Tapeworm (Moniezia expansa) and its effect on sheep production: the evidence reviewed.

Literature relating to the effects of the tapeworm Moniezia expansa on sheep is reviewed. While there are many claims of adverse effects by this organism, none of these withstand critical scrutiny. The balance of evidence indicates that M. expansa infections are generally harmless, even when the tapeworms are present in large numbers in young lambs, and that there is no justification for treating sheep for M. expansa on the basis of any likely benefit to the health or production of the animals. No published experimental results can be found to support claims that heavy M. expansa infections sometimes exacerbate losses from other causes. Anthelmintics for investigative use, and some aspects of the classification, life history and biology of M. expansa and of its intermediate host are also discussed.