Humans can be infected with <i> Echinococcus</i> parasites through direct contact with dogs used for hunting
Humans may become infected by hand-to-mouth transfer of the parasite’s eggs after contact with the fur of an infected dog, for example. In humans, eggs can develop into larval cysts (i.e. hydatid cysts) in the lungs, which grow slowly over the years and may become very large and difficult to treat before more severe symptoms appear.
The best way to prevent canine and human infections is to carefully destroy any moose lungs included in slaughtering offal at hunting sites so as to prevent dogs and predators from eating them. The hydatid cysts in the moose lungs may be small, deep within the organ and difficult to see.
“A hydatid cyst in the lungs of a moose is a cyst filled with clear fluid, limited by a light membrane. If you cut it accidentally, the fluid often spurts out,” says Marja Isomursu, researcher at the Finnish Food Safety Authority Evira’s Production Animal and Wildlife Health Research Unit.
Dogs used for hunting should also be dewormed both before and after the moose hunting season so as to prevent the dog from infecting wild animals in the forest and other animals and people at home. A medication that is effective against tapeworms must be selected.
Moose lungs do not pose a risk to people, as the hydatid cysts only infect canines.
Wolves and dogs are the definitive hosts of
Echinococcus canadensis is a small tapeworm, which lives in the intestine of a wolf as an adult worm and in the lungs of a moose during its larval stages.
Wolves and dogs become infected when they ingest the lungs, or sometimes the liver, of moose that contain hydatid cysts. In the intestines of the canine, the cysts develop into adult tapeworms. The worms produce eggs that are passed in the faeces into the environment.
The moose is an intermediate host, which is infected through the ingestion of parasite eggs in contaminated food plants. In addition to moose, reindeer and wild forest reindeer can become infected and be intermediate hosts.
Distribution concentrated in Eastern Finland
Although wolves and moose tend to move around, the parasite’s area of distribution has remained unchanged since the turn of the century. Its core distribution area is Kainuu. In addition, it is found in Eastern Lapland, mainly in Salla, as well as in Kuusamo and North Karelia. In these areas in particular, attention should be paid to the proper destruction of offal when slaughtering moose. Feeding moose lungs to dogs should also be avoided in other parts of the country.
Evira is monitoring the occurrence of the parasite
Evira is monitoring the occurrence of Echinococcus canadensis in Finland. All wolves received as samples will be examined for the parasite. Moose lungs with suspicious changes can be sent to Evira’s Oulu office. Evira will pay the transportation costs charged by Matkahuolto.
Instructions for sending a wildlife sample (in Finnish)
Elk lungs have also been examined over the years in more extensive surveys in cooperation with hunters.
For further information, please contact:
Marja Isomursu, Researcher, Production Animal and Wildlife Health Research Unit, tel. +358 40 512 1248