Hunting dogs should be treated for Echinococcus tapeworm infection in Eastern Finland
Echinococcus granulosus might infect humans
Echinococcus granulosus is a cestode (tapeworm) of canids (wolves, dogs), whose larval cysts reside in cervids (elk, reindeer, the Finnish forest reindeer). The parasite is a zoonotic disease, which means that it also may affect humans. The consequence may be a serious disease which is difficult to treat.
Echinococcus granulosus is found in the wild in Finland, at least in the areas of Eastern Lapland, Kuusamo, Kainuu and North Karelia. Wolf is the definitive host of the parasite and wild cervid or reindeer are intermediate hosts. The wolf is infected by the parasite when ingesting a larval cyst from the organs of the intermediate host. Small cestodes develop from the larvae in the intestine of the wolf. They produce eggs which spread into the environment in the faeces. The intermediate host animal is infected by the parasite when swallowing eggs along with food plants or water. Humans are infected in a fashion similar to that of natural intermediate hosts.
Human infections are best prevented by protecting dogs from being infected
In practice, the largest risk for infecting humans is caused by a dog infected by Echinococcus granulosus. The dog is infected when ingesting the larval cysts in the lungs of the elk. Rarely, there can also be cysts in other organs of the elk, such as the liver. The cestode itself does not generally harm the dog, but the eggs in the faeces that end up in the environment or in the coat of the dog may infect humans. Humans are infected via mouth, usually transmitted by hands. Liquid-filled cysts are formed in the internal organs of infected humans, usually in the lungs. The cyst may grow for years, and in the end the volume might be several litres.
In order to prevent human infection, it is important to prevent dogs from being infected. This is done in two ways: dogs are not fed raw lungs or liver of cervids and the dogs should be treated with anthelmintic medication effective against tapeworms before and after the hunting season. If internal organs are to be given to dogs, they should be cooked well. Anti-tapeworm medication for dogs can be bought at pharmacies without a prescription.
The parasitic cysts can be difficult to detect in the elk’s lungs, as they can be small and deep inside the lung. By exploring the lungs carefully with the hands you often can feel a roundish cyst filled with liquid. Handling the lungs does not constitute a risk for parasitic infection in humans, but protective gloves should still be used for the sake of general hygiene. Such suspect lungs should be sent as whole for examination to Evira’s Fish and Wildlife Health Research Unit in Oulu.
Instructions for owners of hunting dogs:
1. Do not give the dogs raw internal organs of cervids (especially lungs and liver).
2. Give the dog anthelmintic medication effective against hydatid tapeworms before and after the elk hunting season.
For more information, please contact:
Researcher Marja Isomursu, tel. 02077 24910, 040 512 1248
Head of Unit Varpu Hirvelä-Koski, tel. 020 77 24902, 040 512 1531