Beavers can introduce the parasite Giardia into the water, with diarrhea and vomiting a result, an intestinal ailment known as 'Beaver fever' (Giardiasis) in the USA. Now the City of Oslo's Department of Water and Sanitation is concerned that the revival of the beaver population in the woods around the capital can mean trouble. "We have increased the frequency of taking test samples and we are keeping an eye on where the beaver are. In North America the parasite the beaver carries makes the water undrinkable. We are not worried but are taking a safety first approach," said Terje Wold...