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Endoparasites - Moniezia

Moniezia expansa: Common tapeworm.

General Description: Adult Moniezia expansa tapeworms have a scolex 0.4 to 0.8mm wide, with prominent suckers, no hooks and segments about 1.6cm wide. Length may be up to 600cm. Proglottides are about 4 times as wide as they are long, and, when separate, may appear as cooked rice grains.

Life Cycle: Indirect; intermediate hosts are oribatid mites. Eggs are freed from proglottides in faeces. Mites ingest the eggs, which contain a hexacanth larva. About 15 weeks later, an infective cysticercoid is present in the mite. Ingestion of these mites on pasture and subsequent digestion frees the cysticercoid, and adult tapeworms can be found about 40 days later.

Location: Small intestine.

Geographical Distribution: Worldwide.

Significance: Common tapeworms do not cause serious disease.

Effect on Host: Moniezia tapeworms are not known to damage sheep, but may rob them of material that would be used for production of meat and wool. Decreases in weight gain and wool production may be the only manifestations of infection. Heavy infection may cause obstruction of the lumen of the small intestine. Lambs develop a strong immunity to tapeworms at a reasonably early age.

Diagnostic Information: Proglottides resembling cooked rice grains appear in faeces. When broken, these segments yield eggs, which are roughly triangular in shape (M. expansa) with a thick shell.

Control: Anthelmintic treatment of infected sheep is probably the most efficient means of reducing Moniezia infections. Pasture management may also be beneficial if necessary.

Moniezia – close up of scolex   Moniezia – adult   Moniezia expansa – egg


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