Coenurus cerebralis are found in the brain or spinal cord of sheep.

Geographical Distribution: Worldwide.

Significance: Feeding sheep carcasses to dogs may cause infection and perpetuation of the infection cycle. The intermediary stages (Coenurus) cause severe problems in infected sheep including death.

Effect on Intermediate Host: An acute meningoencephalitis in lambs may occur as a consequence of migration of large numbers of immature stages of this parasite. The chronic stages develop as a result of increased destruction of brain and spinal cord tissue as the Coenurus grows. The neurological clinical signs are recognised as "gid" or "staggers" and are dependent on the location of the cyst in the central nervous system.

Diagnostic Information: Infected dogs pass Taenia-type eggs in their faeces. Sheep at the chronic stage of the infection may show circular movements, jerky movements or staggering gait.

Control: Treat dogs regularly for tapeworms. Dogs should not be fed uncooked sheep carcasses or viscera.

Cyst containing scolices   T.multiceps in muscle


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