Hydatid Disease

Hydatids are the immature form of a tapeworm called Echinococcus granulosus. Echinococcus granulosus is a very small (3-5 m) tapeworm that requires two different animal species, a canid and an ungulate, to complete its lifecycle.
Signs Of Disease
The adult tapeworm occurs in the intestines of wolves, coyotes and foxes but they are generally asymptomatic. The larval form or hydatid cyst occurs in moose, elk and deer, and can occur in humans. In moose, deer, and elk, the cysts have thick walls and are filled with a clear watery liquid. The cysts are usually found in the lungs but can also occur in the liver or other organs. Cysts can vary in size from ¾ to 4 inches in diameter and contain hundreds of juvenile tapeworms. The presence of hydatids in herbivores usually does not cause clinical signs unless the cyst obstructs normal body function. If cysts rupture, illness can be severe.
Where is Disease Found?
Hydatid disease is found around the world including North America where it exists in two forms – a domestic form involving domestic dogs and domestic sheep and a sylvatic form involving wolves or coyotes and ungulates. The most common form of E. granulosus is found in domestic dogs and sheep, and is found worldwide, including the western USA. The form in domestic dogs and domestic sheep is the most common source of the disease in humans. There are numerous strains of E .granulosus worldwide that occur in various host species systems e. g. wolves and wild ungulates in temperate North America, dingos and kangaroos in Australia, and jackels and domestic cattle in Africa. Hydatid cysts have been found in cattle and domestic sheep, deer, elk,. moose and mountain goats in Idaho. Adult tapeworms have been found in wolves and coyotes in Idaho.
How Can I Protect Myself?
Humans can be infected from inadvertently consuming tapeworm eggs found in the droppings of wolves, coyotes, foxes, and dogs. Wear gloves and do not eat, drink or smoke when handling scat from wolves, coyotes or foxes. Contact with or consumption of the hydatid cysts in the lungs or liver of moose, deer, and elk, deer or elk does not result in human infections, but can be a source of infection to domestic dogs. Do not allow domestic dogs or cats to feed on dead wild ruminants or feed them trimmings or offal from wild ruminants. If pets are infected, they can harbor adult tapeworms, which could shed the eggs in the home environment and be a source of infection to humans. Keep dog kennels clean and dispose of dog feces properly to minimize human exposure to parasite eggs. Practice good hygiene- washing hands and washing contaminated clothes, especially after handling animals or feces.
Samples to Collect
The adult tapeworms from the small intestine of infected wolves and coyotes can be collected for identification. Samples of intestinal contents should be refrigerated or preserved in 10% alcohol. The eggs of most tapeworms are indistinguishable on fecal flotation. The hydatids in lungs or liver of ungulates can be identified grossly and histologically. Hydatids can be collected whole and refrigerated or placed in 10% formalin but not frozen. Samples can be delivered a conservation officer or an Idaho Department of Fish and Game Regional Office.
Can I Eat The Meat?
Meat from infected animals is suitable for human consumption. Trim and discard the affected tissues. Tissues or organs containing cysts should be disposed of in a manner to avoid consumption by domestic or wild canids. Do not feed carcass parts containing hydatid cysts, to pet dogs or cats.
What is IDFG doing to help manage this disease?:

Since 1998, IDFG has conducted disease surveillance in wildlife including ungulates and wolves. No evidence of this tapeworm, eggs, or larva was discovered until 2006

In 2006, hydatid cysts were found in the lungs of a mountain goat from Atlanta, ID. The adult tapeworm was also first found in the intestines of wolves in 2006

From 2006 to the present, hydatid cysts have been found in the lungs of numerous deer and elk from central Idaho; and a little over half (62%) of wolves tested were infected with the tapeworm

Currently IDFG is doing the following:

  • Continuing its surveillance and investigations of this parasite
  • Providing public education about this parasite