The gut protozoans Giardia duodenalis and various species of Cryptosporidium are extremely contagious single-celled parasites liable to cause digestive disease in both humans and animals. Some species and genotypes of Cryptosporidium and Giardia are important zooneses, as they occur in both animals and humans. Zooneses are diseases that may be transmitted between animals and people.
Inger Sofie Hamnes showed in her doctorate that parasites of the groups Cryptosporidium and Giardia are extremely widespread in domestic animals, wild deer species and the red fox in Norway. Genotyping of Giardia isolated from elk, wild reindeer and red foxes showed that Giardia duodenalis in these animals may potentially infect humans.
Hamnes studied the occurrence of Cryptosporidium and Giardia in calves, dogs, wild deer species (elk, wild reindeer, red deer, roe deer and Svalbard reindeer), piglets and red fox in Norway, by analysis of scats.
Her studies showed that Cryptosporidium is common among young dogs, calves and piglets and that the parasites also occur to a lesser extent in roe deer, elk, red deer and the red fox. Cryptosporidium was not found in wild reindeer or Svalbard reindeer.
Giardia was more common than Cryptosporidium in calves, and the occurrence of both parasites varied with the calves' age, geographic occurrence, season, and the cleaning frequency of pens. Among wild deer species, Giardia was more common than Cryptosporidium, while roe deer and elk had the highest occurrences of both parasites.
The presence of Cryptosporidium and Giardia in dogs varied with age and geographic location. There was a higher occurrence of diarrhoea in piglets from litters that were infected by Cryptosporidium than in litters free of infection. The occurrence of both parasites was low in the red fox, however, the geographic distribution was extensive.
The results of these studies show that parasites of the groups Cryptosporidium and Giardia are widely distributed among both domestic and wild animals in Norway. Grazing animals may represent a source of transmission to man through drinking water, although people can also become infected through direct contact with infected animals.
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