Officially eradicated in New Zealand in 2002.

Echinococcus granulosus: Hydatid tapeworm

General Description: This is a small tapeworm, 2.1 to 5.0mm long, with only three proglottids, which are long and narrow.

Life Cycle: The principal hosts of Echinococcus granulosus are dogs, wolves and foxes. Intermediate hosts include deer, cattle, sheep, swine and rodents. Ingestion of eggs containing hexacanth embryos results in the growth of a larger metacestode known as a hydatid cyst. Common sites for the hydatid cyst in the intermediate hosts are the liver and lungs. Each hydatid cyst contains many immature scolices. Ingestion of infected tissue by dogs results in the development of mature tapeworms. The prepatent period is 6 to 7 weeks.

Location: Small intestine.

Significance: Hydatid cyst may produce disease in man. More commonly, sheep are affected, causing great economic losses from carcass condemnation.

Effect on Host: Mild infections do not produce disease in dogs. Dogs experience intestinal inflammation in heavy infections, causing diarrhoea, weight loss and a rough coat.

Diagnostic Information: Taenia -type eggs may appear in faeces.

Control: Dogs should be prevented from eating viscera of sheep, and also of deer, moose and similar cervids. Infected dogs should be treated with anthelmintics.

E. granulosus – whole mount
E. granulosus – scolex		E. granulosus – egg
Scolex in intestine of cat		Cyst on brain