What does the term 'beaver fever' refer to?

'Beaver fever' specifically refers to a waterborne illness caused by the protozoan parasite Giardia lamblia. This term is derived from the fact that the Giardia cysts can be found in water contaminated by the feces of infected animals, including beavers. The infection, known as giardiasis, often occurs when people consume untreated water or are exposed to water bodies where these parasites are prevalent. Symptoms of giardiasis can include diarrhea, abdominal cramps, nausea, and fatigue. Understanding the association between this illness and its transmission via water sources is crucial in environmental health, particularly in managing water safety and preventing outbreaks.

The other choices represent different health conditions that are not connected to the specific definition of 'beaver fever', emphasizing the importance of recognizing the accurate relationship between the term and its causes.