Appalachian Trail Histories


Beaver Fever

Hiker's Account: Woody 2007

"By the time I arrived in Vernon, I was feeling pretty low. As my symptoms developed, I recognized the signs of Giardia (Beaver Fever, the Big G) which is not one of life's great pleasures, let me tell you, but not very serious unless it leads to dehydration, malnourishment, etc. I spent alot of time at the hostel, wrapped up in my sleeping bag (or alternately in the bathroom). I learned very quickly not to eat heavy, fatty foods, but have been drinking alot of sugary liquids and eating yogurt when I feel up to it."

Woody had ingested giardia at some point along the trail.  He could have either drunk contaminated water or had come in contact with a contaminated person or surface. 


Giardia was first discovered by Dutch tradesman Antony von Leeuwenhoek in 1681.  Von Leeuwenhoek was known as the “Father of Microbiology”.  He used a microscope to inspect his own stool and discovered particles moving around.   Separately, both Vilem Dusan Lambl in 1859 and Alfred Giard in 1895 clinically described giardia in stool samples.  In 1915 the parasite was named after Lambl and Giard in honor of their research. 

Hikers are exposed to nature and all of its glory, even the nasty parasites that are waiting for a host to come along and ingest them.  It is important to be weary of water sources along the trail.  Animals or humans could have defecated in the upstream water causing their feces to flow downstream. 

What is giardia?

Giardia, or giardiasis, is a parasite that lives in the host’s intestines and is passed out of the body via feces.  It causes diarrhea which can lead to dehydration.  It can also be spread by poor hygiene practice.  It can live outside the body for weeks. 

How do you get it?

Giardia can be contracted by ingesting contaminated water, eating uncooked food, touching dirty surfaces and then mouth, and contact from an infected person.  Water sources can become contaminated when a person or animal affected defecates in or around the water.  Water carries the waste down-stream where it can be ingested by another unsuspecting person or animal.  A hiker could neglect to do a thorough cleaning or neglect to scrub their hands with soap and water.


Diarrhea, gas, greasy stool, stomach pains, nausea, dehydration.  These symptoms start 1-3 weeks after infection and can last from 2-6 weeks.



Erlandsen, Stan Dr. Public Health Image Library. Centers for Disease Control and Prevention. 1999.  Accessed November 23, 2016.

History. Accessed December 3, 2016.

Nazer, Hisham. Giardiasis. Medscape. February 15, 2016. Accessed December 3, 2016.

Parasites – Giardia. Centers for Disease Control and Prevention. July 21, 2015. Accessed November 23, 2016.