Echinococcus multilocularis

Echinococcus multilocularis, the fox tapeworm, is a small cyclophyllid tapeworm found widely across the northern hemisphere. The adult is only about three to six millimetres long and lives attached to the intestinal wall of canids by a head bearing suckers and hooks. Foxes, coyotes and dogs, and less often cats, carry the adult worm, while voles act as intermediate hosts and develop the larval cysts after swallowing eggs shed in canid droppings. Humans can become accidental intermediate hosts by swallowing eggs, and the larval stage then grows through the liver like a tumour, causing alveolar echinococcosis after an incubation of many years. The species is the main reason that fox populations moving into towns are watched as a public health concern.