Hydatid disease and deworming

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11.10.2023Evelyn Ýr

Icelandic people suffered from hydatid disease for many centuries and it was one of the most serious diseases of the country for a long time.

It is well known that Iceland has long been considered the worst hydatid disease area in the North Atlantic and further afield - writes Guðmundur Magnússon in Overview of the History of Hydatid Disease in Iceland (Yfirlit yfir sögu sullaveikinar á Íslandi, Reykjavík 1913).

It is believed that hydatid disease was initially brought to the country by sick dogs imported from the western countries, especially from Germany. The oldest historical sources indicate that by 1200, the hydatid disease was known in both humans and animals.

The cause of the disease is the larvae of several subspecies of Echinococcus tapeworms that use intermediate hosts (f.e. sheep) that contain eggs of the tapeworms and are then infected with tapeworm larvae when the final host (dog) eats the intermediate host's organs that is infected with tapeworm cysts full of larvae. See more here.

The Danish doctor Harald Krabbe came to Iceland in 1863 and stayed here for research on tapeworms in dogs along with Jóns Finsen, district doctor in Akureyri. They found that 28% of the Icelandic dogs were infected. At this time there were about 70,000 Icelanders and the estimated dog population at the same time was 15-20,000, or one dog per 3-4 inhabitants. Krabbe concluded that the spread and prevalence of hydatid disease in Iceland was mainly due to the fact that here, compared to the headcount, there were many more dogs than elsewhere (Guðmundur Magnússon, 1913).

The hydatid disease could kill people and animals and it was estimated that every fifth Icelander was infected with the disease. Krabbe thought that the best way was to reduce the number of dogs and educate the Icelandic people about the nature of hydatid disease and ways of preventing the disease. These conclusions were followed by the Dog Ownership Regulation of 1869 (Tilskipun um hundahald 1869) to reduce the number of dogs and the Dog Tax Law of 1890, but it was not enough to improve the situation. It was common practice on the farms that dogs were allowed to lick people's bowls, eat slaughter waste, hang around yards and barns, sleep in sheep folds at night, and drink from people's water containers.

From the turn of the century, dog deworming came into play. Dogs were collected together for deworming on certain days and were given worm medication. Dog deworming was done in a house or barn, where the floor and walls were made of stone or other dense material, which was easy to clean. The dogs had to be fasted 24 hours before the injection. It was necessary to make sure that the dogs did not throw up after the injection, otherwise it had to be repeated. After they had finished cleaning themselves with enormous diarrhea while they were tied up in the barn for up to six hours, they had to be bathed in a special cleaning agent before they were allowed to go home. This method was used for a long time in some municipalities, see article in Animal Guardian (Dýraverndaranum) from 1 February 1978 .

But as harsh as the dog deworming practice was, it led to hydatid disease being eradicated in Iceland in the 20th century and so the disease is no longer found in Iceland. Today, treating dogs with worm medicine is necessary due to the tapeworm, but fortunately, the methods are different from before. 

The picture above shows the deworming practice in Iceland in the old days. See the full picture here.



Lýtingsstaðir, 561 Varmahlíð.
Phone: +354 893 3817
[email protected]



Lýtingsstaðir, 561 Varmahlíð.
Phone: +354 893 3817
[email protected]